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 gages with built-in electrical switches for tripping alarms and/or shut-down devices.
Ranges are available from 0-15 psi (103 kPa) [1.0 bar] through 0-400 psi (2.8 MPa) [28 bar].
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). Ranges of 30 psi and lower have a small weep hole in the bottom of the case. 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.
For series A20P and A25P, the 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 self-cleaning motion to ensure electrical continuity.
Models A20PE and A25PE have internal snap-acting SPDT switches for three wire control and can be wired to make or to break a circuit. Gage-only models without switches (MurphyGage® instrument) are also available.
A20/A25 Series applications include: engines/ equipment in oil field, marine, irrigation, construction and trucking for lube oil pressure, water pump pressure, hydraulic pressure, air pressure, etc.