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Anonymous Poster

Type K thermocouple

07/08/2008 4:52 AM

how to determine type K thermocouple if the two metal is chromel and alumel. which one is positive ?
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PWSlack
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#1

Re: Type K thermocouple

07/08/2008 5:03 AM

A millivolt meter?

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Anonymous Poster
#2
In reply to #1

Re: Type K thermocouple

07/08/2008 5:16 AM

without using voltmeter how to determinne which one is positive?
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JohnDG
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#3

Re: Type K thermocouple

07/08/2008 5:22 AM

According to Wikipedia, chromel is +ve.

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Anonymous Poster
#4
In reply to #3

Re: Type K thermocouple

07/08/2008 5:38 AM

if chromel is +ve, what is the wire insulation colour code.

your help very much appreciate.
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JohnDG
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#5
In reply to #4

Re: Type K thermocouple

07/08/2008 5:46 AM

If you follow the link to Wikipedia and scroll down the page, there is a table giving IEC, BS and ANSI colour codes.

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Anonymous Poster
#6
In reply to #5

Re: Type K thermocouple

07/08/2008 6:01 AM

thank you JohnDG
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Electroman
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#7

Re: Type K thermocouple

07/08/2008 7:44 AM

You will find for type 'K' thermocouple that the chromel wire is magnetic, so a simple magnet will identify the wires.

I think (might be wrong though)

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JohnDG
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#8
In reply to #7

Re: Type K thermocouple

07/08/2008 8:37 AM

Useful tip (if it works!). Anyone got one to try?

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Electroman
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#9
In reply to #8

Re: Type K thermocouple

07/08/2008 9:36 AM

Yep! I remembered correctly, I've just tried it and the nickel/chrome wire is magnetic, other one isn't...

Back in the late 70s we used to use this method when we made thermocouple sensors...

John.

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wrenchpuller
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#10

Re: Type K thermocouple

07/08/2008 9:40 AM

Alumel is magnetic(negative), this is one of the reasons why I and some of the other instrument techs where I work carry pocket screw drivers with a magnet tip. In the U.S. and Canada red is always negative but not always magnetic. Thank you

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Anonymous Poster
#11
In reply to #10

Re: Type K thermocouple

07/09/2008 12:08 AM

alumel is magnetic(negative) i had this many time, when the insulation melt with high temperature. i use my screw driver with magnet tip. to check which one wire is magnetic. in ANSI color code red is negative(alumel)
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Anonymous Poster (4); Electroman (2); JohnDG (3); PWSlack (1); wrenchpuller (1)

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