FEP-encapsulated silicone ones are nice for non-cryogenic face seals,
by the way. You get most of the material compatibility of teflon but
without the total lack of springiness of teflon o-rings, and they're a
lot cheaper than stainless spring energized teflon o-rings.
I say face seal because they share the teflon characteristic that they
can't really be stretched in the major diameter. You could probably
cram one into a large female gland seal, but a male gland seal like
SAE ORB is usually right out.
On Sat, Aug 22, 2015 at 4:25 PM, David Weinshenker <daze39@xxxxxxxxxxxxx> wrote:
Daryle Dismukes wrote:
In the past I've used silicone, fluorosilicone, and EPDM o-rings with
nitrous oxide, but YMMV. I can't remember why Kalrez wasn't used.
Probably (based on a quick scan of a reasonably recent McMaster
catalog) because that's the variety that's egregiously expensive
(compared to pretty much any other available O-ring material)...
for example, Kalrez rings in size 210 (3/4" x 1" nominal) are $82
(each!)... meanwhile, EPDM and Viton (same size) are about 12 to 25
cents each (in packages of 25 to 50), mil-spec fluorosilicone goes
for about $1.60 ($8/pkg.5), and even "ordinary" exotic flavors like
FEP-encapsulated silicone or Viton are only about $7 each...
-dave w
On Fri, Aug 21, 2015 at 9:37 AM, Doug Jones <djones@xxxxxxxx
<mailto:djones@xxxxxxxx>> wrote:
EPDM burns merrily in N2O. The only elastomer I've found that
neither swells nor burns is Kalrez.