The Effects of Overpressure on Pressure Gauges

Standard pressure gauges are manufactured to withstand a 25% overpressure, but this would be for short periods of time only. In a higher overpressure situation the bourdon tube will enlarge and will not return to normal shape. Thus, the gauge pointer will not return to zero. Once this has occurred, the gauge, in most cases, is not repairable and will need to be replaced.

Under normal working conditions, pressure gauges should be used so that the pointer is at mid range and only for short periods of time at full range. Long periods of use with the pointer at full range may stress the bourdon tube and over a period of time the pointer may no return to zero.

If in the situation of a pump start-up, or a gate valve closing, the gauge could be subject to a spike pressure and this could be ratified by using a higher range gauge, fitting an overload valve, or a snubber to reduce the sudden flow into the gauge.