Hygrometer: what is it and what is it for

A hygrometer is a device used to measure moisture in the air or in solid materials. It works by measuring the amount of water present in the air or in a material and expressing it as a percentage of the maximum possible amount of water vapor that the air or the material could contain at a given temperature and pressure.

Higrometers can use a variety of methods to perform this measurement:

• Capacitive moisture sensor: It measures the electrical capacity of a water sensitive material.
• Resistive moisture sensor: It measures the electrical resistance of a material that changes with moisture.
• Synthetic hair humidity sensor: Change its length in response to moisture changes.

Most modern hygrometers also include a Thermometer to measure the temperaturesince the relative humidity of the air is closely related to the temperature. By combining moisture reading with temperature reading, hygrometers can provide a more precise relative moisture reading. If you would like to have one at home, here you can check its price.

Higrometers are used in a variety of applications, from interior moisture control, such as in homes and buildings, even in laboratories, agriculture, food industry, and even in weather to predict the climate. They are also useful in the conservation of works of art and in the pharmaceutical industry, where humidity can affect the integrity of products.

• They are usually used in homes, offices and other interior spaces to monitor and control the relative humidity of the air. In agriculture, hygrometers are fundamental to measure soil and air humidity in greenhouses and other agricultural facilities. The precise control of moisture is essential to optimize crop growth and prevent diseases caused by excess or lack of moisture.
• In the food industrythese devices are used to control moisture in food processing, storage and transport. Maintaining adequate humidity levels is important to preserve the quality and safety of food products and prevent the proliferation of bacteria and mold.
• They are also used in Laboratory environmentsespecially in research and development laboratories, hygrometers are used to control moisture in crop cameras, incubators and other specialized equipment. The precision in moisture control is essential for the success of many scientific experiments and processes.
• Hygrometers are important components in Meteorological stations and time forecast devices. They help to measure the relative humidity of the air, which is essential to understand and predict climatic patterns and atmospheric conditions.

To learn how a hygrometer works, we must know its main components and what functions insists on each of them:

• Capacitive moisture sensor: One of the most common methods used in modern hygrometers is the capacitive humidity sensor. This sensor consists of two parallel plates, one of which is covered with a moisture sensitive material, such as a porous polymer. When the moisture of the air changes, the sensitive material absorbs or releases water, which alters the dielectric capacity of the sensor. By measuring changes in electrical capacity between the plates, the hygrometer can determine the relative moisture of the air.
• Resistive moisture sensor: This sensor uses a ceramic or polymer material that changes its electrical resistance in response to moisture changes. When moisture increases, the material swells, which increases its electrical conductivity. Measuring the electrical resistance of the material, the hygrometer can calculate the relative humidity of the air.
• Synthetic hair humidity sensor: Although less common in modern devices, some hygrometers use a synthetic hair humidity sensor. These devices consist of a lock of human or animal hair treated chemically to be sensitive to changes in humidity. When moisture increases, hair expands, and when it decreases, it contracts. A sensitive measurement mechanism records these changes and provides a relative moisture reading.

Regardless of the type of sensor used, many hygrometers also incorporate a thermometer to measure the ambient temperature. This is important because the relative humidity of the air is intrinsically related to temperature. Therefore, combining moisture measurement with temperature measurement allows more precise readings of relative humidity.

There are several types of hygrometers with different functions. Let’s see which are the main ones:

• Mechanical hygrometers: They are simple devices that use a moisture sensitive material, such as human or animal hair, which expands or contracts in response to moisture changes. These devices are usually connected to a gear system that amplifies the movement of sensitive material, which allows visualizing relative humidity on an analog scale.
• Psychrometric hygrometers: They use evaporative cooling principles to measure the relative moisture of the air. They consist of two thermometers, one of dry bulb and one with a humid bulb, which are exposed to the same air flow. Measuring the temperature difference between the two thermometers and consulting specific tables, the relative humidity of the air can be determined.
• Shadow hygrometers: These hygrometers are simple devices that consist of a thermometer wrapped in a wet gauze. The evaporation of the water of the gauze will cool the thermometer, and the temperature reading can be used to determine the relative humidity by means of a correction table.
• Capacitive hygrometers: They use a capacitance sensor to measure relative humidity. These devices are common in commercial and domestic applications due to their precision and reliability.

Now that you know what a hygrometer is and why do not miss these articles on the best moisture meters for plants and what is the importance of atmospheric humidity.

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