Thermocouple accuracy

[Nessmuk]

I just got my multi tester with millivolt output. I tested my pyro gauges and figured out where they read at what voltage. Do all thermocouples read accurately as to output at temperatures?
As a beside, I opened up my old Isspro TurboMax gauge I thought was bad. Found a nut and a screw in the egt half, stuck to a magnetic damper. Now I have two of the Isspro, old style and new.
The banks gauge was wacky at first, but then after a run up and down the scale, it's good too. I'm the owner of three egt gauges. The numbers were further apart at the bottom of the scale and close at the top.
Maybe isspro will take the new one back?

As follows,
MilliVolts- Banks temp- Isspro temp
.001-225-
.005-400-
.010-625-400
.015-825-725
.020-1050-1000
.025-1300-1300
.030-1500-1550

 

[Sand]

Ive got a K series thermocouple that outputs from 0 - 3v and I have it wired to a voltmeter on my dash. It seems pretty linear. The factory graph with it is a straight line from 0- 1800 degrees. How about repainting the dash guage to calibrate it LOL. unless its digital of course. I was wondering about the lifespan of a pyro probe too the other day.
Sandy

 

[Nessmuk]

Can you post that graph?

 

[Sand]

 

[Nessmuk]

It looks like they both read high. I found 26 MV is 1150 degrees.
According to that, I can see 1400 on my gauges...
Wired they are both off that amount.
I should try a Millivolt gauge in line with it.

 

[Sand]

Are your guages digital stepper controlled or analog meters?

 

[Nessmuk]

The gauges are analog. At least the Isspro is. The other is sealed.
The tester is digital.

 

[Sand]

Analog guages usually have a resistor inline behind the face to fine tune the guage. You could go up or down in value to correct a wayward guage. They are quite crude overall and just a "guage" of whats happening (haha) My needle is connected to a rubber shaft. As the electro magnet gets more power it twists the rubber shaft further. However resistance from the rubber part climbs rapidly as it twists further. This means the increments at the top of the guage are closer together than those at the bottom. As well I suspect that the rubber fatigues over time and the guage reads higher and higher as 20yrs or so pass.
Im really into my guages at the moment.

 

[Will L.]

Different design thermocouplers generate sligty different voltages. Type K are supposed to be in a set scale with all type K. However, since they are not designed by mfrs to be used separate from their gauge, they can make them out of spec and compensate by gauge adjustments.

Also the spec voltage range can be different. Most commonly, type K is 0-5volt. But again since they are not interchangeable components, they can make it what ever they want.

 

[Nessmuk]

My Isspro that I can open has a spring, and a magnet. It to is more accurate as it climbs. Just plain odd they both the same low at 25 MV.

 

[Sand]

 

[Nessmuk]

Likely the new ones do. My Isspro is 30 plus years old. The banks got 12v'd several times.