2 and 2-1/2 in. (51 and 64 mm.) Dial

• Combination Indicating Gage and Limit Switch
• Critical Pressure Limit Switch Is Visible and Adjustable (Most Models)
• Switch Can Activate Alarms and/or Shutdown Equipment
• Exceeds SAE Standards


The 20 Series (2 inch/51 mm. dial) and the 25 Series (2-1/2 inch/64 mm. dial) SWICHGAGE® models are diaphragm-actuated, pressure-indicating gages, with built-in electrical switches. These switches are used for tripping alarms and/or shutdown devices. Ranges are available from 0-15 PSI (103 kPa) [1.0 bar] thru 0-400 PSI (2.8 MPa) [28 bar]. The gage mechanism is enclosed in a steel case coated to resist corrosion. A poly-carbonate, break-resistant lens and a polished, stainless steel bezel help protect this rugged, built-to-last instrument. 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 models 20P and 25P, 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 are grounded through the SWICHGAGE® case and have self-cleaning motion to ensure electrical continuity. Models 20PE and 25PE have internal snap-acting SPDT switches. Gage-only models, without the switches (MURPHYGAGE®) are also available.


The SWICHGAGE® was specifically designed to protect engines/equipment in Oil Field, Marine, Irrigation, Construction and Trucking applications to monitor Engine Lube Pressure, Water Pump Pressure, Hydraulic Pressure, Air Pressure, etc.




Dial: White on black, dual scale; U.S.A. standard scale is psi/kPa; U.K. standard scale is psi/bar; others available

Case: Plated steel; mounting clamp included (except for direct mount models).

Bezel: Polished stainless steel, standard; others are available (see How to Order).

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):


Lower 1/4

Middle 1/2

Upper 1/4

300 psi (20 Bar)




400 psi (28 Bar)




Maximum Pressure: See Pressure Ranges and Factory Settings table on page 2.

Adjustable Limit Contact (20P and 25P):SPST contact; pilot- duty only, 2 A @ 30 VAC/DC; Normally Close (NC) when the low limit is met. Normally Open (NO) 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.Limit Contact Wire Leads: 18 AWG (1.0 mm2) x 12 in. (305 mm.).

Snap-Switch Rating (20PE and 25PE): SPDT, 3 A@ 30 VDC inductive; 4 A @ 125 VAC inductive.Snap-Switch Wire Leads: 20 AWG (0.75 mm2) x 2 in. (305 mm).

Unit Weight: 20 Series: 8 oz. (0.23 kg). 25 Series Models: 11 oz. (0.31 kg).

Unit Dimensions: 20 Series: 3 x 3 x 3 in. (76 x 76 x 76 mm.). 25 Series Models: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm.).

Base Models

20P and 25P Series SWICHGAGE®
The gage pointer makes with an adjustable contact to complete a pilot-duty circuit.

20PE (was 20EO) and 25PE (was 25EO).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.

Same as 20P and 25P with internal SPDT snap-switch for pre-alarm.

20P7 and 25P7 Lockout SWICHGAGE®
Same as 20P and 25P Series. They also include a front, semi-automatic lockout for startup override. This built-in device holds the pointer away from the contact on startup. When pressure exceeds the set point, the lockout is automatically disengaged

Gage without contact(s).


A two-year limited warranty on materials and workmanship is given with this Murphy product. Details are available on request and are packed with each unit.

**Products covered by this bulletin comply with EMC Council directive 89/336/EEC regarding electromagnetic compatibility except as noted.