On Sun, 12 Mar 2006 06:12:27 GMT, Gunner
wrote:

On Sun, 12 Mar 2006 04:30:49 GMT, "Carl Ijames"
wrote:

Most applications will be for air, in an oily environment, though a
few will be for hydraulic fluids. Is there some material best suited
for general use?

And will they degrade in a short period of time, in the back of my
service truck in hot weather?

What material should I be using?

I will likely purchase from ebay one of those 400 piece selections
for $10 or so, unless someone has better suggestions.

I think Viton is hard to beat as the best general purpose material to
stock. More expensive than Buna or nitrile but much more chemically
resistant when you need that. I don't think I've ever run into an
application that called for Buna or nitrile that Viton wouldn't work in,
and I've had several applications that called for Viton either for
chemical resistance or high temperatures or low outgassing in a vacuum
system. Probably safe for a year or three in a truck toolbox, at least.
It will eventually start to check and then crack when you flex it so it
will be pretty obvious when it's time to toss them. The Parker catalog
is a great resource on materials and especially on oring groove design.
www.mcmaster.com has a great selection, as well as www.sisweb.com (as
someone else mentioned - I've bought several items from them over the
years and think a lot of them, but I am friends with the owners :-)).

Thanks Carl..exactly the sort of answer I was looking for.

Respects

Gunner


I just look in my Parker O-ring book, chemical compatibility section.
I work in the chemical industry. Viton will go to hell in a
handbasket if it sees an amine. EPDM is very good. Buna is fine for
some stuff. I hate Kalrez and won't use it unless I positively have
to (temperatures above high temp silicone).

Look in Section 7 of this link:
http://www.parker.com/o-ring/Literature/ORD5700.pdf . It starts on
Page 163.

Pete Keillor