Hi I was thinking more in terms of:
http://us.flukecal.com/products/temperature-calibration/probessensors/secondary-standard-prts/56265628-secondary-sprt-prt-t It all depends on what you are trying to do. Since I didn't make the original request, and no tolerance was stated, it's all guesswork. Bob On Jan 26, 2013, at 5:12 PM, "J. Forster" <j...@quikus.com> wrote: > http://edl-inc.com/datasheetPDFgallery.php > > For example. > > Unless you are doing fundamental physics research, are you sure you need a > cryo temperature standard? > > -John > > ============== > > >> Hi >> >> Yes, indeed you can buy or rent a calibrated RTD. You might be able to >> rent a quartz thermometer. The HP version (2804) has been history for >> quite a while. In both cases they come with a cute little disclaimer on >> the accuracy that more or less says: >> >> "We can't be sure that this stays calibrated through the shipping process, >> a triple point cell must be used to verify calibration at the use >> temperature". >> >> One of the reasons HP dropped the product was that people discovered that >> need after it had been in production for a quite a while. Hysteresis in >> the LC cut crystals turned out to be one of several issues that >> contributed to the problem. >> >> Pretty much *everything* with a triple point down at 190K is going to have >> something nasty about it. >> >> Bob >> >> On Jan 26, 2013, at 3:57 PM, "J. Forster" <j...@quikus.com> wrote: >> >>> You can't be serious. Ammonia gas or liquid is dangerous. >>> >>> You can buy calibrated RTDs or rent a quartz thermometer and stay alive. >>> >>> YMMV, >>> >>> -John >>> >>> =============== >>> >>> >>>> 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 <time...@austin.rr.com> >>>> 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 <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> >>>>>>> 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 -- time-nuts@febo.com >>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.