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Rubberguy · 08-25-2009, 03:21 PM

You mentioned that you had used ethylene propylene for sealing in the nuclear industry. I can go along with that because typically you would be sealing water or some other polar fluid. EPR/EPDM (ethylene propylene/ethylene propylene diene monomer) are also very good against ethanol. The problem comes from the gasoline, it is non-polar and will swell the EPDM like a balloon. So the problem is one of compatiblity. There is a number that is called the solubility parameter and typically it reaches a maximum when the alcohol portion is at 15%. You might be able to actually increase the ethanol content and reduce rubber swell. (I'd try it in a beaker first!)

I'm concerned about the rust issue with the gas tanks from increased condensation in the tanks. I'll do some more reading on this issue and see what turns up. I know I don't really want to deal with a rusty tank in my '73 Coronado.

08-25-2009, 03:21 PM	#15
Rubberguy Junior Member Join Date: Jul 2009 Location: Bristol NH and Welch Island Posts: 9 Thanks: 0 Thanked 0 Times in 0 Posts	Ethanol, etc. You mentioned that you had used ethylene propylene for sealing in the nuclear industry. I can go along with that because typically you would be sealing water or some other polar fluid. EPR/EPDM (ethylene propylene/ethylene propylene diene monomer) are also very good against ethanol. The problem comes from the gasoline, it is non-polar and will swell the EPDM like a balloon. So the problem is one of compatiblity. There is a number that is called the solubility parameter and typically it reaches a maximum when the alcohol portion is at 15%. You might be able to actually increase the ethanol content and reduce rubber swell. (I'd try it in a beaker first!) I'm concerned about the rust issue with the gas tanks from increased condensation in the tanks. I'll do some more reading on this issue and see what turns up. I know I don't really want to deal with a rusty tank in my '73 Coronado.