How does a pressure switch operate?

• A. When a pressure reaches a desired value, the pressure switch makes or breaks a set of contacts.
• B. It measures temperature to adjust valve.
• C. It stores pressure readings for logging.
• D. It converts pressure to a current proportional to flow.

Answer: (A)

A pressure switch is designed to sense a specific pressure and then change its electrical contacts when that threshold is reached. The sensing element (like a diaphragm or a Bourdon tube) moves with pressure and, at the setpoint, shifts a mechanical linkage to close or open contacts. This makes it a switch rather than a sensor that measures temperature, logs data, or converts pressure into a current for flow measurement. The device may have an adjustable setpoint and sometimes a built-in differential to prevent rapid on/off cycling.

That’s why the best description is: when the pressure reaches a desired value, the pressure switch makes or breaks a set of contacts.