Moving Average Method Pmp

O guia final do método do caminho crítico Em qualquer projeto, você pode ter centenas de tarefas e dezenas de dependências. Pode-se sentir quase impossível identificar as tarefas mais importantes, as que, se perdidas, afetarão todo o seu projeto. Em outras palavras, os que você realmente precisa se preocupar para garantir que você atenda seus prazos. O método do caminho crítico, uma técnica de gerenciamento de projetos criada na década de 1950, permite que você identifique essas tarefas importantes e continue no seu projeto. Começando como diagramas desenhados à mão e evoluindo para o software automatizado, o método do caminho crítico tornou-se parte essencial do planejamento de um projeto. Qual é o Método do Caminho Crítico (CPM) O Conjunto de Conhecimento de Gerenciamento de Projetos (PMBOK), uma coleção de processos e áreas de conhecimento internacionalmente reconhecida como prática recomendada para a profissão de gerenciamento de projetos, define o caminho crítico como a sequência de atividades agendadas que determina A duração do projeto. rdquo É a seqüência mais longa de tarefas em um plano de projeto que deve ser concluído a tempo para que o projeto atinja seu prazo. Se houver um atraso em qualquer tarefa no caminho crítico, seu projeto inteiro será atrasado. Embora muitos projetos tenham apenas um caminho crítico, alguns projetos podem ter múltiplos caminhos críticos. O método do caminho crítico é uma técnica de gerenciamento de projetos passo a passo para identificar atividades no caminho crítico. É uma abordagem para o planejamento do projeto que quebra o projeto em várias tarefas de trabalho, exibe-os em um fluxograma e, em seguida, calcula a duração do projeto com base nas durações estimadas para cada tarefa. Identifica tarefas que são críticas, no tempo, na conclusão do projeto. Dr. Larry Bennett. Um engenheiro civil, gerente de projeto e autor de quatro livros, incluindo um guia sobre o caminho crítico escrito em 1978 e intitulado, ldquoCritical Path Precedence Networks, rdquo explica que o método do caminho crítico ajuda a gerenciar projetos de duas maneiras diferentes: ldquoIt produz um cronograma planejado Para orientar a equipe do projeto e constitui a base para o rastreamento do desempenho do cronograma do projeto comparando o progresso real da tarefa planejada. rdquo O Método do Caminho Crítico De acordo com dois especialistas Pedimos dois usuários do caminho crítico para a melhor maneira de explicá-lo. Aqui, o que eles tinham a dizer: o caminho crítico é apenas uma maneira fantastica de dizer 39 Quanto há cada tarefa antes de terminar o projeto. Use esta informação para descobrir a data final do projeto.39 Se uma tarefa demorar mais do que o previsto, A data de término é recuada. Existem algumas tarefas que não afetam imediatamente a data final do projeto que pode ser repassada por algum tempo. Há todo um monte de cálculos que se destinam a descobrir o que é, a previsão e o agendamento, mas aquilo de onde o software de gerenciamento de projetos vem e facilita a vida de todos. Algumas das atividades devem acontecer em paralelo. Por exemplo, se você tentou fazer um pequeno-almoço frito fazendo uma tarefa por vez, e uma após a outra, as coisas correrão mal. As placas precisam estar aquecendo enquanto outras atividades estão acontecendo. O brinde precisa ser torrado enquanto as salsichas estão fritando e, ao mesmo tempo, o bacon e as salsichas estão debaixo da grelha. Os ovos precisam ser fritos por último. Uma análise do caminho crítico é uma representação diagramática do que precisa ser feito e quando. Timecales e custos podem ser aplicados a cada atividade e recurso. Terence Jackson. Ph. D e CEOManaging Partner no WEpiphany LLC Background amp História do Caminho Crítico Dr. Bennett não é estranho ao caminho crítico. Ele aplicou o planejamento do caminho crítico a uma ampla variedade de projetos desde 1965. Ele também passou 29 anos na faculdade de engenharia da Universidade do Alasca Fairbanks, ensinando cursos de graduação e pós-graduação em gerenciamento técnico, incluindo gerenciamento de projetos e agendamento. Além dos seus livros. Ele escreveu mais de 50 artigos e artigos profissionais sobre temas que vão desde gerenciamento de construção até técnicas de rede para programação de projetos. Dr. Bennett ressalta que o caminho crítico percorreu um longo caminho. Na verdade, o método do caminho crítico original foi feito à mão. Como o Dr. Bennett descreve: ldquo O método do caminho crítico original usou setas para representar tarefas e ligou-as juntas conectando seu começo e terminando em nós, de modo que o seqüenciamento apropriado foi desenvolvido. Essa abordagem persistiu por uma década, quando um método diferente, com os mesmos resultados, tornou-se popular. O professor John W. Fondahl, professor de gerenciamento de construção da Universidade de Stanford, propôs em um artigo de 1961 que cada tarefa fosse representada por um nódulo ndash quadrado, círculo ou oval ndash e os nós fossem amarrados com linhas ou setas que representam a seqüência entre Tarefas. Esta abordagem, referida como o método de atividade-no-nó (AON) ou precedência, pegou rapidamente e suplantou o método anterior de atividade em flecha (AOA) em quase todos os usos. rdquo Como o Método do Caminho Crítico foi Criado Usando O método do caminho crítico para agendar projetos começou no final da década de 1950, com dois projetos simultâneos e não relacionados. O programa de mísseis balísticos de frota navistsquos dos EUA (Polaris) estava atrasado e precisava de ajuda para resolver o problema. A solução sugerida foi dividir o projeto em várias mil tarefas, representar cada tarefa por uma seta, conectar as setas na seqüência apropriada, estimar a duração de cada tarefa e calcular a duração do projeto e o grau de criticidade do cronograma de cada tarefa. Na mesma época, a EI DuPont de Nemours Company, uma empresa química americana, sofreu atrasos nas mudanças de planta, um projeto de reorganização de instalações de produção para diferentes produtos. Eles também precisavam de ajuda e a resposta proposta era semelhante à do Programa Polaris. Os desenvolvedores da abordagem Polaris Programrsquos chamaram sua solução da Técnica de Avaliação e Revisão do Projeto (PERT), enquanto o método DuPont foi chamado Método de Caminho Crítico (CPM). Embora esses métodos sejam semelhantes, eles usaram técnicas diferentes para estimar a duração da tarefa. O método PERT usou três estimativas de tempo diferentes para cada duração da tarefa e calculou a probabilidade de conclusão do projeto em qualquer momento. A abordagem DuPont usou uma duração de tempo para cada tarefa, preocupada não só com o tempo de conclusão do projeto, mas também com a análise dos custos adicionais que se obteriam se a duração do projeto fosse diminuída. O Dr. Bennett diz que hoje, os termos PERT e CPM são usados ​​de forma intercambiável, ambos significando que qualquer método de programação de rede e PERT perderam a inclusão de três estimativas e probabilidades. As Vantagens Diárias do Caminho Crítico Embora se tenha originado no final da década de 1950, O caminho crítico ainda é incrivelmente importante para os gerentes de projeto hoje. Fornece uma representação visual das atividades do projeto, apresenta claramente o tempo necessário para completar as tarefas e rastreia as atividades para que você não esteja atrasado. O método do caminho crítico também reduz a incerteza porque você deve calcular o menor e mais longo tempo de conclusão de cada atividade. Isso obriga você a considerar fatores inesperados que podem afetar suas tarefas e reduz a probabilidade de uma surpresa inesperada ocorrer durante seu projeto. De acordo com o Dr. Bennett, o método do caminho crítico também tem três principais benefícios para os gerentes de projeto: Identifica as tarefas mais importantes: primeiro, ele identifica claramente as tarefas que você terá para gerenciar de perto. Se qualquer uma das tarefas no caminho crítico demorar mais tempo do que suas durações estimadas, comece mais tarde do que o planejado ou termine mais tarde do que o planejado, então todo o projeto será afetado. Ajuda a reduzir as linhas de tempo: em segundo lugar, o ldquoif, após a análise inicial, prevê um tempo de conclusão, há interesse em completar o projeto em um período de tempo mais curto, é claro qual tarefa ou tarefas são candidatos para redução de duração, disse o Dr. Bennett. Quando os resultados de um método de caminho crítico são exibidos como um gráfico de barras, como um gráfico de Gantt, é fácil ver onde as tarefas caem no prazo geral. Você pode visualizar as atividades do caminho crítico (geralmente são destacadas), bem como as durações das tarefas e suas seqüências. Isso fornece um novo nível de visão de sua linha de tempo do projectrsquos, dando-lhe mais compreensão sobre as durações das tarefas que você pode modificar e quais devem permanecer iguais. Compara Planejado com Real: E, finalmente, o Dr. Bennett diz que o método do caminho crítico também pode ser usado para comparar o progresso planejado com o progresso real. Enquanto o projeto prossegue, o cronograma de linha de base desenvolvido a partir da análise do caminho crítico inicial pode ser usado para rastrear o progresso da programação. Ao longo de um projeto, um gerente pode identificar tarefas que já foram concluídas, as durações restantes previstas para tarefas em andamento e quaisquer mudanças planejadas para futuras seqüências e durações de tarefas. O resultado será um cronograma atualizado, que, quando exibido em relação à linha de base original, proporcionará um meio visual de comparar o progresso planejado com o progresso real. Os especialistas compartilham a vantagem do caminho crítico de 1 vantagem. Para mim, a maior vantagem do método do caminho crítico é Que facilita a avaliação de riscos. Se Irsquove tenha dependências planejadas e os planos mudam, itrsquos é muito fácil de dizer, 39Porque você perdeu esse prazo, a próxima entrega será atrasada por X dias, e isso nos ultrapassa o nosso plano por dias de Y.39 Simples. Dito isto, eu não acho que você tenha que adotar completamente um método como caminho crítico para fazer isso em projetos. Itrsquos melhor adotar as partes de qualquer método que trabalhe para o seu projeto e seu teammdashbeing adaptável como PM o ajudará a encontrar o verdadeiro sucesso. Brett Harned, consultor de gerenciamento de projetos digitais. Escritor, palestrante e construtor comunitário. Quatro questões que continuam a praticar projetos são as prioridades concorrentes dos membros da equipe funcional e distrações de 39 noise39 no projeto. Com tanta atividade, o caminho crítico permite uma visão clara e pontuada do que deve acontecer a seguir e do que está no relógio39 para atender aos compromissos do projeto. Robert Kelly, co-fundador do PMChat e sócio-gerente da Kelly Solutions. Uma empresa de gerenciamento de projetos. Especialmente, como os 39 benefícios não planejados39, a análise do caminho crítico (CP) traz, incluindo descobertas de dependências ocultas e conflitos de recursos. A análise de CP também geralmente leva a uma melhor priorização e redistribuição de membros da equipe. E o CP pode expor as oportunidades de necessidade de inserção de atrasos leva a melhorar ainda mais o cronograma. O método do caminho crítico traz um nível importante de clareza para seu projeto. É uma representação visual da fragilidade do equilíbrio de suas restrições: se uma das atividades no caminho for adiada, seu projeto fica atrasado. Também é uma ótima maneira de determinar onde investir recursos se o projeto estiver atrasado. Critérios principais no método do caminho crítico Existem seis etapas no método do caminho crítico: Etapa 1: Especificar cada atividade Usando a estrutura de quebra do trabalho, Você precisa identificar cada atividade (ou tarefa) envolvida no projeto. Esta lista de especificações de atividades deve incluir apenas atividades de nível superior. Quando as atividades detalhadas são usadas, a análise do caminho crítico pode se tornar muito complexa para gerenciar e manter. Uma estrutura de quebra de trabalho quebra projetos em seções gerenciáveis. O primeiro passo é identificar os principais produtos de um projeto. Então você pode começar a dividir as atividades de alto nível em pequenos pedaços de trabalho. Você pode escolher como exibir sua estrutura de repartição do trabalho. Algumas pessoas usam uma estrutura de árvore, enquanto outras usam listas ou tabelas. Um esboço é uma das formas mais fáceis de representar uma estrutura de repartição do trabalho. Passo 2: Estabeleça Dependências (Sequência de Atividades) Algumas atividades dependerão da conclusão de outras. Listar os predecessores imediatos de cada atividade irá ajudá-lo a identificar a ordem correta. Para identificar corretamente as atividades e sua precedência, faça-se estas três perguntas para cada atividade em sua lista da primeira etapa: Qual tarefa deve ocorrer antes que esta tarefa aconteça. Quais tarefas devem ser concluídas ao mesmo tempo que esta tarefa Quais tarefas devem acontecer logo após Esta tarefa Etapa 3: Desenhe o Diagrama de Rede Depois de identificar as atividades e suas dependências, você pode desenhar o gráfico de análise de caminho crítico (CPA), conhecido como diagrama de rede. O diagrama de rede é uma representação visual da ordem das suas atividades com base em dependências. Este diagrama de caminho crítico costumava ser desenhado manualmente, mas agora existem programas de software que podem criar este diagrama para você. Etapa 4: Estimativa do tempo de conclusão da atividade Usando a experiência passada ou o conhecimento de um membro da equipe experiente, agora você deve estimar o tempo necessário para completar cada atividade. Se você estiver gerenciando um projeto menor, provavelmente estimará o tempo em dias. Se você estiver trabalhando com um projeto complexo, talvez você precise medir o tempo em semanas. Se você não se sentir confortável usando suas estimativas de melhor adivinhação, você pode usar o método de estimativa de 3 pontos, que é projetado para colocar mais peso no prazo mais realista. Na estimativa de três pontos, você deve elaborar três estimativas para cada tarefa, com base na experiência anterior ou nas melhores hipóteses. O método de estimativa é apresentado em fórmulas para calcular a duração do tempo de forma mais precisa. A estimativa do melhor caso é a estimativa mais provável b a estimativa do pior caso. Esses três valores identificam o que acontece em um estado ótimo, o que é mais provável e o que ocorre no pior caso. Uma vez que você tenha identificado esses valores, você pode usá-los em duas fórmulas diferentes. O primeiro é usado para encontrar a Média ponderada, que coloca mais peso no valor ldquoMost Likelyrdquo. A fórmula é como abaixo. E significa Estimate, e os 4 e 6 representam o método padrão para colocar mais peso no valor mais realista. A segunda maneira de usar esses valores é conhecida como Distribuição triangular. A principal diferença é que este método não tem mais peso no valor ldquoMost Likelyrdquo. A fórmula é como abaixo. E significa Estimate, e o 3 representa o método padrão. Passo 5: Identificar o Caminho Crítico Existem duas maneiras de identificar o caminho crítico. Você pode observar seu diagrama de rede e simplesmente identificar o caminho mais longo em toda a rede - a seqüência mais longa de atividades no caminho. Certifique-se de procurar o caminho mais longo em termos de duração mais longa em dias, não o caminho com a maioria das caixas ou nós. Você também pode identificar atividades críticas com a técnica Forward PassBackward Pass, identificando as primeiras horas de início e término e as últimas horas de início e término para cada atividade. Se você tiver vários caminhos críticos, você entrará em sensibilidade de rede. Um cronograma do projeto é considerado sensível se o caminho crítico for susceptível de mudar uma vez que o projeto começa. Os caminhos mais críticos em um projeto, quanto maior a probabilidade de mudança no cronograma. Etapa 6: atualize o Diagrama do caminho crítico para mostrar o progresso À medida que o projeto progride, você aprenderá os tempos reais de conclusão da atividade. O diagrama de rede pode ser atualizado para incluir essas informações (em vez de continuar a usar estimativas). Ao atualizar o diagrama de rede à medida que emergem novas informações, você pode recalcular um caminho crítico diferente. Você também terá uma visão mais realista da data de conclusão da conclusão do projeto e poderá saber se você está no caminho certo ou está atrasado. Outros cenários no método do caminho crítico Um dos maiores benefícios do método do caminho crítico é identificar as tarefas cruciais que, se perdidas, afetarão sua data de conclusão do projeto. Também proporcionará visibilidade no status do seu projeto, permitindo que você veja se você está no caminho certo. Reduzir o seu horário Como o seu caminho através do método do caminho crítico, você pode achar que deseja encurtar intencionalmente a duração do seu projeto ou que você precisa compactar o cronograma do projeto para cumprir o prazo. Há duas maneiras de fazer isso: rastreamento rápido ou falha. No rastreamento rápido, você olha o caminho crítico e decide quais atividades podem ser feitas paralelamente entre si, para mover o projeto mais rápido. Você só precisa rever as atividades no caminho crítico, porque todas as outras atividades flutuam (se você encurtar a duração dessas atividades, a sua parte apenas lhe dá mais flutuação). Embora o rastreamento rápido reduza o prazo do seu projeto, ele também envolve risco porque você está realizando atividades paralelas originalmente planejadas para serem executadas em seqüência. Duração do acidente ou falha, refere-se ao menor tempo possível para o qual uma atividade pode ser agendada. Isso acontece adicionando mais recursos para completar essa determinada atividade. No entanto, bloquear o caminho crítico resulta em menor qualidade de trabalho porque o objetivo na duração da falha é a velocidade. Gerenciando Restrições de Recursos À medida que você gerencia seu projeto, você também pode encontrar problemas de restrição de recursos que possam mudar o caminho crítico. Se você tentar agendar certas atividades ao mesmo tempo, você pode achar que você precisa de mais pessoas do que estão disponíveis. Como resultado, essas atividades precisarão ser reprogramadas. O nivelamento de recursos é o processo de resolução desses conflitos. Nivelamento e Expansão de Recursos Com o nivelamento de recursos, você pode resolver conflitos ao alocar recursos. Um cronograma habilitado para recursos pode incluir atrasos devido a estrangulamentos de recursos (um recurso não está disponível no tempo necessário). O nivelamento de recursos também pode resultar em um caminho anteriormente menor tornando-se o caminho mais longo ou mais ldquoresource criticalrdquo. Isso acontece quando as tarefas no caminho crítico são afetadas por restrições de recursos. Um conceito semelhante é chamado de cadeia crítica, que protege as durações de atividades e projetos de atrasos inesperados devido a restrições de recursos. Avaliando o projeto final Esses cenários demonstram todas as mudanças inesperadas que podem ocorrer ao gerenciar um projeto e como eles podem afetar o caminho crítico. Embora as coisas estejam sempre sujeitas a mudanças, a boa notícia é que você pode medir a variação do seu cronograma original do projeto e acompanhar a forma como impactou seu projeto final. Flexibilidade e avaliação de atrasos Um cronograma criado a partir do método do caminho crítico naturalmente envolve muita flutuação porque você precisa usar estimativas de melhor estima para calcular o tempo. Se um erro for feito no tempo de conclusão da atividade, seu cronograma do caminho crítico inteiro poderá mudar. Ou, talvez seja necessário atrasar intencionalmente as atividades do projeto devido a restrições de recursos. Determinar esses atrasos e determinar o que os causou pode ajudá-lo a evitar problemas semelhantes no futuro. Uma parte importante do seu plano pós-projeto é o Caminho Crítico Construído, que analisa as causas e impactos específicos das mudanças entre o cronograma planejado e o cronograma real implementado. O Caminho Crítico As-Construído é um cronograma que mostra as datas em que as atividades realmente ocorreram e aloca tempo, determinando a responsabilidade pelos atrasos no caminho crítico. Como usar o PERT no método do Caminho Crítico Se você lembrar o histórico do método do caminho crítico descrito anteriormente neste artigo, yourquoll lembre-se de que o PERT (Avaliação do Programa e Técnica de Revisão), desenvolvido pela Marinha no final da década de 1950 para ajudar a produzir mísseis Mais rápido, é uma variação no método do caminho crítico que leva uma visão mais cética das estimativas do tempo de atividade. O que é PERT Método de caminho crítico e PERT são freqüentemente usados ​​nos mesmos contextos e cenários. Embora sejam semelhantes, você deve entender cada conceito e suas diferenças. Um gráfico de PERT ou diagrama de atividade em seta, é uma representação visual de seu cronograma de projectrsquos, mostrando a seqüência de tarefas e que pode ser completada ao mesmo tempo. Um gráfico PERT é feito com muita da mesma informação que é usada no método do caminho crítico, como as datas de início mais antigas e mais recentes, datas de término mais antigas e mais recentes e folga (ou flutuação) entre as atividades. Mas, a maior diferença entre o método do caminho crítico eo PERT é a estimativa do tempo. No método do caminho crítico, a variação do tempo não é contabilizada. Yoursquore usando estimativas de melhor estima para o tempo de conclusão, e esses tempos podem mudar. Com o PERT, o seu meio de colocar mais peso no tempo de conclusão mais realista. Método do Caminho Crítico e PERT Você pode usar PERT no seu método de caminho crítico na etapa quatro do processo, quando você precisa estimar os tempos de conclusão da atividade. O objetivo do uso do PERT é estimar as estimativas de tempo para o cenário mais provável e se afastar de prazos de tempo pouco realistas. Para usar o PERT, você deve estimar o menor tempo possível que cada atividade leve, o período de tempo mais provável e o tempo mais longo que pode demorar se a atividade dura mais do que o esperado. Com essa informação, você pode usar esta fórmula quando precisar estimar os tempos de conclusão da atividade no método do caminho crítico (passo quatro). Tempo mais curto 4x tempo provável tempo mais longo 6 tempo de conclusão da atividade esperada Como encontrar o caminho crítico em um gráfico PERT Você pode identificar o caminho crítico em um gráfico PERT porque o gráfico inclui a mesma informação necessária para o diagrama de rede no método do caminho crítico. Um gráfico PERT é desenhado com círculos para cada atividade, com o nome da atividade e duração estimada em cada círculo. As setas representam os caminhos que se relacionam com as dependências. Para encontrar o caminho crítico no gráfico PERT, primeiro identifique quantos caminhos você pode pegar do início ao fim. Então, adicione a duração total das atividades nesse caminho. Por exemplo, Caminho 1 duração: 12 dias (tarefa 1 e tarefa 3) Caminho 2 duração: 11 dias (tarefa 2 e tarefa 3) Caminho 3 duração: 10 dias (tarefa 4) Neste caso, o caminho crítico é a tarefa 1 e Tarefa 3 porque tem a duração mais longa. Software de caminho crítico Quando o método do caminho crítico foi desenvolvido pela primeira vez, você precisou identificar o caminho crítico à mão, desenhando o diagrama de rede com ldquonodesrdquo para apresentar os estágios de um projeto e conectar os nós com setas ou ldquoarcs. rdquo No entanto, nós de desenho, Tabelas e setas podem ser uma tarefa difícil e demorada, especialmente quando as coisas mudam constantemente no início de um projeto. Ao invés de confiar em diagramas de desenho a mão, há uma série de programas de software de gerenciamento de projetos disponíveis hoje que farão o trabalho para você e identificarão o caminho crítico com o clique de um botão. Aqui estão duas ferramentas diferentes com recursos de caminho crítico: Encontre o caminho crítico com o Microsoft Project Você pode exibir o caminho crítico na visão de gráfico do Gantt do Microsoft Project. Primeiro, você deve inserir todas as suas tarefas, suas datas de início e fim, a duração de cada tarefa e identificar os antecessores. Então, você pode ajustar a exibição do arquivo do MS Project para exibir o caminho crítico. Clique em Exibir gt Gantt Chart. Clique em Formatar e, em seguida, selecione a caixa de seleção Tarefas críticas. As tarefas no caminho crítico agora possuem barras Gantt vermelhas. Identificar o caminho crítico em outras visualizações Você pode ver o caminho crítico em qualquer visualização de tarefa destacando-o. Clique na guia Exibir e selecione uma exibição no grupo Tarefas de Exibição. Permanecendo dentro da guia Exibir, clique em Crítico na lista Destaque. O caminho crítico aparece em amarelo. Para ver apenas as tarefas no caminho crítico, clique na seta Filtro e selecione Crítica. Em um diagrama de rede, as tarefas no caminho crítico aparecem automaticamente em vermelho. Não é necessário ressaltar. Veja o Caminho Crítico em um Projeto Mestre Subprojetos inteiros podem estar no caminho crítico quando o seu gerenciar um projeto mestre. Para identificar subprojetos no caminho crítico, você pode ajustar o Microsoft Project para tratar os subprojetos como tarefas de resumo. Clique em Opções do arquivo gt. Selecione Agenda e, em seguida, role para baixo para as opções de Cálculo para este projeto. Certifique-se de que os projetos Inseridos são calculados como caixa de tarefas de resumo selecionada. Alterar as tarefas no caminho crítico As tarefas críticas geralmente não têm folga. No entanto, você pode informar o Microsoft Project para incluir tarefas com um ou mais dias de folga no caminho crítico, para que você possa identificar eventuais problemas que possam surgir. Clique em Opções do arquivo gt. Clique em Avançado. Então role para baixo para as opções de Cálculo para esta área do projeto. Adicione um número às Tarefas são críticas se a folga for menor ou igual à caixa. Identifique o Caminho Crítico em Segundos com Smartsheet Smartsheet, uma ferramenta de gerenciamento de trabalho e colaboração em um layout de planilha, oferece um modelo de gráfico Gantt pré-formatado para tornar ainda mais fácil encontrar o caminho crítico. Com este modelo de gráfico Gantt pré-fabricado, complete com seções, subtarefas e sub-sub-tarefas já formatadas, tudo que você precisa fazer é inserir suas próprias informações de planejamento de projeto. Um gráfico de Gantt será feito automaticamente para você, e com o clique de um botão, você pode identificar o caminho crítico no gráfico de Gantt. Herersquos como encontrar o caminho crítico no Smartsheet, usando um modelo de gráfico Gantt: 1. Escolha um modelo de gráfico Gantt Vá para Smartsheet e faça login em sua conta (ou inicie uma versão gratuita de 30 dias). Na tela inicial, clique em Criar novo e escolha Procurar modelos. Digite ldquodependenciesrdquo na caixa Modelos de pesquisa e clique no ícone da lupa. Selecione o projeto básico com dependências de amplificador de Gantt e clique no modelo de uso azul no canto superior direito. Nomeie seu modelo, escolha onde salvá-lo e clique no botão OK. 2. Lista de informações da sua tarefa Um modelo pré-elaborado e formatado será aberto com o conteúdo da amostra preenchido para referência. Esta seção é onde você adiciona suas atividades, ou tarefas, da estrutura de repartição do trabalho. Isso também é onde você pode mostrar a hierarquia, ou relacionamento, entre tarefas. As células amarelas no topo são simplesmente para referência instrucional. Para excluí-los, clique com o botão direito do mouse em cada caixa amarela e selecione Excluir linha. Adicione suas tarefas na coluna Nome da tarefa. Use as células denominadas Seção 1, Seção 2 e Seção 3 para estabelecer hierarquia (para mais informações sobre hierarquias, clique aqui). Se você precisar excluir uma linha, clique com o botão direito do mouse na célula na fila que você deseja excluir e selecione Excluir linha. No lado esquerdo de cada linha, você pode anexar arquivos diretamente a uma tarefa ou iniciar comentários com um colega sobre uma tarefa, adicionando mais contexto ao seu projeto. 3. Forneça datas de início e fim Adicione datas de início e término para cada tarefa. Se você clicar e arrastar a extremidade de uma barra de tarefas verde à direita na visão de Gantt, a Smartsheet alterará automaticamente as datas de correspondência na tabela de tarefas. Selecione uma célula na coluna Data de início ou Data final. Clique no ícone do calendário e escolha uma data. Você também pode inserir manualmente uma data na célula. A Smartsheet calculará automaticamente a duração de cada tarefa para você. 4. Adicionar completo e atribuído a informações As colunas Completa e Atribuída a fornecem mais contexto em torno de seu projeto. Na visão de Gantt no lado direito, você pode ver rapidamente o quanto de uma tarefa foi completada pelo comprimento das barras cinza finas dentro das barras de tarefas. A coluna Assigned To permite atribuir a tarefa a um membro específico da equipe, fornecendo visibilidade sobre quem está fazendo o que. Na coluna Completa, insira a porcentagem de trabalho concluída para essa tarefa. Digite um número inteiro e a Smartsheet preencherá automaticamente o sinal de porcentagem. Na coluna Assigned To, escolha um nome no menu drop-down ou digite manualmente um novo nome. 5. Estabelece Predecessores Os predecessores são usados ​​para criar dependências entre tarefas (identificando quais tarefas devem ocorrer antes ou depois de outra tarefa). Na extremidade esquerda da folha, cada linha recebe um número. Na coluna Predecessor, insira o número da linha que representa a linha da tarefa anterior. Isso criará um link da linha atual (a tarefa dependente) para a linha especificada (a tarefa anterior). Digite os números de linha de todos os outros predecessores na coluna Predecessor. Você também pode criar dependências predecessoras a partir do gráfico Gantt à direita. Arraste a parte inferior, canto direito de uma barra Gantt até a barra Gantt da tarefa que deve seguir. A coluna Predecessor será atualizada automaticamente. 6. Identificar o caminho crítico Agora que você criou um gráfico de Gantt na Smartsheet, você pode identificar o caminho crítico no gráfico de Gantt com o clique de um botão. No lado direito da tela, onde seu gráfico de Gantt é exibido, clique no botão de extrema direita que representa um caminho crítico (as duas barras de Gantt vermelhas). No gráfico de Gantt, as tarefas que estão no caminho crítico serão delineadas em vermelho. Como importar um arquivo do Microsoft Project (.MPP) para o Smartsheet da Smartsheet funciona com o Microsoft Project, então, se você já possui as informações de planejamento do projeto armazenadas no Microsoft Project, você pode importá-lo diretamente para o Smartsheet. Clique na guia Início e clique no botão Importar cinza. Escolha o arquivo Import MS Project. Clique em Selecionar, escolha o arquivo que deseja importar e clique em Abrir. Clique em Continuar e um formulário Configurações de importação é exibido. Selecione a linha no formulário que contém os cabeçalhos das colunas (provavelmente será a primeira linha) e clique em Importar. O arquivo importado aparecerá como uma nova folha no Smartsheet. Clique no nome da folha para abri-lo. Estudando para o exame PMP É o que você precisa saber sobre o método do caminho crítico Para ganhar sua credencial de Gerenciamento de Projetos (PMP), você precisa passar no exame PMP, um teste de múltipla escolha de 200 perguntas oferecido pelo Project Management Institute ( PMI). O caminho crítico é uma parte importante do exame PMP e certamente haverá dúvidas sobre isso no teste. Yoursquoll precisa ser capaz de desenhar um diagrama de rede, identificar o caminho crítico, usar a técnica Forward PassBackward Pass e calcular a folga. Aqui está uma visão geral das coisas mais importantes para saber sobre o método do caminho crítico para ajudá-lo a passar no exame PMP: Como desenhar um diagrama de rede No exame PMP, você será solicitado a desenhar um diagrama de rede. O exame listará todas as atividades em um projeto e informará quando as atividades podem começar. Com essa informação, solicite-se que você identifique o caminho crítico e sua duração. Para explicar como desenhar um diagrama de rede, a Bennett criou um projeto de amostra de oito tarefas: Design Tank Project (10 dias) pode começar de imediato. A Construct Tank Foundation (25 dias) e Select Tank Supplier (8 dias) podem começar assim que o Design Tank Project estiver concluído. Os componentes do tanque de fabricação (10 dias) podem começar assim que o Fornecedor do Tank Select for concluído. O fornecimento de tanque para o local de trabalho (4 dias) pode começar assim que os componentes de fabricação do tanque estiverem finalizados. Preparar os Desenhos de Instalação (3 dias) podem começar assim que o Fornecedor do Tank Select for concluído. Assemble Tank (15 days) can start as soon as Deliver Tank to Jobsite, Prepare Installation Drawings and Construct Tank Foundation are all finished. Test amp Commission Tank (4 days) can start as soon as Assemble Tank is finished. After Test amp Commission Tank is finished, the project is complete. To answer the question, yoursquoll need to draw a network diagram. Draw a box and label it as your first activity (Design Tank Project). In the box, make sure to write the duration in days (in this case, it is 10 days). Begin your diagram by drawing the relationship between Design Tank Project, and Construct Tank Foundation and Select Tank Supplier. You can do this by drawing a box for the other activities, and drawing arrows to these boxes from Design Tank Project. Continue drawing boxes to represent activities, and arrows to represent when an activity can begin. After you have drawn the network diagram, you will be able to find the critical path. Remember: the critical path is the longest duration path throughout the network in days, not the path with the most boxes. In this example, the critical path is Design Tank Project, Construct Tank Foundation, Assemble Tank, and Test amp Commission Tank, with a total duration of 54 days. You can identify the critical path by eyeballing the diagram to find the longest duration in days, or you could use the Forward PassBackward Pass Technique outlined in the next section. How to Use the Forward PassBackward Pass Technique The Forward PassBackward Pass technique is another way to find the critical path. It is best used when you have multiple branches, or multiple entry points, for an activity. You may also need to use the Forward PassBackward Pass technique if you are asked to identify the earliest start or finish times, or latest start or finish times, for an activity. Or, to find the slack (or float) for each activity. Before you start using the Forward PassBackward Pass technique, here are some terms that you first need to understand: Earliest start time (ES): The earliest time an activity can start once the previous dependent activities are completed. Earliest finish time (EF): The earliest start time for the activity plus the time required to complete the activity (the earliest an activity can be completed). Latest finish time (LF): The latest time an activity can be completed without delaying the entire project. Latest start time (LS): The latest finish time minus the time required to complete the activity. As you run the Forward PassBackward Pass technique through your network diagram, arrange each value according to the follow legend (SL stands for slack, which wersquoll cover in the next section). How to Do the Forward Pass: Finding the Earliest Start Time and Finish Time There are two formulas in the Forward PassBackward Pass technique. The first is the Forward Pass formula for you to use as you move from beginning to end in your network diagram (from your first activity to your last). This formula will find the earliest start time (ES) and the earliest finish time (EF) for each activity. To start the Forward Pass, make the ES of the first task zero. For all other tasks, the ES is the same as its immediate predecessorrsquos EF. Use this formula to calculate EF: EF ES Duration So, for Design Tank Project, the ES is zero and, the EF is 10 (10 duration of 0). We also know that the ES for Select Tank Supplier is 10 and the EF is 18 (10 duration of 8). Continue like this throughout the network diagram. How to Do the Backward Pass: Finding the Latest Start Time and Finish Time The second formula is for Backward Pass, when you are moving from the last activity to the first activity (you are moving backwards). This formula will find the latest start time (LS) and latest finish time (LF) for each activity. To start the Backward Pass, make the last activities LF the same as its EF. For all other tasks, the LF is the same as its immediate predecessorrsquos LS. Use this formula to calculate LS: LS LF - Duration For the Test amp Commission Tank, the LF is 54 and, the LS is 50 (54 - duration of 4). For Assemble Tank, the LF is also 50 and, the LS is 35 (50 - duration of 15 days). Continue this formula throughout the network diagram. To check that yoursquove done Backward Pass correctly, the first activity (Activity A) should have an LS (latest start time) of 0. Herersquos the completed Forward PassBackward Pass technique: Two Rules to Remember for Forward PassBackward Pass During the Forward Pass, if you find activities that join (multiple activities that flow into one activity), you must run the Forward Pass formula for each entry point and use the highest value from the formulas. During the Backward Pass, if you have activities that join, you must run the formula for each entry point and use the lowest value. How to Calculate Float or Slack on the PMP Exam Now that you have calculated ES and LS for each activity, you can find the float (or slack). The slack time, also known as float time, for an activity is the time between the earliest and latest start time. Critical activities, activities on the critical path, will always have zero slack. There are two formulas to calculate slack based on the values you identified in the Forward PassBackward Pass technique. You will have to use this process if you are asked to identify an activityrsquos slack on the PMP exam. Or, if yoursquore not sure which activities are on the critical path, you could find the slack of each activity, knowing that activities on the critical path always have zero slack. The final figure below shows the slack values for each task. You can see that the four tasks on the critical path have zero slack -- Design Tank Project, Construct Tank Foundation, Assemble Tank, and Test amp Commission Tank. Key Critical Path Terms for the PMP Exam Here are the most important terms related to the critical path method that you should understand before taking the PMP exam. Critical path method (CPM): The critical path method is a step-by-step project management technique for process planning that identifies critical and noncritical tasks, preventing timeframe problems and process bottlenecks. Critical Path DRAG (Devauxrsquos Removed Activity Gauge): The amount of time that an activity on the critical path is adding to the projectrsquos duration. Or, alternatively, the amount of time the project completion date would be reduced by decreasing a critical path activityrsquos duration to zero. Criticality Index: Used in risk analysis, the Criticality Index shows how often a particular task was on the critical path during analysis. Tasks with a high Criticality Index are more likely to cause delay to the project since theyrsquore more likely to be on the critical path. Earliest start time: The earliest time an activity can start once the previous dependent activities are completed. Earliest finish time: The earliest start time for the activity plus the time required to complete the activity. Latest finish time: The latest time an activity can be completed without delaying the entire project. Latest start time: The latest finish time minus the time required to complete the activity. Total float: The amount of time an activity can be delayed from its early start date without delaying the entire project. Free float: The amount of time an activity can be delayed without delaying the early start date of a successor activity. Forward pass: The process to determine the early start or early finish times for activities in the critical path method. Backward pass: The process to determine the late start or late finish times for activities in the critical path method. Network diagram: A schematic display of the relationships between project activities, always drawn from left to right to reflect the order of the project. Network analysis: The process of breaking down a complex project into components (activities, durations, etc) and plotting them to show their interdependencies and interrelationships. The Easiest Way to Find the Critical Path The critical path method is one of the most frequently used and most effective techniques in project planning. When yoursquore managing dozens of tasks, dependencies, and people, the critical path method helps you keep your project on track and on budget, providing visibility into the most important tasks of your project. The good news is that finding the critical path in your project continues to get easier and easier. Traditionally drawn by hand, you can now find the critical path in seconds with project management software. When it comes to the right tools, Smartsheet is the easiest, fastest way to identify critical path. Smartsheet is a cloud-based work collaboration tool that is powerful enough for project managers, yet easy enough for anyone to use. Built with a familiar, spreadsheet-inspired layout, Smartsheet enables you to coordinate anything: creating project plans, sharing content, providing visibility, and of course, finding the critical path. Experience firsthand how easy it is to use Smartsheet in your project planning and sign up for a free 30-day trial. There is no obligation and trial users have access to a number of templates, training, and support resources to get started in minutes. If you liked this article, visit our Resources page for more tips and best practices in project management. From a quotbattle-scarred veteran, quot CPM is a great tool, I039ve used it on almost all of my projects. However, some additional considerations for the novice-on any large andor complex, especially long duration projects, the CP will change, sometimes weekly. The CPM is only as good as the estimates of the task resources and effort, so it039s critical to continuously reevaluate the CP and task estimates and not just chase the initial critical path. Especially on technology projects, where percent complete is often a matter of speculation. Also, consider task risk. Some high risk tasks may not show up on the CP until the risk is realized, so be sure to flag these high risk tasks and watch them as well. Finally, I039ve also encountered some PMs who thought, if a task wasn039t on the CP, it didn039t need to be completed (go figure). if you039re thinking this, then ask why are you doing the task at all Submitted by Emily Esposito on Mon, 08312015 - 13:48 Hi Dave -- Great points Those are important things to remember when developing the critical path. Obrigado pela leitura. - Emily Question Dave. Why do we continue to contravene standard mathematical convention by putting the Early dates (the subtrahend) on the TOP and the Late dates (Minuend) on the bottom I039ve done some research and it appears that the only reason John Fondahl did it this way is because it was how the US Navy did it to schedule their ships. Other than that, there is no logical or rational reason so why should we continue to perpetuate a practice that totally contravenes mathematical convention I think mathematical conventions have nothing to do with this. This is a project management practice, and, as such it is not required to follow mathematical conventions. You say there is no logical or rational reason for it. That is the definition of convention itself. When there is not a logical or rational reason, you decide it by a convention. By convention, we write from left to right, drive on the right lane, etc. it is totally arbitrary, as Arab and English people can attest. Why did calculator makers not follow the quottelephone conventionquot of arranging the numbers in the keypad from top to bottom as 123 456 789 and instead arranged them as 987 654 321 was really useful video and explained in a great way thank you very much. Rubber Pure biodiesel will eventually devour any natural or butyl rubber parts in the fuel system (hoses and seals). Check with the vehicle manufacturer and replace the parts with resistant synthetic parts (such as Viton B). See Durability of plastics table, and Identifying plastics . Newer motors dont use rubber. See also Biodiesel and your vehicle . The Biodiesel Bible by Keith Addison, Journey to Forever This is the only book that thoroughly covers the entire subject of making your own biodiesel 150 all the information at the Journey to Forever website and very much more. Learn how to make top-quality biodiesel that will pass all the quality standards requirements every time. We havent had a failed batch for 11 years (But if you do have a failed batch we tell you how to rescue it 150 and how to improve your processing so it wont happen again.) Save money Making your own biodiesel will save you thousands. Make your own biodiesel (contd.) Ethyl esters -- making ethanol biodiesel Making ethyl-esters biodiesel using ethanol is a tricky process, not as simple as making methyl esters with methanol. Its not for novices -- learn how to make biodiesel with methanol first. Methods and recipes for ethyl-esters biodiesel are available here, along with a How-To from a master home-brewer who has been making and using his own ethyl-esters biodiesel for years. Reclaiming excess methanol Depending on the kind of oil youre using, it takes from 110-160 millilitres of methanol per litre of oil to form the methyl esters molecule. But you also need to use an excess of methanol to push the conversion process towards completion -- the total amount of methanol used is usually 20 or more of the volume of oil used, 200 ml per litre or more. Much of the excess methanol can be recovered after the process for re-use, simply by boiling it off in a closed container with an outlet leading to a simple condensor. Methanol boils at 64.7 deg C, 148.5 deg F, though it starts vaporizing well before it reaches boiling point. Unlike ethanol, methanol does not form an azeotrope with water and relatively pure methanol can be recovered -- pure enough to re-use in the next batch. The methanol can be recovered at the end of the process, or just from the glycerine by-product layer, since at least 70 of the excess methanol collects in the by-product and its that much less material to heat. Recovering the methanol at the end of the process seems convenient because its already hot, and you can get the methanol back from both the fuel and the glycerine by-product at the same time. But it can push the reaction into reverse, converting the biodiesel back into glycerides. Prof. Michael Allen says: Removing methanol from the reactor product is a no-no because it reverses the reaction you have just carried out. Without the excess methanol, the ester and the glycerol react to provide an equilibrium mix which is less than desirable. That excess methanol serves a very real purpose in pushing the equilibrium yield up. But once the glycerol is completely separated, the reverse reaction cannot take place and we can get back the excess methanol. Some people do it before separating it anyway (they often use a vacuum). Wed rather not risk ending up with anything less than good process completion. Its best to recover the methanol after separating the biodiesel and the glycerine by-product. The methanol left in the biodiesel can be reclaimed, but it takes more energy than youll recover and it probably isnt cost-effective. Best to write it off as a loss -- washing the biodiesel removes the methanol, and it does no harm in the wash-water (see Wash-water disposal ). If youre planning to separate the by-product into its components, do so before removing the methanol. Adding phosphoric acid to the by-product separates the soaps from the glycerine and releases the lye catalyst, but it wont separate without the methanol. After separation the methanol is left in the glycerine fraction and can then be removed as below, by boiling and condensing. To recover the methanol from the by-product, heat the by-product to 65-70 deg C (149-158 deg F) in a closed container fitted with a condensor. As the methanol evaporates, leaving an ever-lower proportion of methanol in the mixture, the boiling point will increase, so keep the heat on to keep it boiling. The temperature goes up to 100 deg C (212 deg F) or a bit more, and then it starts to froth and you have to stop or youll get frothy brown by-product in your methanol condensate. But most of the methanol will have been recovered by then. Rich Clark of Berkeley, California writes: My theory is that the froth is caused by the dissolved methanol becoming a gas before it can get out of the glycerine by-product. There seems to be a critical frothing temperature depending on the amount of methanol remaining in the glycerine. This critical frothing temperature gradually increases as the methanol cooks off. The way to avoid the froth and thus avoid getting glycerine contaminating your methanol is to reduce the heat and the rate of temperature increase so you stay just below that critical temperature as the cooking proceeds. Ive cooked glycerine up to 130 deg C (266 deg F) with no froth at all, recovered water-clear methanol, but it took about five hours to complete the process, applying heat very slowly with 15 gallons of glycerine by-product in my kettle. At that 130 deg C point, I stopped because the methanol flow had become drop-by-drop, but not because of froth. Another item of interest is that the recovered methanol tests out by hydrometer at around 97 purity at the beginning and drops to 90 at the end. Putting it all into the same bottle gives about 94 purity. This compares to store-bought methanol at 99.5 and means that when you make your biodiesel with recovered methanol, you need to use more of it and also more catalyst to get the same quality of biodiesel as with commercial methanol. Rather than using more methanol and more catalyst, mixing 30 recovered methanol with 70 fresh methanol (99.5) gives good results. Where does the water in the recovered methanol come from There is probably a little water left in the WVO, even after dewatering Some water is formed during the reaction that produces the methoxide Some water is produced as FFAs are converted to soaps during the reaction process The acid stage of the acid-base two-stage process generates some water Some water is formed when phosphoric acid is used to separate the glycerine by-product prior to methanol recovery (from the glycerine portion). The biodiesel process can tolerate this small amount of water without loss of production or quality, if everything is done well, but the water content should be kept to a minimum -- use dry chemicals, dewater the WVO as much as possible. Flash evaporators vaporize the methanol from a thin film of by-product flowing over a hot plate, more efficient than boiling it off. See Flash evaporator for methanol recovery How much lye to use It requires 3.5 g of NaOH lye or the equivalent of KOH (see above) per litre of oil as catalyst to transesterify new, unused oil. This makes standard-quality biodiesel within the usual processing parameters of methanol quantity, agitation, processing duration and processing temperature. Free Fatty Acids (FFAs) can slow or stop the transesterification process. Fresh cooking oil contains a standardised amount of FFA. The lye is alkaline and neutralises the FFA by turning it into soap, which drops out with the glycerine layer, and with 3.5 grams of NaOH per litre of oil theres enough left over to catalyse the biodiesel reaction. Used cooking oil (WVO) needs more lye than new oil, not to serve as the catalyst but to neutralise the extra FFAs formed in cooking the oil. The hotter and longer its cooked, the more FFA it contains, and the more lye is needed to neutralise it. You have to titrate the oil to determine the FFA content and, from that, how much extra lye will be required. Titration measures the pH of the oil, that is, the acid-alkaline level (pH7 is neutral, lower values are increasingly acidic, higher than 7 is increasingly alkaline, or quotbasequot). From this you can calculate how much extra lye will be needed to neutralize the extra FFA. Too much lye will make extra soap, with very alkaline biodiesel thats difficult to wash, with loss of production, or it can ruin the reaction when the ratio of soap to biodiesel reaches a point where the whole batch turns into quotglop soapquot. Too little lye will mean some of the oil is left unreacted. See below: How the process works The basic lye quantity -- 3.5 grams Good-quality oil that hasnt been cooked too much or overheated is quite forgiving, but with poor-quality WVO with a high Free Fatty Acid (FFA) content, accurate titration is more important. The higher the FFA level, the more sensitive the reaction, the more precise you have to be with titration and everything else, the more reactive agents youll need -- and the lower will be the production rate. More about lye The catalyst used in transesterification of vegetable or animal fats and oils is lye -- either sodium hydroxide (NaOH, caustic soda), or potassium hydroxide (KOH). NaOH might be easier to get and cheaper to use, KOH is easier to use and it mixes with methanol much more easily. KOH does an all-round better job than NaOH. From a faulty batch of lye (rare) -- the semi-translucent half-pearls are fresh, but the chalky white lump on the right is carbonated. After only a second or two exposed to the air the fresh half-pearls are already absorbing a sheen of moisture. Lye is hygroscopic -- it absorbs water from the atmosphere. So make sure you get fresh lye, and keep the container tightly sealed. When weighing it out, dont leave it exposed to the air for any longer than necessary. In humid weather we weigh it out into plastic bags, one on either side of the scale to equalise the extra weight of the bag. As soon as its weighed out, close the container, close the bag, and add the lye to the methanol as quickly as possible. If the weathers really damp, you can do the whole weighing process entirely inside a big clear plastic bag. If you feel it still might be too moist even inside the bag, put some lye in an open container inside the bag to absorb the moisture first. We buy 85 KOH in 20 kg lots, 44 lb, and transfer it from its tough airtight clear plastic bag this way: Everything goes inside a large clear plastic bag -- the sealed bag of KOH, 10 empty 500 g HDPE plastic containers with wide mouths, bungs and tight-fitting lids, a little KOH in another 500 g HDPE container with the lid off to absorb moisture, some tough cord, and a pair of scissors. Then use two knots of cord to seal the large bag closed. We cut two holes in the side of the large bag and taped a resistant plastic glove into each of them. With your hands in the gloves, its easy to work efficiently and safely transferring the KOH inside the large bag, with no water present. When its done, press all the air out of the KOH bag and tie it closed with two knots of the cord. Make sure all the filled HDPE containers are properly closed. Take your hands out of the gloves, cut the knots closing the big bag, take out all the HDPE bottles, the scissors and the remaining cord. Press all the air out of the big bag, and tie it closed with two knots of cord. Lye also absorbs carbon dioxide from the atmosphere and becomes carbonated if not stored properly. Carbonated lye is chalky white, fresh lye is almost translucent. You can still use carbonated lye if its not too severe, but youll have to use a bit more. Add about 25, or better, check it against a titration with fresh lye. You can get both NaOH and KOH from soapmakers suppliers and from chemicals suppliers. You can buy high-quality KOH and NaOH online from Dudas Alternative Energy Store . dudadiesel . Lye usually comes in flakes and 5mm pearls or half-pearls, or small pearls (1-2 mm), which with NaOH are usually 99, but might be more expensive. Any of these will do if the purity is about 96 or better for NaOH. The Red Devil-brand NaOH lye drain-cleaner previously sold in the US is no longer made. Dont use Drano or ZEP drain-cleaners or equivalents with blue or purple granules or any-coloured granules, its only about half NaOH and it contains aluminium -- it wont work for biodiesel. Its best to get high-quality lye from soapmakers or chemicals suppliers. Basic titration For processing used oil, its essential to titrate the oil to determine the Free Fatty Acid (FFA) content and calculate how much extra lye will be required to neutralise it. An electronic pH tester is best, but you can also use phenolphthalein solution (from a chemicals supplier). Dissolve 1 gram of pure sodium hydroxide lye (NaOH) in 1 litre of distilled or de-ionized water (0.1 wv NaOH solution) (weight to volume). In a smaller beaker, dissolve 1 ml of dewatered WVO in 10 ml of pure isopropyl alcohol (isopropanol). Warm the beaker gently by standing it in some hot water, stir until all the oil dissolves in the alcohol and the mixture turns clear. If youre using phenolphthalein, add 2 drops of phenolphthalein solution. Using a graduated syringe, add the 0.1 NaOH solution drop by drop to the oil-alcohol-phenolphthalein solution, stirring all the time. It might turn a bit cloudy, keep stirring. Keep on carefully adding the lye solution until the solution stays pink (actually magenta) for 15 seconds. Take the number of millilitres of 0.1 lye solution you used and add 3.5 (the basic amount of lye needed for fresh oil). This is the number of grams of lye youll need per litre of oil to process the WVO. Potassium hydroxide (KOH) can also be used for titration, see Using KOH . below. Dudas Alternative Energy Online Store supplies phenolphthalein solution in convenient 18-ml dropper bottles, enough for about 180 titrations, as well as a variety of syringes, beakers, chemicals for titration, and gloves, sold separately and as part of their WVO Titration Kit . buy online: dudadiesel Electronic pH testers With an electronic pH tester, use the same procedure as above but without the phenolphthalein. Dip the pH tester electrode in the oil-alcohol mixture, add 0.1 sodium hydroxide (NaOH) solution drop by drop while stirring until the pH tester reads 8.5. Take the number of millilitres of NaOH solution you used and add 3.5 (the basic amount of lye needed for fresh oil). This is the number of grams of lye youll need per litre of oil to process the WVO. For potassium hydroxide, see Using KOH . below. Do a few practice runs first to get used to the pH tester. Sometimes they can be a little slow to register. Stop adding the NaOH solution and stirring the mixture for half a minute or so to see if the tester needs time to catch up. To be accurate, pH testers need regular calibration using buffer solutions, normally supplied with the tester, along with directions for use. See: pH meters pH testing gt Techtips Better titration Unless you have a very accurate scale, its not easy to measure exactly 1 gram of lye. Its much easier to measure 5 g accurately than 1 g. So mix 5 g of NaOH (or KOH) with 500 millilitres of distilled or de-ionized water to make a stock solution. Before titration measure out 5 ml of the stock solution, add 45 ml of distilled or de-ionized water. This makes a 0.1 wv lye solution (weightvolume). Its also not easy to measure exactly 1 millilitre of oil. Instead of the usual 1 ml of oil and 10 ml of isopropyl alcohol, mix 4 ml of oil in 40 ml of isopropyl alcohol in a glass beaker. Warm the mixture gently by standing the beaker in hot water, stir until all the oil disperses and it becomes a clear mixture. If youre using phenolphthalein, add 2 drops as usual -- no need to add four times as much, 8 drops gives the same result as 2 drops. Titrate as usual, measuring millilitres of 0.1 lye solution used. When it reaches pH8.5 count up the number of millilitres used as usual and divide by 4. This will give a much more precise measurement. To save on isopropyl alcohol, use 2 ml of oil in 20 ml of isopropyl and divide the results by two -- still twice as accurate. KOH is not as strong as NaOH -- use 1.4 times as much KOH (actually 1.4025 times). Titration is basically the same. You can use either KOH solution or NaOH solution for titration. Unlike NaOH, your KOH probably wont be pure, but as long as you use the same strength of KOH for both the titration solution and the reaction it wont make any difference. Mix the KOH solution the same as for NaOH: add 1 g of KOH to 1 litre of distilled water to make 0.1 KOH solution. Or do it the Better titration way. For each 1 millilitre of solution used in the titration add 1 g of KOH to the basic amount. You can also use the usual 0.1 wv NaOH solution and convert the end result for KOH, see below. Instead of the basic 3.5 grams of NaOH per litre of oil, use 3.5 x 1.4 4.9 grams of KOH (4.90875). So, if your titration was 3 ml of 0.1 KOH solution, use 3 4.9 7.9 g KOH per litre of oil. One more complication: KOH is generally not as pure as NaOH. KOH is usually 92, 90 or 85 pure -- check the label. We use half-pearls assayed at 85, with good and reliable results. KOH is available at 99 strength, but its hard to find and its expensive, and anyway 92 or 85 work just fine. Adjust the basic lye quantity according to the strength of the KOH: the basic 4.9 grams of KOH at 100 strength would be: 85 KOH -- 5.8 (5.775) grams 90 KOH -- 5.5 (5.454) grams 92 KOH -- 5.3 (5.336) grams To substitute KOH for the 3.1 grams of NaOH per litre of oil used in the acid-base process: 85 KOH -- 5.1 (5.115) grams 90 KOH -- 4.8 (4.831) grams 92 KOH -- 4.7 (4.726) grams To convert NaOH quantities for KOH: For 85 KOH use 165 of the NaOH amount (x 1.65). For 90 KOH use 155.83 of the NaOH amount (x 1.56). For 92 KOH use 152.45 of the NaOH amount (x 1.52). Example . Youre using 85 KOH and the titration needed 3 ml of KOH solution to bring the pH to 8.5. Number of grams of KOH required for the reaction: Basic amount: 5.8 g KOH (5.775) Titration result: 3 ml Add: 3 g KOH Total: 8.8 g (8.775) of 85 KOH required per litre of WVO. Using 0.1 NaOH solution for titration and the same WVO as above: the titration result is lower, it only needs 1.8 ml to reach pH8.5. (Actually 1.82 ml, according to the calculation.) Basic amount: 3.5 g NaOH Titration result: 1.8 ml (1.82) Add: 1.8 g NaOH (1.82) Total: 5.3 g NaOH (5.32) Convert for 85 KOH: 5.3 (5.32) x 1.65 8.8 g (8.778) of 85 KOH per litre of WVO. We usually use NaOH solution for titration and convert the result for our 85 KOH, but in practice NaOH solution and KOH solution both work equally well. One reason for preferring NaOH solution is that its usually the standard used in describing FFA content of different oils -- 2 ml titration WVO or 5 ml titration WVO invariably refers to ml of 0.1 NaOH solution, unless otherwise specified. In the example above, the WVO would be described as 1.8 ml titration WVO. KOH dissolves in methanol much faster and more easily than NaOH does, and doesnt quotclumpquot together as NaOH can do. When you use KOH the glycerine by-product is liquid and wont solidify. KOH is easier to use than NaOH. Its more flexible and adaptible and it gives generally better results -- all round its a better catalyst than NaOH. We seldom use NaOH (except for titration). Note Dont mix KOH and NaOH in the same batch. If you use KOH as the catalyst, you must also use KOH if you make soap from the glycerin by-product, and again you must use KOH if you deacidify the WVO as a pre-processing step. Accurate measurements When quotnewbiesquot have problems making their first test batches and it doesnt pass the quality tests its most often because of inaccurate measurements, or they didnt follow the instructions closely enough. Heres some general advice on being more accurate. Truly accurate scales are expensive, unless you can pick up a second-hand set in good condition. Even then, it pays to check your scales for accuracy. A good way of doing this is with new coins. Find out from your bank, or the Central Bank, what the weight is (in grams) of the coins in your country. If you get a full set of new coins you can use them in combination to check the accuracy of a wide range of weights. With a balance-type scale (two sides with a fulcrum between them), get two full sets of coins, and figure out different combinations to put on each side you should also be able to use this to achieve smaller gradations than your scale allows: aim to measure a tenth of a gram, 0.1 grams, preferably less -- 0.01 grams is best. At 0.1-gram accuracy, with a one-litre test batch, measuring the 3.5 grams of NaOH required might give you 3.4 grams or 3.6 grams instead, or anything in between the two. With fresh oil this margin of error or even more wont matter, if you get everything else right youll have good results. That margin of error wont matter with test batches of used cooking oil (WVO) either, IF you heed the advice to avoid oils with titration levels higher than about 3 ml of 0.1 NaOH solution for your first test batches. WVO with higher titration levels and higher levels of Free Fatty Acids will not be so forgiving, theres much less margin for error -- leave them for later when youre more experienced. Small test-batches of high-FFA oils with titration levels higher than 6 or 7 ml will be easier with scales accurate to 0.01 grams and might need bracket tests as well, and youll probably do better with the two-stage acid-base process. which is also not for novices. If you have a standard millilitre measure that you know is accurate, use it to check all your various measuring flasks, syringes, pipettes, etc. Otherwise, check them against each other. With syringes or pipettes, or whatever you use to add the 1 ml of oil and the 0.1 lye solution to the titration mixture, you should be able to measure 0.1 ml accurately or better. Smaller syringes are more accurate for titration, 5 ml syringes are a bit big, 2.5 ml will do. We use 1 ml clear plastic syringes, long and narrow, marked in tenths and hundredths of 1 ml -- 0.01 ml. The measurement scale is 2-14quot long (5.5 cm) so its easy to read. Theyre cheap, you can get them from hobby shops or laboratory equipment suppliers. Dudas Alternative Energy Store supplies 1 ml clear plastic syringes, both separately and as part of their WVO Titration Kit . which includes a variety of syringes, beakers, the titration chemicals and gloves, buy online: dudadiesel When doing titration work with good lighting and on a white surface. First draw the syringe plunger back about 18quot (2 mm) to take in some air. Then insert the end into the oil or NaOHKOH solution and fill the syringe. Hold it up level with your eye, preferably with a well-lit white wall in the background, keep it vertical, and carefully empty a few drops, drop by drop, until the bottom of the surface meniscus is level with the 1 ml mark. When emptying the syringe into the titration vessel, dont empty it completely -- the one millilitre volume ends at the end of the scale, which leaves a little extra in the spout. Empty the syringe only to the end of the scale, with the bottom of the surface meniscus level with the 0 mark. Use measuring flasks the same way. When filling them hold them vertical, with a well-lit white wall in the background, and with the gradation mark for the quantity you want level with your eye. Measure from the bottom of the surface meniscus. Always keep your glassware and other measuring equipment meticulously clean. Barely visible smears of dried caustic residue or other chemicals can upset your results. Joe Streets titrator Constant heat, constant agitation of the titration sample (note the test tube at the right end of the box) Joe Street of Ontario, Canada, made a titrator kit that he says makes the process easy and repeatable even in the field, by incorporating a small heater and magnetic stirrer in a small portable low-cost unit. quotWhat I needed was a way of warming the mixture of test oil and isopropyl alcohol, which is required for an accurate titration, and I thought it would be nice if agitation was included so that it would not be necessary to stop and shake or stir the solution with a stick while simultaneously trying to carefully control the flow of 0.1 caustic solution used in the titration. A laboratory grade stirring hotplate would be really nice but I could not justify the cost of 500.00 to 1000.00. Necessity is the mother of invention. quot Joes titrator only cost him a few dollars. quotIt was quite simple to put together and was done in less than a day, quot he says. quotNow I have both hands free and can dribble the solution smoothly without interruption just watching for the indicator to go off. I made my life easier by fixing two of the variables: the heat is always consistent, and so is the agitation. quot Its said you cant reliably use an electronic pH meter for titration, nor to check the pH of biodiesel, because biodiesel is not an aqueous solution. Not quite true -- biodiesel is hygroscopic and will always have about 1,200-1,500 ppm water content absorbed from the atmosphere, if from nowhere else. With titration, youre adding water with the 0.1 NaOH solution. And laboratory-standard titration equipment uses electronic pH meters. We have three pH meters, one of them rather expensive, and we did some comparisons, with phenolphthalein, fresh from a laboratory supplies company in Tokyo, and with various test strips. We used WVO from several sources, and fresh oil as a check. The results were checked with test batches. In each case, the three pH meters agreed with each other and produced good test-batch results. Phenolphthalein results were consistently slightly higher, but the test-batch results were still good. The test-strips came a poor third -- not as precise as pH meters and phenolphthalein. People do use them with apparent success, but we dont think test strips are precise enough for titration -- why risk compromising the quality of your fuel Cheap testers can be a false economy. Good instruments are available for a reasonable price. Its worthwhile to spend a bit extra and get one with a replaceable electrode (sensor), and with Automatic Temperature Compensation (ATC). Resolution should be 0.01, accuracy should be plusmn0.1 or better, preferably plusmn0.05 or plusmn0.01. Extech PH100 ExStik Waterproof pH Meter -- pH: 0.00 to 14.00pH, Temperature: 23 to 194 deg F (-5 to 90 deg C), Resolution: 0.01pH,0.1 deg, Accuracy: plusmn0.01pH, plusmn1.8 deg Fplusmn1 deg C, Automatic Temperature Compensation, replaceable electrode. Buy at Amazon: ExStik Waterproof pH Meter PH-200 Waterproof pH Meter . from HM Digital -- Waterproof, pH Range 0-14, Temperature Range 0-80 deg C (32-176 deg F), Resolution 0.01 pH, Temperature resolution 0.1 deg CF, Accuracy - 0.02 pH, Digital automatic calibration, Replaceable electrode. Buy at Amazon: PH-200 Waterproof pH Meter Hanna Instruments pHep4 Digital pH Tester -- Waterproof, pH Range 0.0 to 14.0, Accuracy:plusmn0.1 pH, Temperature Range 0-60 deg C32-140 deg F, replaceable electrode. Buy at Amazon: Hanna pHep4 Digital pH Tester See Technical tips for advice on using and maintaining pH meters. Phenolphthalein Phenolphthalein is often confused with quotphenol redquot (phenolsulphonephthalein), obtained at pool supply stores and used for checking water. Its not the same thing, and phenol red wont work for titrating WVO, its pH range isnt broad enough. It ranges from about pH 6.6, at which point its yellow, through orange, to a maximum of pH 8.0, red. Its at its most accurate at pH 7.4. For accurate titration you need to be able to measure pH 8.5. Phenolphthalein is colourless up to pH 8.3, then it turns pink (magenta), and red at its maximum of pH 10.4. When it just starts turning pink and stays that way for 15 seconds, its measuring pH 8.5. With good-quality oil with low FFA levels you might just get away with using phenol red for titration, but for higher FFA levels it isnt accurate enough. Use phenolphthalein -- specifically, 1 phenolphthalein solution (1.0wv) with 95 ethanol. Phenolphthalein lasts about a year. Its sensitive to light, store it in a cool, dark place. You can buy phenolphthalein solution online from Dudas Alternative Energy Store . in convenient 18-ml dropper bottles, enough for about 180 titrations, buy online: dudadiesel pH meters vs phenolphthalein Which is better Theres lots of argument about it. Biofuel mailing list member Jim MacArthur (aka quotthe skapegoatquot), who teaches chemistry at Three Rivers Community College in Poplar Bluff, MO, USA, had this to say about it: I can shed some light on using pH meters vs. phenolphthalien (PHTH) for titration from a chemists perspective. As acids become weaker, it is important to become more careful in the selection of a chemical indicator (such as PHTH), as the change in pH is much slower than it is for a strong acid titration. PHTH is the most commonly used indicator for strong acid titrations because it has such a clear color change. Fortunately it appears to change color over the same range as the equivalence point for FFAs (Free Fatty Acids). The difficulty in either method is knowing what the equivalence point is going to be. This will vary based on the type of oil and the degree of hydrogenation. I dont suspect it will vary much, but it will vary. If your goal is a pH of 8 or 9, then using PHTH is going to be as good as a pH meter. If you have a better idea of what the equivalence point is going to be, then a pH meter works better. The point is there are a number of reasons why PHTH may not work as well as a pH meter in some cases yet works fine in other cases. This is something I think everyone will have to decide for themselves. -- the skapegoat, Jun 2005 High FFA levels Most people find their used cooking oil generally gives a titration of 2-3 ml, but some used oils can have much higher FFA levels than this -- weve seen horrific titration levels of 9.6 ml. quotHorrificquot because FFAs are not good for you -- its a bad idea to eat food from a restaurant that does that to their cooking oil. Another biodieseler reported restaurant oil with titration levels of 16 ml -- black stuff with the consistency of sump oil. We did succeed in making biodiesel with our 9.6 ml oil. Its not easy to process oil like this with the usual single-stage base process. Youre likely to end up with about 50 production half the time, and maybe not a very good product, and glop the rest of the time. If youre really precise with everything you can do it -- we managed to get a consistent 75 production with the single-stage base process, good product, easy wash. The oil has to be thoroughly dried first -- traces of water make a bigger difference with high FFA levels, because theres more lye for the water to react with. And the reaction itself releases traces of water, especially with high levels of lye. The better answer is to use the Foolproof two-stage acid-base method, which handles high FFA levels effectively and still produces high production rates with low levels of reactants and easy washing. You can also deacidify the oil. Deacidifying WVO Raw oils straight from the oilseed press commonly have high levels of Free Fatty Acids. Before they can be sold as edible oils, the acid level must be reduced to the food-standards specifications. In commercial oil refining this is done with lye (sodium hydroxide, NaOH) and water, which saponifies the Free Fatty Acids, converting them to soaps which can then be removed, but it takes a centrifuge to separate it. This is an easier way, no need for a centrifuge -- but it needs care, you have to be gentle Use the titration amount of lye -- eg, 9.6 grams NaOH per litre of oil for our 9.6 ml WVO (see above). Mix the NaOH with 40 ml of water per litre of oil (same for KOH). It gets hot. Use a stainless steel container, mix it outside (by stirring it a few times), and take care This is very corrosive stuff, take full safety precautions, have running water handy. When the lye is fully dissolved add the solution to the oil (room temperature), stir gently by hand until thoroughly mixed. Be gentle Settle overnight. This leaves soapstock at the bottom. The water stays with the soapstock. Filter to remove the soapstock -- no need for fine filtering, fine steel mesh will do (like a fine tea strainer). Again, do it gently Now process the filtered WVO as usual for fresh oil, with 3.5 grams NaOH (or equivalent KOH) per litre of oil, but use 25 methanol, process at 55 deg C (130 deg F), with good and prolonged agitation as usual. As ever, make a small, 1-litre test batch first. If you have difficulties, you might try titrating the WVO again, but to get an accurate result youll have to wash it, and then dry it. If youve been careful, it should work with 3.5 grams NaOH or the equivalent amount of KOH. In our tests deacidifying 9.6 ml 0.1 NaOH titration WVO the biodiesel was good quality, the production rate was 80 (with two by-products, the soapstock and the usual glycerine cocktail). If you use KOH (potassium hydroxide) for the deacidifying process, then KOH, not NaOH, must also be used to process the deacidified WVO into biodiesel, see Using KOH . above, and KOH must also be used if you saponify the glycerine by-product, see Soap . This method is easier than using the normal single-stage base process with high-FFA oil, and its nice not to have to make such strong methoxide as a straight single-stage process would require with this oil, 13.1 grams of lye per litre oil, or more like 13.6 grams (it needs a bit of excess lye). Its an alternative -- better than straight single-stage base for high-FFA oil, and while it wont get as a high a production rate as the acid-base method, and it uses more catalyst and gives you more co-products, its quick and simple. Its also useful if youre making ethyl esters biodiesel . using ethanol rather than methanol: the ethyl esters process doesnt work well with oils with more than about 2 ml titration. As always with a new process, try it first with a small sample, say 1 litre of oil. Be gentle when mixing it -- if you agitate it too much it wont separate easily. If that happens, try heating it, let it settle again, and be more gentle next time. You can add the soapstock to the glycerine layer after separation and neutralize as usual to separate catalyst, glycerine and FFAs . The soapstock can be used for producing soap, or turned into calcium soap, which is something like Dubbin and has an extremely low water solubility. Useful stuff. quotThus an equimolar amount of calcium chloride may be directly added to the soapstock and prompt separation of the calcium soap by precipitation from a relatively pure saline (NaCl) solution will ensue. Calcium soaps are useful industrial ingredients, for instance as demoulding agents. quot -- Chemical Reactions of Oil, Fat and Fat Based Products -- Neutralization (chemical processing) alfa. ist. utl. pt Mix some calcium chloride in a little water (careful, it gets hot, dont splash) and add it to the soapstock a little at a time, stirring it in, until it separates. No titration There are three ways of avoiding titration: Use the two-stage base-base method Use the two-stage acid-base quotFoolproofquot method Do a series of test batches using graded quantities of lye and compare the results. Start off with maybe 6 g of lye per litre (3.5 g for the transesterification and 2.5 g for extra FFAs). If that works really well, then go ahead. Otherwise try more tests, at 5 g, then at 7 g if, say, 7 g is better, try 6.5 g and 7.5 g, and so on until you get satisfactory results. See also Stock methoxide solution and Poor mans titration . below. Satisfactory results mean that you get a good, clean quotsplitquot (ie separation), that it settles well, leaving a clear product with not too much soap formation, a good production rate, and, most important, that it washes easily without frothing. There are people who claim titration isnt necessary, just use 6 or 6.5 g per litre and youll be fine. Dont listen to them They might have always done it that way and theyve driven 20,000 miles already in their diesel without any problems, but 20,000 miles is nothing in the life of a diesel motor. Oils vary considerably from place to place -- even the fabled quotstable source of supplyquot cant be all that stable, unless its a food processing factory with a standardized operation. If its the usual restaurant or canteen, that would mean they cooked exactly the same number of identical meals in exactly the same way, every day. It just aint so. Sometimes the quotno titrationquot folks point to Aleks Kacs two-stage methods, neither of which use titration, though theyre both based on an quotaveragequot lye requirement of 6.25 glitre. But two-stage processes work in a different way, and this cannot be applied to a single-stage process. In fact even with two-stage processes we do a titration, just to know what sort of oil were working with. They also point to Mike Pellys statement that he usually needs between 6 and 7 g of lye -- but Mike also says titration is the quotmost criticalquot step in the process: quotMake your titration as accurate as possible. quot And: quotIts a good idea to do this entire process titration more than once to ensure that your number is correct. quot In fact Mike has a stable source of supply for his WVO, but he checks it regularly just the same, by titration andor with test batches. Titration wont tell you everything about your oil, but it will tell you more than anything else will (short of Gas Chromatograph analysis), and the more you know about your oil the easier your life will be. It is a basic technique in making biodiesel, not to be avoided. The basic lye quantity -- 3.5 grams This is the amount of lye (NaOH, sodium hydroxide) required as catalyst to transesterify 1 litre of fresh, uncooked oil. For used oils, titration determines the amount of lye needed to neutralize the Free Fatty Acid (FFA) content, and this quantity is added to the basic figure of 3.5 grams per litre. In fact 3.5 grams is an empirical measure -- an average. Different oils have slightly different requirements, and even the same type of oil varies according to how and where its grown. Other estimates are 3.1 g, 3.4 g, and some people have set it as high as 5 g. Here is what weve found. For most fresh oils and low-FFA used oils (with titration levels less than 2-3 ml), 3.5 grams works just fine. For high-FFA used oils, use more lye -- up to about 4.5 g instead of 3.5 g. Do small test batches to see what works best. Different oils also require different amounts of methanol -- see How much methanol For oils and fats requiring more methanol -- coconut, palm kernel, as well as tallow, lard, butter -- again, use more lye, up to 4.5 g, even with new oils, and especially when its used. Once again, do small test batches first. Mixing the methoxide See Methoxide the easy way . You can use the easy method with 4-gallon HDPE carboys or similar containers with screw-on caps (preferably with bungs as well). First the methanol, then add the lye gradually. Swirl it about from side to side rather than shaking it up and down. If you shake it a lot, and often, it can be ready a lot sooner than 24 hours -- in just a few hours or even as little as half an hour, some people say. But DONT use it until ALL the lye is thoroughly dissolved. If you use a white translucent HDPE container you can see any undissolved lye at the bottom of the container. KOH -- potassium hydroxide -- dissolves in methanol much faster than NaOH, sodium hydroxide. It can be ready in as little as 10 minutes. We use HDPE carboys with two screw-on caps and an aquarium air-pump to transfer the mixed methoxide to the reactor vessel via plastic tubing (the braided translucent type), with no exposure at all. Clean, safe and simple. See Methoxide transfer . We transfer the methanol from its tank to the carboys the same way. For HDPE, see below, Identifying plastics Stock methoxide solution Stock methoxide solution is very useful for making test batches, with a series of tests made in a blender using different amounts of lye for each. Rather than measuring tiny amounts of lye for each half-litre (or whatever) test batch, make a stock solution using one litre of methanol and 50 grams of NaOH lye (or equivalent of KOH). Then you can dilute quantities of the stock solution to whatever strength each test batch requires. Actually it needs a little more lye to be accurate: mix one litre of methanol and 51.25 grams of NaOH. The extra 1.25 grams makes up for the volume of the NaOH (about 2 grams per cc), giving the required concentration of 0.05 grams of NaOH per millilitre of methanol. If youre making half-litre test batches and using 20 methanol, measure out the methoxide this way: If titration was, say, 3 ml, youll need 3 3.5 grams of NaOH (the basic amount) for the reaction -- thats 6.5 grams per litre of oil. For half a litre of oil, that would be 3.25 grams and 100 ml of methanol at 20. Its easy to calculate that 65 ml of the stock methoxide solution will contain 3.25 grams of lye. So measure out 65 ml of the stock, and top it up with 35 ml of pure methanol to make 100 ml (20). For a test of 6 grams per litre of oil, youll need 60 ml of the stock, top it up with 40 ml of pure methanol to make 100 ml. For a 7 grams per litre test, measure out 70 ml of the stock, top up with 30 ml of pure methanol. And so on. Didnt figure the calculation For a half-litre test at the rate of 6.5 grams of NaOH per litre of oil, divide 6.5 by 2 3.25 grams. To calculate the amount of stock solution needed, multiply 1000 (1000 ml per litre) by 3.25 divided by 50 65 ml. For 20 methanol, 20 of 500 ml (half a litre) 100 ml. 100 ml minus 65 ml 35, so add 35 ml of pure methanol to the 65 ml of stock to make up 100 ml containing 3.25 grams of lye, equivalent to 6.5 grams of lye per litre of oil with 20 methanol. Once mixed, methoxide wont last forever, but its good for a few weeks. Dont make large amounts -- one litre is good for a dozen or more tests. If in any doubt, make up a fresh batch. Include whats left of the old mixture in the methoxide for your next full-sized batch of biodiesel. (With thanks to Todd Swearingen of Appal Energy.) Poor mans titration The quotpoor mans bracket methodquot of titration is lining up a half-dozen pint jars (half-litre) of the same type, placing 200 millilitres of heated oil in each, adding methoxide of differing concentration to each and observing the reactions. The easiest way to alter the methoxide concentration is to prepare a stock solution of methoxide. Mix a stock solution of 20.5 grams of NaOH (or equivalent measure of KOH) with 400 ml of methanol for a concentration of 0.05 grams of NaOH per millilitre of methanol. Your oil volume of 200 ml is 15th of one litre, meaning that you should reduce the usual 20 methanol volume proportionately, to 40 ml. However, we suggest you reduce it only to 50 ml to ensure that there is no shortage of alcohol. For instance, if you want to see what 6.5 grams of NaOH per litre of oil will achieve in the way of a reaction, you need 1.3 grams of NaOH for a 200 ml test batch (6.5 divided by 5 1.3). Its easy to calculate that 26 mls of stock methoxide will contain 1.3 grams of NaOH (400 x 1.3 20 26). Combine 26 mls of the stock methoxide with 24 mls of pure methanol (26 24 50). With 15-litre samples, that amount is exactly what you want, the same ratio as 6.5 grams of NaOH and 200 ml of methanol to one litre of oil. Number your six identical test jars from 1 to 6. For this example, theyll contain the equivalent of 5.0 grams, 5.5 grams, 6.0 grams, 6.5 grams, 7.0 grams and 7.5 grams of NaOH per litre of oil processed. Youll have 15th of one litre of oil in each jar (200 ml), with 50 ml of methanol, however, each jar will have a different concentration of lye, ranging from 5.0 grams to 7.5 grams. Calculate the proportions of stock methoxide solution and pure methanol for each of the samples as in the paragraph above. Add the following to each sample: 1) 20 ml stock solution 30 ml pure methanol (5.0 gramslitre of oil) 2) 22 ml stock solution 28 ml pure methanol (5.5 gramslitre of oil) 3) 24 ml stock solution 26 ml pure methanol (6.0 gramslitre of oil) 4) 26 ml stock solution 24 ml pure methanol (6.5 gramslitre of oil) 5) 28 ml stock solution 22 ml pure methanol (7.0 gramslitre of oil) 6) 30 ml stock solution 20 ml pure methanol (7.5 gramslitre of oil) When all of the methoxide portions are prepared, add them to their respective jars of heated oil. Seal all lids tightly. Vigorously shake each jar 50 times. Repeat the agitation several times over 10 minutes. Let all the samples settle. If you can settle the samples in a shallow water bath at 120 deg F (49 deg C) all the better. The reason for using jars of the exact same type is for more accurate visual comparison and conclusions. You can also transfer the contents of the jars to a 250-500 ml graduated cylinder for a more precise comparison. The correct amount of lye required can be judged by the volume of glycerin by-product that settles out in each sample. To fine-tune the result, try one test batch with 0.25 g on each side of the batch that had the most glycerin by-product. Say that was with the 5.5 gram sample, do three more tests, for 5.25 grams, 5.5 grams and 5.75 grams. (With thanks to Todd Swearingen of Appal Energy.) How much glycerine Why isnt it solid Just made 20 minutes earlier, and still settling. Newcomers to biodiesel making their first batches sometimes think it all went wrong because the glycerine didnt go solid. Messages sent to the Biofuel mailing list . quotI did my first test batch of wvo biodiesel over the weekend. Although I appear to have formed a layer of glycerine on the bottom of the flask, it is not congealed, but is still liquid at room temperature (24 hours later). Did something go wrongquot quotThe glycerin I got from my first batch is thinner than molasses at room temp. Why would it remain so thin The information I have found suggests that it should be solid, or close to it, at room temperature. quot Others think it quotdidnt workquot because there wasnt quotenoughquot glycerine: quotI did a first test batch of 3 litres WVO, adding 600ml methanol and got only 350ml of glycerine. I didnt really know what to expect, but 10 relative to the original stock seemed kind of low to me. quot quotI did a blender test batch of biodiesel last night. I titrated to 2ml, so I used 5.5g of lye and mixed it in with 200ml of methanol. I then heated the oil up (1 litre), and put it in the blender, and mixed for 15-20 minutes. It quickly began to separate and the biodiesel at the very top inch of the blender after the first 15 minutes or so was quite clear. I woke up in the morning and only 125 ml or glycerine settled out. Shouldnt there be at least 200 ml of glycerine settled at the bottom There are only two layers, the top, light and slightly cloudy, and the dark glycerine. Where is the extra 75 ml of glycerinequot In fact in all four cases the tests worked just fine. There is no quotsetquot amount of by-product, such as 200ml per litre, and there is no rule that the by-product must be solid at room temperature. Whats much more important is that in each of the cases above, the test batch produced a good quotsplitquot -- the glycerine separated and settled to the bottom, and, if theyd followed the directions carefully, the rest would have been good biodiesel, needing no more than settling and washing. It quotworkedquot, its just fine, move on to bigger and better things How much glycerine quotFor back of the envelope accuracy, whether fat or oil, to two significant digits one can estimate the molecular weight of the oil to be about 900 (slightly high) and the density is about 0.9 so the fatoil contains about one mole per liter, therefore one mole of glycerin is present. The molecular weight is 94 so you would get about 94 grams of glycerin from a liter of fatoil. The density is about 1 so you would get about 94 ml per liter of oil. quot -- Bob Allen, Biofuel mailing list But the so-called quotglycerine layerquot is not just glycerine, its a variable mixture of glycerine, soaps, excess methanol, and the catalyst (lye). Better to call it the by-product layer. The overall amount varies according to the oil used (more soap with heavily-used oil), the process used (less soap with the acid-base two-stage method ), the amount of excess methanol used (most of the excess methanol ends up in the by-product layer). Why isnt it solid Its mainly the soaps combined with the glycerine that can cause it to solidify. Soaps made from saturated fats such as stearin are harder than those made from unsaturated fats such as olein, so the type of oil used makes a difference (see How much methanol for compositions of different oils). More important is how much soap there is -- the more soap, the more likely the by-product layer will solidify, no matter what oil you used. Excess methanol makes the by-product layer thinner Too much lye creates excess soap Using potassium hydroxide (KOH) as the catalyst instead of sodium hydroxide (NaOH) produces a liquid by-product that wont solidify. (See Using KOH .) PET bottle mixers Despite claims to the contrary, this is not a good way of making biodiesel. It is useful if youre doing a demonstration, though it makes it look simpler than it really is. PET bottles are transparent plastic soft-drinks bottles, generally 12 or 1 or 2 litres. quotPETquot stands for Polyethylene Terephthalate -- see below, Identifying plastics Heres how the PET bottle fans do it: warm up the oil (or maybe not), funnel it into the PET bottle, add the (pre-mixed) sodium methoxide, screw on the cap, shake the bottle up and down 10 times or maybe 40 times, leave it for an hour, and its done. Well, maybe. Or maybe not -- its a good recipe for an incomplete reaction. For test batches, heres a better way: warm the oil to 55 deg C (131 deg F). Pour it into the PET bottle, add the methoxide, screw on the cap, shake vigorously up and down 40 times or more. Then stand the bottle in a bath of hot water to maintain the temperature -- keep the water in the bath at around 55 deg C. Shake again every 5 minutes, for up to two hours, maintaining the heat all the time. This will have a much better chance of not leaving unreacted and partly reacted material in the mix. See below: How the process works . Better still, make one of these instead: Test-batch mini-processor Biodieseler Greg Yohn, who developed this technique in the first place, along with Steve Spence and other seasoned biodieselers whove used it for years, all say its useful ONLY for demonstration purposes, and so do we. Use new oil, and best do it in private first so you dont risk making a fool of yourself. The value of the quotmethodquot for demonstrations is that it doesnt matter much if the reaction is incomplete and leaves unreacted material in the mix, just as long as you get separation and the glycerine drops out -- youre demonstrating the process, NOT making fuel, and in a transparent PET bottle you can clearly see it all happening. And its non-messy. Viscosity and specific gravity tests Viscosity levels are a comparative indicator of biodiesel quality. Unfortunately, and despite claims to the contrary, thats all they are, a comparative indicator: this batch is better than that batch. Even at the laboratory or industrial level, viscosity testing alone cannot tell you if the process has gone far enough before reaching equilibrium and that there are not unacceptably high levels of harmful unreacted and partly reacted materials in your fuel. Unconverted monoglycerides (MGs) and diglycerides (DGs) are fuel contaminants that can cause injector coking and engine damage. MGs and DGs are very similar in viscosity to biodiesel and stay in solution with it after an incomplete reaction, they cant be washed out. The allowed maximums are low: less than 0.8 by mass for MGs and less than 0.2 for DGs. Viscosity tests might get you within 5 accuracy, not nearly close enough for a useful quality check. The same goes for density -- specific gravity measures (SG). Even both viscosity and density together cant assure you that the reaction has gone far enough towards completion. About the only sure way to know that is with a Gas Chromatograph or expensive laboratory tests which few biodieselers can afford. Short of a Gas Chromatograph the best indicator of reaction completion is to use the Wash test and the Methanol test -- see Quality tests . See also How the process works . below. Nonetheless, viscosity can be a useful indicator, when comparing test batches. You can check viscosity with a 100 ml pipette and a stopwatch -- time exactly how long it takes 100 ml of your fuel to empty from the pipette. Or use a viscosity meter. Excess methanol in the fuel will render the results meaningless, so you must wash the biodiesel first. Measure some petro-diesel for a comparison. Remember that viscosity is sensitive to temperature -- try it at two or three different temperatures. See the various quality-specification tables here for some guidance. Aleks Kac offered this advice to a Biofuel mailing list member struggling to get his home furnace working with biodiesel: Kinematic viscosity is measured in quotStokesquot. You cannot measure it at home without a viscosimeter. There is a comparative way, though. Take a liquid with a known viscosity value (petroleum heating oil, look the value up in an engineering manual) and let a known volume flow through an upside-down plastic water bottle with a drinking straw glued in a hole in the screw top. Stop the time with a stopwatch. Do the same with your biodiesel (same volume) and compare the results. Generally a smaller diameter straw will produce more accurate results. If the time of your sample is 1.5 the time of your control sample (petroleum oil), this means its viscosity is roughly 1.6-ish that of the control sample. -- Aleks Kac, 6 Nov 2001 You can use two straws, the second one to let air in for a smooth flow of oil -- see how we do it with small test batches of methoxide: Adding the methoxide Measure specific gravity (SG) by weighing a specific volume of the fuel. Remember that volume is also sensitive to temperature. A litre of biodiesel should weigh 860 to 890 g at 15.5 deg C. You can also use a hydrometer. Biodieselers using the Wash test and the Methanol test to maintain high quality seldom find any use for viscosity or SG tests. How the process works First, vegetable or animal fats and oils are triglycerides (TGs), composed of three chains of fatty acids bound together by a glycerine molecule. Triglycerides are esters. Esters are acids, such as fatty acids, combined with an alcohol, and glycerine (glycerol) is a heavy alcohol. The transesterification process converts triglyceride esters into mono-alkyl esters (biodiesel) by means of a catalyst (lye) and an alcohol reagent, usually methanol, which yields methyl esters biodiesel -- the methanol replaces the glycerine. In transesterification the triglyceride molecule is broken into three separate methyl ester molecules plus glycerine as a by-product. The lye catalyst breaks the bond holding the fatty acid chains to the glycerine, the glycerine falls away, and each fatty acid chain then bonds with a methanol molecule. It happens in three stages (this has nothing to do with the single-stage or two-stage processes). First, one fatty acid chain is broken off the triglyceride molecule and bonds with methanol to form a methyl ester molecule, leaving a diglyceride molecule (DG) -- two chains of fatty acids bound by glycerine. Then a second fatty acid chain is broken off the diglyceride molecule and bonded with methanol to form another methyl ester molecule, leaving a monoglyceride molecule (MG). Finally the monoglycerides are converted to methyl esters -- completion. However, the process can run out of reagent or catalyst before it gets as far as completion, or the agitation, temperature or processing time may not be adequate. The result is some unconverted or partly converted material remaining in the biodiesel. Well, so what if the process isnt completed SVO (straight vegetable oil) is a good fuel anyway, so whats it matter if some of it is unreacted But its not just unreacted material thats the problem so much as the partly-reacted stuff. Diglycerides and monoglycerides are fuel pollutants: diglycerides dont combust well and lead to coking problems, monoglycerides can lead to corrosion and other problems -- bad fuel. quotThe level of glycerol, mono - and diglycerides at levels of 0.1 (a factor of 11000 or less of the main ester components) or lower appears necessary for optimum engine performance. quot (International Conference on Standardization and Analysis of Biodiesel, Session 2, quotInteraction Between Engine and Fuelquot, Vienna, November 6-7, 1995 -- to be published.) -- From quotAnalytical Methodologies for the Determination of Biodiesel Ester Purity -- Determination of Total Methyl Estersquot, NBB Contract :520320-l, Richard W. Heiden, Ph. D. R. W. Heiden Associates, February 27, 1996 biodiesel. orgresourcesreportsdatabase reportsgen19960227gen-221.pdf So, either dont process it at all and use SVO (which can have its own problems), or process it PROPERLY. In fact the process never reaches 100 completion, it always reaches equilibrium first, so there will always be some unreacted glycerides left. The various national biodiesel standards stipulate just how much is allowable, and its not very much: diglycerides range from less than 0.4 to less than 0.1 by mass, monoglycerides less than 0.8 by mass. The first part of the process happens rapidly, which is why some people think it only needs a few shakes and thats it. Not so. If it takes X minutes to convert half the TGs to DGs, it takes almost as long, another X minutes, to convert half the remaining TGs, then a further X minutes for the remaining half, and so on. So the process goes more and more slowly, and never quite arrives -- theres always half left. Finally comes a point when the remaining half is insignificant, and, indeed, within the limitations set by the various quality standards. But its very easy to fall short of that point and end up with nasties in your beautiful clean eco-friendly nice-smelling home-brewed fuel, and in your motor. See Kinetics of Palm Oil Transesterification in a Batch Reactor . by D. Darnoko and Munir Cheryan, University of Illinois, for what actually happens during the biodiesel process reaction. (Acrobat file, 72Kb) You CAN make high-quality biodiesel, all it takes is a little care. On analysis, biodiesel made by home-brewers with no qualifications and no special equipment using the methods detailed at this website has proved the equal of professionally made commercial fuel or better. Professional mechanics checking their motors have been amazed by the lack of wear and corrosion. You can do it too. See Quality Message to the Biofuel mailing list from a biodiesel dealer in the US: quotCurrently I resell commercial manufactured biodiesel in Atlanta, GA. Over the past two years I have seen the quality of this fuel vary greatly. Funny thing about the quotcommercially manufacturedquot biodiesel. One of the big arguments against backyard biodiesel (from industry folks) is quality, yet every batch that I have made, and every batch I have seen by a homebrew biodiesel maker has been much better than the quotfuelquot I am reselling. Individuals with small-scale setups seem to really care, take their time, and craft their fuel. after all, most are using it in their own cars, not selling to the boiler fuel market. quot For beginners, start off with good practices: follow the instructions carefully, be meticulous with your titration, make sure your measurements are as accurate as you can make them. Learn as much as you can. Youll soon get a feel for it, and then, once youre familiar with the process in all its aspects, youll be able to decide whats best for you in your situation, with your source of oil, on your budget, and just where you can relax a little and take calculated shortcuts, based on your own experience. NOTA . Its a common misconception that biodiesel has lower viscosity than SVO or WVO because the transesterification process shortens the carbon chain length of the fatty acid molecules in the oil. This is not so. The biodiesel molecule is indeed smaller and less complex. Transesterification converts the triple-chain triglyceride vegetable oil molecule to three single-chain methyl ester molecules, but the chain lengths of the fatty acids themselves remain the same. The fatty acid composition of biodiesel depends on the feedstock and is not changed by transesterification. Animal fats, tallow and lard Many people make biodiesel from tallow, lard or chicken fat. It makes great fuel, but like the fat its made from, it has a high melting point -- when the temperature falls below about 15 deg C (60 deg F), the fuel starts to go solid. Its strictly summer fuel. Some people have difficulty processing animal fat. Frequently asked question . quotI have access to a source of animal fat that is used for deep frying. I have tried to make biodiesel from it but only succeed in producing a very soapy gloop. Is there a difference between using animal fat and waste veggie oil Helpquot -- Leo, Biofuel mailing list, 26 Apr 2006 Answers . quotNo real difference between the two, at least not relative to making fuel. The suggestion would be to use KOH instead of NaOH for starters. That should help end your thickeningsoap issue. Dont jump the gun with large batches until you get the small stuff right if youre still having problems. quot -- Todd quotAnimal fat (tallow) has a different chemical make-up than vegetable oil. You need to do much more purification. You get soap (glycerin) like results with vegetable oil, just not as much. I think that if you use a stronger caustic agent to separate mixture components, you may have more success. quot -- Randall quotYoure aware that saturated fats and oils tend to make harder soaps Combining factors such as the greater ratio of saturated glycerides and the common practice of overdosing caustic as insurance by new initiates to biodiesel and the groupies of others who prescribe the method as a guaranteed cure-all, there will be inevitable and needless occurences of failed reactions due to the formation of glop soap. Animal fats do need to be rendered thoroughly to remove as much proteinaceous material as possible prior to processing. But the chemical make-up is essentially no different than any other triglyceride, other than the ratio of saturated acids to unsaturated acids. Its the ratio of fatty acids to each other that defines an oil or fat, giving each its general properties. quot -- Todd quotTallow, lard, butter, vege oil, etc. are all the same chemically save very, very minor differences which dont impact the transesterification reaction. Fats and oils are treated the same as to volume of methanol, reaction time, and amount of catalyst. Impurities, mainly water present, will impact yields, and soap production, but starting with relatively pure oils and fats requires no different treatment. quot - Bob A. quotI stand corrected. quot -- Randall quotI have processed 100 virgin beef tallow fat with the 2 stage base - base process with great sucess. I used 200 ml methanol liter fat and 6.7 g NaOH Processed for 2 x 2hours at 58 - 60 deg C. That batch washed better and easier then any other WVO I had dealt with. The only drawback is cold weather, it will crystalize around 15 deg C (59 deg F). Otherwise it is great fuel with a light yellow color like the fuel from virgin rapeseed oil. Good luck with it. quot -- Andrew quotI have also had excellent results from beef tallow using the acidbase two stage process. Although when washing, I thought I was getting loads of soap out even on the third or fourth washes. It turned out that my water was too cold, I was bringing the temperature of the biodiesel down to below 15 deg C and forming waxes. I then washed with lukewarm water and got perfect results, crystal clear wash water on the third wash. quot -- Bob C. quotLast time we rendered deer tallow and made biodiesel from it we were stonewalled after an overnight temp of 56 deg F (13 deg C).quot -- Todd What are Free Fatty Acids Again, vegetable or animal oils and fats -- what we make biodiesel from -- are triglycerides, composed of three chains of fatty acids bound by a glycerine molecule. (See above, How the process works .) Free fatty acids (FFAs) are fatty acids that have become separated from the triglycerides, leaving diglycerides, monoglycerides and free glycerine. This is caused by heat, water in the foods cooked in the oil, or oxidation. The hotter the oil gets and the longer its cooked, the more FFAs it will contain. As glycerine is an alcohol (glycerol), a fatty acid attached to it (a glyceride) forms an ester. A quottransesterificationquot is the conversion (switching) of one ester into another -- a glyceride ester into an alkyl ester in the case of biodiesel, where methanol (or ethanol) replaces the glycerine. An quotesterificationquot is the conversion of a non-ester into an ester. FFAs are non-esters. FFAs are converted into esters by acid esterification in the first stage of the two-stage acid-base biodiesel process, but cannot be converted by the more common single-stage base transesterification process. Here the FFAs must be removed from the process, or they will dissolve in the biodiesel being formed, yielding an acidic, poor-quality fuel that will not meet quality standards. In transesterification, extra lye is used to neutralize the FFA content of the oil, turning it into soaps. These soaps drop out of the process as a by-product, joining the so-called quotglycerine layerquot at the bottom -- often more of a quotsoap layerquot as it may contain more soap than glycerine. The basic lye quantity used in transesterification acts as a catalyst, not a neutralizer. Lye attacks ester bonds, breaking the bond, and the alcohol drops off, leaving an open-ended fatty acid chain. With glycerides the alcohol that drops off is glycerine. The affinity of the replacement methanol or ethanol for the resulting open bond is strong enough to prevent the glycerine reattaching to the fatty acid. This is also why it is critical that a minimal amount of lye is used, as lye will continue to attack ester bonds, even those of biodiesel. Too much lye will break the biodiesel ester bonds some of the broken bonds will mate with the lye and form excess soap, and others will match up with a water molecule to form FFAs, which dissolve back into the biodiesel. It is this excessive formation of FFAs that the quotacid numberquot in the US ASTM and other national quality standards refers to. While it is unavoidable that some FFAs are formed by biodiesel ester bonds being broken, excess lye increases the proportion. According to the Fuel Injection Equipment (FIE) Manufacturers (Delphi, Stanadyne, Denso, Bosch), FFAs can corrode fuel injection equipment, cause filter plugging and the build-up of sediments on fuel injection parts. -- With information from Todd Swearingen of Appal Energy, and DieselNetEcopoint Inc. dieselnet Which method to use Three main choices, all of them here: Single-stage base -- Mike Pelly Two-stage base-base -- Aleks Kac Two-stage acid-base quotFoolproofquot method -- Aleks Kac . Whats the difference The single-stage base method is the place to start. The two-stage processes are advanced methods, not for novices -- learn the basics thoroughly first. Single-stage base is the original method, and still the most widely used, tried and trusted. Its the simplest method, especially for new oils which dont need titration. A lot of beginners want to use WVO but theyre put off by the titration, thinking its too complex. Actually its simple enough -- just follow the directions. However, the single-stage process produces more and more uncertain results the higher the FFA content gets in WVO, with lower production levels even when it works well. The two-stage base-base method avoids the need for titration and produces good results even with higher FFA levels. Its the method-of-choice for animal fats. Growing numbers of biodieselers are now turning to the quotFoolproofquot two-stage acid-base method, especially with high-FFA oils. Here are some of the reasons: Less base catalyst needed. Less soap production. Higher conversion rates as a result of less soap formation. Less emulsion formation in the wash. Less loss of fuel in the wash as a result of emulsion formation. Less wash water as a result of less soap formation. Less neutralizing acid needed for the wash. Less acid needed to neutralize base during glycerine recovery. High-quality product. A little extra processing time. Even with higher-FFA oils the production rate should be 100 or more by volume (biodiesel has a lower density than the original oil). In fact the same advantages apply to new oil, although to a lesser extent. Many biodieselers who turn to the quotFoolproofquot method for high-FFA oils soon make it their method-of-choice for all oils. Heres some advice from Aleks Kac on using the Foolproof method: quotStick to the recipe, to the letter. Theres two years of trial and error research in this. Do not change, simplify or speed up anything. It will take care of all sorts veg fats, even heavily used. The solid portion must be reduced to less than 50 because of the much lower acid-stage temperature. Animal fats content is best at less than 25 for pork or chicken and less than 10 for bovine. These fats at greater concentration should be processed with the two-stage base-base method. quot Still, if your oil is quite good and usually titrates at 3 ml or less, you might well be satisfied with the single-stage process. Why cant I start with the Foolproof method It says at the top of the Foolproof acid-base process page: quotNOTE: The two-stage biodiesel processes are advanced methods, not for beginners -- learn the basics thoroughly first. The single-stage base method is the place to start. Start here. quot But novices sometimes take no notice and plough ahead with the acid-base process anyway. Sometimes they also take no notice of the advice on Test batches: quotWhenever youre trying a new method, its always a good idea to make small test batches of a litre or less first to familiarize yourself with the process before moving on to bigger batches. quot All too often it results in a highly discouraging 40 gallons of glop. quotIt doesnt workquot they wail. Funciona. It also works to heed the advice of the many whove gone before you. quotDO AS THEY RECOMMEND and bio will come, quot said a recent novice at the Biofuel list. quotBut it doesnt sound difficult at all, in fact it sounds easier since there is no need to titrate. So what am I missingquot Quite a lot. First, we think its worthwhile titrating your oil anyway -- the more you know about it the better, and titration will tell you more than anything else does. Avoiding learning how to do titration is a VERY BAD reason for using the acid-base process Titration is a basic skill needed for making biodiesel, no matter which process you use. Anyway, its easy enough: Basic titration Better titration Second, its not just a question of whether or not novices can get it to work. Some do -- mostly they seem to get away with it. But thats a pity just the same, because its doubtful that theyll get the best out of it. The acid-base method is very flexible, people bend it and twist it every which way in adapting it to their preferences and needs, and you just cant do that unless you have a good overall feel of the process as a whole, not just of this one method. Another novice at the Biofuel list said he had good chemistry knowledge so he could afford to skip the quotnewbiequot stuff. But: quotWell, my first test batch is done, and the end result is less than spectacular. quot Suddenly he found himself facing an ocean of variables, and since he had no quotfeelquot for what was supposed to be happening he had no way of finding out what hed done wrong. Several things, as it turned out. quotThis is why this isnt a good place to start. If you were more experienced you might have had a better idea of how to translate the mixing instructions for a full-sized batch to the small scale youre using. Maybe it translates direct, maybe not -- I dont know how fast your drill stirs it, nor what rate of agitation it gets with that paint stirrer, but, comparatively, neither do you, and that makes it difficult for you. Starting instead with single-stage base and fresh oil, you begin with fewer variables and theyre less critical, and its a logical progression from there. Now youre facing too many variables and you dont have the experience to assess them -- and youre more likely to make mistakes anyway because you lack a basis of comparison. quot He relented and went back to the beginning, processing 1 litre of fresh oil by the single-stage base method. quotDespite people saying that in different ways, I hadnt heard it until now. All I was hearing was that you have to start with the single-stage process then graduate to the foolproof process. This just seemed like trying to learn something one way then do it in a completely different way, which doesnt make sense. quot quot. so what am I missingquot quotIf everything goes exactly right, nothing. The problem is when something doesnt, and you have NO IDEA whats going on cuz youve never seen all the possible quirks of even the basic process. Quot. Whats all this white stuff. Nothing seems to be happening. Theres this weird layer, and Im wondering if its biodiesel. etc etc. quot quotI can mention that from a beginners perspective, starting with pure vegetable oil and single-stage base is a really valuable learning process. It gives you an idea of what outcomes look like, and the shake test provides feedback on the quality of the process. I am still playing around with variables (processing time, lye, methanol, etc.) using pure vegetable oil, before moving to waste vegetable oil. quotAs many people continue to emphasize, process quality is really important, and that seems to be best learned in small steps. My game plan is also to get to the 2-stage acidbase with waste vegetable oil, but I still have a lot to learn before getting there. I think what the experienced folks are cautioning is that troubleshooting a more complex process is extremely difficult (and perhaps frustrating) if you dont have a solid grounding in the basics. I hope this helps. Good luck with your experimentsquot quotAfter reading the links to the discussion groups that you attached I see that the basics is to get a feel of the process and see the correct colors and textures using the process that has the best chance of success, then use that as a baseline for future mini batches using WVO. Then progress to larger scaled processing, then full scaled process, and then finally graduate to the two-stage method, with knowledge that the resultant biodiesel is clean and pure enough to run through my beloved TDI. quot quotI would like to testify that the acid base method on JtF WORKS and it works well. That said you will never get it to work unless you start at the beginning. Keith is not kidding - get to know the oil. quot -- Jim, Biofuel mailing list, 12 May 06. I am interested in biodiesel and used your foolproof method to make biodiesel. Four litres so far. wow eh However I have since constructed a 200-litre biodiesel reactor out of scrap stainless steel so I can run my VW TDI without modification. My degree is in chemistry but my main forte is a mechanical aptitude. The main question I do have about your foolproof method of making biodiesel is during the acid catylized process. I have tried four times to get separation. I have 100 litres in my new reactor and I do not want to have a goopy mess. It says at the top of Alekss pages: quotNOTE: The two-stage biodiesel processes are advanced methods, not for beginners -- learn the basics thoroughly first. The single-stage base method is the place to start. Start here. quot Please dont take offence, but while you may have a background in chemistry, you wouldnt be the first chemist who had to go back to the beginning with this and got it right in the end. With only four litres behind you (four failures apparently) youre a beginner, you have to get a feel for it first, and youre not starting at the beginning. Youre not ready for 100-litre batches yet, stick to one-litre tests. Even if you can get it to work at that level, transferring the process from a one-litre batch to a 100-litre reactor that youve never used before might not be as simple as you think. The only good advice is to go back to the beginning, with small batch tests of new oil using the standard single-stage base method. From D. P. some months later -- quotStarting from the beginningquot: Just a short note to thank you for such an excellent website for biodiesel. I took your advice and went back to the basics. I am now making quality biodiesel with excellent seperation and water washing is easy. Test batches thru my home-made reactor are a must. Keep up the good work and keep encouraging anyone who wishes to make a difference. Biodiesel in gasoline engines Biodiesel can also be used in gasoline (spark-ignition) engines, but only as an additive. People have had good results with it, but its still experimental, there are no guarantees. Biodiesel in 2-stroke gasoline engines . Many people have used biodiesel as replacement 2T lube oil in two-stroke gasoline (petrol) engines. Biofuel mailing list member Martin R. of Australia uses it in his chain saw, at a mix of 1 to 20 with gasoline. quotIt works fine, quot he says. quotAfter using the saw for 2.5 hours in one go on dead Australian hardwood with no hiccups I was very impressed to say the least. quot List member Franklin Del Rosario . biodiesel maker in Manila in the Philippines, uses it in his motorcycle: Biodiesel was first used as 2T replacement in the Philippines by a group who added a viscosifier and sold it as 2T replacement for tricycle taxi use at several places outside Manila. The biodiesel, pure or blended with oil additive, performed better than 2T mineral oil as lube oil, according to the testimony of the tricycle drivers who tried it. Their motors ran smoother and quieter than before, the engine block did not heat up, others experienced better engine performance, no more carbon build-up inside the cylinder and muffler, no oil dripping on the exhaust pipe and most of all no more smoke. I use B100 biodiesel as lube oil for my 1983 Yamaha 125 cc two-stroke motorcycle instead of Shell 2T lube oil which I previously used. I mix biodiesel with gasoline at a ratio of 1:20. I replaced all rubber fuel lines, carburetor gasket etc. cleaned the fuel tank, and changed to a new spark plug. The motor is running smoothly on city driving, the smoke has improved because no more 2T lube oil. The Yamaha was retired before because of the smoke it produces using mineral 2T oil. With biodiesel as a lube oil it runs better than before and with less smoke at the exhaust pipe. I took my motorcycle to the emission test center and it passed the gas standard limit with better results than a new motorcycle which used mineral 2T oil. The results were as follows: Data reading CO2 -- 2.90 CO -- 3.39 HC -- 5396ppm O2 -- 13.29 AFVR -- 20.95 LAMBDA -- 1.44 Standard Gas Limit CO2 -- 20.00 CO -- 6.00 HC -- 10000PPM LAMBDA -- 1.00 - 0.99 The main property of the lube oil is not the viscosity but rather the ability to mix well with gasoline while maintaining its lubricity (ability to provide a film of oil at the metal surface) to prevent wear of the crank shaft, connecting rod amp piston pin and cylinder wall. Biodiesels lubricity is enough to do the job and it can be improved by adding compatible oil additives to increase the film strength of of the biodiesel. BD is a fuel with 11 of oxygen by weight, this property alone can help gasoline to burn well reducing smoke emission and leaving no trace of oil at exhaust muffler. -- Franklin Del Rosario, January 2004 Biodiesel in 4-stroke gasoline engines . List member Gregg Davidson wrote: In June of this year, I posed a question about quotBiodiesel in gasoline enginesquot. I received a reply from list member JC in Taipei. He advised me that he had mixed biodiesel with gasoline for his car, using no more than a 15 mix. I have had success following his example and had no engine problems. One of the three vehicles I tested this in is a Chrysler Town amp Country mini van with a 3.3 L V-6 Flex Fuel Engine, the other two are Jeep Grand Cherokees with 4.0 L I-6 engines. Even though the van can run on E-85, I do not use ethanol blends because E-85 is not available in my home state of Georgia. -- Gregg Davidson, October 2004 Franklin Del Rosario wrote: Im please to inform our group about using a biodiesel blend with gasoline fuel to power a 4-stroke gasoline engine. The company I work with has a fleet of service cars, most of them are Japanese Nissan, Toyota and Honda. I persuaded one of our company drivers to try biodiesel in a gasoline engine at 200-300 ml of biodiesel to 50 litres of gasoline mixed together in the fuel tank. We choose a Nissan Cefiro because it emitted a foul odor of unburned hydrocarbons irritating to the eyes and nose during engine warm up and idling. I poured 200 ml of biodiesel into the tank, shook the body for a while and started the engine. After 5 to 7 minutes of idling speed, the exhaust odor improved dramatically and at the end of the day of driving the odor of unburned hydrocarbon was gone and engine purred better than before because biodiesel lubricates the fuel system, the upper combustion chamber, as well as the valve ports. Because of this other drivers tried it in Honda cars. The immediate result was no more odor of unburned hydrocarbons and visible trace of water condensation at the exhaust tail pipe as if the car was new. I tried using biodiesel as an anti-wear additive for a four-stroke gasoline motorcycle engine and the result was the same. My friend owns a surplus service car, a gasoline engine Toyota. His car was due for the yearly renewal of LTO registration, and he had a problem because his old car smoked badly and one of the requirement for LTO registration is to test the car at the emission test center. Cars must pass the Emission Standard set by the government before renewal of LTO registration. I challenged him to try biodiesel as a fuel additive, without any engine modification, changing of oil or cleaning of air filter except cleaning of exhaust pipe by water hose to remove carbon particle clinging to the pipe wall. He did so and took the car to the emission test center. The result was very promising Emission Standard CO (V) -- 3.5 HC (ppm) -- 600 Running condition gradual increase of rpm Gas analyzer final result of service car were the following CO -- 1.25 HC (ppm) -- 278 PASSED Biodiesel as an anti-wear and smog additive for gasoline fuel is very encouraging. -- Franklin Del Rosario, January 2004 Storing biodiesel Frequently asked question . quotI read somewhere that biodiesel has a short shelf life. Does biodiesel have an expiry date or a use-by datequot Answer . We have some biodiesel we made six years ago that hasnt degraded. Its been kept sealed in an HDPE plastic container with a bung and a lid. Others report 4-year-old biodiesel still being usable. quotWe opened up a drum from our first reactor that was four years old a couple of weeks ago, 45 gallons of it. It had been sitting outside in a 55 gal steel drum with approximately 5 inches of airspace over the it. It has been through some record-breaking winters and several high-heat cycles unattended. Even though this was an unintentional test, its showing us some things. This batch was 50 soy 50 wvo processed at the same time. There was a little bit of cloudiness but not much, which was easily removed by simply stirring. One of our trucks has run almost a week on it with no change in performance from the freshest batch. quot -- Philip S. Okey, Biofuel mailing list, 28 Jul 2004 quotThe findings that we have are that biodiesel does more readily oxidize than petrol diesel. So if left in an open container the shelf life is very short. It will still burn after being oxidized but not nearly as well. On the other hand, most of us would be storing our biodiesel in a sealed container, which limits the oxidation to the amount of air and surface area. The best thing to do is to store it in a sealed container that is as full as practically possible. This limits oxidation to a level that probably wont be noticeable. quot -- Doug Memering, Biofuel mailing list, 11 Sep 2005 quotA study on the stability of the methyl and ethyl esters of sunflower oil reports that ester fuels (biodiesel) should be stored in airtight containers, the storage temperature should be lt 30 C, that mild steel (rust-free) containers could be used, and that tert.-butylhydroquinone (TBHQ), an oxidation inhibitor, has a beneficial effect on oxidation stability (166). Methyl esters were slightly more stable than ethyl esters. quot -- From . Storage stability, Biodiesel: The Use of Vegetable Oils and Their Derivatives as Alternative Diesel Fuels . G. Knothe, R. O. Dunn, and M. O. Bagby, in Fuels and Chemicals from Biomass . Washington, D. C. American Chemical Society. Download full-text article: Acrobat file, 912kb MS Word file, 212kb The US industry group, the National Biodiesel Board (NBB), recommends using biodiesel within six months, but theyre being overcautious as usual. Or maybe its not overcautious if the fuel is to be subjected to the existing petro-diesel infrastructure (dirty and wet). But homebrewers dont have that problem. Frequently asked question . What is the shelf life of biodiesel Can I make 6 months of fuel at a time Answer . Yes, if you store it properly. Lamps and stoves Lamps that work with biodiesel. Stoves that work with biodiesel. Other uses Wood treatment . Biodiesel is very useful stuff. quotWe must be crazy to burn itquot Mike Pelly once said, only half-jokingly. Hes a carpenter and had just finished refitting his house with wooden interiors. He and his wife treated all the wood with biodiesel, floors included. The smell was soon gone (and its a pleasant enough smell anyway), and the results were fine. We also use it for wood treatment, nice (But we found it can attract mould, especially in wet weather.) Its an excellent lubricant . very slippery. Its better than household lubricating oils, and its non-obnoxious and non-toxic -- it wont matter much if the kids swallow some by mistake. Great for gardeners, especially organic gardeners, nothing better for lubricating your tools and keeping them clean and rust-free, and non-toxic. Great in the workshop too. Great if you live in an old Japanese farmhouse with wooden sliding doors Biodiesel is used as a lubricating additive for low-sulphur petroleum diesel fuels. With diesel engines, upper engine parts are lubricated by the fuel itself. Diesel motors are not lasting as long as they did because of the lack of lubrication with low-sulphur fuel (500ppm), let alone the new ULSD ultra-low-sulphur fuel (15 ppm), and biodiesel solves the problem. Adding just 1 biodiesel improves the lubricity up to 65. Research suggests that just 0.4 to 0.5 is enough. In France its compulsory, biodiesel is added to all diesel fuel at between 3 and 5 other countries are following suit. Better than detergent quotA couple of weeks ago, while doing laundry, I opened up the dryer and found all the clothes and the inside of the dryer coated in a multitude of colors. A box of crayons had made the trip through the wash and disintigrated in the heat of the dryer. I tried using regular liquid detergent on a rag to remove the crayon stains and got almost nowhere with a lot of vigorous scrubbing. Well, I saturated a cloth with some homebrew biodiesel and started on the stains, with very little scrubbing, all the crayon was easily removed in seconds. totally took everything that was stained off the dryer drum, in seconds, no work at all. quotSo, I sat down with a toothbrush and bowl of BD and started in on the 8 pairs of khakis, the scrubbing starting freeing up the chunks of crayon imbedded in the material, it didnt take it totally out but seemed to break it up greatly. After the pants were all scrubbed and saturated with BD, I put back into the wash on hot with normal liquid detergent and everything came out perfectly clean after the first wash, really impressive quotSo I had a shirt with a deep ink stain in the pocket, poured some BD in the pocket and scrubbed with a toothbrush, went through a normal wash and the ink stain was gone in one wash, again, impressive quotI do have one pair of white khakis that I havent attempted to clean yet. Im trying to quotforcequot my son to wear them to school as an attempt to teach him a lesson about checking his pockets before washing the clothes. What I want to do is just soak them in BD and see if that would work instead of all the toothbrushing that was involved in cleaning his other clothes. quotAnyway, sometimes it pays to look outside the box, in this case, the detergent box. quot -- k5farms, Biofuel mailing list . 15 Mar 2003 quotFound the same thing in dissolving Ohio crude oil and crudegrime out of work clothes. Lay the clothing in a bathtub, saturate the stain with a homemade liquid veg oil soap, brush a few seconds with a warm-water soaked scrub brush, apply biodiesel from a dish soap squeeze bottle. Scrub to your hearts content. quotThe soapwater suspension pulls a good bit of the surface grunge off first, with the biodiesel removing the balance of the oil embedded and soaked into the fibers. The suspension also seems to keep the oily effect of the biodiesel from getting locked into the fiber, which can give the look of wet spots (oil soaked spots) even when the garment is dry. quotPrior to figuring this out the alternative was lacquer thinner, soap and water --- home dry cleaning and toxic as hell. quot -- Todd Swearingen, Biofuel mailing list . 15 Mar 2003 Oil spill remediation -- CytoCultures CytoSol Process cytocultureprocess. html quotCleaning Oiled Shorelines with a Vegetable Oil Biosolventquot, Port Technology International, 1998, London, UK cytoculturecytosolarticle. htm gtgt Renewable Energy Online Newsletter gtgt August 24, 2001 gtgt Environment News Service: gtgt European Government Support Growing for Biofuels gt gt ltsnipgt gtgt Since biofuels release none of the greenhouse gas carbon dioxide, gt gt Interesting. Perhaps a silicon-based fuel With sand for exhaust gt Tom gt New Mexico, USA Silicon and sand Whatever makes you think that Bit primitive arent you We do it this way. Of course we use only the most advanced techniques to make our biodiesel, from whatever feedstock, and then use it in the normal way, giving a thorough application to all the exposed woodwork on the wagon, the wheel hubs, the front axle steering bolt, the canvas tarp cover, and all the leatherwork, harnesses, etc. Then we add the glycerine to the yak-dung in the biogas generator, which powers a small motor with an elbow crank connected to a long forward-mounted bamboo shaft on an offset fulcrum, causing it to waggle, shaking the carrot tied to the end of the shaft enticingly at some suitable point between the yaks noses and our destination. No carbon emissions, just a bit of odd methane escaping when the yaks fart, but you get used to it. We only use organically grown carrots, of course. Keith Addison Journey to Forever For an explanation of quotcarbon neutralquot fuels, see Greenhouse gases and global warming Identifying plastics What is this quotHDPEquot plastic that people use for mixing chemicals, and how do you identify it What sorts of plastics can withstand what sorts of chemicals HDPE is High-Density Polyethylene, a tough, translucent, highly resistant plastic used for bottling chemicals, among other things -- 2 plastic, usually marked with the symbol on the right. PET bottles are the transparent plastic bottles that soft-drinks and bottled water usually come in, generally holding 14, 12, 1 or 2 litres. PET stands for Polyethylene terephthalate, a tough, light, resistant plastic thats easily recycled. The recycling code on the bottle is 1. Identifying different kinds of plastic and their properties . American Plastics Council (120kb pdf): americanchemistrysplastics bin. aspCID1102ampDID4645ampDOCFILE. PDF Plastics Identification -- from the Society of Plastics Engineers, Mid-Michigan Section -- 28kb pdf file, download here . Chemical compatability -- Chemical Resistance Database, Cole-Parmer: To search, select at least one of three criteria to search on, Chemical, Material, Compatibility Level. If you wish to search by compatability level, you must specify a chemical or material. coleparmertechinfoChemComp. asp copy Copyright of all original material on this website is the property of Keith Addison, unless otherwise stated. It may not be copied or distributed without the explicit permission of the copyright holder. All material is provided quotas isquot without guarantees or warranty of any kind, either expressed or implied. Save your time and get on time success in itil foundation and pmp exam prep exams by using our latest 350-030 and other superb exam pass resources of VCPVCD510 and 642-436.