Thermocouple 1

[pedersonpoint]

Is it important to keep thermocouple wires the same length between the thermocouple and the pyrometer?

 

[Compositepro]

No, within reason. Omega has an excellent technical reference in their printed catalog. It is broken up into pieces on line.

http://www.omega.com/temperature/Z/pdf/z021-032.pdf

 

[roydm]

Looking at your question, "Pyrometer", are you refering to an old moving coil type non-electronic meter. If so, yes adding extra resistance will cause too much Voltage drop.
Roy

 

[pedersonpoint]

Yes the pyrometer is a analog typy made by Alnor!

 

[waross]

The old pyrometers I remember were used with companion thermocouples and the length was critical. The analog meter was powered by the thermocouple output and the meter was calibrated to take into account the resistance of both the pyrometer movement and the thermocouple leads.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

The newer analogue pyrometers by Alnor seem to have amplifying circuitry on-board. That would make the wire length a non-issue.

What model is it?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[danw2]

Anyone know how the older style Alnor's (without the circuitry) accomplished cold junction (ice point) compensation?

A fixed offset assuming a constant ambient temperature?

 

[rasevskii]

The cold junction compensation in Honeywell-Brown moving coil pyrometers was a mechanical pointer showing the ambient at the pyrometer instrument. The zero setting of the moving coil was shifted by a bimetal spiral to agree with the ambient as shown by the pointer on the main temperature scale.

At calibration checks, the zero of the instrument had to agree with the mechanical pointer at open TC circuit, and could be adjusted.

Other suppliers used similar methods.

Obviously the TC extension wires had to be correct for the type of TC used, so that the cold junction was at the instrument.

rasevskii

 

[danw2]

Interesting.

Thank you, Rasevski.