OT Using Galvanized for Biodiesel

My son and I are interested in making a biodiesel processor. He brought home a barrel he though was stainless but it is actually galvinized.

Can a galvanized barrel be used to warm the oil to dry it, and to mix the methanol and lye, or will the zinc react with the chemicals.

Also, if anyone knows of a good biodiesel bulleting board, that info would be apprieciated.

Thanks,
Tim

The lye (Sodium Hydroxide) will react with the galvanizing (zinc), and strip it right off the barrel. So that's out. You could probably use it to preheat the waste vegetable oil, but even then some folks say to avoid using galvanized fittings in any diesel fuel application, for fear of the zinc flaking off and eventually getting into fuel injectors.

i am with David, never use any galvanised with diesel fuel.

Usually metals are acid sensitive, so with that respect the zinc should be fine. However, zinc is a catalyst for certain organic reactions. Since your are performing an organic reactions (transesterfication) you may induce other reactions that you don't want. Also you may not be able to get the galvanization as clean as you want. For lab settings glass is used for its nonreactiveness. For an industrial scale stainless would probably be better or a dedicated plastic container designed for the purpose. The second problem with galanization is it is just a surface treatment. The zinc 'rusts' and in doing so sets up an electric current that prevents the underlying iron from corroding (cathodic protection). The iron is protected only until there is no zinc left. Heating and cooling could accelerate this process and destroy the barrel. Stainless steel uses cathodic protection as well but the chromium is fully interspersed, not just a surface plating.
Finally, you should be careful about where you get your information, may of the sites do not correctly describe the process (you never actually form methoxide by mixing lye and methonal) and the technique for titration are usually not very accurate. These might not seem like big deals but lye can be just as dangerous as battery acid and not fully understanding what you are doing could lead to a dangerous situation.

PS warming the oil won't dry it unless you get above the boiling point of water, and think of what happens when you bacon in a hot pan of grease........(a funnel separator would be better to get most of the water out)

Sodium Hydroxide should not, on its own react with zinc (the degradation of zinc is an electrochemical on that require an acid as the electrolyte), however I am not saying it wouldn't react with regular diesel fuel. If it is slightly acidic from either additives or naturally occurring organic acids that would explain the reaction.

Thank you for the excellent replies gents. I will avoid using the galvanized barrel for bio-diesel.

Also, I went out to take a closer look at the barrel (son and freind brought it home late last night) it is actually a neat, very heavy duty old thing.

About 60 - 75 gallons, heavy gauge steel, re-inforced ribs around the mid-section and re-inforce lips on the ends - looks like lots of hand welding. Also quality galvanization - thougt is has sat in the woods for decades at least, very little rust, mostly on the lips where it has been abraided.

Has what looks like a manufacture date stamped into it 5-16-15

I'm not sure what I will do with it, but probably would not want to cut it up and weld onto it to make a processer anyhow.

It has a small amount of liquid in it, area around the spigot smells like oil. Hopefully what ever it is it is not hazardous otherwise it will go back to the freinds house.