The A20 Series (2 inch/51 mm dial) and the A25 Series (2-1/2 inch/64 mm dial) Swichgage instruments are diaphragm-actuated, pressure-indicating gauges with built-in electrical switches for tripping alarms and/or shutdown devices. These rugged, built-to-last 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. Ranges above 30 psi (207 kPa) [2 bar] are sealed from the external environment (except PE Series). Accuracy and protection from moderate overpressure is assured by a unique, unitised diaphragm chamber. A built-in pulsation dampener helps eliminate pointer flutter and is removable for cleaning.
For series A20P and A25P, the gauge pointer acts as a pressure indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contacts have self-cleaning motion to ensure electrical continuity.