Hi If the intent is to come up with a triple point cell to calibrate your thermometer, acetone's triple point (at 178.5K) is a bit low. I still think I'd go with ammonia.
Bob On Jan 26, 2013, at 2:51 PM, Graham / KE9H <[email protected]> wrote: > On 1/26/2013 1:29 PM, Paul Amaranth wrote: >>> Message: 4 >>> Date: Sat, 26 Jan 2013 16:28:19 +0100 >>> From: Fabio Eboli <[email protected]> >>> To: Discussion of precise time and frequency measurement >>> <[email protected]> >>> Subject: Re: [time-nuts] OT, looking for a good science forum >>> Message-ID: <[email protected]> >>> Content-Type: text/plain; charset=UTF-8; format=flowed >>> >>> 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 > > == > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
