Steel Plumbing
 Steel plumbing is the best.  If you want your biodiesel processor to last a long time then
buy one with steel plumbing.  If you want a disposable processor then buy one with PVC.  
This should not be a hard choice.  Steel plumbing can handle temps over 200 deg F.  Steel
plumbing will not break.  If you have ever done any plumbing work on old houses you know
if you look at PVC the wrong way it breaks.  With 50 gallons of hot oil you don't want your
plumbing to blow out or break.  If this happens you can bet you will have a real mess to
clean up!