Toluene is used in auto fuel for an octane booster but is not compatible with Buna N O-rings. Where I get my ethanal free fuel the distributor says that it is 50ppm Toluene. I haven't researched it yet.....but what's the deal? A while back I had an o-ring swell up in my fuel selector valve, it restricted flow to about 12gph from one tank. Was it from the Toluene? I test my fuel regularly and know I haven't run ethanol through it. Does Toluene fit in with the auto fuel STC?
Not airplane related, but I recently had buna-n o-ring problems in my powerstroke because the ultra low sulphur fuel would make them shrink/harden. I swapped them for viton o-rings and haven't had any issues.
Sure glad you posted. Just think of the bad rap ethanol has gotten and probably as much or more the gasoline was the problem. I know of a fuel selector that has had E10 going through for almost 5 years and it doesn't leak. That o-ring is way older than 5 years also.
Last edited by 180Marty on Wed Nov 09, 2011 4:26 pm, edited 1 time in total.
This is a materials chart showing basic compatibility with fluids for the different compounds of O-Rings. Viton 75 is not very good for Steam or standard automotive type brake fluids.
If you really want to do your research you can go here http://www.marcorubber.com/compatibility.htm and look up the particular fluid in the drop down list and see what rating the O-Ring is at for that fluid. On this list Viton A is listed as a #2 (scale 1-4) at a 10 to 20% swell for Toluene. Butyle is rated 4 - not recomemded.