Swichgage Series

These pressure-indicating gauges feature built-in electrical switches for activating alarms and/or shutting down equipment.

  • Corrosion resistant polycarbonate case
  • Internal pulsation dampener helps eliminate pointer flutter
  • Maintains accuracy and protection from moderate overpressure

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  • Overview
  • Specifications
  • Diagrams
  • Literature

The A20 Series (2 in./51 mm dial) and the A25 Series (2-1/2 in. /64 mm dial) Swichgage instruments are diaphragm-actuated, pressure-indicating gauges with built-in electrical switches for tripping alarms and/or shutdown devices.

Ranges are available from 0-30 psi (207 kPa) [2.0 bar] through 0-300 psi (2.1 MPa) [20 bar].

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 gauges are sealed from the external environment.  Accuracy and protection from moderate overpressure are assured by a unique, unitized diaphragm chamber. A built-in pulsation dampener helps eliminate pointer flutter and is removable for cleaning.

For series 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.

Model A20PE has internal snap-acting SPDT switches for three wire control and can be wired to make or to break a circuit.

Gauge only models without switches are also available.

A20/A25 Series applications include engines/equipment in oil field for lube oil pressure, water pump pressure, hydraulic pressure, air pressure, etc.

Base Models

A25P Series Swichgage
The gauge pointer makes with an adjustable contact to complete a pilot duty circuit.

A20PE Swichgage
A20PE (was A20EO). 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).

A20PG Murphygage instrument
Gauge without contact(s)

  • Dial: White on black, dual scale; U.S.A. standard scale is psi/kPa; U.K. standard scale is psi/bar
  • Case: Polycarbonate/glass filled, corrosion-resistant; steel mounting clamp included
  • Bezel: Polished stainless steel, standard; others available
  • Pointer: Tempered nickel silver; red tip
  • Lens: Polycarbonate, high-impact
  • Oil: Silicon oil
  • Temperature Range:
    • Ambient: -40°to 150° F (-40° to 66°C)
    • Process: -40° to 250° F (-40° to 121°C)
  • Process Connection: 1/8-27 NPTM brass
  • Sensing Element: Beryllium copper diaphragm
  • Gage Accuracy (% of Full Scale):
=300 psi (20 Bar) ±3% ±2% ±3%
  • Maximum Pressure: See Pressure Ranges and Factory Settings in bulletin
  • Adjustable Limit Contact (A20P and A25P): SPST contact; pilot-duty only, 2A@30 VAC/DC; Closed when the low limit is met, open when pointer is in normal operating range
    • Contacts are gold flashed silver
    • Limit Contact Adjustment: by a 1/16 in. hex wrench through 100% of the scale
  • Wiring: A25P: Number 6 screw terminals
  • Snap-Switch Rating (A20PE): SPDT, 3 A@ 30 VDC inductive; 4 A @ 125 VAC inductive
  • Wiring: A20PE: Number 4 screw terminals
  • Unit Weight: 
    • A20 Series: 8 oz. (0.23 kg)
    • A25 Series Models: 11 oz. (0.31 kg)
  • Unit Dimensions: 
    • A20 Series: 3 x 3 x 3 in. (76 x 76 x 76 mm)
    • A25 Series Models: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm)

Dimensions A20 Series

A20 Swichgage Series Dimensions



Dimensions A25 Series

A25 Swichgage Series Dimensions



Typical with 117 Magnetic Switch

Typical with 117 Magnetic Switch


Typical with 518PH Magnetic Switch

Typical with 518PH Magnetic Switch



Typical Wiring Diagrams

Typical Wiring Diagrams

For more information about this product, you can download the related literature here:

Sales Bulletin (94030; revision date – 05/2019)

Installation Manual (00-02-0162)