Thermocouples, bimetallic thermometers, and thermometer casings
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Bimetallic thermometer: An instrument that can automatically and continuously record changes in temperature. The sensing element is a bimetallic strip, made by welding two metals with significantly different coefficients of expansion together; one end of this strip is fixed, while the other end moves as the temperature changes, and the amount of displacement is approximately linearly related to the temperature. The recording system consists of a recording clock and a recording pen; the recording pen is connected to an amplifying lever and is controlled by a sensing element. A thermocouple is formed by welding two conductors or semiconductors of different materials, A and B, together to create a closed circuit, as shown in the figure. When there is a temperature difference between the two contact points 1 and 2 of conductors A and B, an electromotive force is generated between them, resulting in the flow of an electric current in the circuit. This phenomenon is known as the thermoelectric effect. Thermocouples work by utilizing this effect. http://baike.baidu.com/pic/28/11937326007331394.jpg Please introduce me to the thermometer sleeve.
Is there anything special? I usually use 32-inch pipes with the ends sealed.
What material should be used for thermometer casings in acidic and alkaline environments?
It depends on what the medium is; it’s not possible to classify it generally based on whether it is acidic or alkaline
It is important to note that thermometer casings come in either fully drilled or welded types, and the pressure and temperature ranges they can handle differ. In the petrochemical industry, material 321 is commonly used.
The person on the 4th floor is right; it’s related to the actual operating conditions – process media, temperature, pressure, and so on may all play a role. Each case needs to be analyzed on its own.