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
- Strain Gauge
- Semiconductor Piezoresistive
- 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