A20P / A25P Series (Mechanical Pressure Gauges)

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 shutdown 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.

Base Models

A20P and A25P Series Swichgage
The gage pointer makes with an adjustable contact to complete a pilot duty circuit.

A20PE and A25PE Swichgage
A20PE (was A20EO) and A25PE (was A25EO). 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).
Model A25PE is CSA listed for non-hazardous areas.
Model A25PE-EX is CSA listed for Class I, Division 1, Groups C and D hazardous areas.

A20PABS and A25PABS Swichgage instrument
Same as A20P and A25P with internal SPDT snap-switch for pre-alarm

A20PG and A25PG Murphygage instrument
Gage without contact(s)

Specifications

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 are available.

Pointer: Tempered nickel silver; Red tip.

Lens: Polycarbonate, high-impact.

Oil: Silicon Oil.

Temperature Range:

• Ambient: -40°F (-40°C) thru 150°F (66°C).
• Process: -40°F (-40°C) thru 250°F (121°C).

Process Connection: 1/8-27 NPTM brass.

Sensing Element: Beryllium copper diaphragm.

Gage Accuracy (% of Full Scale):

RANGE	LOWER 1/4	MIDDLE 1/2	UPPER 1/4
=300 psi (20 Bar)	±3%	±2%	±3%
400 psi (28 Bar)	±3%	±3%	±5%

 

Maximum Pressure: See Pressure Ranges and Factory Settings table.

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: A20P: Number 4 screw terminals; A25P: Number 6 screw terminals

Snap-Switch Rating (A20PE and A25PE): SPDT, 3 A@ 30 VDC inductive; 4 A @ 125 VAC inductive

Wiring: A20PE: Number 4 screw terminals; A25PE: Number 6 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)