Thermocouple color code standards...

[PKTKS]

I am replacing a thermocouple with a more robust shielded (in figure) with metallic braid ...but... after some long searches about POS/NEG color codes I got more confused than when started...

I would expect that RED  would be positive while BLUE negative.. but no thermocouple color code sheet can agree even in the colors used and while Japanese JIS stands RED positive nobody else does that...

This is a default made in china "K" thermocouple ... with BLUE/RED wiring..

Which is positive?  any clue welcome

Paul

[jpanhalt]

On my K thermocouples, the colors are red and yellow.  Red is negative.  It's also magnetic.  The positive is non-magnetic.

[Conrad Hoffman]

I remember some confusion about color codes, but it seems simple enough to heat it up and measure it with a DVM. The signal is small, but there should be enough to tell. The magnetic clue is also excellent.

[PKTKS]

I am building a vote list...

so far  RED is winning the NEGATIVE position... 

 
Paul

[PKTKS]

I remember some confusion about color codes, but it seems simple enough to heat it up and measure it with a DVM. The signal is small, but there should be enough to tell. The magnetic clue is also excellent.

Yep.. that hint of heating it up with a dmm attach should do the trick...

I was so deeply buried in searching color codes that forgot about simple testing.... 

Paul

[TimFox]

I have a cheap digital thermocouple meter where it is easy to invert the thermocouple plug into the meter (bad tolerancing on the slots).  I checked the TC by sticking it under my tongue, then called the coroner to establish the time of death since my body temperature had fallen to 55^o F.

[PKTKS]

I have a cheap digital thermocouple meter where it is easy to invert the thermocouple plug into the meter (bad tolerancing on the slots).  I checked the TC by sticking it under my tongue, then called the coroner to establish the time of death since my body temperature had fallen to 55^o F.

I even tried to invert them on the PID controller ...  just to test the PID itself..

Funny thing that the PID should be able to detect the inverted thermocouple..

So far it worked both ways... 
go figure..

Paul

[jpanhalt]

It all depends on where you put "zero".  Most commonly, it is at +273°K.

[jonpaul]

Used them for decades,  type K  TC USANuniversal code is yellow pos red neg

many other types of TC exist eg iron constantan, with different color code.

Codes vary in other countries.

https://reotemp.com/wp-content/uploads/2015/12/thermocouple-wire-color-codes.jpg

Jon

[bill_c]

Another info source: https://www.omega.com/en-us/colorcodes  They may be a bit expensive, but they do have some good info.