Heat Flux Sensor Calibration Technique

A new heat flux sensor calibration technique has been developed that is traceable to the National Bureau of Standards. It can be used to calibrate sensors at the temperature and heat flux levels typically found in the field, without requiring any expensive equipment or special experimental techniques. Sixty-four sensors have been calibrated with a mean precision of 2.2%. Three sensors were independently calibrated by Dynatech, and their calibration factors were all within 2% of the Massachusetts Institute of Technology (MIT) values, whereas the manufacturer's calibration factors ranged from 99 to 151% of the respective MIT values and so are effectively useless. There is evidence that the thermal conductivity of a sensor may vary by as much as a factor of two from sensor to sensor, and therefore a technique for measuring this is discussed.