The high and low temperature box is tested and operated according to the dry and wet bulb method. Its mechanism is to use two dry and wet bulb temperature sensors with equal precision and a distance of 20mm under the same wind standard to measure the temperature. The difference between the ranges, and then the method to obtain the air humidity according to the measurement or look-up table. Now, a simple and detailed introduction to these methods to accurately measure the air humidity:

First, use two thermometers with the same model and specifications and basically the same characteristics. The axis center lines of the two thermometer sensors should be parallel to each other, and the distance between the thermometers should not be less than 3 times the total diameter of the wet bulb sensor (including wet bulb cloth) , Accurately measure that the tap water cup has a lid and is filled with pure water. The distance from the river surface in the cup to the bottom of the wet bulb is 30mm. The penetration height of the wet bulb water is (7080) mm. Read the range of the dry and wet bulb thermometers and calculate the dry and wet bulb Ball thermometer error, according to the dry and wet bulb list to find the corresponding air humidity value.

The temperature and humidity recording experimental equipment such as high and low temperature boxes is designed and conceived based on the above-mentioned dry and wet bulb measurement method. Electric heaters are used to heat pure water to generate steam, and the steam is sent out into the box by a motor, and spreads evenly. The sensor and the wet bulb sand cloth test the environmental humidity and natural environment of the box, and then feedback the measured results to the control instrument connected to the sensor, indicating the environmental humidity in the experimental box. This method is quick to humidify, and the actual operation is simple and convenient. , it is not easy to cause problems such as precision reduction, and maintenance is required in the middle and later stages.