Temperature sensor calibration is not something industrial technicians often deal with. At most, they’re going to tweak a transmitter or some receiver device to reduce or eliminate the inherent error in the sensor. Unfortunately, that can only be done at a single temperature.

Martel 3001

It’s a different story for higher end devices like the Martel 3001 Bench Calibrator or even our hand held MC-1200 and DMC-1400 multifunction calibrators. For them you can enter constants for your temperature sensor so it is matched to the calibrator across the entire measurement range. This makes the calibrator into a very accurate thermometer.

This begs 2 questions. One, how do I get those contants to enter into the calibrator, and, two, what’s the point of doing this?

First, let’s make one point clear. The probes we’re talking about are resistance temperature detectors (RTDs), sometimes also called PRTs or SPRTs. The Hart Scientific guys over at Fluke have a very nice white paper about how to take a probe more or less off the shelf and get the constants for it. However, you normally get the constants from the probe vendor. These kind of probes cost more as you have to pay for the data.

The 3001 can use either Calendar-Van Dusen constants or ITS-90 data for curve fitting. The hand held calibrators only work with the Calendar-Van Dusen constants.

Other than for checking the temperature of something what’s the point of this? Well, that is the point and the most useful and common application is to use the calibrator/probe combination with a dry well temperature calibrator to improve its overall performance in testing and calibrating temperature loops.