What is the total uncertainty of a PCI-4351 connected to a CB-68T?

[slnisupport]

Hi;

I have been requested by our accreditation board to find out the total uncertainty of our data logging systems.  The uncertainty is requried for the ISO 17025 quality system. Throughout our lab we are using PCI-4351's connected to CB-68T.  I have seen that the accuracy of the card is 0.42°C (I assume that means +/- 0.42°C and not +/- 0.21°C), but what is the uncertainty of those measurements, and does the CB-68T add additional error when connected to the card?  Any possible help would be appreciated. 

Thank you for your time.

Michael Carter

[Now_With_Underscores]

Hey Michael,

From the information you provided, I gather that you're using a J type Thermocouple with a 10 Hz Filter.  In this case, the maximum error for the 4351 at 0 and 760 degrees C is +/- 0.42 degrees when the device is between 15 and 35 degrees C.  This is the maximum amount of error, so it specifically IS the uncertainty of the measurement.  As long as the CB-68T is in the 15 through 35 degree C range, no additional accessory Error needs to be added.  If you fall into the 0 to 15 or 35 to 55 C degree range, then you will need to include the additional error.  If you look at Page A-1 of the 435x manual, all of this information is listed, as well as the additional accessory error coefficients that need to be added if you're below or above the 15 to 35 degree C range.  Have a great afternoon!