Bill:
as you will have seen from my reply to Dr. Mayf, there are a lot of ways to
consider testing the system, and I (or anyone) would be guessing about
priorities, until we get some data to think about.
Since you have a heat-treat furnace available-- and since the accuracy of
your ET readings is probably most important to you-- I suggest the
following:
1. Provide a way to get all your ET TCs in the furnace (and the TC leads
"out" to the outside environment). It would be best if you leave the "back"
part of the TC sticking out of the wall into the cooler air, since some TC
brands have materials that can melt, where the leads go into the rigid part
of the TC.
2. Inside the furnace, "bundle" the ET TCs in close proximity with the
reference TC, and shield all the TCs from direct radiant heat transfer (if
you have a ceramic tube to stick them into, that should work well.
3. Adjust the furnace for-- say-- three different stable temperatures,
bracketing your expected exhaust temp by 150-300deg. F, plus and minus.
Collect your ET data on your datalogger, and write down the corresponding
temperatures of your reference device. Run long enough to see (from the
traces) furnace stability before you go to the next temp.
4. At one or more of the temp points, try varying the 12V supply to the TC
field amp by +1 and -3 volts; note any change in TC output. Now try varying
the voltage to the datalogger.
5. At one or more of the temp points, try "swapping" the two (I assume you
have two) field amps-- do all the TCs maintain their same recorded temps, or
are there changes?
6. If you have the field amps on a table-- bang the table repeatedly with
something; does that show-up on the temperature chart?
I would think that by the time you do all that, you'll know just about
everything (that is important to us) about the basic accuracy of these
units.
Expect 3-5deg F bias differences between the type-K TCs, at 1300 deg. F.
Anything up to that amount is of no concern at all.
I'll expect a complete report! (P-u-h-l-e-e-z-e?) I'll bet Mayf would like
one, too.
Good luck.
Russ, #1226B
p.s. yes, I know OMEGA; have done business with them for many years. I've
learned a lot from them.
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