10703186 Murphy Temperature Swichgage Model A20T-300-25-1/2


A20T-300-25-1/2: 2″ Temperature Swichgage®; Polycarbonate Case; 140-300°F Temp Range; 25 Ft Capillary Length (10703186)

The A20 Series (2 inch/51 mm dial) are models are diaphragm-actuated, temperature-indicating gages, with built-in electrical switches for tripping alarms and/ or shutdown devices. 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. In this model the gage pointer makes with an adjustable contact to complete a pilot-duty circuit.

Estimate available in 28 working days from Italy to Italy

This product may vary on delivery times, as factories do not guarantee production due to lack of raw materials.

Availability: Available on backorder SKU: 10703186 Categories: , Tag:


  • Dial: White on black; U.S.A. standard scale is dual scale °F/°C; others available (see How to Order)
  • Case: Glass filled/Polycarbonate, corrosion-resistant; steel mounting clamp included
  • Bezel: Polished stainless steel, standard; others available
  • Pointer: Tempered nickel silver; red tip
  • Lens: Polycarbonate, high impact
  • Sensing Element: Beryllium copper diaphragm
  • Capillary: PVC armored copper; 25 ft. (7,50 m) Stainless steel armor optional
  • Sensing Bulb: Copper
  • Gage Accuracy: See Temperature Accuracy Chart
  • Maximum Temperature: 140°F (60°C) – 300° F (149°C)
  • Adjustable limit Contact: 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
  • Unit Weight: A20 Series: 11.9 oz. (0.37 kg)
  • Unit Dimensions: 4-3/4 x 4-3/4 x 3 in. (121 x 121 x 76 mm)
Dimensions – A20 Series Models (typical)

dimension a20 series murphy


Temperature Ranges and Factory Setting


  1. Values in () are matematical conversions from °F to °C – they do not reflect actual second scale range. USA standard scale is °F/°C
  2. For models A20TE and A25TE; the switch trip point cannot be set at either the low or high extreme of the scale. The trip point must allow for the reset differential. Only certain models are adjustable.
  3. For adjustable switch models, the trip point is adjustable only the upper half of the scale.

temperature ranges factory settings a20 series murphy

Temperature Accuracy Chart

temperature accuracy chart a20 series murphy

Magnetic Switch

Inductive and high current loads require the use of a magnetic switch. The Swichgage contacts are for light-duty electrical switching to operate alarms or control devices. Enovation Controls manufactures the Magnetic Switch for protection of the pilot-duty Swichgage limit contacts.
Tattletale® Magnetic Switches show the cause of the shutdown for applications that include: capacitor discharge or magneto ignitions, battery systems and electric motor driven equipment. Typical wiring diagrams are shown.

magnetic switch a20 series murphy

Pre-Alarm using A20/A25TABS

The A20TABS and A25TABS feature a standard limit contact for equipment shutdown on high temperature and an internal SPDT snap-switch to signal an alarm before shutting down. When the snap-switch trips (preset point) on rising temperature, the switch completes a circuit to activate an alarm.
If the temperature continues to increase, the face-adjustable pointer contact will make and the shutdown circuit will be completed (see the typical diagram). The front contact shutdown limit setting (wich is adjustable) and the snap-switch are preset at the factory. Refer to Temperature Ranges and Factory Settings table for settings. For alternative alarm before shutdwon, see Magnetic Switch model 760A or 761APH.

pre-alarm using a20 a25tabs murphy

Typical Internal Wiring Diagrams

typical internal wiring diagrams a20t murphy

How to order:

Base Model: A20T
300 = 140-300 F° (60°-149° C)
25 = 25 feet = 7,50 m
Adapter Nuts = 1/2

20t a20t 25t a25t series thermowells

20t a20t 25t a25t series thermowells

20t a20t 25t a25t series thermowells

Additional information

Weight0,37 kg


10703186, A20T-300-25-1/2