How to calculate humidity on a hygrometer: a guide to using instruments + calculation examples

Possible malfunctions and measures for their elimination

Any device can break down, a hygrometer is no exception. The main thing is to know how to fix this problem correctly:

• The hygrometer has glass parts that are easy to damage or break, so you need to be especially careful. Otherwise, you will have to replace this part of the device;
• if the feeder is destroyed, it must be replaced. The kit includes a spare feeder, which must be fixed with a spring located behind the base. If a spare part is not available, then you need to purchase a new one, in accordance with the technical data sheet, which lists all the components of the device;

Important! Before a new feeder can be installed, the old feeder must be removed and any residue removed.if there is a break in the liquid in the thermometer, then you need to heat the tank to the desired temperature, you can not overheat, otherwise it may collapse

if there is a break in the liquid in the thermometer, then you need to heat the tank to the desired temperature, you can not overheat, otherwise it may collapse.

Thus, a psychrometric hygrometer is a very important and necessary device. If you do not measure the moisture in the premises, then numerous health problems can arise, fungus and mold can appear on the walls in the apartment, the condition of pets and houseplants will worsen

A psychrometer is a fairly cheap but useful tool that should be in every room in order for the owner to sleep peacefully in a comfortable environment.

How to use?

The correct use of each hygrometer, as well as the frequency of verification, is, of course, most fully reflected in the accompanying instructions. But in any case it is forbidden:

• throw the device;

• subject it to strong mechanical stress;

• treat with acids, alkalis and other caustic substances;

• overheat devices over 45 degrees.

Only in this case, the readings of the hygrometer will be really accurate and adequate. If you need to pour water to operate the device, you should take distilled liquid, even when the instructions do not directly say so. Calibration of the device deserves special attention. Electronic models are in many cases impossible to tune - they should already have been properly tuned at the factory.

It is recommended to use a salt test to simplify the process:

• put the hygrometer in a glass jar or container with a tight-fitting lid;

• ¼ of the container is filled with saline;

• put the device above it on a stand;

• after 8 hours, check whether the value of 75% humidity has been reached (this is exactly what it will be).

If the desired figure is determined correctly, then the meter does not need to be calibrated. If a mechanical hygrometer fails, you must manually (as quickly as possible) set the pointer in the desired position. Electronic devices are usually set up by service providers under warranty. If it has already ended, then the chances that something can be done are small.

See below for how to use the hygrometer.

Technical documentation

The device must have a technical passport, which contains the main data:

• how and where to use the device;
• a table showing the characteristics of the device;
• equipment included in the kit, indicating the article numbers of each component;
• possible corrections for each thermometer;
• the conditions under which the warranty obligations are fulfilled;
• also in the passport there is a stamp that is put at the first check and further checks are noted. When conducting an inspection, they are guided by a special GOST, which indicates all the conditions under which an inspection can take place.

Video text

Hygrometer Vit-2. How to use a hygrometer. Humidity and health. Overview of the hygrometer. Psychrometer

Here are links to Aliexpress (aliexpress) If you just “play around”, then it’s better to take the cheapest Hygrometer for 100r, so that you don’t feel sorry for the money, but the accuracy is poor. Here are 3 options: ►http://ali.pub/2etxel (digital) ►http://ali.pub/2etxhw (analogue) ►http://ali.pub/2etxle (analogue with a thermometer) And if, more accurate – ►http://ali.pub/2etxr1 Was like this until it crashed. He was replaced by Vit. Bought at one time for 700r.Now it costs 570 (if it's fast) and 392r (if you're not in a hurry and you can wait a month). I’ll probably order another for 390 r and compare it with VIT-2.

►Salinometer (ppm-metr) TDS-meter. Very cheap ►http://ali.pub/2vyftn

► Portable Humidifier for 250r for any capacity (pour water into a glass and lower the humidifier element into it) http://ali.pub/2tteie

#Psychrometric hygrometer - a device for measuring air humidity and temperature.

The rate of evaporation of moisture increases as the relative humidity of the air decreases. Evaporation of moisture, in turn, causes cooling of the condensed liquid. Thus, the temperature of the wet object decreases. The temperature difference between the air and the wet object can be used to determine the rate of evaporation, and hence the #humidity of the air. (Wikipedia)

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Maintenance of Chilled Mirror Hygrometers

What does the instruction manual recommend to the user of the device in this sense. The hygrometer, which is sensitive to contamination, must be cleaned periodically to ensure measurement stability, although this may increase its maintenance cost. Inspection of the instrument's mirror is usually performed using the built-in microscope, and its maintenance is carried out manually after opening the measuring compartment.

If the cleaning of the mirror surface is carried out at the intervals required in the instructions for its operation, then in this way it is possible to maintain the accuracy of measurements. Convenient access to the mirror surface for cleaning is usually provided by a hinge between the optical components and the mirror. You can now find any condensation hygrometer that the consumer needs on the market. The photo below shows an example of its execution.

Psychrometer - device, principle of operation

Humidity in the apartment is one of the main indicators of the home microclimate. Too much or too little moisture in the air can cause discomfort and negatively affect your well-being.

Humidity is a measure of the amount of water vapor in the air. Humidity at home varies depending on weather conditions and human life processes.

Without special equipment, it is difficult to determine the relative exact level of air humidity. However, the concentration of moisture that does not correspond to the norm can be determined by dryness of the skin and mucous membranes or the accumulation of condensate (dew point) on windows and mirror surfaces.

Relative humidity is the content of water vapor in the air and its interaction with air temperature.

A device for measuring air humidity is called a hygrometer.

There are several types of hygrometer:

• hair,
• film,
• weight,
• condensation,
• psychrometric,
• electronic.

Psychrometric hygrometer

The psychrometer is based on the interaction between "dry" and "wet" thermometers. The device has two thermometers with tinted liquids (red and blue). One of these tubes is wrapped in cotton cloth, the end of which is immersed in a reservoir of solution. The fabric gets wet, and then the moisture begins to evaporate, thereby cooling the "wet" thermometer. How lower indoor humiditythe lower the thermometer reading will be.

To calculate the percentage of air humidity on a psychrometer, you should find the value of air temperature in the table on the device according to the readings of the thermometer and find the difference in values ​​at the intersection of the indicators.

There are several types of psychrometers:

• stationary. Includes two thermometers (dry and wet). Works according to the principle described above. The percentage of air humidity is calculated according to the table.
• aspiration. It differs from a stationary one only in the presence of a special fan, which serves to blow the thermometers with an incoming air stream, thereby speeding up the process of measuring air humidity.
• remote. This psychrometer is of two types: manometric and electrical. Instead of mercury or alcohol thermometers, it has silicon sensors. However, as in the first two cases, one of the sensors remains dry, the second remains wet.

The operation of the psychrometer is based on the degree of cooling by evaporation of the "wet" thermometer reservoir with a balance of heat transfer and a constant speed depending on the amount of moisture in the ventilated air stream.

Relative humidity is determined from the temperature of the "wetted" thermometer and the air temperature.

The psychrometer consists of two main parts - head 1 and thermal holder 3 (Fig. 1).

Inside the head there is an aspiration device, consisting of a winding mechanism, key 2 and a fan for the MV-4-2M psychrometer; the M-34-M psychrometer uses an electric motor with a fan, connected to an alternating current network with a voltage of 220 V.

Thermometers 4 are installed on the thermoholder 3, one of which is “wetted”, and the other is used to measure the air temperature.

Thermometers are protected from the effects of solar radiation both from the side - by slats 5, and from below - by tubes 6.

At the bottom of the thermoholder there is a device for regulating the aspiration rate. It consists of a cone-shaped valve 8 and a spring-loaded screw 7. When the screw is turned, a certain part of the section of the tube 9 is blocked, which leads to a change in the aspiration rate.

Speed ​​adjustment to the set value is carried out at the factory and, if necessary, at the verification office.

Rice. 1. Scheme of aspiration psychrometer MV-4-2M

When the fan rotates, air is sucked into the device, which flows around the tanks of thermometers, passes through the tube 9 to the fan and is thrown out through the slots in the aspiration head. The psychrometer is supplied with: a wetting pipette consisting of a glass tube inserted into a rubber balloon with a clamp; shield (wind protection) to protect the aspirator from the influence of wind; a metal hook for hanging the device by the ball on the aspiration head, calibration certificates for thermometers and a passport. To calculate humidity according to thermometer readings, psychrometric tables are used or calculated using a formula. Formulas and auxiliary tables for calculating absolute and relative humidity are presented in Appendix 1

Recommendations for safe operation

There are a large number of models of hygroscopes, but they all require compliance with the rules.

Any instrument must be handled with care to prevent falling. Vibrations during their work are also undesirable.
It is strictly forbidden to clean all devices with detergents containing aggressive substances (acid, alkali, etc.).

d.).
The correct location is the next requirement. Moisture meters should not be located in direct sunlight, near heaters or air conditioners.
Contact with high temperature is prohibited for psychrometric devices in which thermometers contain toluene (VIT-1, VIT-2). This liquid is not only highly toxic, but also flammable.

It is best to use distilled water, devoid of all unwanted impurities, for the operation of the device. Even filtered boiled water is less than ideal as it contains salts which will affect the equipment and the accuracy of the results.

At the end of the topic of moisture meters - an interesting video that talks about the "most mysterious" type of hygrometers:

Choosing a hygrometer

There are many hygrometers (moisture meters, psychrometers, weather stations) on Aliexpress.
The range can be divided into mechanical (pointer, hair) and electronic (digital) hygrometers. Mechanical pointer hygrometers are simple, cheap, easy to adjust. Electronic digital hygrometers differ from each other in size, additional, sometimes dubious functions (lunar calendar, cuckoo clock , CO2 measurement, etc.). At the same time, they suffer from the accuracy of the readings and exclude the possibility of adjustment.

To begin with, out of 6 (six!) hygrometers I ordered from 2017 to 2020 on Aliexpress, only one got to me, the remaining 5 (five!) disappeared without a trace. Everything that is sold on Avito is the same Chinese hygrometers, only added in price. Perhaps, among them, even those who, before reaching addressees like me, were intercepted by the Postal Pirates of Russia (there is such an organization) for subsequent resale.
Despite all the efforts of the postmen, I still managed to test several electronic hygrometers, such as Exodus HTC 1, HTC 2, thermopro tp16, tp60, CX-201A, Dykie.The test showed that regardless of color, shape and functionality, hygrometers from Aliexpress are nothing more than a toy. Their accuracy is plus or minus ten bast shoes in psychrometric equivalent.

At the beginning of 2020, a seemingly solid device was also purchased at the local Saray hypermarket for 900 rubles, called “Digital thermo-hygrometer with clock T-17 403318”. It turned out that this Chinese craft displays completely arbitrary numbers instead of real humidity. Here we don’t even have to talk about any error, since the readings of the T-17 403318 change non-linearly and stay around 30%, both in the driest room and when the device is placed directly above the air humidifier. When this rubbish was handed over to Saray, bonus points were not returned, so I do not recommend either their hygrometers or the supermarket itself for purchase.

If you need any accurate hygrometer, you need to buy it in a reputable store (based on the experience described above in 2020, this also does not give guarantees). At the very least, a hygrometer of inadequate quality can be exchanged or returned. Of course, a high-quality electronic hygrometer will cost much more than on Aliexpress.
As an accurate and at the same time budget option, you can use a psychrometer, for example, VIT-2. Yes, this is such a not very convenient thing, with two thermometers and a humidity calculation table.

Is it possible to do without devices?

"Folk" methods for assessing air humidity

If we talk about the complete absence of instruments, then, yes, there are a couple of methods, however, a very approximate assessment of the relative humidity of the air.

Use for these purposes an ordinary candle.To conduct the "experiment" it is necessary to completely eliminate the draft in the room, that is, close all windows and doors. It is desirable to achieve the maximum possible darkness.

The flame of a candle can indicate excessive humidity in the air.

After the candle is lit, watch its flame.

- An even vertical flame with a yellow-orange tongue and clear boundaries indicates a normal level of humidity.

- If the flame "plays", and the areola around the tongue takes on a crimson color, one can assume excessive humidity.

And that is all…

The second way is using a glass of chilled water.

For the experiment, you need to collect a glass of ordinary tap water and place it in the refrigerator for several hours. It is required that the water cools down to about 5÷6 degrees.

Experience with a glass of water

After that, the glass is taken out, placed on the table in the room where the humidity study is being carried out. You should immediately visually evaluate the condensate that appeared on its walls after being transferred from the refrigerator.

It is important that the glass is no closer than 1 meter from windows, walls and heaters. In this position, avoiding a draft, it is left for about 10 minutes.

After that, an evaluation can be carried out.

- If the condensate on the outer walls is dry, this indicates insufficient air humidity.

- The condensate, in principle, has not undergone any special changes - the humidity can be considered within the normal range.

- The condensate collected in drops and even dripped onto the surface of the table - the humidity in the room is clearly increased.

Again, there is no need to talk about accuracy. And the preparation for the experiment, which requires several hours, is also not attractive.

But in general, without devices, otherwise it will not work.

Homemade psychrometer from an ordinary home thermometer

Well, if you have the most common glass alcohol or mercury thermometer at your disposal, then humidity can be determined with an accuracy no less than that of professional instruments.

With a conventional thermometer it is fashionable to obtain a very accurate value of relative humidity.

To begin with, you need to put the thermometer in the room where the humidity determination is carried out, so that direct sunlight does not fall on it. Best of all - on a table in a shaded place closer to the center of the room. Naturally, the draft must be excluded. After 5÷10 minutes, temperature readings in the room are taken and recorded.

After that, the thermometer flask is wrapped with a richly moistened cloth (room temperature!), And put in the same place. After 10 minutes, readings are taken, as for a “wet” thermometer in a psychrometer. Record them too.

Having two thermometer readings on hand, for “dry” and “wet”, you can find the psychrometric table, go into it and determine the level of relative humidity. And even better - to conduct a more thorough calculation.

Do not be alarmed, the author is not going to "load" you with formulas. All of them are already included in the online calculator offered to your attention.

The calculation algorithm was compiled for the normal movement of air in a house or apartment, which is characteristic of the normal operation of natural ventilation.

The calculator asks for another value - the level of atmospheric pressure in millimeters of mercury. If it is possible to specify it (there is a barometer at home or there is information from a local weather station) - excellent, the results will be as accurate as possible. If not, well, then yes, leave normal pressure, the default is 755 mmHg. Art., and the calculation will be carried out from it.

This calculator should not cause more questions.

Top Models

The device "Evlas-2M" is excellent for controlling the moisture content of bulk solids. This device is used in agriculture, food industry and pharmacy. It will also be possible to control the humidity of building materials. The microprocessor is designed to prevent computational errors. Verification of the device is carried out according to the requirements of Rosstandart.

The Venta hygrometer can memorize the minimum and maximum temperature and humidity. The device will allow you to set temperatures from -40 to +70 degrees. The error of the main measurement is 3% in both directions. Powered by a pair of AAA batteries.

Boneco can offer people the A7057 model. This device has a plastic case. Installation is only possible on the wall. Any solid surface is suitable for mounting. However, the reviews note doubts about the accuracy of the device.

Momert's Model 1756 is a good alternative. The case is made of white plastic. The device is compact. Thanks to the round corners, the hygrometer is very pleasant to the touch. Attractive and small thickness - 0.02 m.

The Beurer HM 16 is no longer a single hygrometer, but an entire meteorological station. It can measure temperature from 0 to 50 degrees. External humidity can be measured not lower than 20% and not higher than 95%. Other features:

• batteries CR2025;

• monochrome reliable screen;

• folding stand for installation on the table;

• the ability to hang the device;

• sleek white body.

The Ohaus MB23 moisture analyzer is also included in the list of the best models.The device operates in accordance with GLP and GMP standards. The device will determine the moisture content by gravimetry. The system can determine the temperature with an error of up to 1 degree, and the weight of the device is 2.3 kg.

Sawo can offer the 224-THD Square Thermohygrometer. The model has a classic rectangular design. Two dials display information separately. Cases are made from various types of wood. The device is great for baths and saunas.

Model 285-THA is housed in a wide solid aspen frame. As in the previous case, a thermometer and a hygrometer with separate dials are used. The size is 0.17x0.175 m. Company warranty - 3 years. This device is also suitable for climate control in bathrooms and saunas.

IVA-8 is another attractive hygrometer. The display unit is made according to the panel scheme. It is possible to connect 2 frost point indicators to one device. There are 2 relay outputs with adjustable trigger levels. Relative humidity can be measured in the range of 30 to 80%; the mass of the device is 1 kg, it consumes no more than 5 watts per hour of operation.

The Baikal 5C model also deserves attention. This is an industrial-grade digital single-channel device. The system can measure not only humidity, but also the molar concentration of water in non-toxic gases. Measurements can also be made in gas mixtures, including ordinary air. The device has a bench or desktop version; it must be operated with grounding in a room where explosion safety is ensured.

Subject to the proper conditions, you can use "Baikal":

• in petrochemistry;

• in the nuclear industry;

• in the polymer industry;

• at metallurgical and metalworking enterprises.

It is appropriate to complete the review on the Elvis-2C moisture analyzer. These devices are designed to measure the degree of moisture:

• solid monoliths;

• bulk substances;

• liquids;

• fibrous substances;

• pasty compositions of various kinds.

The device is based on the thermogravimetric method. The system can display both the percentage of moisture and the percentage of dry matter in the analyzed sample. The indicator device also shows the mass of the sample and the duration of heating.

Instructions for use

To understand how to use the thermal device, it is necessary to study the instruction manual. You should start by unpacking the tool and comparing it with the existing passport. There is no distilled water; it is drawn into the tank immediately after the thermal equipment is taken out. The base is easily removed. The feeder will need to be lowered into a container with liquid

It is important that the soldered end is on the bottom. After the feeder is installed in the place allotted to it, the distance from the thermometer to the feeder opening should be 2 centimeters, but the wick should not touch it

In the working position, the wick must be well moistened with water. Place the tool on a flat surface.

Using the data presented in the table, it is important to maintain the required rate of evaporation of moisture, that is, the flows affecting the device. They measure the speed before they are going to know the level of relative humidity

For this, a U5 vane anemometer is used. The values ​​that will be received will need to be rounded to tenths. The calibration interval is important.

While working with a psychrometer, the readings of two thermometers are taken into account

It is important that the scale relative to the eye of the beholder is straight. You can not breathe on the device, from this the readings will be inaccurate

First of all, tenths of the existing degree are determined, then integers. The result obtained is added to the amendments in the passport. After counting the difference. Relative humidity is determined by the intersection of the temperature indicated by the dry bulb and the resulting difference. Otherwise, the principle of use is similar to VIT-1. When there are no amendments in the passport, linear interpolation is done by approximate values.

If the feeder is destroyed, it will need to be replaced. All residues must be completely removed. The passport clearly spells out the actions in case liquids spill out of the flasks.

In order for the psychrometer to work stably, it must be constantly filled with distilled water. When the level drops, the water is added after the readings are received or 30 minutes before the use of the thermal device. Boiled water is allowed, but only the exposure should be at least 15 minutes. Before filling the feeder with liquid, it is cooled to room temperature. For accurate readings, the wick will need to be kept clean and damp. If it gets dirty, then it is changed. The tank must be wiped with cotton wool soaked in warm water.

The length of the wick is not less than 6 centimeters. The free end must be 7 mm. You can tighten the wick with a thread. A loop is made at the top and bottom of the tank. Accurate readings will be only when the wick fits snugly around the flask.

If the diameter of the tank is wider than the cut, then the wick is sewn together. The height of the seam after trimming should not be more than 1 centimeter and 5 millimeters.After leaving the factory, the device must be checked every 24 months.