The refrigerant pressure gauge is a commonly used temperature measuring instrument in cold storage installation, operation and maintenance. There are glass tube liquid thermometers, wet and dry bulb thermometers and electronic thermometers.

(1) Glass tube liquid thermometer The glass tube thermometer is the most commonly used thermometer, which is generally used to measure the temperature in the range of 30 to 50°C. Typical values are high measurement accuracy, simple structure, but easy to break .

(2) Dry and wet bulb thermometer, which is composed of a dry bulb thermometer and a wet bulb thermometer. The former is an ordinary thermometer, which directly measures the dry bulb temperature of the air; and the temperature sensing bag is covered with wet gauze and a wet bulb of air. temperature. The difference in temperature between the dry and wet bulbs can reflect the humidity of the air. The temperature difference is large, the air is dry; the temperature difference is small, the air humidity is large . The relative humidity of the air can be obtained by checking the table according to the temperature difference between the dry and wet bulbs.

(3) Electronic thermometer. The electronic thermometer adopts digital display and uses thermistor or semiconductor diode as the temperature sensor, with stable performance, convenient and accurate reading. Figure 2-11 shows the DS-1 electronic thermometer.