THERMOHYGROMETER: CHARACTERISTICS, TYPES, HISTORY - CHEMISTRY - 2025

The thermohygrometer or hygrometer, also known as a climate indicator, is an instrument used to measure mainly the humidity of the air or any other gas.

However, over the years and the evolution of the thermohygrometer today, it can measure other aspects such as air temperature.

This type of instrument is helpful in several situations, whether it is to determine the humidity of a tank (in which the state of a product must be maintained), the humidity of a space to be cultivated (since these spaces need an exact level of humidity and temperature) or the purity of the air in a room (where a family will live, for example).

With the advancement of the thermohygrometer, using it has become easier and easier. For example, there are different models and sizes, which makes it easy to carry it.

In addition, the readings received can be saved in the instrument's memory for transfer to a computer for better analysis.

The different models of the thermo-hygrometer not only vary in size, but also in the level of humidity or other aspects that they can measure.

The first model was created by Leonardo Da Vinci and Johann Heinrich Lambert contributed to the creation of a more modern model.

History of the thermohygrometer

The thermo-hygrometer or humidity meter is an instrument that has had several stages of invention. The first version of this device was created by Leonardo Da Vinci, in 1480.

Being the first idea, the model was among very simple parameters. It was not until 1664 that Francesco Folli improved it with some more practical ideas.

It should be noted that this instrument takes the name of a hygrometer in 1755, when the polymath Johann Heinrich Lambert created a more modern version.

Other people who participated in the evolution of the hygrometer or similar devices were: Guillaume Amontons, James Hutton and Richard Assmann.

However, it was Horace-Bénédict de Saussure who created the first hair tension hygrometer. In this model, the Swiss physicist and geologist used a human hair to measure humidity levels.

This device worked because organic substances respond to moisture by either expanding or contracting.

In 1820, John Frederic Daniell (British chemist and meteorologist) created a hygrometer to determine the dew point. That is, to measure the temperature at which air becomes saturated and at which water vapor condenses.

Furthermore, it is necessary to highlight that Robert Hooke is an important participant in the evolution and invention of many meteorological instruments.

How do you use a thermohygrometer?

In situations of everyday life, people are able to measure or calculate in different types of scientific units that are popularly known, whether in kilometers, kilograms, seconds, liters, among others.

However, although humidity is not calculated with common scientific units, it should not be exempt from being measured. In some cases, humidity must be controlled, either for professional or health reasons.

The units of a thermohygrometer are more difficult to read, because a hygrometer projects several results in a single measurement. This is because it is designed to measure absolute, specific, and relative humidity.

Absolute humidity indicates how much water vapor is in each unit of volume in the air, which is measured in grams and cubic meters.

Specific humidity shows the unit of mass present in water vapor. This is represented in units of grams per kilogram. For its part, relative humidity is the amount of water vapor in the air and is represented as a percentage.

Turning on a device will always be straightforward, but understanding the drives they dial isn't always easy. Therefore, to use a thermohygrometer in order to understand the results, it is necessary to have knowledge about the units that it uses.

Types

Initially, a thermo-hygrometer was used to measure the humidity of a closed space.

However, it can now be used for open spaces, such as a walk through a forest. In these uses, the first difference is found, so there are two types:

Indoor thermohygrometer

For example, the BZ05 model from the German company Trotec. This model is electronic and can be placed on a table or on a wall. It shows the humidity and temperature levels of the area where it is located.

However, the levels it can measure are limited as it is designed for a home or office. In addition, it incorporates a clock.

Outdoor thermohygrometer

For example, the T260 infrared professional use model from the German company Trotec. Being for professional use, this device is designed to read lower and higher levels than the previous one.

It is also incorporated with an infrared system that allows temperature measurement, a USB port to speed up the data transfer process and a touch screen. It also has a function to measure high temperatures.

This difference in the model was created with the aim of facilitating the transfer of the device and making it more comfortable and manageable in its portable design.

Although it is important to note that both indoor and outdoor hygrometers work in both spaces.

However, these two are not the only types of thermohygrometers that exist. There are also modern hygrometers that are incorporated as sensors, in another type of mechanism and in homes. Some of the most common thermohygrometers on the market are:

Gravimetric thermohygrometer

Ranked as one of the best methods for calculating humidity. It is used to measure and compare the mass found in an air sample with an identical volume of dry air.

Capacitive thermohygrometer

Used to measure the humidity in an electrical insulator of a polymeric material (material made up of macromolecules).

Resistive thermohygrometer

It analyzes the changes in the values ​​that occur in the resistance of a material due to humidity.

Thermal thermohygrometer

This type of sensor measures absolute humidity and how it affects the air's ability to conduct heat.

References

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5. About humidity meters / hygrometers. Retrieved on September 13, 2017, from instrumart.com.
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7. Oblack, R. What is a hygrometer and how does it work? (2016, June 30). Retrieved on September 13, 2017, from thoughtco.com.