On 1/26/2013 1:29 PM, Paul Amaranth wrote:
Message: 4
Date: Sat, 26 Jan 2013 16:28:19 +0100
From: Fabio Eboli <fabi...@quipo.it>
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: Re: [time-nuts] OT, looking for a good science forum
Message-ID: <5ef3f142b075fcab38182666a4e50...@quipo.it>
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Il 2013-01-26 14:58 Bob Camp ha scritto:
Hi
Platinum RTD's are a pretty good bet for -80C, they hold up well down
there. For calibration, ammonia and acetylene both have triple points
in the vicinity. I'd probably try ammonia first, but not for any good
Doesn't acetylene have a bad habit of dissociate when pure liquid?
Fabio.
Yes, it's normally stored disolved in acetone. It also spontaneously
dissociates
if pressures exceed 15 psig or 30 psi absolute. That could put a real damper
on your day.
Just pure acetone works well at dry ice temperatures. We used crushed
dry ice
in acetone as an alternative when the liquid nitrogen truck was late
making its delivery
for the cryro lab.
--- Graham / KE9H
==
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