Key Takeaway
Another name for a pressure switch is a pressure control switch or simply a pressure controller. In some applications, it may also be referred to as a pressure-operated switch or pressure-actuated switch. While all these terms describe the same basic device—one that responds to changes in pressure by opening or closing an electrical circuit—specific industries may have preferred terminology. For example, in HVAC systems, it might be called a cut-out switch or low/high-pressure switch, depending on its function. Despite the naming differences, the core functionality remains the same: the device senses pressure and triggers control actions at preset levels.
Pressure Actuated Switch and Its Variants
There are different types of pressure-actuated switches based on what you’re controlling:
On/Off Switches: Most common; used in compressors, tanks, and pumps
SPDT/DPDT Contact Switches: For advanced logic control
Vacuum Switches: Trigger at negative pressures
Differential Pressure Switches: Monitor pressure difference between two points
Explosion-proof Switches: For hazardous environments
Each has different pressure ranges, contact ratings, and enclosure types. Selecting the right variant ensures safety, compliance, and long-term durability in your automation setup.
Comparison with Limit Switches and Flow Switches
Pressure switches are often confused with:
Limit switches: Triggered by mechanical position (not pressure)
Flow switches: Triggered by movement or volume of fluid/gas
While all are used in automation, they serve different roles:
Pressure switch → controls based on pressure
Limit switch → controls based on movement
Flow switch → controls based on flow presence/rate
For example, a cooling system may use:
A flow switch to ensure water is flowing
A pressure switch to stop the pump at high pressure
A limit switch to detect valve position
Use the right sensor for the right purpose.
Industry Nicknames and Abbreviations (P-switch, PSW)
In real-world usage, pressure switches are often abbreviated in drawings or conversations:
P-switch: Pressure switch
PSW: Pressure switch (common in PLC wiring)
LPS/HPS: Low/High Pressure Switch
PRSW: Pressure Reset Switch
DPS: Differential Pressure Switch
Knowing these shortcuts helps when reading P&IDs, control panel wiring, or supplier datasheets. It also speeds up communication between operators, electricians, and instrumentation engineers.
Use of Relays in Conjunction with Pressure Switches
Pressure switches alone can’t handle large electrical loads. That’s where relays come in. They act as intermediaries to:
Switch higher current loads safely
Interface with control circuits or alarms
Enable logic-based operations in PLC systems
For example:
A pressure switch activates a relay, which in turn starts a motor or pump
Relay contacts can also trigger indicator lights or alarm buzzers
Use:
SPDT relays for changeover logic
Latching relays for memory-based systems
Time-delay relays to avoid false trips due to pressure spikes
This integration expands the switch’s functionality, enabling smarter and safer automation.
When a Pressure Sensor Is Mistaken for a Pressure Switch
It’s common for users to confuse pressure sensors, switches, and transmitters — especially when they all sit in the same panel.
Pressure sensor: Converts pressure to an electrical signal. It measures.
Pressure switch: Activates/deactivates based on setpoints. It acts.
Transmitter: Sends pressure data over longer distances, often in 4–20mA format. It communicates.
Mistakes happen when:
A sensor is expected to cut off power (it won’t)
A switch is assumed to provide continuous readings (it can’t)
A transmitter is used where instant reaction is needed
Choosing the wrong device causes system failures, inefficiencies, or dangerous delays. Always read the datasheet, and consult engineering before replacing or installing pressure equipment.
Conclusion
Whether you call it a pressure switch, pressure actuator, pressure relay, or P-switch—it all comes down to one function: reacting to pressure changes by turning something on or off. These naming variations appear across industries, but the core purpose is the same. The switch detects when a threshold is crossed and activates a circuit. It’s important not to confuse them with sensors, which measure but don’t control. Pressure switches are about action, not just data. Understanding their aliases helps with cross-industry integration and sourcing. Regardless of the name, their job is vital—protecting equipment, maintaining process flow, and providing automatic pressure-based responses you can count on.