What is the difference between a pressure gauge and a pressure switch?

Pressure is one of the most common pump system variables that is measured and provides valuable information about the pump operation and system condition. 

A pressure gauge is a device that indicates the pressure in the pumping system locally. Gauges can be mechanical with a dial indication or digital with a numerical reading.

Digital pressure instruments can be equipped with a transmitter that sends a signal proportional to a data acquisition system. This is advantageous when changing the pump or system operation to maintain a pressure set point.

A switch, on the other hand, is a device that, after a deviation of a physical quantity such as pressure, opens or closes a set of contacts. Therefore, it is used for on/off or open/close applications. For example, a pressure switch could be used to start a pump at minimum pressure and then shut it down when a maximum pressure is reached.

For more information on pump system instrumentation and control, refer to HI’s Pump System Assessment Professional (PSAP) Certification Study Guide at www.pumps.org.   

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