[Healeys] Ethanol effects on rubber

Tim Davis BN7 tld6008 at mchsi.com
Fri Jun 22 19:15:17 MDT 2018

You might want to look at these 
I used these recently, they were the only supplier that related what the diaphragm material was and I know Viton is superior where alcohol is present

Tim Davis BN7

----- Original Message -----
From: Bob Spidell <bspidell at comcast.net>
To: Tim Davis BN7 <tld6008 at mchsi.com>
Cc: Healeys <healeys at autox.team.net>
Sent: Fri, 22 Jun 2018 21:07:59 -0400 (EDT)
Subject: Re: [Healeys] Ethanol effects on rubber

Tom's sells Moss parts--at a 15% discount BTW--and I've never seen the 
composition of these listed anywhere (the jet itself, of course, is 
brass).  I doubt there's a lot of sources for these (I'd guess these 
come from Burlen).

It's the same as the ones in my BJ8; I want to see how it holds up.


On 6/22/2018 5:41 PM, Tim Davis BN7 wrote:
> What material is the Toms diaphragm made of? That's what you need to know.
> Tim Davis BN7
> ----- Original Message -----
> From: Bob Spidell <bspidell at comcast.net>
> To: Healeys <healeys at autox.team.net>
> Sent: Fri, 22 Jun 2018 15:19:17 -0400 (EDT)
> Subject: [Healeys] Ethanol effects on rubber
> Just when you thought you'd heard the last on this ...
> Having bragged about my scientific creds, I decided I needed to do some
> 'scientific' experimenting.  I bought a new HD8 diaphragm jet from Tom's
> and put it in a jar submerged in denatured alcohol.  If you're not
> familiar with denatured alcohol, it's ethanol--i.e. booze--with one or
> more denaturing chemicals to make it unpalatable to drink.  When I first
> did this thought experiment, I thought DA was mostly ethanol, but the
> quart I bought at a hardware store claims to be 45-50% ethanol and the
> remainder methanol (and probably some water as both alcohols are
> hygroscopic).  Though this mixture doesn't represent the 10% or so of
> ethanol in gasahol, IIRC from my college chemistry and lab technician
> days that methanol is even more corrosive than ethanol.  So, this should
> be a good test of the rubber part of the jet's resistance to these
> solvents (and the brass part too, I suppose).  I put new jets in my
> BJ8's HD8s two years/12K miles ago, and should have done this then in
> case the results were scary, but maybe this will tell us something.
> I'll check the jet periodically for degradation and, if anybody's
> interested let you know.
> Cheers,
> Bob

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