The Murphy 130-250F Mechanical Temperature Swichgage 2" with 20 Ft Capillary and Internal SPDT Snap-Switch for Pre-Alarm 20TABS-250-20-1/2 is a diaphragm-actuated, temperature-indicating gage with built-in electrical switch for tripping alarms and/or shutdown devices. 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. This vapor actuated gage features 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.
The 20TABS-250-20-1/2 features a standard limit contact for high temperature equipment shutdown. It also has an internal SPDT snap-switch to signal an alarm before shutting down. When the low side of 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. The front contact shutdown limit setting (which is adjustable) and the snap-switch are preset at the factory.
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. This gage has a self-cleaning motion to enhance electrical continuity. Applications: Industrial engines and equipment in Oil Field, Marine, Irrigation Construction and Trucking industries. Monitoring Engine Coolant, Crankcase Oil and Transmission Oil.
- 2 inch/51 mm Dial
- Steel Case Coated to Resist Corrosion
- Polycarbonate, High-Impact Lens
- Polished Stainless Steel Bezel
- Combination Indicating Gage and Limit Switch
- Switch Can Activate Alarms and/or Shut Down Equipment
- Contact Grounds Through Case
- Internal SPDT Snap-Switch for Pre-Alarm
- Part No.: 20TABS-250-20-1/2
- Range: 130-250°F (60-121°C)
- Adapter Nut: 1/2-14 NPT
- Dial: White on black; U.S.A. standard scale is dual scale °F/°C
- Case: Plated steel; mounting clamp included (except for direct mounting models)
- Bezel: Polished stainless steel
- Pointer: Tempered nickel silver
- Lens: Polycarbonate, high-impact
- Sensing Element: Beryllium copper diaphragm
- Capillary: PVC armored copper; 20 ft
- Sensing Bulb: Copper
- Gage Accuracy: 130 to 250°F (54 to 121°C) Temperature Range; ± 9°F (± 5°C) Lower 1/3 of Scale; ± 5°F (± 2.4°C) Middle 1/3 of Scale; ± 4°F (± 2°C) Upper 1/3 of Scale
- Maximum Temperature: 310°F (154°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 thru 100% of the scale
- Limit Contact Wire Leads: 18 AWG (1.0 mm2) x 12 in. (305 mm)
- Unit Weight: 12.7 oz. (0.39 kg)
- Unit Dimensions: 4-3/4 x 4-3/4 x 2-3/4 in. (121 x 121 x 70 mm)