SELECTING A DIFFERENTIAL PRESSURE GAUGE
Differential pressure gauges are vital in applications that require pressure to be monitored across an orifice. They can reduce operator headaches by providing information necessary to keep a process seamlessly operating.
In a closed system, it is important to measure the pressure of media on either side of a pump, filter or other equipment. Components in a process such as motors are forced to work harder if these items become clogged. This can result in premature wear or catastrophic failure requiring the process to be unexpectedly shut down while repairs are made. An increase in system pressure can be an indicator that an orifice has become obstructed by particulate. Historically the installation of pressure gauges on either side of the orifice allows the operator to identify unexpected increases in pressure and perform preventative maintenance at a time that causes minimal disruption.
Now, one differential gauge can replace the need to install pressure gauges on either side of an orifice, simplifying the pressure measurement. These gauges are simple to install with one port designated for the low-pressure side and one for the high. Installing a differential gauge provides the operator with an instant measure of the change in pressure across an orifice eliminating the need to manually calculate the difference in pressure between two gauges.
The three main gauges for measuring differences in pressure are differential gauges, duplex gauges and low-pressure (resistance-free) differential gauges. Each gauge has been engineered for a specific purpose.
The differential gauge (PDT Differential Pressure Gauge) has a single pointer that indicates the difference in pressure between two inputs. The gauge dial is available with either a conventional or a balanced scale depending on the application. The conventional scale measures the total pressure in the system from 0 to the maximum pressure of the gauge. The balanced scale has the 0 at the 12 o’clock position and the pointer moves left or right of the 0 depending on which side of the gauges is monitoring higher pressure. The gauge is available in ranges from 15 to 600 psi and is used in general purpose, medium to high-pressure applications, for static pressure up to 900 psi.
The duplex gauge (PDX Duplex Pressure Gauge) is manufactured with two bourdon tubes and two pointers. Each pointer measures the pressure from one pressure source on the gauge’s conventional scale. Process obstructions are determined by the increase in pressure indicated by the media’s specific pointer. The gauge is available in ranges from 15 to 600 psi, and like the differential pressure gauge, the duplex gauge is used in general purpose, medium to high-pressure applications, for static pressure up to 900 psi.
The other common differential gauge is a resistance-free low-pressure differential gauge (PFD WinAIR Differential Pressure Gauge). This gauge is used to measure air and non-combustible gases. One pointer is used to indicate the difference between high and low pressure on one conventional scale. Unlike the differential and duplex gauges, the resistance-free differential gauge uses a rubber diaphragm and a magnetic movement instead of a bourdon tube to convert system pressure to mechanical movement. The gauge measures pressure in “H2O, mmH2O kPa, PSI or PA.
Winters manufactures gauges for a multitude of differential applications. These gauges can be further engineered for specific needs. For more information on instrumentation for your application, contact your local Winters representative.
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