How to measure temperature

[sman]

Hi

I have two attachments, one is labview showing the VI set up used to measure temperature (thermo couple type K) and other one is the physical set up of the instruments.  For some reason when the surface inside the vacuum chamber is heated or cool down I am not able to read the changes in temperature.  I've checked, there's no shortage inside the chamber, thermocouple and the amplifier and so I can not understand what could cause my system not to recognize the change.

Thank you in advance.

I am sorry, I am unable to attach a file from paint and a VI....

[LV_Pro]

Without either the attachments, or a detailed description of how you are measuring the temperature it is difficult to tell you what is wrong. Is the data acquisition portion of your program in a loop (the part that actually measures the temperature.) If yes, is the display of it also within the loop? You mention that it doesn't read the change, indicating that it does make at least one measurement. More detail will aid in helping you.

[Russ_Evans]

Hi sman,

Putnam is right more details are needed. You mention that you checked for a short but can you actually measure a voltage response? Forget trying to acquire with Labview for a moment can you use a oscilloscope or voltmeter to see a voltage response due to a temperature change?

Cheers,

--Russ

[shoneill]

You mention you are measuring the temperature in a vacuum chamber.

You do know that the temperature sensor must make good contact with the walls of the chamber to register any temperature change, right?

A vacuum is a very good insulator so if the thermocouple is in the middle of the chamber, the surface inside the chamber can heat and cool all it likes, your Thermocouple won't change temperature.

This is also why many vacuum chambers of this type employ IR heating which does not require contact.

Just a thought.

Shane.