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

J. Forster jfor at quikus.com
Sat Jan 26 17:12:11 EST 2013


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" <jfor at 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 <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
>>>>
>>>> ==
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at 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 at 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 at 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 at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>




More information about the time-nuts mailing list