The 20 Series (2 in./51 mm dial) and the 25 Series (2-1/2 in./64 mm dial) Swichgage models are diaphragm-actuated, temperature-indicating gauges 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 gauge 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 instrument.

These vapor-actuated gauges 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 gauge reading.

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

These instruments are used on equipment in the oil field monitoring engine coolant, crankcase oil and transmission oil.

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