Thermocouple Type R and S ... Identification

[AF PMEL]

Anyone got some insights on determining or identifying a thermocouple if it is R or S Type other than at time of purchased?

[spanishfly25]

both TCs look identical, but the mv curve is different type R at 1768C should read 21.1 mv
and Type S should read 18.7 mv

[metrologygeek]

Or perhaps an easier test temperature to achieve: 300°C type R = 2.401mV and type S = 2.323mV.

[spanishfly25]

I went with the higher temperature because at 300°C the 0.078mV difference could be hard to see once you add the inaccuracies of the mV meter and the zero compesation junction. but also most labs can't go that high in temperature.

[AF PMEL]

Other than inserting the TC into a temp bath monitored with a temp probe and the mV read on a millivolt meter would be the sure method of identifying the type of TC (R or S).

[metrologygeek]

No. Platinum 10% Rhodium looks just like Platinum 13% Rhodium.

[AF PMEL]

So what other ways to identify type R and Type S?

They look identical. Reason being is I have TC wires but can tell which one is Type R or Type S.

[jimmyc]

http://www.omega.com/techref/thermcolorcodes.html

[Hawaii596]

If its bare wire, running them up to some known hot temp and comparing mV values is about the only way to identify them.

[AF PMEL]

After a discussion with a Omega Engineer, Type R and Type S TC wire are identical in looks with the wire color siverish. Whereas if the wire color is of copper, it is identified as R/S TC extension wire.

Therefore, in response to my post, what I have are R/S Extension wires (copper color wires) and it does not matter if the TI is a Type R or a Type S as long as my setup is for extending the TC wire.

What matters is if I have a setup of dissimilar metals then I would need to ensure that I use the correct TC wire (R or S).

[spanishfly25]

I would not use the color for identification,  the difference on color between the two types of TCs is very small and with time the change of color could also be due to exposure to sun light. plus you would need to have both types of TCs sitting next to each other to notice the difference.