FW Murphy 5704315 A20PE-OS-150 Differential Pressure Gauge, 150 PSI

The A20 Series (2 inch / 51 mm dial) Swichgage instruments are diaphragm-actuated, pressure-indicating gages with built-in electrical switches for tripping alarms and shut-down devices. These rugged instruments are face sealed from the environment by the unique combination of a polycarbonate case and lens, a polished stainless steel bezel and O-ring seals. These gages are sealed 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. Contacts have self-cleaning motion to ensure electrical continuity.

The A20PE features internal snap-acting SPDT switches, instead of the single pole/pointer contacts. When the switch closes on falling pressure, it becomes set, as pressure rises the switch resets (refer to wiring diagram).