EFFECT OF LINE PRESSURE ON THE ZERO STABILITY OF A DIFFERENTIAL QUARTZ BOURDON GAUGE FOR VARIOUS GASES

In this paper results obtained on the effect of line pressure on the zero stability of a differential quartz Bourdon gauge are presented. The gauge studied has a helical fused-quartz Bourdon tube as the pressure-sensing element with an electromagnetic nulling device. The full scale pressure range of the gauge is 110 kPa. Zero shift values at different line pressures for various gases under different conditions have been measured. It is observed that when the line pressure is increased from an initial pressure of zero, the zero shift is negative: conversely, it is positive for decreasing line pressures. The magnitude of the zero shift for all the gases under different experimental conditions is found to be directly proportional to the change in the line pressure. The results obtained for helium and hydrogen show a completely different behaviour of the quartz Bourdon gauge from those observed for nitrogen, argon and oxygen. An analysis of the experimental results reveals that this gauge behaves in different ways with different gases. The possible causes of this behaviour are briefly discussed.