How to measure a VXI board's thermal / air flow performance?

[MichaelC]

I am looking for information on requirements and testing procedures as they relate to the VXI bus and cooling. Specifically, I would like to make some temperature measurements on some VXI cards to see if the increase in airflow temperature (temperatuer of exhaust minus temperature of intake) is within 10 degrees C.

Quite a few documents reference a document called VXI-8 (Cooling Characterization Methodology Specification). I have not been able to locate this document. Would you happen to have it?

Also, any information you can provide on the best procedures for measuring temperature drop, pressure drop, air flow, etc. across a VXI card would be much appreciated.

Thank you.

[Jason_D]

MichaelC,

It looks like this is a IEEE document that can be found here if you have a IEEE account.

[MichaelC]

Thanks. But the document didn't really answer my question. Perhaps an example would be better.

The NI VXIpc-872B embedded controller, for example, has an ambient operating range of 5 to 50 °C. What exactly does this mean?
 
If you were performing a test to determine if the temperature of the VXI card is being exceeded, how would you do it?

Let's say you installed the controller in a VXI chassis (with integral cooling fan), put the chassis+card in an environmental chamber, and turned the unit on. One thermocouple measures the temperature entering the card (at the bottom), while another thermocouple measures the air temperature exiting the card (at the top). The chamber temperature's setpoint can be varied up and down.

In this example, would the intake air temperature (i.e. air temperature entering the bottom of the card) have to be less than 50 °C? Or would the exhaust air temperature (i.e. air temperature exiting the top of the card) have to be less than 50 °C? Or does it mean the surface temperature of any component on the board must be less than 50 °C?

Thanks,

Michael

[Scott-M]

Hi MichaelC

Ambient temperature range reefers to the temperature of the air surrounding your device, in the example you sited this would mean that the in take air should be between 5-50 degrees C.

For a detailed description of the test we do to check ambient temperature range you would have to look at the documents for IEC-60068-2-1 and IEC-60068-2-2.

Scott M.

Application Engineering