Bimetal Thermometer

A bimetal thermometer uses a helical strip of two bonded metals with different expansion rates; as temperature changes the helix twists and turns the pointer directly. There is no fill fluid, no capillary and no electronics, which makes it the most robust and economical dial thermometer for local indication and the one most often paired with a thermowell on process piping.

Thermometers cover −50 to +500 °C in multiple scale ranges with class 1 accuracy to EN 13190. Case, stem and process connection are 304 or 316 stainless steel, with a ½" or ¾" thread and a back, lower or adjustable-angle connection that lets the dial be turned to face the operator after installation. Insertion lengths from 63 to 1,000 mm suit everything from small-bore pipes to tanks. Cases can be liquid-filled to damp vibration and protect the movement on pumps, compressors and engines, and a zero adjustment on the dial allows on-site correction.

Accessories are compression fittings for adjustable insertion, a support tube for long stems, case filling and zero adjustment.

Bimetal thermometers serve general process temperature indication in harsh and vibration-prone environments across chemical, petrochemical, oil and gas, power, mining and glass industries. For remote reading, panel mounting or temperatures beyond 500 °C, see the gas-actuated thermometer.