Pressostat

Pressostat, commonly known as a pressure switch, is a device that detects pressure and actuates electrical contacts when a specified pressure is reached. It is used to start or stop equipment, such as pumps and compressors, or to trigger alarms. Most pressostats are mechanical, employing a sensing element such as a diaphragm, bellows, or piston that converts pressure into a mechanical movement that operates a snap‑action switch. Some units are electronic, using a pressure sensor, signal processing, and a solid‑state output.

Pressostats are distinguished by the type of pressure they measure: gauge pressure (relative to ambient), absolute pressure, or differential pressure between two ports. They may be configured as single‑point or multi‑point devices with one or more setpoints. Many include adjustable setpoints and differential or hysteresis, and can incorporate relays or solid‑state outputs compatible with PLCs or controllers.

Common applications include HVAC and refrigeration systems for maintaining refrigerant or air pressure, water supply networks and pumps for cycling control, industrial automation, hydraulic and pneumatic systems, and automotive or engine monitoring. They are selected for pressure range, media compatibility, response time, electrical rating, and environmental protection.

Important considerations when selecting and maintaining a pressostat include operating range, accuracy, repeatability, hysteresis, response time, electrical load, connection type and size, and protection against moisture or dust. Regular calibration and inspection ensure reliable operation, and installation should avoid vibration and ensure proper pressure port orientation and sealing.