What is a temperature gauge?

Temperature gauge measures the thermal state of a homogeneous substance. Distance between the measuring system and the body as minimum as possible to get accurate results. The most widely used measuring methods for temperature measurement rely on temperature-dependent characteristics of the body and substance.

How does a bimetal temperature gauge work?

Bimetal temperature gauges operate with a measuring system in the form of a helical or spiral tube. The measuring system consists of two sheets with different expansion coefficients, which are inseparably joined. Through the mechanical deformation of the bimetal strips in the aforementioned tube types, a rotational movement results, caused by temperature changes. If one end of the bimetal measuring system is firmly clamped, the other end will rotate the pointer shaft. Bimetal temperature gauges are available with a measuring range of -70 … +600 °C (-94 … +1,112 °F) in accuracy classes 1 and 2 in accordance with EN 13190.

When is an expansion temperature gauge suitable?

An expansion temperature gauge consists of a temperature probe, a capillary and a Bourdon tube, and is also suitable for temperature measurement at remote measuring locations. The measuring system itself is filled with a liquid. If the temperature changes, the internal pressure of the temperature gauge with probe will change as well. The pressure is transferred via a tube to a pointer shaft and thus the temperature value is indicated on the scale. Using remote capillaries from 500 … 10,000 mm long, measurements can also be taken from remote measuring locations. The measuring ranges for expansion temperature gauges lie between -40 … +400 °C with class 1 and 2 accuracies in accordance with EN 13190. Only gas-actuated thermometers can be combined with a capillary. In In the reaction to a temperature change, both dial thermometer types function in accordance with the expansion principle. But the rotation of the helix in bimetal thermometers can only react directly and without “detour” on the indication. Whereas a gas-actuated thermometer is also suitable for the transmission of the measured value via capillary, due to its helium filling. Such a capillary has an outer diameter of only 2 mm and an inner diameter of 0.1 to 0.2 mm.

Benefits of capillary type temperature gauge:

A dial thermometer with capillary puts users in the position to be able to measure the process temperature, even at inaccessible points. By means of a contact bulb it can also be measured on the smallest pipelines. Another advantage is the bridging of greater distances. In this way, thermometers can be centrally integrated in an instrument panel, a switch cabinet or a control panel. With a gas-actuated temperature gauge the stem, the capillary and the Bourdon tube are joined together into one unit. The instrument is filled with inert gas. If the temperature changes, the internal pressure will also change. The pointer is moved by the action of the pressure via a measuring tube. To compensate for the ambient temperature, a bimetal element is mounted between the movement and the measuring tube. Gas-actuated temperature gauges are available with scale ranges between -200 … +700 °C (-328 … +1,292 °F) in accuracy class 1. Do check our range of temperature gauges here.