The indoor climate plays an important role. Scientists have proven that humidity has a significant impact 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 humidity levels. When using other types of devices, you have to perform a number of actions, independently calculate. This requires some knowledge, so you need to understand how to calculate the humidity on a hygrometer correctly.
Next, we will talk about what devices are for measuring humidity in a room, we will understand the principle of their operation. In addition, from our material you will learn how to choose the right moisture meter.
The content of the article:
- What are hygrometers for?
- Popular types of devices
-
How to use a hygrometer?
- Option number 1 - electronic devices
- Option number 2 - mechanical hygrometers
- Option number 3 - condensing devices
- Option number 4 - psychometric hygrometer
- Safe operation rules
- Which hygrometer is better?
- Conclusions and useful video on the topic
What are hygrometers for?
A hygrometer is a laboratory equipment used to measure the relative or absolute humidity of atmospheric air and gases. This device is also called a hygroroscope.
Hygrometer translated from Greek, "ὑγρός" means "liquid", and "μετρέω" - "measure". Such a device will be useful both in everyday life and in the industrial sphere.
Humidity, like temperature, is an important indicator of the microclimate. It is recommended to maintain it within the standard: Each type of room has its own optimum level. It is useful for human health and the safety of things, structures, food.
Fungus and viruses spread quickly from too humid air, vegetables and fruits begin to rot, and mold on the walls. Condensation, settling on electrical equipment, metal structures, paper, leads to their deterioration. Also, the chemical composition of drugs is disrupted.
An overdried atmosphere impairs the protective properties of the nasopharyngeal mucosa. This leads to the fact that a person becomes susceptible to the influence of various viruses and infections.
Also, a low level of humidity has a bad effect on the quality and safety of food: they begin to wither and lose their useful properties. An optimal microclimate is important during construction and renovation work, especially if different solutions are used.
There are many types of hygrometers. Their accuracy can vary. The choice of the device should be made based on the area in which it is planned to be used.
To maintain humidity at the desired level, it is necessary to regularly measure it and take appropriate measures if the indicator deviates from the norm.
The hygrometer is used in various fields:
- Food Industry;
- trade;
- animal husbandry;
- plant growing;
- pharmaceutical industry;
- greenhouse, communal services;
- construction, etc.
Despite their usefulness, hygrometers are not widely used in residential environments. They are usually used at weather stations and control services.
It is highly recommended to regularly measure the humidity level in hospitals, kindergartens and schools. It is worth purchasing such equipment for the home. By maintaining humidity in a given range, you can significantly improve all areas of your life.
Popular types of devices
The procedure and features of measuring the humidity level with a hygrometer depend on the type of laboratory equipment used. Such devices differ among themselves by the device, the principle of operation and a number of other parameters.
By design, hygrometers are mechanical and electronic. The first ones have a dial with an arrow, the second ones have a display on which information is displayed.
According to the principle of operation, there are such types of devices:
- film;
- hairy;
- weight;
- capacitive;
- resistive;
- ceramic;
- condensing;
- electrolytic;
- psychometric.
Film hygroscopes have a dial with an arrow. A special film acts as a sensor. It consists of organic material and is connected to an arrow.
Under the influence of a drop in atmospheric humidity, the film changes its size. This causes the hand to move to the right or left, showing the result on the dial.
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 fat-free human or synthetic hair stretched over a frame with an arrow. The principle of operation of the device is similar to film types of hygrometers.
When moisture changes, the length of the hair changes. This leads to a deflection of the arrow in a certain direction.
Weighing hygroscopes are used to calculate the absolute humidity. They are equipped with hygroscopic tubes. As the air passes through, the filler absorbs moisture and increases in weight.
The sample is taken with a special pump. The system is weighed before and after air injection. The absolute humidity is calculated based on the values obtained, the volume of the passed air mass.
Capacitive hygrometers incorporate an oxide capacitor. Its capacity varies with the concentration of moisture in the air. Such models need to be calibrated periodically. This is due to the fact that the capacitance of the detector decreases over time, which affects the measurement accuracy.
Resistive hygroscopes work on the principle of changing the level of humidity depending on the electrical resistance of salts and polymers. The ceramic instruments consist of a dial with an arrow. A special ceramic mixture (clay, silicon) acts as a sensor. Its electrolytic resistance depends on the level of humidity.
Ceramic hygrometers show only humidity levels. There are no additional functions in them. But they are accurate and allow you to monitor changes in the indoor climate.
Condensing type devices are also called hygrometers. Lambrecht. The principle of operation of the equipment is based on the use of a built-in mirror. The temperature of this element changes with the temperature of the outside air.
The main element of electrolytic devices is a glass, polystyrene or other insulating plate covered with an electrolyte layer. Depending on the concentration of moisture in the air, the resistance of the electrolyte changes.
The condensation hygrometer is highly accurate. But for domestic use, it is not very suitable due to certain difficulties of use.
Psychometric hygrometers measure the humidity of the ambient air based on the decrease in the temperature of the wetted body. They consist of two thermometers: dry and humid.
The device is also equipped with a feeder - a glass flask that is filled with water. The calculation is carried out by the researcher independently. The table supplied with the device helps to determine the relative humidity of the air with a hygrometer.
In addition to instruments, there are alternative ways to measure moisture. More details - read on.
How to use a hygrometer?
Instructions for use are attached to each type, model of the hygrometer. It should be strictly adhered to. The accuracy of the result depends on this.
Psychometric devices have two advantages: they are accurate and show not only humidity, but also the temperature level in the room.
The passport for the device says how to correctly measure the humidity level. Provides safety rules and precautions for using the device. Recommendations for the maintenance of laboratory measuring equipment are given.
Today, in everyday life and at work, as a rule, mechanical, electronic, condensation and psychometric hygrometers are used.
Option number 1 - electronic devices
Electronic hygrometers are easy to use. They do not need any settings, they are completely ready to go. Before using the device, it is necessary to inspect for visible defects - cracks, chips.
The algorithm for measuring the level of humidity with an electronic hygroscopes is as follows:
- turn on the device by pressing the power button;
- if necessary, set the day of the week, time, set the alarm clock and other parameters using the buttons "UP", "MODE" and "DOWN»;
- wait while the device calculates the humidity level;
- evaluate the result on an electronic scoreboard.
Typically, these hygrometers are used in everyday life. Some use them in incubators.
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, they show the air temperature, light level, day of the week, etc.
Option number 2 - mechanical hygrometers
The accuracy of mechanical hygrometers is poor. The error is 5-8%. Before using the device, it is recommended to calibrate it. For adjustment, a reference hygrometer is required to show accurate humidity values.
You need to place two devices side by side. If the indicator of the mechanical device does not correspond to the reference, then it must be corrected using the adjusting screw. This item is located on the back of the equipment.
Mechanical hygrometers can additionally show the temperature level in addition to the humidity level in the room. Their accuracy is higher than that of electronic
The mechanical hygroscopes are easy to use. It is necessary to install the device in the right place (put it on the table or hang it on the wall) and evaluate the result.
Option number 3 - condensing devices
The condensing 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.
The condensation hygrometer is accurate enough. But to determine the level of humidity, you need to perform a number of actions. In terms of ease of use, it is inferior to electronic models
Algorithm for using a condensation-type hygrometer:
- pour ether (alcohol) into the box;
- start pumping air with a pear until the first drops of dew appear;
- record the reading of the thermometer;
- see the humidity level in the table attached to the device.
As you can see, there is nothing difficult in determining humidity using a condensation-type hygrometer. It is enough to follow the instructions above.
Option number 4 - psychometric hygrometer
The psychometric hygrometer is quite accurate. Such equipment is checked by metrological services. You can trust the results of this device.
Usually psychometric hygroscopes are used in hospitals, clinics, schools, public canteens. They also buy them for the home. Psychometric hygrometers are represented by the VIT-1 and VIT-2 models. How they look can be found in the figure below.
The VIT-1 psychrometer is used at temperatures ranging 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 using the device directly, it is necessary to carry out a number of preparatory work:
- Unpack the hygroroscope. Make sure that the equipment of the device corresponds to the data specified in the passport.
- Inspect equipment items for integrity.
- Remove the feeder from the base. Dip it into a container with distilled water with the sealed end down.
- Moisten the wick by dipping the reservoir of the wet thermometer into a glass flask filled with water.
- Install the feeder so that the wick does not touch its walls, and there is a distance of at least 2 cm from the edge of the open end of the flask to the thermometer reservoir.
- Place the hygroscopes in an upright position at eye level. The psychometric device does not have a support. 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 stage is completed, you can proceed to the direct determination of the humidity level with a psychometric hygrometer.
The feeder must always be filled with water. The liquid should be topped up in advance. The water level in the flask must be monitored. If it is topped up before taking a measurement, then you need to wait half an hour, and then proceed to determine temperatures on wet and dry thermometers
The device should be kept in the measured environment for at least 30 minutes. Otherwise, the accuracy of the result will be questionable.
How to use a psychometric hygroscopic scope:
- stand in front of the device at a distance of good visibility of the scale marks. It is important not to breathe on the thermometers in order to avoid distorting the result;
- record the readings of the dry type thermometer. It is located on the left side and is marked accordingly. Record the result obtained with an accuracy of 0.1 ° С;
- take readings on a wet thermometer;
- make amendments to the results obtained in accordance with the recommendations given in the passport to the measuring device;
- subtract the wet bulb value from the dry bulb thermometer;
- determine the relative humidity using the table on the right side of the instrument. The sought value will be at the intersection of the dry bulb temperature lines and the difference between the two thermometers.
The figure below shows how moisture is determined using a psychometric hygrometer.
A dry thermometer shows a temperature of 20 ° C, and a wet one - 19 ° C. The difference between these values is 20-19 = 1 ° C. In the table, in the column of indicators of a dry thermometer, we find the indicator "20", draw a straight horizontal line. In the values of the temperature difference, we find "1" and draw a vertical line. At the intersection of the two lines there is an indicator of the relative humidity level - 90%
To psychrometer showed an accurate result, you need to regularly carry out its maintenance.
So, the water should be at room temperature. It is permissible to use boiled liquid. The water must be pre-purified using a filter. It should be boiled for at least 15 minutes.
The reservoir filter of a wet-type thermometer should always be soft, clean and damp. It is periodically necessary to replace this element. If the dust content of the air does not exceed 5 mg / m3, 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, wipe the thermometer reservoir with a cotton swab dipped in warm water.
The hygrometer should be checked periodically. The accuracy of the device is assessed immediately after release from production. Further, the device should be checked 1-2 times a year.
Safe operation rules
Although there are different types of hygroscopes, there are general rules to be followed when using them. All equipment should be handled with care. The device must not be dropped.
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 used is given in its accompanying instructions.
It is important to choose the right location for the hygrometer. There should be no sources of cold or heat near the equipment. The absence of vibration is important. Avoid placing hygroscopes in direct sunlight
It is important to remember about safety measures when using devices containing toxic substances. For example, the thermometers of the VIT-2 psychometric apparatus are filled with toluene. It is a toxic and flammable liquid.
Therefore, it is important to avoid breaking and overheating the device. If there is a rupture of the reservoir, you can remove the toluene from the surrounding objects with water and detergent.
If you need to use water to measure moisture, then distilled water should be used (even if the instructions do not say anything directly about this). Untreated tap liquids contain salts that will deposit on device components, reducing the shelf life and accuracy of the results.
Which hygrometer is better?
Which type of hygrometer is best to buy in order to control the level of humidity depends on the type of room, the purpose and the regularity of the measurements. For warehouses, production halls, schools and medical institutions, it is better to choose psychometer. It features a high level of accuracy and reliability.
For household purposes, a mechanical or electronic hygrometer will suffice - these devices can be purchased at the nearest hardware store. In addition, a variety of models will help you choose the device in the style of the room.
It is not recommended to use psychometric models containing toluene at home, especially if there are children and animals in the family. Accidentally breaking the device can lead to a number of unpleasant consequences.
To control the level of humidity in the house, it is better to purchase a mechanical hygroscopic. It is more accurate than electronic. At the same time, it lacks many additional functions, unlike the latter type of equipment.
In addition, you can assemble a moisture meter with your own hands. And how to do this, you can read in this material.
Conclusions and useful video on the topic
The video below describes the principle of operation of a psychometric device and the procedure for calculating the humidity level:
The accuracy of the psychometric and electronic hygrometers can be judged from this video:
The most common psychometric devices VIT-1 and VIT-2. They are accurate and additionally show the air temperature.
For domestic use, electronic devices can be used. They are usually multifunctional and show not only humidity, but also temperature, illumination, time, day of the week, etc. Their accuracy is poor.
Mechanical hygroscopes also have some uncertainty, but they can be adjusted by calibration.
Do you use moisture meters at home? Which device did you prefer and are you satisfied with its work? Please leave your comments in the block below the article.
