At 08:08 AM 8/10/2004, you wrote: > For best chemical resistance, recommend that you use vinyl ester resin > for the fuel tank construction. Epoxy will work ok as long as you only > use aviation grade 100 octane LL fuel. Automotive fuels may contain > alcohol and aromatic additives that will attack the epoxy. Vinyl ester > resin is not susceptible to chemical attack by automotive fuels.
It is a common misconception that autofuel will degrade epoxy resin. This is not necessarily so. I prepared two sample coupons of Last-A-Foam and EZ-Poxy. One coupon was saved as a control. One half of the test coupon was fully submerged in autogas and the other half was not. This coupon remained in a sealed container for over four years with absolutely no degradation. There was no loss of strength, there was no sediment, and there was no discoloration of the gasoline. After the coupon was removed and dried off, it was impossible to tell the difference between it and its control coupon. The two things that must be done to ensure a chemically resistant gas tank is to have the mixture ratio correct and completely mixed. If your resin/hardener ratio is off, there will be an uncured component in the final epoxy matrix. It can dissolve in an solvent. The same is true if you do not mix the components sufficiently. Epoxy will work with autogas but your quality control is important. Don Reid - donreid "at" erols.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://www.eaa231.org/AeroFoil/index.htm KR2XL construction: http://users.erols.com/donreid/kr_page.htm Aviation Surplus: http://users.erols.com/donreid/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA State Fly-in: http://vaeaa.org
