[AR] Re: Explosive decompression of wallet with o-rings

  • From: "Monroe L. King Jr." <monroe@xxxxxxxxxxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Sat, 22 Aug 2015 13:55:24 -0700

Ah ha ha!

How long is the exposure time with these O-rings?

-------- Original Message --------
Subject: [AR] Explosive decompression of wallet with o-rings
From: David Weinshenker <daze39@xxxxxxxxxxxxx>
Date: Sat, August 22, 2015 1:25 pm
To: arocket@xxxxxxxxxxxxx


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.

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