[time-nuts] OT, looking for a good science forum

[J. Forster]

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 <timenut at 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 <FabioEb at quipo.it>
>>>> To: Discussion of precise time and frequency measurement
>>>> 	<time-nuts at febo.com>
>>>> Subject: Re: [time-nuts] OT, looking for a good science forum
>>>> Message-ID: <5ef3f142b075fcab38182666a4e5073b at 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
>>
>> ==
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