The effect of moisture meter and classification

Hygrometer is property analysis instrument of measuring gas humidity, made up of two identical thermometer, in which a thermometer for dry bubble thermometer, another for wet thermometer. Said levels of water vapor in the gas humidity, absolute humidity and relative humidity of two kinds of representation. Absolute humidity refers to the absolute content of water vapor in the gas, the most commonly used unit is g/m ^ 3; Per unit volume in a certain temperature and pressure, the water vapor content has a certain limit, called the saturated water vapor content. Refers to the relative humidity of water vapor in the gas content with the same temperature and pressure of saturated water vapor content in the gas volume ratio, for commonly used symbols % R. H。 。 Moisture meter USES is very wide, such as ultra-pure metal smelting, textile processing, paper making and printing and dyeing production process, and food storage and meteorological measurement, etc. , often need to use a moisture meter to measure or control the humidity of air or industrial process gas. Hygrometer principle: as the wet bubble the temperature of the thermometer bubble wrapped in cotton yarn, cotton yarn of the bottom is immersed in the water, the evaporation of water soaked the temperature of the thermometer in dry bubble is always lower than the temperature of the thermometer readings ( The temperature) The temperature difference value and water evaporation speed ( The relative humidity at that time) According to the two thermometer readings, from the table or curve can be found to the relative humidity of the air. Hair hygrometer hygrometer classification: the length of the hair, and some synthetic fiber with surrounding gas relative humidity change: the higher the relative humidity, the bigger the length. Use of this principle can be made into hair hygrometer. When synthetic fiber length varies with the change of relative humidity changes, will through mechanical transmission mechanism to change the position of the pointer. The moisture meter has simple structure, it is widely used in meteorological measurement. Lithium chloride humidity meter: the hygrometer detecting element surface is a thin layer of lithium chloride coating, it can absorb water vapor from the surrounding gas and electric. Surrounding gas relative humidity is higher, the lithium chloride bibulous rate, the greater the thus resistance between two electrodes. Therefore, by the size of electrode current can reflect the relative humidity of the surrounding gas. This kind of moisture meter it is widely used in industrial process. Psychrometer: common psychrometer by two in the neighboring position, the same glass thermometer, one bulb are coated with a nylon net, net at the other end of the immersed in the water. Due to the capillary effect, warm bag net always around moist state. Net surface evaporation heat reduce net set temperature. So, this a thermometer ( Referred to as the wet bulb) And the indicated temperature than the other don't pack quilt thermometer ( Known as dry bulb thermometer) Indicated by low temperature. Surrounding gas relative humidity is lower, the net sets the faster the rate of evaporation, and therefore the greater the amplitude of temperature decrease. According to the temperature difference and dry bulb temperature, can be found in the instrument attached table of the surrounding gas relative humidity. The moisture meter has simple structure, is mainly used for weather and indoor air humidity measurement. Alumina hygrometer, its working principle is: aluminium oxide film can be caused by the water from the surrounding gas itself the change of capacitance and resistance value, change the magnitude of the applied to the relative humidity of the surrounding gas. The moisture meter is mainly used for industrial process gas humidity measurement, measurable relative humidity range is very wide.