The working principle of common thermometers.
This article introduces five industrial common thermometers : liquid expansion thermometer, solid expansion thermometer, pressure thermometer, thermocouple thermometer, and thermal resistance thermometer. 1. Liquid expansion thermometer Liquid expansion thermometers are manufactured based on the thermal expansion and contraction properties of liquids. The most common one is the glass tube liquid thermometer, which uses the principle that the volume of liquid in the glass tube expands as the temperature increases. The liquid expansion thermometer consists of four parts: liquid storage, capillary tube, ruler, and safety bubble. The liquid can be: mercury, alcohol, toluene, etc. 2. Solid expansion thermometer Solid expansion thermometers are made of two materials with different expansion coefficients. Common types include: rod thermometer (generally made of solid material with a large expansion coefficient), bimetal thermometer (its temperature sensing element is made of two metal sheets ...