Differential pressure gauges measure the difference between two pressures. They are suitable for the monitoring of filter contamination, monitoring of bags for clogging in the dust collectors, for level measurement in closed vessels, for overpressure measurement in clean rooms, for flow measurement of gaseous and liquid media and for the control of pumping plants.
Many filter housings are supplied fitted with ‘Differential Pressure Gauges’ or ‘Differential Pressure Indicators’. They indicate differential pressure by means of a moving needle, pop up indicator or digital display. Although common in the industry, the accuracy & purpose of these devices is often misunderstood.
Generally, all of these devices, no matter how they display the change in differential pressure are only ‘indicators’ and are not precise ‘gauges’. They typically have an accuracy of around +/-25%. Calibration certificates will not be available for these devices.
Many of these devices mimic a real gauge, having graduated scales in mbar or psi, others simplify their display, dividing it either into two segments to indicate “Working within Parameters or Service Required” or three segments to include a “Needs Attention” warning. Segments can also be colour coded “Green / Red” or “Green / Amber / Red”. The default for these devices is always “Green” or “Good” doesn’t indicate a problem with the filter element should the filtration media tear or rupture.
In differential pressure gauges, different pressure elements and tube forms are used (diaphragm element, capsule element, Bourdon tube, etc.). This enables scale ranges of 0 … 0.5 mbar up to 0 … 1,000 bar to be covered, with a very high single and dual-sided and also bidirectional overload safety up to 400 bar.
