Thermometer is a general term for temperature measuring instruments. Thermometers are made using thermoelectric phenomena. The two different wires of the thermometer are welded together to form the working end, and the other ends are connected to the measuring instrument to form a circuit. When the working end is placed at the temperature to be measured, when the temperature of the working end and the free end are different, an electromotive force will appear, so a current flows through the loop. Thermometers measure electrical quantities and use the temperature at a known location to determine the temperature at another location.
1. Classification;
According to the different temperature measuring substances used and the different temperature measuring ranges, there are kerosene thermometers, alcohol thermometers, mercury thermometers, gas thermometers, resistance thermometers, thermocouple thermometers, radiation thermometers and optical thermometers. There are infrared thermometers, etc. With the development of science and technology and the needs of modern industrial technology, temperature measurement technology has been continuously improved and improved. As the temperature measurement range is getting wider and wider, according to different requirements, different temperature measurement instruments are manufactured.
Gas thermometers mostly use hydrogen or helium as the temperature measurement material. Because the liquefaction temperature of hydrogen and helium is very low, close to absolute zero, it has a wide temperature measurement range. This kind of thermometer has high accuracy and is mostly used for precision measurement.
Resistance thermometers are divided into metal resistance thermometers and semiconductor resistance thermometers, both of which are made according to the characteristic of resistance value changing with temperature. Metal thermometers are mainly used for pure metals such as platinum, gold, copper, and nickel, as well as rhodium-iron and phosphor bronze alloys; semiconductor thermometers are mainly used for carbon, germanium, etc. Resistance thermometers are easy to use and reliable, and have been widely used. It has a measurement range of around -260°C to 600°C.
2. Purpose:
It is suitable for two substances with a large temperature difference, and is mostly used for high temperature and low turbidity measurement. Some thermocouples can measure high temperatures up to 3000°C, and some can measure low temperatures close to absolute zero.
3. Principle;
Thermometers are made using thermoelectric phenomena. The two different wires of the thermometer are welded together to form the working end, and the other ends are connected to the measuring instrument to form a circuit. When the working end is placed at the temperature to be measured, when the temperature of the working end and the free end are different, an electromotive force will appear, so a current flows through the loop. Thermometers measure electrical quantities and use the temperature at a known location to determine the temperature at another location. This thermometer is mostly composed of copper--constantan, iron--constantan, nickel--constantan, gold-cobalt--copper, platinum--rhodium, etc.
4. Scope of use:
Measure the temperature of various solid surfaces, gases, liquids, as well as rubber, asphalt, plastics, etc. Widely used in rubber, textile, paper, shipbuilding, food, iron and steel non-ferrous metals, petroleum products, ceramics, glass and other industries.
