What Kind of Thermometer Is This?

Just a guess..could be the thermometer used for measuring body temperature of cattle. ( used rectally..)

cheers.

Oh..... what a lovely thought..... do cows need an accuracy of 0.05*C??

Looks like an ordinary laboratory thermometer. Immersion depth is at least enough to cover the bulb at the bottom.

What with a range of 2½ degrees centigrade???

My standard thermometers cover a much wider range than that.

I would love to know how these are manufactured, to be able to blow a bubble into the capillary to give an offset zero must be very difficult?

John.

Oops! I didn't notice that the range was so small! I have seen thermometers around this university which have relatively small ranges, but none as low as 2.8 deg. C. I have also seen thermometers which start their calibration marks at 35 deg. C, for example.

I would guess that it would be used in some sort of lab procedure/process where temperature is very critical. I made a controller once which kept temperature constant within 0.1 deg. C at around 500 deg. C for a toluene/pitch mesophase reactor. The actual temperature at which there is a phase change is not so critical as maintaining the temperature at that point.

Who knows?

So the question would be what process needs to be kept at 40^oC? I would hazard a guess at an old industrial yoghurt makers thermometer!

I was just going to say Yoghurt......

Damn...you know where you can shove it...(if other posters are to be believed).

Maybe it's for checking the fertility cycle of cows or some such? Too big for a cat

Del

No, Del,

it's not too big for a cat.

WOOOF!

Yeast for baking?

Looks like a thermometer for a cow or another animal. Cows have a very narrow temperature limit as do many other warm blooded mammals. Typically, these range from 38.3 - 39.4 °C, but this one seems slightly elevated, so it is probably specialized to a particular animal.

Since these are typically rectal thermometers, I hope that I am not too late to stop you from putting it under your tongue!

Ohhh excellent link Techno...

It has the model number as mine ASTM 120C /IP 92C

So it is accurate to 0.05*C for total immersion...

Great!

Now can anyone tell me how on earth they make the capillary tube bubble allowing 0 *C to be shown as part of the scale???

I presume it is either a logarithmic scale, or it has a narrow section where the scale is marked.

No Techno, if you look at the third picture the capillary tube has a 'bubble' between the zero +/- 0.3*C and the main scale of 40 +/- 1.4 *C

The bubble must have the exact volume of about 40 inches of the main scale to allow a step from approx. 2*C to 36*C...

As the scale markings are about 1"+ per degree the thermometer would have to have been about 4 foot in length if it was a linear scale, quite how they produce that bubble in such an exact way baffles me...

John.

Reference point......the bubble

The marked scale at 0 and 40 is narrower then the bubble.

Ok even I don't believe me, but the physics is the same.

I am sure they put the scale on last, or have an exact amount of air blown into a softened tube.

Now can anyone tell me how on earth they make the capillary tube bubble allowing 0 *C to be shown as part of the scale???

How about making a thermometer which is good for about 0 to 7^oC then heating the central section and raising the bulb to a well calibrated 42^oC. The tube fills and the bubble must expand by exactly the right amount to "fill the gap" between 1 and 38^o.

Of course the little bit of mercury in the bubble is now too hot so you'd have to adjust the procedure to take this into account.

There's another problem: if you now accidentally heat a thermometer made in this way to greater than 42^o it explodes. So there must be another way of opening up the "safety" expansion bubble at the top end.

...and this article explains briefly why that is important.

http://www.engineeringtoolbox.com/dynamic-absolute-kinematic-viscosity-d_412.html

Ahh good link there bubbapebi...

So that's what its all about then...

Some of these Lab thermometers have similar ranges. Perhaps a Saybolt Viscosity (Reid Vapor Pressure).

http://www.millerweber.com/c3.htm

Well, doesn't any one think the writing on the back is a clue for something?

I mean it clearly states its 'kinematic viscosity' and give an immersion depth of N168 whatever that is...

I assume it must be calibrated against 0 *C as the scale is offset to give an accurate 0 +/- 0.3 *C

It strikes me as being a bit unusual but I was hoping someone recognised the scaling or the wording...?

its too delicate for a rectal thermometer, the mercury bulb is enormous, about an inch long...

John.

http://www.petrotest.com/petrotest_product_20-0150_en.pdf

Judging by the very small range, and the brass "caps" on both ends, seems to me it is intended to be mounted on something in order to measure very small temperature excursions from some "normal" around 100°F (37.8°C)...and should never be immersed. Seems its intention might be to hold some "environment" within a specific narrow temperature range. Funny thing....it's range approximates the range of body temperatures (below critical or fatal) which might be measured in a human being with fever. Not that I'm drawing any such conclusion, though.

It is for veterinary use.

You wrote: Does anyone have a clue as to what it what used for and the immersion depth of it???

It Depends on how deep is the butt...

Wangito.

LOL Good one. And it comes with matching case, too.

Whats great in offsetting? Mark a line where mercury is there at 38.6 deg.

Regarding Resolution of o.05 deg.: Smaller the capillary diameter, more is the resolution.

"What's great about offsetting...."

Look at the third picture and read the posts above then tell me how they put a calibrated (roughly) bubble into the capillary tube!!

Maybe the filling of the tube to a specific gradient line, with a tightly controlled environmental temperature will compensate for any manufacturing differences in the glass blowing process.

Hmmm could be...

I'm sure they can set 40*C and etch the scale at the correct point afterwards...

I'm just sooooooooooo curious as to how they make these 'impossible' things on a production line???

Because the 'bubble' looks like two cones back to back I was wondering if they could cut the tube and drill the two cones in each end and then invisibly glue / melt them back together again??

John. I must google thermometer making... LOL

Actually the bubble looks quite smooth and rounded. It only looks like a cone because it is half filled with mercury. This could easily be done by heating one section of the tube and blowing.

How about they form the tube, let it cool to a certain temperature where the glass will not expand if extra air is blown in, then they heat just the portion where the bubble will be and blow in enough air to create the bubble? To keep the outside diameter of the tube the same, they can use a collar to restraint it, or stretch the tube.

I suppose it must be something like that... a ring of flame to heat the one section hot enough..

But Hey! I would hate to have to design something like that for a production line!!

Mind you they can't sell many of them, the prices I've come across say these type of thermometers sell for $100 a piece, so maybe they are made almost by hand??

John.

What region did it come from?

How about used fully immersed (as per the labeling) in something like a batc fermentation process...as in brewing...or baking...etc?

I do not believe the "deformation" in the capillary tube is of any great consequence, since fabrication imperfections are commonplace, even typical, of glass capillary (factory calibrated) thermometers of narrow measuring range...such as, for example, body temp clinical grade (oral and anal) thermometers...although I suppose it's possible that having a glump of mercury could help to inertially stabilize the entire mercury column.

Please note, also, that both ends of the instrument (capillary tube) are fitted with (let's call them) metal heat transfer probes, which suggest that, when immersed (when both ends are immersed), the mercury column will be constrained at both ends...will generally expand and contract bi-directionally (not like a shake-down, say, oral or other single probe thermometer). The purpose of the "zero" scale, then, would/could be for calibration purposes (similar to a vernier if you will) for the purpose of adjusting the visual read to "true read" value.

An additional possibility—this of course would be conjecture, since the posted photo magnification does not permit close inspection—could be that the instrument serves secondarily as a sensor (as in, alarm actuator of feedback enabler) since mercury is conductive.

While interesting, I doubt the importance (or, at least, the criticality) of knowing this instrument's exact usage history; simply knowing how it works would bring to mind pertinent applications...such as suggested above. Also, Cowanon's post suggests to me another possible, practical application to which a devise of the sort might be put to use: the monitoring of circulating whole blood temperature (and, hence, blood viscosity and patient somatic compatibility) in a heart-lung machine.

Anyway, just something to ponder. Hope it's stimulative, if not useful.

I was working in an defunct Auto body shop last year and there were about 40 to 50 of those thermometers there. nobody knew what they were used for. I thought that they used them for fibreglass preparation or special paint mixing. no brass cases. about 12-14 inches [30-40 cm] we threw them out.

Electroman purchased one of these.

Yes, and I got a bargain!

A calibration grade thermometer accuracy of 0.05*C at 0 *C and 40*C

If you look at the links above you will see they cost over $100 each new, so $4 was a great buy!!

Pretzel, you either threw away over $5000 of thermometers or you threw out the normal cheap, standard ones

John

or electroman bought a throwaway?