Temperature measurement sensor
Temperature is defined as the energy level of a substance and can be proved by certain changes in the substance. There are many types of temperature measurement sensors and they have one thing in common: they all measure temperature by sensing certain changes in physical characteristics. The seven basic types of temperature measurement sensors discussed here are thermocouples, resistance temperature devices (RTDs, thermistors), infrared radiators, bimetal devices, liquid expansion devices, molecular state changes, and silicon diodes.
Thermocouples are voltage devices that indicate temperature measurement when voltage changes. As the temperature increases, the output voltage of the thermocouple increases-not necessarily linearly.
Thermocouples are usually located in a metal or ceramic shield to protect them from exposure to various environments.
2. Resistance temperature measuring device
Resistance temperature measurement equipment is also electrical. Instead of using voltage like thermocouples, they take advantage of another property of a substance that changes with temperature-resistance.
3. Infrared sensor
Infrared sensors are non-contact sensors. For example, if you lift a typical infrared sensor contactless to the front of a table, the sensor tells you the temperature of the table through its radiation-about 68 ° F at normal room temperature.
Bimetal devices take advantage of metal expansion when heated. In these devices, two metals are joined together and mechanically connected to a pointer. When heated, one side of the bimetal strip will expand more than the other. When the pointer is aligned correctly, the temperature measurement is displayed.
Thermometers are well-known liquid expansion devices and are also used for temperature measurement. Generally, they fall into two main categories: mercury types and organic (usually red) liquid types. The difference between the two is clear because mercury devices have certain limitations in how they can be safely transported or transported.
6. State change sensor
State change temperature sensors can only measure such changes, that is, changes in the state of the material caused by temperature changes, such as changes from ice to water to steam. Commercially available devices of this type come in the form of labels, granules, crayons or varnishes.
7. Silicon Diode
Silicon diode sensors are specially developed devices that have been used in low temperature ranges. In essence, they are linear devices in which the conductivity of the diode increases linearly in low and low temperature regions.
Among them, the thermometer is driven by gas, bimetal or expansion principle. They can measure temperatures between -200 ... + 700 ° C. All instruments are also suitable for thermowells. A thermometer measures the thermal state of a homogeneous substance. The measurement system must be as close as possible to the object being measured. The most widely used measurement methods rely on temperature-dependent physical and material properties.