What are the basic types of temperature sensors?

Temperature is defined as the energy level of a substance, which can be verified by certain changes in the substance. Temperature sensors are a key component of temperature measurement instruments, which can be divided into contact and non-contact types based on measurement methods. They measure temperature based on certain changes in perceived physical properties. This article mainly introduces seven basic types of temperature measurement sensors (RTDs, thermistors), infrared radiators, bimetallic devices, liquid expansion devices, molecular state changes, and silicon diodes, including thermal resistors and resistance temperature devices.

Different types of sensors can measure temperature, whether it is a thermometer or a thermistor.

1. A thermal resistor is a voltage device that can mark temperature detection when voltage changes. As the temperature increases, the output voltage of the thermal resistor increases - not necessarily linearly.

The thermal resistor is usually located in a metal or ceramic shield to prevent it from being exposed to various environments. The thermal resistance of metal sheaths can also provide various external coatings, such as fluorinated iron dragon, which can be used faultlessly in acid and strong alkaline solutions.

2. Resistance temperature measurement device

The resistance temperature measurement device is also a charge. It does not use voltage like a thermal resistor, but uses another characteristic of the material - resistance, which changes with temperature.

The resistance devices used can be divided into metal resistance temperature devices (RTDs) and thermistors.

Generally speaking, RTDs are more linear than thermistors. They rise in the positive direction, and the resistance increases with the increase of temperature. The structural characteristics of thermistors are completely different. It is an extremely nonlinear semi conductive device that reduces resistance as the temperature increases.

3. Infrared sensor

Infrared sensors are non-contact sensors. For example, if you lift a typical infrared sensor non-contact to the front of a table, the sensor will use its radiation to tell you the temperature of the table - about 68 ° F at normal room temperature

In non-contact ice water measurement, due to volatility, ice water should be measured slightly at 0 ° C, which will slightly reduce the expected temperature reading.

4. Bimetal equipment

The bimetallic device has the advantage of metal expansion during heating. On these devices, two metals are bonded together and mechanically connected to the pointer. When heated, one side of the bimetallic strip will greatly expand to the other side. When the pointer is accurately aligned, the temperature measurement value will be displayed.

The advantages of bimetallic devices are portability and power awareness. However, they are usually not as accurate as electrical equipment, and you cannot easily record the temperature values of electrical equipment such as thermal resistors or RTDs. However, scalability is a major advantage of the correct application.

5. Thermometer is a famous liquid expansion device that is also used for temperature detection. Generally speaking, they are divided into two key types: mercury type and organic liquid type (usually red). The difference between the two is obvious because mercury devices have certain limitations in how to safely transport or transport.

For example, mercury is referred to as an environmental pollutant, so damage may be dangerous. Before transportation, please be sure to check the current restrictions on air transportation of mercury cargo.

6. Situation change sensor

The temperature sensor detects material changes caused by temperature changes, just like changes from ice to water and then to steam. The types of devices available on the market include labels, particles, crayons, or paint.

For example, this symbol can be used for steam traps. When the drain valve needs to be adjusted, it will become hot; Then, the white dots on the sign are blackened to describe the increase in humidity. Even if the temperature recovers, the white dot will remain black.

The temperature detection is indicated in units of ° F and ° C for the situation change identification. For such machines, when the displayed temperature is exceeded, the white dot will turn black; It is an inevitable sensor, and once it changes color, it will remain black. When you need to confirm that the temperature does not exceed a certain level, the temperature sign will be very effective, possibly due to engineering or legal reasons during transportation. Due to changes in the situation, devices are non charged like bimetallic bands, so they have advantages in certain applications. Some methods of this series of sensors (paint, crayons) will not change color, and their markings will only fade. Granular shapes can visually deform or completely dissolve.

Limitations include relatively slow response times. Therefore, if you have a temperature peak that rises and then immediately decreases, it may not significantly reflect. The accuracy is not as high as most common equipment in other industries. However, they are very practical in the application field, do you need power non reverse labeling.

The operating principle of other rotatable labels is completely different from the application of LCD screens. According to the temperature, the displayed color changes from black to brown, blue, or green.

For example, when a typical label is below the sensing temperature, it is all black. For example, 33, as the temperature detection value increases, there will be a color at the ° F position - first blue, then green, and finally brown, depending on the specific temperature. On any specific LCD device, you usually see two adjacent color dots - blue dots slightly lower than the temperature indicator, and brown dots slightly higher than the temperature indicator. This allows you to estimate the temperature between ° C and 90 ° F at the age of 85.

Although not entirely accurate, its advantages are exquisite, sturdy, and non electronic indicators that can continuously update temperature detection.

7. Silicon diode

Silicon diode sensors are equipment specifically developed for the low-temperature field. Fundamentally, they are linear devices. In low-temperature regions, the conductivity of diodes increases linearly.

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