Bailey & Mackey’s range of Differential Pressure Gauges are built to the highest standards of workmanship required for such precision instruments. Each individual Pressure Gauge is subject to a series of stringent pressure and calibration tests before despatch.



Differential Pressure Gauges are used to measure the difference in pressure between two points in a pressurised system.

They can be connected across filters to indicate the condition of the filter, or across a boiler to play an important part in energy management. They can be used to measure the content of a pressurised tank. They can be calibrated with square root scales to measure the flow through orifice plates, pitot tubes, venturies or pumps.


Using a diaphragm with pressure applied to either side allows for higher static (line) pressures than a double bourdon tube differential pressure gauge when measuring low pressure differences. The diaphragm chambers are machined to restrict movement of the diaphragm under out-of-balance pressures greater than the maximum calibration of the gauge. With balanced pressure chamber the accuracy does not vary with changes in static pressure.

It is recommended that a bypass valve is connected between the high and low pressure chambers, this valve is opened when the system is started and closed when the system is running at full system pressure.


Both Diaphragm and Differential Pressure Gauges should not be exposed to excessive heat or cold since this causes them to indicate incorrectly and if the measured fluid is allowed to freeze damage can occur to the diaphragm.

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