Cheap thermometer calibration technique?

[jasen]

~130F, max. I am frequently asked to measure the temp of a stack of press
output (big 6-color sheet-fed presses) to determine if the IR dryer lamps are
functioning properly. Sometimes using an IR gun is fine, but some press
operators prefer the traditional method of a probe inserted halfway down the
stack. It would be nice if my tools' readings corresponded.

Re. the ice "calibration": as someone pointed out, ice & h2o isn't very
IR-emissive, it it? Would it help to mix in a little black ink? (Lots lying
around a print shop...)

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

Bye.
Jasen

 

[The Great Attractor]

There are various temp sensor IC's (LM35 et.al) that can be had in
+/-0.5degC accuracy grades.
If you can get some samples, then they are FREE.

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

Dave.

There's that word again...

SURFACE!

 

[Chuck]

I know this subject of "cheap" and "calibrate" used in the same sentence may
well be anathema to some of you but I need to verify that either my IR temp
gun is accurate or my DMM/thermocouple is, or neither. Accuracy to 2 or 3
degrees F is fine.

I'm looking for suggestions for a simple way to provide some kind of common
temperature "standard" (I use the term loosely, here) I can compare these
against.

Thanks,

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:

http://www.oznet.ksu.edu/library/fntr2/mf2440.pdf

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:

http://www.aemc.com/techinfo/appnotes/EnvironmentalTesters/CA870_872_876_CalProcedure.pdf

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

 

[RST Engineering \(jw\)]

A crude way of checking the temperature accuracy is to use ice water
with crushed ice, and measure the water. This should read within about
0.5 C under ideal conditions.

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

borametric pressure facture must be considered.

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

reference to within about 0.5 C. The water must be purified water.
Tap water will have minerals in it, and its boiling point will be
effected.

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

Jim

 

[Michael A. Terrell]

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 and you'll see that he just doesn't
care. I looked at his business website once, and it was just as bad.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[The Great Attractor]

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

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

 

[The Great Attractor]

In the first place, the OP was dealing in F, not C.

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.

 

[The Great Attractor]

In the second place,
this is neither a crude nor inaccurate method of calibration.

It has errors for IR instrument 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.

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.

 

[The Great Attractor]

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.

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

All three have different temps.

 

[The Great Attractor]

This should be able to

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

Jim

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

 

[The Great Attractor]

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

Said the slanderous, retarded fucking bastard of aed, aee, aem, aee,
etc.

 

[Lamey]

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

"Off your rocker" is a step up for you Prongtard.

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[Lamey]

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

You don't, that's why the regs laff@you.

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[Lamey]

Said the slanderous, retarded fucking bastard of aed, aee, aem, aee,
etc.

You slander and lie in every post you make Archboi.

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[Meat Plow]

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

Nah you're just a drunk and that's forgivable.
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COOSN-266-06-25794

 

[The Great Attractor]

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

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

 

[John Larkin]

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

Bye.
Jasen

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

 

[Angelo Campanella]

I know this subject of "cheap" and "calibrate" used in the same sentence may
well be anathema to some of you but I need to verify that either my IR temp
gun is accurate or my DMM/thermocouple is, or neither. Accuracy to 2 or 3
degrees F is fine.

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

 

[Fred McKenzie]

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-

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

 

[Jim Yanik]

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

so stick a piece of aluminum in the water.
Use an anodized heat sink. Or use a black pot to hold the water.
Measure that.