The method for measuring the relative humidity by the dry and wet ball method according to the JJF1101-2003 standard constant temperature and humidity test chamber is as follows:
1. Select two thermometers with the same model and the same characteristics. The axis of the two thermometer sensors should be parallel. The distance between the thermometers should be no less than the total diameter of the wet bulb sensor (including the thickness of the wet ball gauze cover). 3 times.
2. Wet ball gauze adopts No. 120 weather gauze or special gauze, which is about 100mm long. The wet bulb is distilled water or deionized water.
3, the cup is best covered with distilled water, the distance from the water surface to the bottom of the wet ball is about 30mm.
4. When dressing the wet ball gauze, wash the handle, then wash the wet ball with clean water, then wrap the gauze on the wet ball with the thread on the gauze. The overlap should not exceed the circumference. 1/4, do not tie too tight, so as not to affect the water absorption, and cut off the excess yarn.
5. The wet bulb should be kept clean, soft and moist.
6. Read the indication values ​​of the dry and wet bulb thermometers separately and calculate the difference between the dry and wet bulb temperatures. The relative humidity value at this temperature was determined according to GB6999-1986.
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