Cheap thermometer calibration technique?

This popped up -- a home-made RTD:

He's proven himself to be both stupid and illiterate, so please be nice and stop riling him by shoving his nose at documents that he can neither read nor understand.

robert

There are various temp sensor IC's (LM35 et.al) that can be had in

Of course then you have all the other surface issues that everyone else is talking about.

Dave.

maybe put it in a black matte metal vessel, (eg a stainless bowl that's been blackened by heat.)

Bye. Jasen

There's that word again...

SURFACE!

Having suggested in an earlier post that water and ice might not be "friendly" sources in IR pyrometer calibration, it is worth reading the following thermometer calibration guide:

While the guide provides detailed methods for using water in the calibration of bi-metal, thermocouple, thermistor, and other thermometers, it says the following about IR thermometer calibration:

IR thermometers are calibrated using a ?Blackbody,? which emits a given amount of energy at a given temperature. A blackbody calibration instrument is expensive. However most manufacturers of NIST IR thermometers provide a calibration service for a nominal fee for yearly calibration and certification.

On the other hand, AEMC (an instrument manufacturer) offers the following water/ice calibration technique:

Please note AEMC's concept of acceptable errors using these standards! That should explain why serious calibration requires a cavity-type blackbody source.

One can usually calibrate an instrument using a variety of standards, but it is prudent to understand the errors each introduces.

It's yet another instance of the "good, cheap or fast - choose any two" constraint.

Chuck

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In the first place, the OP was dealing in F, not C. In the second place, this is neither a crude nor inaccurate method of calibration. In the third place, we have data that shows that for crushed ice, water, inside of a decent thermal chamber (like a thermos bottle) it will be within millidegrees of 32 °F.

You can boil some water, but the

That's "barometric" last I looked. The correction factor has already been posted ... 29.92" Hg. is the reference pressure and the correction is approximately 1 °F for each 1" Hg. drop in pressure ... which is one HELL of a drop. Just for reference, 1" Hg. is approximately 1000' of altitude from sea level.

This should be able to

The spelling is "affected" and the requirement for purified water is horsefeathers.

Jim

You're wasting your time trying to correct Jerry. Read some of his posts on news:sci.electronics.repair and you'll see that he just doesn't care. I looked at his business website once, and it was just as bad.

The "experts" in the group would rather simply have you and everyone else believe that I am off my rocker.

You're kidding, right?

I am quite sure that the OP knows all about scale conversions, and even likely has a good grasp on direct "off the top of one's head conversions.

Pedantic idiocy, is what that remark is.

It has errors for IR instrument calibration.

Which is fine and dandy, HOWEVER, for IR, there ARE issues to consider.

For someone so pedantic, one would think you would care about such issues.

A black body CAVITY is the better source.

So... what... barely boiling... roiling boil... hearty, full boil?

All three have different temps.

For such a pedantic twit, you sure don't know when what matters and what doesn't.

Nah you're just a drunk and that's forgivable.

Not drinking, and you're just a goddamned retard.

Both ice and water have IR emissivities of about 0.98... they are already as 'black' as things get. So crushed ice in water, freshly stirred, is a near-perfect 0 degree C IR target in any vessel. A thermos is ideal to keep it very close to 0 C.

John

One stove and one bucket of ice. Put thermometer in Boiling water. tha's 212F (100C) (at sea level).

Put thermometer ic ice bucket that has water up to just cover the ice. that;s 32F (0C). (We did this often in physics lab in high school and college!)

Angelo campanella

Angelo-

I've used this technique for standard thermometers.

However, the IR gun is a different animal. Its reading is dependent on the "emissivity" of the surface being measured. If DaveC looks at the specs of his, he will probably see an emissivity factor mentioned along with the accuracy data.

Fred

I would put money on the therocouple thermometer, for what it's worth.