How to calculate humidity on a hygrometer: a manual for the use of devices + calculation examples

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Julia Oschepkova
Last update: January 2020

The indoor microclimate plays a big role. Scientists have proven that humidity has a significant effect on human health. Therefore, it is desirable that this indicator is always within the normal range. Do you agree?

Hygrometers are used to measure humidity. They differ in the principle of action, there are different types. Some models automatically detect moisture levels. When using other types of devices, you have to perform a number of actions, independently calculate. This requires certain knowledge, so you need to understand how to calculate humidity on a hygrometer correctly.

Next, we will talk about what are the instruments for measuring humidity in the room, we will understand the principle of their work. In addition, from our material you will learn how to choose a suitable instrument for measuring humidity.

What are hygrometers for?

A hygrometer is a laboratory equipment by which the relative or absolute humidity of atmospheric air and gases is measured. This device is also called a hygroscope.

Multifunctional electronic hygrometer
The hygrometer is translated from Greek, “ὑγρός” means “liquid”, and “μετρέω” - “measure”. Such a device will be useful both in everyday life and in the industrial field.

Humidity, like temperature, is an important indicator of the microclimate. It is recommended to support it. within the norm: Each type of room has its own optimal level. It is useful for human health and the preservation of things, structures, food.

From too humid air, fungus and viruses spread quickly, vegetables and fruits begin to rot, appears mold on the walls. Condensation settling on electrical equipment, metal structures, paper, leads to their damage. The chemical composition of drugs is also disrupted.

An overdried atmosphere worsens the protective properties of the nasopharynx. This leads to the fact that a person becomes exposed to various viruses and infections.

Also, a low level of humidity has a bad effect on the quality and safety of food: they begin to fade, lose their beneficial properties. An optimal microclimate is important during construction and repair work, especially if different solutions are used.

Types of Hygrometers
There are a lot of types of hygrometers. Their accuracy may be different. The choice of the device should be made based on the sphere in which it is planned to be used.

To maintain humidity at the right level, it is necessary to regularly measure it and take appropriate measures if the indicator deviates from the norm.

Hygrometer is used in various fields:

  • Food Industry;
  • trade;
  • animal husbandry;
  • crop production;
  • pharmaceutical industry;
  • greenhouse, utilities;
  • construction, etc.

Despite its usefulness, hygrometers are not widely used in residential premises. They are usually used at weather stations and in control services.

It is strongly recommended that you regularly measure humidity levels in hospitals, kindergartens and schools. It is worth purchasing such equipment for the home. Maintaining humidity in a given range, you can significantly improve all areas of your life.

Popular types of appliances

The order and features of measuring the humidity level with a hygrometer depend on the type of laboratory equipment used. Such devices differ in their device, the principle of operation and a number of other parameters.

By design, hygrometers are mechanical and electronic. The former have a dial with an arrow, the latter have a display on which information is displayed.

According to the principle of action, there are such types of devices:

  • film;
  • hairy;
  • weighted;
  • capacitive;
  • resistive;
  • ceramic;
  • condensation;
  • electrolytic;
  • psychometric.

Film hygroscopes have a dial with an arrow. The sensor is a special film. It consists of organic material and is connected to the arrow.

Under the influence of atmospheric humidity, the film changes its size. This leads to the fact that the arrow moves to the right or left side, showing the result on the dial.

Hair Hygrometer Device
The advantage of a hair hygrometer is its simple design. This device can be used to determine air humidity at temperatures below zero degrees

The main element of hair devices is skimmed human or synthetic hair stretched over a frame with an arrow. The principle of operation of the device is similar to the film types of hygrometers.

When humidity changes, the length of the hair changes. This leads to a deviation of the arrow in a certain direction.

Weighted hygroscopes are used to calculate absolute humidity. They are equipped with tubes with absorbent material. When passing through the air mass, the filler absorbs moisture and increases in weight.

Sampling is carried out by a special pump. The system is weighed before and after air injection. Absolute humidity is calculated, based on the obtained indicators, the volume of the missed air mass.

Capacitive hygrometers incorporate an oxide capacitor. Its capacity varies depending on the concentration of moisture in the air. Such models must be calibrated periodically. This is due to the fact that over time, the detector capacitance decreases, which affects the accuracy of the measurement.

Resistive hygroscopes work on the principle of changing the humidity level depending on the electrical resistance of salts and polymers. Ceramic appliances consist of a dial with an arrow. The sensor is a special ceramic mixture (clay, silicon).Its electrolytic resistance depends on the level of humidity.

Round mechanical hygrometer
Ceramic hygrometers show only the level of humidity. There are no additional functions in them. But they are accurate and allow you to monitor the change in the microclimate in the room

Condensation devices are also called hygrometers.Lambrecht. The principle of operation of the equipment is based on the use of an integrated mirror. The temperature of this element varies with the temperature of the air.

The main element of electrolytic devices is a glass, polystyrene or other insulating plate coated with a layer of electrolyte. Depending on the concentration of moisture in the air, the resistance of the electrolyte changes.

Lambrecht Hygrometer Device
The condensation hygrometer is highly accurate. But for domestic use, it is not suitable due to certain difficulties of use

Psychometric hygrometers measure atmospheric humidity based on lowering the temperature of the wetted body. They consist of two thermometers: dry and wet.

The device is also equipped with a feeder - a glass flask, which is filled with water. The calculation is carried out by the researcher independently. Helps determine the relative humidity with a hygrometer table attached to the device.

In addition to instruments, there are alternative methods for measuring moisture. More details - read on.

How to use a hygrometer?

For each type, model of the hygrometer, instructions for use are attached. It should be strictly adhered to. The accuracy of the result depends on this.

Psychometric Hygrometer
Psychometric devices have two advantages: they are accurate and show not only humidity, but also the level of temperature in the room

The passport to the device says how to properly measure the humidity level. Safety rules and precautions for handling the device are provided. Recommendations for the care of laboratory measuring equipment are given.

Today, in everyday life and in production, as a rule, mechanical, electronic, condensation and psychometric hygrometers are used.

Option number 1 - electronic devices

Electronic hygrometers are easy to operate. They do not need settings, they are completely ready for work. Before use, the device must be inspected for visible defects - cracks, chips.

The algorithm for measuring the level of humidity by an electronic hygroscope is as follows:

  • turn on the device by pressing the power button;
  • if necessary, set the day of the week, time, set the alarm and other parameters using the “UP”, “MODE"And"Down»;
  • wait until the device calculates the humidity level;
  • evaluate the result on an electronic scoreboard.

Typically, such hygrometers are used in everyday life. Some use them in incubators.

Electronic hygrometer
Electronic hygrometers have a fairly high level of error. Therefore, you should not completely trust their results, it is better to check the results using a mechanical device

Modern models of electronic hygrometers are equipped with various additional functions: for example, show air temperature, light level, day of the week, etc.

Option number 2 - mechanical hygrometers

The accuracy of mechanical hygrometers is low. The error is 5-8%. Before using the device, it is recommended to calibrate it. A reference hygrometer showing accurate humidity values ​​is required for adjustment.

It is necessary to place two devices side by side. If the indicator of the mechanical device does not match the reference, then you need to adjust it with the adjusting screw. This item is located on the back of the equipment.

Mechanical hygrometer
Mechanical hygrometers can in addition to the humidity level in the room additionally show the temperature level. Their accuracy is higher than electronic

Using a mechanical hygroscope is quite simple. It is necessary to install the device in the right place (put on a table or hang on the wall) and evaluate the result.

Option No. 3 - condensing devices

The condensation hygrometer consists of a thermometer, a metal box and a rubber bulb. It determines the absolute humidity at the dew point. Differs in high accuracy. In everyday life, such a device is usually not used.

Condensing hygrometer
Condensing hygrometer is quite accurate. But to determine the level of humidity you need to perform a number of actions. It is inferior to electronic models in terms of ease of use.

Algorithm for using a condenser-type hygrometer:

  • pour ether (alcohol) into the box;
  • start pumping air with a pear until the first drops of dew appear;
  • record the thermometer;
  • see the humidity level in the table attached to the device.

As you can see, there is nothing complicated in determining moisture from a condenser-type hygrometer. It is enough to adhere to the above instructions.

Option No. 4 - psychometric hygrometer

The psychometric hygrometer is fairly accurate. Such equipment is checked by metrological services. The results of this device can be trusted.

Usually, psychometric hygroscopes are used in hospitals, clinics, schools, public canteens. Buy them for the house. Psychometric hygrometers are represented by the VIT-1 and VIT-2 models. You can see how they look in the image below.

Models of a psychometric hygrometer
The VIT-1 psychrometer is used at temperature indicators from 0 to +24 degrees. VIT-2 is recommended for use in rooms where the temperature is in the range from +16 to +40 degrees

Before the direct use of the device, it is necessary to carry out a number of preparatory work:

  1. Unpack the hygroscope. Make sure that the equipment of the device matches the data specified in the passport.
  2. Inspect items for integrity.
  3. Remove the feeder from the base. Dip it in a container with distilled water with the sealed end down.
  4. Moisten the wick by dipping the wet thermometer tank in a glass flask with water.
  5. Install the feeder so that the wick does not touch its walls, and there is a minimum distance of 2 cm from the edge of the open end of the bulb to the thermometer tank.
  6. Install the hygroscope in an upright position at eye level. The psychometric device does not have supports. The device can be hung on the wall. For this, there is a special hole in the upper part of the product.

After the preparatory phase is completed, you can begin to directly determine the level of humidity with a psychometric hygrometer.

Air humidity measurement
The feeder should always be filled with water. Liquid should be added in advance. The water level in the flask must be monitored. If it is topped up before the measurement, then you need to wait half an hour, and then proceed to determine the temperatures on wet and dry thermometers

In the medium to be measured, the device must be kept for at least 30 minutes. Otherwise, the accuracy of the result will be doubtful.

The procedure for using a psychometric hygroscope:

  • stand in front of the device at a distance of good visibility of the scale marks. It is important not to breathe on thermometers in order to avoid distortion of the result;
  • record the readings of a dry type thermometer. It is located on the left side and has a corresponding mark. Record the result with an accuracy of 0.1 ° C;
  • take readings on a wet thermometer;
  • amend the results obtained in accordance with the recommendations given in the passport to the measuring device;
  • subtract the wet value from the dry thermometer;
  • determine the relative humidity using the table located on the right side of the device.The desired value will be at the intersection of the temperature lines on a dry thermometer and the difference in the indicators of two thermometers.

The figure below shows how humidity is determined using a psychometric hygrometer.

Determination of air humidity
Dry thermometer shows a temperature of 20 ° C, and wet - 19 ° C. The difference between these values ​​is 20-19 = 1 ° C. In the table in the column of dry thermometer indicators we find the indicator "20", draw a straight horizontal line. In the values ​​of the temperature difference we find "1" and draw a vertical. At the intersection of the two lines is an indicator of the relative humidity level - 90%

Topsychrometer showed the exact result, it is necessary to regularly carry out maintenance.

So, water should be at room temperature. It is acceptable to use boiled liquid. Water must be pre-treated using a filter. Boil it should be at least 15 minutes.

The wet-type thermometer tank filter must always be soft, clean and moist. Periodically, it is necessary to replace this element. If the dustiness of the air does not exceed 5 mg / cubic meter, then this procedure should be performed every two weeks.

If the parameter under consideration is higher, then the wick must be changed as it becomes dirty. Before installing a new wick, it is necessary to wipe the thermometer tank with a cotton swab dipped in warm water.

It is necessary to periodically check the hygrometer. The accuracy of the device is evaluated immediately after release from production. Further, the device should be checked 1-2 times a year.

Rules for safe use

Despite the fact that hygroscopes come in many forms, there are general rules that must be followed when using them. Any equipment should be handled with care. Do not drop the appliance.

It is also forbidden to treat the device with aggressive chemicals: for example, solutions containing alkali or acid. It is not recommended to overheat the device. The maximum permissible temperature at which the equipment can be operated is given in its accompanying instructions.

Hygrometer in the interior
It is important to choose the right location for the hygrometer. There should be no sources of cold and heat near the equipment. Important lack of vibration. Do not place hygroscopes in places of direct exposure to sunlight

It is important to remember safety measures when using devices containing toxic substances. For example, thermometers of the VIT-2 psychometric apparatus are filled with toluene. It is a toxic and flammable liquid.

Therefore, it is important to prevent the device from breaking and overheating. If there is a rupture of the tank, then toluene can be removed from surrounding objects with water and detergent.

If you need to use water to measure humidity, then you should use distilled water (even if the instructions do not say anything directly). Tap raw liquid contains salts that will settle on the elements of the device, reducing its shelf life and the accuracy of the results.

Which hygrometer is better?

What type of hygrometer is better to acquire in order to control the level of humidity depends on the type of room, goals and the regularity of measurements. For warehouses, production halls, schools and medical institutions it is better to choosepsychometer. It has a high level of accuracy and reliability.

Mechanical hygrometer in the interior
For domestic purposes, a mechanical or electronic hygrometer will be sufficient - these devices can be purchased at the nearest hardware store. In addition, a variety of models will help you choose a device in the style of the room

Psychometric models containing toluene at home, especially if the family has children and animals, are not recommended. Accidentally breaking the device can lead to a number of unpleasant consequences.

To control the humidity level in the house, it is better to purchase a mechanical hygroscope. It is more accurate than electronic. At the same time, it is deprived of many additional functions, unlike the latter type of equipment.

In addition, you can do-it-yourself to assemble a device for measuring humidity. And how to do this, you can read in this stuff.

Conclusions and useful video on the topic

The video below describes the principle of operation of the psychometric device and the procedure for calculating the humidity level:

The accuracy of psychometric and electronic hygrometers can be judged by this video:

The most common psychometric devices are VIT-1 and VIT-2. They are accurate and additionally show the air temperature.

For domestic use, you can use electronic devices. They are usually multifunctional and show not only humidity, but also temperature, lighting, time, day of the week, etc. Their accuracy leaves much to be desired.

Mechanical hygroscopes also have a certain error, but they can be adjusted by calibration.

Do you use moisture meters at home? Which device was preferred and are you satisfied with its work? Please leave your comments in the block under the article.

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