• Murphy by Enovation Controls

A20T / A25T Series Temperature Swichgage®

The A20 Series (2 inch/51 mm dial) and the A25 Series (2-1/2 inch/64 mm dial) Swichgage models are diaphragm-actuated, temperature-indicating gages, with built-in electrical switches for tripping alarms and/ or shutdown devices. Ranges are available from 32°-120° F (0°-45° C) through 300°-440° F (160°-220° C).

Swichgage® instruments are built in the USA and have protected engines and equipment in applications such as oil and gas, marine, irrigation, construction and trucking applications to monitor engine coolant, crankcase oil, transmission oil and others for more than 80 years.


  • CE (European Conformity) mark
Base Models Specifications Downloads How to Order
Specifications Drawer: 
  • Dial: White on black; U.S.A. standard scale is dual scale °F/°C; others available
  • Case: Glass filled/Polycarbonate, corrosion-resistant; steel mounting clamp included
  • Bezel: Polished stainless steel, standard; others are available.
  • Pointer: Tempered nickel silver; red tip
  • Lens: Polycarbonate, high-impact
  • Sensing Element: Beryllium copper diaphragm
  • Capillary: PVC armored copper; 4 ft. (1.2 m).* Stainless steel armor optional
  • Sensing Bulb: Copper*
  • Gage Accuracy: See accuracy chart in Technical Bulletin
  • Maximum Temperature: See Temperature Ranges and Factory Settings table in Technical Bulletin
  • Maximum Ambient Temperature: -40° F (-40° C) through 150° F (66° C) Adjustable Limit Contact (A20T and A25T): SPST contact; pilot-duty only, 2 A @ 30 VAC/VDC; isolated from case ground Closed when the high limit is met. Normally 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: A20T - Number 4 screw terminals; A25T - Number 6 screw terminals.
  • Snap-Switch Rating (A20TE and A25TE): SPDT, 3 A @ 30 VDC inductive; 4 A @ 125 VAC inductive
    • Wiring: A20TE - Number 4 screw terminals; A25TE - Number 6 screw terminals
  • Unit Weight:
    • A20 Series: 11.9 oz. (0.370 kg)
    • A25 Series Models: 13.3 oz. (0.413 kg)
  • Unit Dimensions:
    • A20 Series: 4-3/4 x 4-3/4 x 3 in. (121 x 121 x 76 mm)
    • A25 Series Models: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm)

*For optional capillary lengths, engine adapters, sensing bulbs and range combinations, see Murphy bulletin 8428.

WARNING: This product may expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information about California Propsition 65, go to www.P65Warnings.ca.gov or visit our California Proposition 65 page.

Additional product documentation can be found on our product support website or by clicking the Help Center button above.

Part NumberDescription
05702176A20 Series Clamp Lite Assembly; 12V
05702177A20 Series Clamp Lite Assembly; 24V

All configurations may not be available. Call your sales representative or Enovation Controls for more information.

All models of these rugged, built-to-last instruments are fully sealed from the environment by the unique combination of a polycarbonate case and lens, a polished stainless steel bezel and O-ring seals. These vapor/pressure actuated gages feature a sealed capillary tube and a sensing bulb. When subjected to heat, the liquid in the sensing bulb changes to vapor creating pressure against a diaphragm mechanism. The diaphragm translates this vapor pressure into a mechanical gage reading. For series A20T and A25T, the gage pointer acts as a temperature indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contact(s) are isolated from ground. They have a self-cleaning motion to enhance electrical continuity.

Coolant or Oil Temperature

  • A20T and A25T Series Swichgage
    For these models the gage pointer makes with an adjustable contact to complete a pilot-duty circuit.
  • A20TL and A25TL Swichgage instrument
    For use on Ford Worldwide engines. Supplied with special sensing bulb.
  • A20TE (was A20ESR) and A25TE (was A25ESR) Swichgage instrument internal snap-switch
    Models with internal SPDT snap-switches instead of the single pole/pointer contact(s). When the switch closes on rising temperature, it becomes set. As temperature decreases, the switch resets.
    Model A25TE is CSA listed for non-hazardous areas.
    Model A25TE-EX is CSA listed for Class I, Division 1, Groups C & D hazardous areas.
  • A20TABS and A25TABS Swichgage instrument
    Same as A20/A25T with internal SPDT snap-switch for pre-alarm.

Cylinder Head Temperature

  • A20TH (was A20TL8133) and A25TH (was A25TL8133) Swichgage instrument
    For use on air-cooled engines.

Gauge–Only Models

  • A20TG and A25TG MurphyGage
    Gauge without contacts.