Yes but water can be "superheated" too if there are no nucleation points for
bubbles to form and like super-cooling this can amount to a couple of deg C
in a very clean container. However the vapour cannot be superheated without
increasing the pressure .....as in a steam engine, or autoclave. I may not
be as accurate as "temperature nuts" would like but unless you are very sure
of your conditions it is probably more reliable. I notice the wiki on
"temperature scales" doesn't include boiling water (or steam) these days,
but if does say is 17mK low of an exact 100 :-))
http://en.wikipedia.org/wiki/Temperature_scales#International_temperature_scale_of_1990
I note it doesnt actually say where you place the sensor :-))
Alan
G3NYK
----- Original Message -----
From: "Brooke Clarke" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Monday, July 21, 2014 9:11 PM
Subject: Re: [time-nuts] temperature sensor
Hi:
The temperature of steam can be anything above boiling water.
http://en.wikipedia.org/wiki/Steam
Super heating of steam was common railroad practice.
Boiling pure water will get rid of any trapped gases quickly.
In fact this is the recommended thing to do to tap water before using it
for freshly cut roses.
Of course you need to let the water cool before putting them into it.
Removing the trapped oxygen makes them last longer.
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Alan Melia wrote:
er not boiling water....steam. Water's boiling point is affected by the
dissolved gasses and other contaminants.
Alan
G3NYK
----- Original Message ----- From: "Bill Dailey" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Monday, July 21, 2014 5:43 PM
Subject: Re: [time-nuts] temperature sensor
Ice water and boiling water coupled with altitude will give you two
points.
Sent from mobile
On Jul 21, 2014, at 10:12 AM, Attila Kinali <[email protected]> wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer <[email protected]> wrote:
NTC are not that very stable, they are amorphous material winch could
recrystallize slowly and therefore change it's electrical behavior ,
PT100 style is more reliable since it is pure metal
How long is the time constant for NTCs?
I guess, it wouldn't matter for most of the measurements we do,
as NTCs need to be "calibrated" before precision measurements
anyways. Unless one measures over several months, or years.
But on this timescales, i wouldn't really trust an off the shelf
PT100 either. Not unless i measure its stability
For use in GPSDOs and OCXOs, i guess it doesn't really matter,
as long as the NTC stays within spec. There an external loop
corrects for the variation/drift of the measurement.
While we are at it: what is a good way to calibrate/characterize
temperature sensors that is available to hobbyists?
Attila Kinali
--
I pity people who can't find laughter or at least some bit of amusement
in
the little doings of the day. I believe I could find something
ridiculous
even in the saddest moment, if necessary. It has nothing to do with
being
superficial. It's a matter of joy in life.
-- Sophie Scholl
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