Doesn't 63/37 solder melt at 485° F at sea level?
That would calibrate the thermocouple.
The IR is a bit trickier as the surfaces you examine have differing
You likely have a calibrated instrument, but forget to shift for
For the IR to cal correctly, you need a "black body calibration source,
which is typically an Aluminum ingot painted with IR paint.
You can learn a lot here:
These guys are the tops.
Actually, the international standard is a bunch ice covered in water a
stirred well. The standard clearly says that this must be done in
your own coffee cup and the stirring must be done with a plastic
coffee stirrer. You have to stir it up while standing in the company
kitchen and then measure as soon as you are done stirring. You can't
stop to answer the "What the heck are you doing?" question from the
You really need a set of temperature standards. Temperature standard
equipment is expensive.
On a laser temperature reader, there is the EMS "emisivity) factor.
You must set the EMS of the reader to be proper for the type of object
you are measuring. If the EMS is not adjustable on your reader, then
the reference object must be of the correct colour and type of
material to be referenced.
If your reader is expensive to replace, I would suggest you send it to
a calibration lab that can check these types of units.
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. You can boil some water, but the
borametric pressure facture must be considered. 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
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
This should be able to
The spelling is "affected" and the requirement for purified water is
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.
Service to my country? Been there, Done that, and I've got my DD214 to
On Thu, 10 May 2007 08:22:09 -0700, "RST Engineering \(jw\)"
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.
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.
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
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
It's yet another instance of the "good,
cheap or fast - choose any two" constraint.
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
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.
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