How come some low-end thermometers are still made in mercury version?

Why are some thermometers are available in both spirit and mercury
version?

i.e. ERTCO 613-3S spirit filled -20 to 150C 1C div
ERTCO 613-3 mercury filled -20 to 150C 1C div
They are both supposedly rated for same accuracy of +/- 1 div up to 100C
and 1.5div from 100 and up.
They're both within NIST tolerance.

-20 to 110~150 ish is your average high school chemistry thermometer.

Why is there a mercury version still available if they both provide same
accuracy and repeatability?

Besid the obvious spill containment, red spirit is a lot easier to read.

Who'd want a hard to read, clean up nightmare mercury thermometer over
the easy to read red spirit type?

in article [Only registered users see links. ], AC/DCdude17 at
[Only registered users see links. ] wrote on 11/8/03 1:56 AM:


I used to be an active fly fisherman. One of the tools of the trade is a
thermometer to measure water temperature. Fish activity is closely tied to
water temperature/

I had a thermometer using a red spirit column. It had very slow response.
One could freeze a butt off waiting to reach equilibrium. Then I go a
mercury thermometer with a large bulb. In comparison to the other one, it
was a dream to use.

Bill

Dear Repeating Decimal:

"Repeating Decimal" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...
....
to

It wouldn't fix the need for "personal" thermometers, but it sounds like
thermal conductivity is the problem with red spirit. If you immersed the
entire thermometer into the environment to measure, you'd get a faster
reading.

David A. Smith

In sci.physics AC/DCdude17 <[Only registered users see links. ]> wrote:

Price?

"[Only registered users see links. ] \(formerly\)" <dlzc1.cox@net> wrote:



I agree that it sounds like a thermal conductivity problem, but I'm
not sure that total immersion will solve anything. The (relatively)
large reservoir of fluid in the bulb may be the culprit, being slow to
equilibrate. It's also possible that the glass sheath of the bulb
area of the spirit thermometer was thicker for some reason. Glass is
a pretty poor conductor of heat.

Steve Turner

Real address contains worldnet instead of spamnet

AC/DCdude17 <[Only registered users see links. ]> wrote:


There are a large number of temperature controllers in the industry
(the I2R Therm-O-Watch line) which detect the position of the mercury
thread via capacitance. These do not work with spirit thermometers.

Also, spirit thermometers seem to be much more prone to separation of
fluid column. Just rolling around in a drawer is enough to do it. Of
course, this destroys accuracy. While this can be fixed, it's a pain
in the butt.

Steve Turner

Real address contains worldnet instead of spamnet

in article DS8rb.22968$PD2.22238@fed1read05, [Only registered users see links. ] (formerly) at
dlzc1.cox@net wrote on 11/8/03 8:30 AM:


That was the method. Both thermometers has loops thaat could be used to dip
them into the water.

Bill

Repeating Decimal <[Only registered users see links. ]> wrote in message news:<[Only registered users see links. ]>...
Snip

Because, to those familiar with them, mercury just plain works
better.

BTW - This business of treating a broken thermometer as a toxic
disaster is a beautiful example of what can happen when you allow a
bureaucrat to advance beyond his level of competence.

Pragmatist

X-No-Archive: Yes

Ian Stirling wrote:


Surprisingly, exactly the same.

X-No-Archive: Yes

Repeating Decimal wrote:


I believe that such thermometer have higher accuracy than a high school
chem/phys lab thermometer which is in order of +/- 1°C. Since mercury have
better linearity and repeatability, sometimes spirit can't replace it in
accurate measurement.

But as for "student grade" toss around the lab, -10 to 105 or -20 to 110 C
type thermometers that will probably never face automatic control system that
uses capacitance or require fastest response, what benefit does mercury
version provide? Teachers go crazy when one of these breaks in the lab..