Hi All,

Can anyone please tell me, how I tell if the bio-diesel is acid free? Do I re-titrate after the washing & drying process?

Will this then tell me that it's ok to use in my car?

Thanks

You could re-titrate, but there is not much to be gained. That type of test quantifies the amount of free fatty acid in oil by measuring the amount of caustic needed to convert it to soap. In the reactor/processor the first action when the meth is added is the same conversion of FFA to soap. Ergo there is no ffa to measure in finished biodiesel. If bio is badly stored for a long period, it will start to oxidise, producing acid by-products which can once again be measured.
The sensible acceptance test for fresh biodiesel is the 3/27 test. There are good descriotions of this in the 'Quality' section.

Tibby, I wouldnt worry - there are many people who run their cars on unwashed biodiesel which is still a little caustic with no problems.

ok thanks guys for your help, much appreciated