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 z ero stability of a differential quartz Bourdon gauge are presented. Th e gauge studied has a helical fused-quartz Bourdon tube as the pressur e-sensing element with an electromagnetic nulling device. The full sca le pressure range of the gauge is 110 kPa. Zero shift values at differ ent line pressures for various gases under different conditions have b een measured. It is observed that when the line pressure is increased from an initial pressure of zero, the zero shift is negative: converse ly, 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 pressur e. The results obtained for helium and hydrogen show a completely diff erent behaviour of the quartz Bourdon gauge from those observed for ni trogen, argon and oxygen. An analysis of the experimental results reve als that this gauge behaves in different ways with different gases. Th e possible causes of this behaviour are briefly discussed.