pressostato

A pressostato, or pressure switch, is a device that uses a pressure-sensing element to actuate an electrical switch when process pressure reaches a programmed value. It provides a binary output, turning connected equipment on or off, and is commonly used to control pumps, compressors, boilers, and hydraulic systems.

Construction and operation: A typical pressostato consists of a sensing element—usually a diaphragm, bellows, or piston—connected to a switch mechanism. The electrical contacts can be normally open or normally closed. An adjustment mechanism sets the operate and release pressures (setpoint and hysteresis). When the sensed pressure reaches the setpoint, the switch changes state, enabling automatic control or safety interlock.

Types: Mechanical pressure switches with fixed or adjustable setpoints; differential pressure switches monitor the pressure difference between two ports and are used in filtration, HVAC, and fluid handling; vacuum switches respond to below-atmosphere pressure. Some models include electronic signaling or digital readouts and have rugged enclosures for harsh environments. Materials of wetted parts vary to match the media (water, oil, gas).

Applications: Widely used in water supply and irrigation, heating, ventilation and air conditioning, refrigeration, and process industries. They protect pumps from running dry, control fluid circuits, and serve as safety devices by interrupting circuits if pressure becomes too high or too low.

Maintenance and standards: Regular inspection for leaks, corrosion, and contamination is advised. Calibration may be required to maintain accuracy. Pressure switches are designed to meet standards and ratings (UL, CE, IEC) and are selected according to electrical load, setpoint range, hysteresis, media compatibility, and enclosure protection.