The instrument consists of a measuring system, indicating device, magnetic electrical contact assembly, housing, adjustment mechanism, and terminal box (plug socket).
Its working principle is based on the Bourdon tube within the measuring system. Under process pressure, the free end of the Bourdon tube undergoes elastic deformation, which is transmitted and amplified through a linkage and gear mechanism. The pointer fixed on the gear shaft indicates the measured value on the dial, together with the contact element. When the pointer contacts the preset upper or lower limit contacts, the electrical circuit is switched on or off instantaneously, enabling automatic control and alarm functions.