SPL Series Temperature Gauge – 4-1/2 in. Dial with Adjustable High/Low Limit Switches

The SPL Series temperature gauge delivers reliable local temperature indication and active process protection within a single, field-proven instrument. Its clearly readable 4-1/2 in. dual-scale °F/°C dial allows operators to monitor temperature at a glance, while the two independently adjustable limit contacts enable precise alarm and shutdown setpoints to be configured without removing the gauge from service. Built around a vapor-actuated capillary sensing system with a die-cast aluminum enclosure, the SPL Series is well-suited to demanding environments including gas compressor stations, diesel engine installations, industrial heaters, and water pump systems. Two model variants — the surface-mount SPLC and the panel-mount SPLFC — along with multiple capillary lengths, material options, and enclosure configurations make it straightforward to match the right instrument to virtually any temperature monitoring requirement.

• Integrated Temperature Indication and Limit Switching: The SPL Series combines a precision vapor-actuated temperature dial gauge with two independently adjustable pointer-type limit contacts in a single compact instrument. When the process temperature reaches either the high or low setpoint, the gauge pointer physically contacts the corresponding limit arm, completing the pilot circuit and triggering whatever control action — alarm annunciation, equipment shutdown, or process interlocking — has been wired to the output terminals. This mechanical switching approach requires no separate transmitter, controller, or external power supply to function.
• Field-Adjustable High and Low Limit Contacts: Both the high and low temperature limit setpoints can be adjusted directly from the instrument face by turning the fingertip-type adjustment knobs, without any disassembly or special tools. Operators can change alarm or shutdown thresholds during commissioning or process modifications quickly and safely while the gauge remains in service. Both limit contacts are clearly visible on the dial face, making it straightforward to verify setpoint positions at any time.
• Start-Up Lockout Toggle Switch (SPLC Models): On surface-mount SPLC models, an integrated toggle switch allows the low limit contact to be temporarily bypassed during equipment start-up. This prevents nuisance shutdowns in the period after initial startup when process temperature has not yet risen above the low limit setpoint. The toggle switch must be manually reset once temperature reaches normal operating range, ensuring that low-limit protection is restored after the start-up period has passed.
• Vapor-Actuated Capillary Sensing System: The SPL Series uses a sealed capillary tube connected to a copper sensing bulb immersed directly in the process medium. Heat causes the sensing fluid to vaporize, generating pressure within the sealed system that is transmitted through the capillary to a bourdon tube mechanism in the gauge head. This all-mechanical vapor-pressure principle requires no electrical power at the sensing point, making it inherently suitable for remote sensing locations and electrically classified areas when used with appropriate enclosure options.
• Die-Cast Aluminum Enclosure with Multiple Protection Options: The standard instrument housing is constructed from die-cast aluminum, providing a durable and corrosion-resistant enclosure for outdoor and industrial environments. For more demanding conditions, an environmentally sealed (ES) option offers enhanced ingress protection, while an oil-sealed (OS) case provides additional resistance against vibration, corrosion, and electrical arc. An explosion-proof (EX) enclosure option is available for installations in Class I, Division 1, Groups C and D hazardous areas.
• Dual-Scale °F and °C Dial for Versatile Readout: Every SPL Series gauge is fitted with a standard 4-1/2 in. white-on-black dial displaying temperature simultaneously in both Fahrenheit and Celsius. This dual-scale configuration eliminates unit conversion errors in multinational operations and makes the gauge immediately readable by personnel working in different measurement systems. The high-contrast dial format ensures clear readability at working distances typical of compressor stations and engine rooms.
• Choice of Capillary Lengths and Material Configurations: Standard capillary length is 5 ft. (1.5 m), with extended lengths available in 10, 15, 20, 25, and 30 ft. options to accommodate installations where the gauge head must be located away from the temperature sensing point. Two material configurations are available: a standard PVC-armored copper capillary with copper sensing bulb, and a fully stainless steel armored capillary with stainless steel sensing bulb for corrosive or mechanically harsh environments.