Precautions of hygrometer
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Aside from greenhouses and industrial spaces, hygrometers are also used in some incubators, saunas, humidors and museums. They are also used in the care of wooden musical instruments such as pianos, guitars, violins, and harps which can be damaged by improper humidity conditions. In residential settings, hygrometers are used to assist in humidity control (too low humidity can damage human skin and body, while too high humidity favors growth of mildew and dust mite). Hygrometers are also used in the coating industry because the application of paint and other coatings may be very sensitive to humidity and dew point. With a growing demand on the amount of measurements taken the psychrometer is now replaced by a dewpoint gauge known as a dewcheck. These devices make measurements a lot faster but are often not allowed in explosive environments.
Humidity measurement is among the more difficult problems in basic meteorology. According to the WMO Guide, "The achievable accuracies [for humidity determination] listed in the table refer to good quality instruments that are well operated and maintained. In practice, these are not easy to achieve." Two thermometers can be compared by immersing them both in an insulated vessel of water (or alcohol, for temperatures below the freezing point of water) and stirring vigorously to minimize temperature variations. A high-quality liquid-in-glass thermometer if handled with care should remain stable for some years. Hygrometers must be calibrated in air, which is a much less effective heat transfer medium than is water, and many types are subject to drift[7] so need regular recalibration. A further difficulty is that most hygrometers sense relative humidity rather than the absolute amount of water present, but relative humidity is a function of both temperature and absolute moisture content, so small temperature variations within the air in a test chamber will translate into relative humidity variations.
In a cold and humid environment, sublimation of ice may occur on the sensor head, whether it is a hair, dew cell, mirror, capacitance sensing element, or dry-bulb thermometer of an aspiration psychrometer. The ice on the probe matches the reading to the saturation humidity with respect to ice at that temperature, i.e. the frost point. However, a conventional hygrometer is unable to measure properly above the frost point, and the only way to go around this fundamental problem is to use a heated humidity probe.
Hygrometer is a geographical device which is used to measure the humidity present in the air,soil or in any other environment.
Precautions of using hygrometer:
1) keeping the device completely dry
2) keeping the device completely clean and dirt free
3) avoiding any heating source nearby
4) avoiding optimum environnements like extremely humidor extremely dry
And many more...