Type of temperature measuring instrument

With the development of science and technology and the needs of modern industrial technology, temperature measurement technology has also been continuously improved and improved. Due to the increasingly wide temperature range, according to different requirements, but also to create different needs of the temperature measuring instrument. Here are a few of them.

Rotary Thermometer The rotary thermometer is made of a coiled bimetal. One end of the bimetal is fixed and the other end is connected with a pointer. Due to the different degree of expansion of the two metal pieces, the degree of curling of the bimetal is different at different temperatures, and the pointer is then pointed at different positions on the dial. From the reading on the dial, the temperature can be known.

Semiconductor thermometers have different resistances from metals and metals. When the temperature rises, the resistance of the semiconductor decreases, and the change is large. Therefore, a small amount of temperature change can also make a significant change in the resistance, the thermometer has a higher precision, often referred to as a temperature sensor.

Thermocouple Thermometer A thermocouple thermometer consists of two different metals connected to a sensitive voltmeter. Metal contacts produce different potential differences at both ends of the metal at different temperatures. The potential difference is very small, so you need a sensitive voltmeter to measure it. From the reading of the voltmeter, you can know the temperature.

When the temperature of a pyrometer object is high enough to emit a large amount of visible light, the temperature of the object can be determined by measuring the amount of thermal radiation. Such a thermometer is a photometric thermometer. This thermometer is mainly made of a telescope with a red filter and a set of circuits with a small bulb, an ammeter and a variable resistor. Before use, establish the relationship between the temperature corresponding to the different brightness of the filament and the reading on the ammeter. When using, align the telescope with the object to be measured and adjust the resistance so that the brightness of the bulb is the same as the object to be measured. At this time, the temperature of the object to be measured can be read from the ammeter.

LCD liquid crystal thermometers made with different formulations, the phase transition temperature is different, when the phase change, its optical properties will change, so that the liquid crystal looks color. If liquid crystals with different phase transition temperatures are coated on a piece of paper, the temperature can be known from the change in the color of the liquid crystal. The advantage of this thermometer is that it is easy to read, but the disadvantage is that it is not accurate enough. It is often used in ornamental fish tanks to indicate the water temperature.