Fields of application of bimetallic thermometers

Bimetallic thermometer is a kind of contact measuring instrument, which is suitable for on-site temperature measurement in medium and low temperature environments. It can be used to directly measure the temperature of gas, liquid and steam in the range of -80~500℃. It is an ideal product to replace industrial mercury thermometers. It is widely used in petroleum, chemical industry, machinery, shipbuilding, power generation and other industrial and scientific research departments. It has the advantages of no mercury hazard, easy to read, durable and so on.

The principle of the bimetallic thermometer is to measure the temperature by using the principle that two kinds of metal composite sheets of different materials have different coefficients of thermal expansion and contraction, resulting in distortion and driving the pointer deflection. One end of the bimetal sheet is fixed, and the other end is connected to the rotating shaft. When the temperature changes, the bimetal sheet twists axially, thereby driving the rotating shaft to rotate, and the rotating shaft drives the pointer to deflect an angle to point to the temperature value on the dial. The basic structure consists of a dial, a corner spring, a rotating shaft, a temperature sensing element, a protection tube, and various fixing devices. (table cover, casing, glass, sealing ring, panel, pointer, corner spring lower fixing, corner spring, corner spring upper fixing, rotating shaft, temperature sensing element, protection tube, protection tube joint, external thread and cap). The nominal pressure is generally at the specified working temperature, the static pressure that the protective tube can withstand without breaking. The nominal pressure is not only related to the protection tube material, diameter and wall thickness, but also related to its installation method, insertion depth, and the type and flow rate of the measured medium. The length of the protective tube of the bimetallic thermometer inserted into the measured medium is the minimum insertion depth, which is 8 times the diameter of the protective tube.

According to the connection direction of the pointer plate of the bimetal thermometer and the protective tube, the bimetal thermometer can be divided into four types: axial type, radial type, 135° direction type and universal type.

1. Axial type bimetallic thermometer: the pointer plate is connected vertically with the protective tube.
2. Radial type bimetallic thermometer: the pointer plate is connected in parallel with the protective tube.
3. 135° bimetallic thermometer: the pointer plate is connected to the protective tube at 135°.
4. Universal bimetallic thermometer: the connection angle between the pointer plate and the protective tube can be adjusted arbitrarily.