Pressure switches are also employed in numerous automotive applications, for example, monitoring engine oil, power steering and transmissions. Hydraulic and pneumatic pressure switches control the air bellows in trucks and brake pressure in trains. They are widely used in the industrial control of equipment such as press machines, plastic molding injection and welding machines. Pressure switches are used in a large number of industries. In comparison to electromechanical pressure switches, they have much longer longevity. They are highly resistant to shock and vibration with an accuracy to ☐.25%. Solid state pressure switches have a broad range of operating pressures and frequency response. Most current models are fully programmable and can interface with a PLC or computer. They not only open and close the pressure switch circuit but include digital displays and provide analog or digital output. Solid state pressure switches may have one or more switch points. The sensor detects the pressure difference between two sources and actuates the switch. They have two pressure ports, one for high and low process pressure. Their operating pressure is to 12,000 psi and their accuracy is to ± 0.2%.ĭifferential pressure switches may have a diaphragm, metallic or elastomeric sensor. Piston switches employ a piston to directly activate the switch. Their operating pressure is from vacuum to 1600 psi and accuracy is to ± 0.2%. Operating pressure ranges from 50 to 18,000 psi and accuracy is to ± 0.5%.ĭiaphragm piston switches are equipped with an elastomeric diaphragm which acts on a piston. They have an operating pressure up to 150 psi and an accuracy to ± 0.5%.īourdon tube switches use a weld-sealed bourdon tube for switch actuation.
The attributes of the sensor demarcate the relative accuracy and longevity of the switch and include the following types:ĭiaphragm switches employ a weld-sealed metal diaphragm to activate the switch. Electromechanical pressure switches employ several types of sensors. There are two basic types of pressure switches: electromechanical and solid state. The precise features and capabilities depend on the type of pressure switch. Selecting a pressure switch with a switch point in the proper operating pressure range is important to ensure accuracy and longevity. The set point may be fixed or adjustable. The switch opens and closes a contact at a specific pressure referred to as the set point. Understanding Deadband for Pressure SwitchesĪ pressure switch consists of a sensing component and an electrical switch.
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