Hygrometers and hygrographs

21 January 2024, 19:09

These devices are used to determine the moisture content in air, other gases or solid substances. The main types are as follows:

1. Chemical hygrometers, based on the absorption of moisture by chemical substances, which are then weighed.

2. Condensation hygrometers, or dew point hygrometers, in which the "dew point" method is used (that is, the temperature at which water vapor begins to condense).

3. Hair hygrometers, based on changes in the length of one or several hair strands or plastic strips depending on whether they are dry or moist. The hair strands or plastic strips are stretched on a frame, loaded with a counterweight and mounted on a pulley whose shaft is equipped with a needle moving along a circular scale. In some devices, this movement is converted into an electrical signal.

4. Hygrometers consisting of a glass tube in the shape of a torus, partially filled with mercury and closed at one end by a membrane semipermeable to water vapor present in the atmosphere. The pressure of water vapor acts on the mercury and displaces the tube around a shaft connected to a needle on a circular scale. In some devices, displacement of the tube is converted into an electrical signal.

5. Hygrometers with metallic strips wound in a spiral and coated with a substance that reacts to humidity. The hygroscopic reaction changes the length of the metallic strips. This movement is transmitted to an axis fixed at the end of the metallic strips and equipped with a needle moving along a circular scale. In some devices, this movement is converted into an electrical signal.

6. Electrical hygrometers. The operation of electrical hygrometers is usually based on changes in the specific conductivity of special absorbing salts (for example, lithium chloride) or on changes in the capacitance of an electrical component depending on humidity. (These instruments are sometimes calibrated to indicate the "dew point" of the measured element.)

Source: "Explanations to the Harmonized Commodity Description and Coding System for Foreign Economic Activity of the Russian Federation (HSN of Russia)" (prepared by the Federal Customs Service of Russia) (volume 4, sections XVI - XXI, groups 85 - 97)

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Морфология

Род

Понятие «гигрометры и гигрографы» мужского рода.

Склонение и число

Падеж	Единственное число	Множественное число
Р	гигрометра и гигрографы	гигрометров и гигрографы
Д	гигрометру и гигрографы	гигрометрам и гигрографы
В	гигрометр и гигрографы	гигрометры и гигрографы
Т	гигрометром и гигрографы	гигрометрами и гигрографы
П	гигрометре и гигрографы	гигрометрах и гигрографы