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

Bob Camp lists at rtty.us
Sat Jan 26 22:20:46 UTC 2013


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" <jfor at 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" <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.
>> 
>> 
> 
> 
> _______________________________________________
> 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_lists.febo.com mailing list