Pyrometer is a kind of thermometer, using the principle of infrared transmission to sense the surface temperature of objects, easy to operate, especially suitable for high temperature objects. Pyrometer is widely used, such as measuring the surface temperature of cast steel parts, furnace temperature, machine parts, glass, room temperature, body temperature and other objects.

　　With the needs of modern industrial technology and the development of science and technology, temperature measurement technology continues to improve. As the range of temperature measurement becomes wider and wider, different pyrometers are manufactured according to different requirements. Here are some common pyrometers.

　　1、Gas pyrometer. Because the liquefaction temperature of hydrogen and helium is very low, hydrogen or helium is often used as a temperature measurement material, and it has a wide temperature measurement range because it is close to zero degrees. This pyrometer is mostly used for precision measurement with high accuracy.

　　2, resistance pyrometer. Divided into semiconductor resistance thermometer and metal resistance thermometer, both are made according to the characteristics of the resistance value changes with temperature. Metal pyrometer is mainly made of pure metals such as platinum, gold, copper, nickel and rhodium-iron-phosphor bronze alloy, semiconductor thermometers mainly use carbon, germanium, etc.. Resistance pyrometer is easy to use and reliable, measuring range of about -260 to 600 degrees, has been widely used.

　　3, thermocouple pyrometer is a widely used temperature measuring instrument in industry, consisting of thermoelectric phenomenon. Two different metal wires are welded together to form the working end, and the other two ends are connected to the measuring instrument to form a circuit. When the working end is placed at the temperature being measured, if the temperature at the working end differs from the temperature at the free end, an electric potential is generated, and a current flows through the circuit. By measuring the electric potential, the temperature at one known place can be used to measure the temperature at another. This kind of pyrometer is suitable for the measurement of high temperature and low turbidity between two substances with large temperature difference. Some thermocouples can measure high temperature up to 3000 degrees, and some can measure low temperature near zero degrees.

　　4, high temperature thermometer is specifically used to measure the temperature of 500 degrees or more thermometer, including colorimetric thermometer, optical thermometer and radiation thermometer. High-temperature thermometer is not suitable for low-temperature measurement, its measurement range from 500 to 3000 degrees or more.

　　5, pointer thermometer is a thermometer shaped like a dashboard, used to measure room temperature. It is made according to the principle of metal thermal expansion and contraction, the use of bimetal as a temperature sensing element to control the pointer. The bimetal usually consists of copper and iron pieces riveted together, with the iron piece on the right and the copper piece on the left. Due to the thermal expansion and contraction of copper is much more obvious than iron, when the temperature rises, the copper sheet pulls the iron sheet to the right bend, the pointer in the bimetal driven to the right deflection; on the contrary, when the temperature becomes low, the pointer in the bimetal driven to the left deflection.

　　6, glass tube pyrometer. Glass pyrometer using the principle of thermal expansion and contraction to measure the temperature, due to the expansion coefficient of the temperature measurement medium is different from the boiling point and freezing point, we are common glass tube thermometer mainly kerosene thermometer, red pen water thermometer, alcohol thermometer, etc..