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Humidity measurement has always been one of the well-known problems in the field of social metrology. A seemingly complex quantity, when you go deeper, touches the rather complicated physical-chemical analysis and calculation, the first person can neglect many factors that must be paid attention to in the humidity measurement, so it will strike a reasonable use of the sensor. The rarer methods for measuring humidity in high and low temperature test chambers are: static method (double pressure method, dual temperature method, shunt method), static method (saturated salt method, sulfuric acid method), dew point method, dry and wet bulb method and electronic sensors law.
Method for detecting humidity test chamber:
Due to the use of ancient measurement and control wrists, this type of high and low temperature test chamber can be made very delicate, but because of the complicated mechanical equipment, the price is relatively expensive, the operation costs time and time, and it is important as a standard measurement. Its precise measurement accuracy exceeds ± 2 % RH up and down. The two-pressure method and the two-temperature method are based on the thermodynamic P, V, and T equilibrium reasons, and the equilibration time is longer. The separation method is based on the precise mixing of relative body moisture and relative dry vapor.
Humidity Test Chamber
The dew point method measures the temperature of the humid air when it reaches saturation, which is an indirect consequence of thermodynamics. It has high accuracy and a wide measurement range. The precision of dew point meter for measurement can reach ± 0.2 â or higher.
Electronic humidity sensor products and humidity measurement are industries that have been declining in the 1990s. In recent years, the research and development of international humidity sensors has greatly improved.
The high and low temperature test chamber dry and wet bulb method is a very common measurement method. It is a direct method. It uses the wet and dry bulb equation to convert the humidity value. This equation is conditional: the wind speed near the wet bulb must Reach above 2.5m / s. This condition is simplified by the ordinary wet and dry bulb thermometers, so its accuracy is only 5 ~ 7% RH, and the dry and wet bulbs are not static methods. Don't think that you only need to improve the measurement accuracy of two thermometers, it is equivalent to progress. The measurement accuracy of the hygrometer.
The saturated salt method in the static method of the high and low temperature test chamber is a rare method in humidity measurement, which is complicated and easy to implement. However, the saturated salt method has strict requirements on the equilibrium of liquid and gas phases, and has higher requirements on the fluctuation of ambient temperature. It takes a long time to equalize, and the low humidity point requires longer. Especially when the difference between the humidity in the high and low temperature test box and the humidity in the bottle is large, it needs to be balanced for 6 to 8 hours each time it is opened.