The A20P-400 Pressure Swichgage is a 2" dial, diaphragm-actuated pressure-indicating gage with a built-in electrical limit switch, which is used for tripping alarms and/or shutdown devices. This dual-scale instrument has a range of 0-400 psi (2.8 MPa) [28 bar]. The gage mechanism is enclosed in a polycarbonate, break-resistant case and lens. A polished stainless steel bezel and O-ring seals help protect this rugged instrument from the external environment. Accuracy and protection from moderate overpressure is assured by a unique, unitized diaphragm chamber. A built-in pulsation dampener helps eliminate pointer flutter and is removable for cleaning. Inside the A20P-400, the tempered nickel silver gage pointer acts as a pressure indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contacts have a self-cleaning motion to ensure electrical continuity. The A20P-400 Pressure Swichgage was specifically designed to protect engines and equipment in oil field, marine, irrigation, construction and trucking applications by monitoring engine lube pressure, water pump pressure, hydraulic pressure and air pressure. This popular instrument features a beryllium copper diaphragm sensing element and a 1/8-27 NPTM brass process connection. The adjustable limit contact is an SPDT contact; pilot-duty only, 2A @ 30 VAC/DC; closed when the low limit is met, and open when the pointer is in normal operating range.