An investigation on the effect of humidity on the zero signal of a strain gauge measuring system

Abstract

Humidity is one of the most important ambient factors influencing torque calibration readings. The present study addresses the effect of relative humidity on the readings of reference torque transduction and amplification devices. The results revealed a linear effect of increasing humidity on the readings of a DMP40 torque amplifier and a torque transducer at four different temperatures. Furthermore, humidity effects were smaller on the DMP40 amplifier than on the torque transducer across all four temperatures. The results also showed that the summed effects of humidity on amplifier and transducer calibration readings were larger when each device was operated under different humidity and temperature conditions (i.e. torque amplifier placed inside a controlled climate chamber and transducer outside, and vice-versa); as opposed to smaller summed effects, observed when both devices were operated under the same ambient conditions (i.e. both inside the chamber). Therefore, it is recommended to test the effect of humidity in setups where the two devices are under common humidity conditions. This is likely to lower the uncertainty parameter of obtained torque calibration readings and is a useful consideration for inter-laboratory comparisons and performance testing.

Keywords

• Strain gage
• torque amplifier
• relative humidity
• ambient temperature
• international system