Pressure Switch

on . Posted in Pressure Instrument

Pressure switch, abbreviated as PS, provides a discrete input to the PLC. It is a device used to monitor and control the pressure of a fluid or gas in industrial processes.  It's a type of sensor that detects changes in pressure and triggers a response when the pressure reaches a certain set point.  The pressure switch is typically used as a method of control in tanks, vessels and over all process control.

Note, a pressure switch is different than a pressure transmitter in that a pressure switches sole function is to provide a binary TRUE or FALSE into the PLC.  This approach simplifies programming.

how it typically works

  • Pressure Sensing  -  The pressure switch contains a sensing element, such as a diaphragm or a Bourdon tube, that reacts to changes in pressure.
  • Switch Mechanism  -  When the pressure reaches a predetermined threshold, the switch mechanism is activated.
  • Electrical Signal  -  The activation of the switch usually results in the creation of an electrical signal, which can be used to trigger alarms, control valves, or initiate other actions within a control system.

Instrumentation pressure switches are commonly used in various industries such as manufacturing, oil and gas, petrochemical, water treatment, and HVAC systems.  They provide a simple and effective means of monitoring and controlling pressure levels in different processes to ensure safety, efficiency, and reliability.

Pressure Switch Types

  • Mechanical Deflection
  • Piston
  • Strain Gauge
  • Semiconductor Piezoresistive
  • Piezoelectric
  • Thin Film
  • Variable Capacitance

Configuration and Alarms

Configuration (Normal State):

  • NO - Normally Open
  • NC - Normally Closed

Alarms in the PLC can be:

  • PSH - Pressure Switch High
  • PSL - Pressure Switch Low
  • PSHL - Pressure Switch High/Low

Piping Designer Logo 1



Tags: Instrumentation