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The 20 Series (2 inch/51 mm dial) and the 25 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 shut-down devices.

Ranges are available from 32°-120°F (0°-45°C) through 300°-440°F (160°-220°C).

The gage mechanism is enclosed in a steel case coated to resist corrosion. A polycarbonate, break- resistant lens and a polished, stainless steel bezel help protect this rugged, built-to-last instrument.

These vapor-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 the diaphragm mechanism. The diaphragm translates this vapor pressure into a mechanical gage reading.

For series 20T and 25T, 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 grounded through the Swichgage case. They have a self-cleaning motion to enhance electrical continuity.

Models 20TE and 25TE have internal snap-acting SPDT switches. Gage-only models without contacts (Murphygage® instrument) are also available.

These instruments are used on industrial engines and equipment in oil field, marine, irrigation, construction and trucking industries and for monitoring engine coolant, crankcase oil and transmission oil.

Base Models

Coolant or Oil Tempature
20T and 25T Series Swichgage: For these models the gage pointer makes with an adjustable contact to complete a pilot-duty circuit.

20TL and 25TL Swichgage instrument: For use on Ford Worldwide engines. Supplied with special sensing bulb.

20TE and 25TE Swichgage instrument internal snap-switch: 20TE (was 20ESR) and 25TE (was 25ESR) 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.

20TABS and 25TABS Swichgage instrument: Same as 20/25T with internal SPDT snap-switch for pre-alarm.

Cylinder Head Temperature
20TH and 25TH Swichgage instrument: 20TH (was 20TL8133) and 25TH (was 25TL8133). For use on air-cooled engines.

Direct Mount Models
20TD Swichgage instrument: Same as 20T. Available ranges: 220°F (104°C) or 250°F (121°C). Includes 1/4 x 4 in. (6 x 102 mm) sensing bulb.

20SD Swichgage instrument: Same as 20T. Available ranges: 220°F (104°C) or 250°F (121°C). Includes 11/32 x 1-1/2 in. (9 x 38 mm) sensing bulb.

Gage–Only Models
20TG and 25TG Murphygage: Gages without contact(s).

  • Dial: White on black; U.S.A. standard scale is dual scale °F/°C; others available (see How to Order)
  • Case: Plated steel; mounting clamp included (except direct mount models)
  • Bezel: Polished stainless steel, standard; others available (see How to Order)
  • Pointer: Tempered nickel silver
  • 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 Temperature Accuracy Chart
  • Maximum TemperatureSee Temperature Ranges and Factory Settings Table
  • Maximum Ambient Temperature-40°F (-40°C) through 150°F (66°C)
  • Adjustable Limit Contact (20T and 25T): SPST contact; pilot duty only, 2 A @ 30 VAC/ VDC; Ground path through encasement. Normally Closed (NC) when the high 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 mm) 2 x 12 in. (305 mm)
  • Snap-Switch Rating (20TE and 25TE)SPDT, 3 A @ 30 VDC inductive; 4 A @ 125 VAC inductive
  • Snap-Switch Wire Leads: 20 AWG (0.75 mm2) x 12 in. (305 mm)
  • Unit Weight: 20 Series: 12.7 oz. (0.39 kg); 25 Series Models: 13.8 oz. (0.43 kg)
  • Unit Dimensions
    • 20 Series: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm) 
    • 25 Series Models: 4-3/4 x 4-3/4 x 3 in. (121 x 121 x 76 mm)
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