Humidification in laboratories. Air humidification in clean rooms Humidification systems and air humidity standards for clean rooms

Finally, I bought a moisturizer (Real), which really moisturizes! Evaporates 15 liters in less than a day. He quickly raised the humidity level in a 21 sq m room from 18 to 45 percent. It became pleasant to be in the room, there was a feeling of freshness. Before that, there was a Koenig wash, then an ultrasonic one. Only Real coped with the task. I sold an expensive Koenig sink and ordered another Real (in the second room).

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Olga E.

Store employees always call back quickly, the goods can be picked up immediately. Pickup is not far from me, so I usually pick it up.

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Elena V.

I bought a rather expensive air purifier, maybe that's why the communication was the way it was. A call in a couple of minutes, they worked out my comment on the order, waited until I fill up the order on their website. Delivered the next day. The courier, maybe, wanted to steer right after delivery, but when he saw my interest in continuing communication, he unpacked everything at once, showed it, inserted an additional filter, connected it. All at the highest level.

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Vyacheslav K.

I liked this store for its wide assortment. And since I am in the office all day, where there is a large influx of customers, I agreed with the management on the purchase of an air cleaner. The manager told me in detail about the advantages of the device and helped me make a choice. I quickly placed an order, and after 2 days the air cleaner was delivered to the address. This made me happy, as it is pretty quick. I paid in cash, which is also convenient and reliable for such a transaction. Hope it will last a long time. The cooperation with the store was pleasant.

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Yulia Frolova

Good store. Everything for people. We ordered a call from the manager, who explained everything correctly and picked up the goods that we need. He told why it is not necessary to take the goods more expensive. Delivery to Ulyanovsk, the manager said that you can pay in cash upon receipt, which is a big plus. After 3 days, the goods arrived to us. The cleaner turned out to be very good. Literally 2 hours later, it became easier to breathe in the apartment.

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Ekaterina Tikhonova

I bought a humidifier from this store. In winter, the air in the apartment is very dry, and this is harmful not only for the skin, but also for health in general. A consultant helped me decide on the choice of a humidifier, he quickly picked up the model I needed. Delivery to St. Petersburg was made the next day !!, I paid in cash upon receipt of the goods. Which I think is a big plus, since I trust such payments more.

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Olga P.

We ordered an air cleaner. A pleasant girl-manager helped with the choice of a cleaner, put everything on the shelves. I liked the simple and understandable form of ordering and payment (paid for the purchase upon receipt). They brought it straight home, the box was free of dents and damage. The manager, when placing an order, conducted an educational program for operation. Thank you for good service!

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Anna Smirnova

We decided to buy an air purifier, at the insistence of the doctor. I suffer from asthma attacks and since we have not encountered this type of technique, the choice was problematic. We called and consulted with a specialist by phone. Chose more expensive in the end. I doubted about the delivery, since it is quite problematic to transport the cleaner to the Khabarovsk Territory from Moscow, given the rather heavy weight. But the delivery service delivered our equipment in integrity and safety right to the door, and for free) We thought that they would have to fiddle with the installation themselves, but they turn out to do everything themselves. Very comfortably.

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Maria S.

I decided to find the best cleaner, after spending a day I realized what to take in this store. I ordered a model with a charcoal filter, took an additional filter, made a discount, nice.) I paid with a card on the site and by the evening it was already brought home, and for free, although at such a high price it is not surprising. I was glad that the courier had some kind of expensive sensor that determines how dirty the air is. Showing me how this cleaner works, he attached this sensor to it and the sensor showed the number zero, and then I decided that I needed to check Bork, which my neighbor had recently bought, the courier agreed to conduct an experiment. As a result, the neighbor was upset, since his zero did not show even close.))) The guys worked well, I'm happy with the purchase and service, I recommend.

Humidification is one of the most complex and knowledge-intensive processes in ventilation and air conditioning., determined by a number of fundamental documents of a regulatory and reference nature.

The successful engineering and technical implementation of air humidification systems requires the right choice the methods and means of steam generation used, compliance with rather strict requirements for its distribution inside the serviced room, or inside the inlet part ventilation system, as well as the correct organization of the drainage of excess moisture.

From a practical point of view, points accompanying the operation of the humidifier

Of particular importance is the use of feed water of adequate quality.... The requirements for this are fundamentally different for humidifiers, the principle of operation and design of which are very diverse. Unfortunately, this issue has not yet found adequate coverage in the literature, which in a number of cases leads to operational errors and premature failure of expensive hardware.

Notable publications are mostly related to water treatment in heating systems and hot water supply of buildings, which is significantly different from water treatment in air humidification systems. This article is an attempt to clarify the essence of the requirements for the quality of feed water for the main types of humidifiers by analyzing the physicochemical features of the behavior of substances of varying degrees of solubility during the transition of water to steam, implemented in one way or another. The presented materials have enough general character covering almost all known methods of air humidification. However, based on personal experience the author's specific constructive designs units are limited to the nomenclature supplied by CAREL, which includes air humidifiers different types in a wide range of operating principles used.

There are two main ways to humidify the air in practice: isothermal and adiabatic.

Isothermal humidification occurs at constant temperature (∆t = 0), i.e. with an increase in the relative humidity of the air, its temperature remains unchanged. Saturated steam enters the air directly. The phase transition of water from a liquid to a vapor state is carried out by an external heat source. The following types of isothermal air humidifiers are distinguished, depending on the way the external heat is realized:

• with submersible electrodes (HomeSteam, HumiSteam);
• with electric heating elements (HeaterSteam);
•  gas humidifiers (GaSteam).

Adiabatic humidification Only by the content of harmful substances in drinking water 724 indicators are normalized . General requirements to the development of methods for their determination are regulated by GOST 8.556-91. From the point of view of water use in air humidification systems, not all of the above indicators are of significant importance.

The most important are only ten indicators, detailed below:

Fig. one

Total dissolved solids in water(Total Dissolved Solids, TDS)

The amount of substances dissolved in water depends on their physicochemical properties, the mineral composition of the soils through which they infiltrate, the temperature, the time of contact with minerals and the pH of the infiltration medium. TDS is measured in mg / L, which is equivalent to parts per million (ppm) by weight. In nature, the TDS of water ranges from tens to 35,000 mg / l, which corresponds to the saltiest seawater. According to the current sanitary and hygienic requirements, drinking water must contain no more than 2000 mg / l of dissolved substances. In fig. 1, on a logarithmic scale, the solubility of a number of chemicals (electrolytes) most commonly found in water under natural conditions is presented as a function of temperature. Noteworthy is the fact that, unlike most salts (chlorides, sulfates, sodium carbonate) present in water, two of them (calcium carbonate CaCO3 and magnesium hydroxide Mg (OH) 2) have relatively low solubility. As a result, these chemical compounds form the bulk of the solid residue. Other characteristic feature concerns calcium sulfate (CaSO4), the solubility of which, unlike most other salts, decreases with increasing water temperature.

Total hardness (TH)

The total hardness of water is determined by the amount of calcium and magnesium salts dissolved in it, and is divided into the following two parts:

•  constant (non-carbonate) hardness, determined by the content of calcium and magnesium sulfates and chlorides that remain dissolved in water at elevated temperatures;
•  variable (carbonate) hardness, determined by the content of calcium and magnesium bicarbonates, which at a certain temperature and / or pressure participate in the following chemical processes that play a key role in the formation of a solid residue.

Сa (HCO3) 2 ↔CaCO3 + H2O + CO2, (1) Mg (HCO3) 2 ↔Mg (OH) 2 + 2 CO2.

With a decrease in the content of dissolved carbon dioxide, the chemical balance of these processes shifts to the right, leading to the formation of poorly soluble calcium carbonate and magnesium hydroxide from calcium and magnesium bicarbonates, which precipitate from the water solution with the formation of a solid residue. The intensity of the processes under consideration also depends on the pH of the water, temperature, pressure and some other factors. It should be borne in mind that the solubility of carbon dioxide sharply decreases with an increase in temperature, as a result of which, when water is heated, a shift in the balance of processes to the right is accompanied by the formation, as indicated above, of a solid residue. The concentration of carbon dioxide also decreases with decreasing pressure, which, for example, due to the aforementioned shift of the considered processes (1) to the right, causes the formation of solid deposits in the mouths of the nozzles of spray-type air humidifiers (atomizers). Moreover, the higher the velocity in the nozzle and, accordingly, according to Bernoulli's law, the deeper the rarefaction, the more intensively the formation of solid deposits occurs. This is especially true for atomizers without the use of compressed air (HumiFog), which are characterized by a maximum speed at the mouth of a nozzle with a diameter of no more than 0.2 mm. Finally, the higher the pH of the water (more alkaline), the lower the solubility of the calcium carbonate and the greater the solid residue formed. Due to the predominant role of CaCO3 in the formation of the solid residue, the measure of water hardness is determined by the content of Ca (ion) or its chemical compounds. The existing variety of units of measurement of stiffness are summarized in table. 1. In the United States, the following classification of water hardness is adopted for domestic needs:

• 0.1-0.5 mEq / l - almost soft water;
• 0.5-1.0 mg-eq / l - soft water;
• 1.0-2.0 mg-eq / l - water of low hardness;
• 2.0-3.0 mg-eq / l - hard water;
• 3.0 mEq / l - very hard water. In Europe, water hardness is classified as follows:
• TH 4 ° fH (0.8 meq / l) - very soft water;
• TH = 4-8 ° fH (0.8-1.6 meq / l) - soft water;
• TH = 8-12 ° fH (1.6-2.4 mg-eq / l) - water of medium hardness;
• TH = 12-18 ° fH (2.4-3.6 meq / l) - practically hard water;
• TH = 18-30 ° fH (3.6-6.0 mEq / l) - hard water;
• TH 30 ° fH (6.0 meq / l) - very hard water.

Domestic standards for water hardness are characterized by significantly different values. According to the sanitary rules and norms of SanPiN 2.1.4.559-96 "Drinking water. Hygienic requirements for water quality in centralized drinking water supply systems. Quality control" (clause 4.4.1), the maximum permissible water hardness is 7 mg-eq / l. At the same time, the specified value can be increased to 10 mg-eq / l by order of the chief state sanitary doctor in the relevant territory for a specific water supply system based on the results of an assessment of the sanitary and epidemiological situation in locality and the applied water treatment technology. According to SanPiN 2.1.4.1116-02 "Drinking water. Hygienic requirements for the quality of water packaged in containers. Quality control" (clause 4.7), the standard of physiological usefulness of drinking water in terms of hardness should be in the range of 1.5-7 mg-eq / l. At the same time, the quality standard of packaged waters of the first category is characterized by a hardness value of 7 mg-eq / l and the highest category- 1.5-7 mEq / l. According to GOST 2874-82 "Drinking water. Hygienic requirements and quality control" (clause 1.5.2), water hardness should not exceed 7 mg-eq / l. At the same time, for water pipelines supplying water without special treatment, in agreement with the authorities of the sanitary and epidemiological service, water hardness up to 10 mg-eq / l is allowed. Thus, it can be stated that in Russia it is allowed to use water of extreme hardness, which must be taken into account when operating humidifiers of all types.

This is especially true humidifiers of adiabatic type, unconditionally requiring appropriate water treatment.

As for isothermal (steam) humidifiers, it should be borne in mind that a certain degree of water hardness is a positive factor contributing to the passivation of metal surfaces (zinc, carbon steel) due to the formed protective film which helps to inhibit corrosion caused by the chlorides present. In this regard, for isothermal electrode-type humidifiers, in a number of cases, limit values ​​are set not only for the maximum, but also for the minimum values ​​of the hardness of the water used. It should be noted that on the territory of Russia, the water used differs significantly in terms of hardness, often exceeding the above standards. For example:

•  the highest water hardness (up to 20-30 mg-eq / l) is typical for Kalmykia, southern regions of Russia and the Caucasus;
•  in the underground waters of the Central Region (including the Moscow Region), the water hardness ranges from 3 to 10 mg-eq / l;
•  in the northern regions of Russia, water hardness is low: within the range from 0.5 to 2 mg-eq / l;
•  water hardness in St. Petersburg does not exceed 1 mg-eq / l;
• hardness of rain and melt water ranges from 0.5 to 0.8 mg-eq / l;
• Moscow water has a hardness of 2-3 meq / l.

Dry residue at 180 ° С(Dry residue at 180 ° C, R180)
This indicator quantitatively characterizes dry residue after complete evaporation of water and heating to 180 ° С, differing from the total amount of dissolved solids (TDS) in the contribution that dissociating, volatile and absorbable chemical compounds make. These are, for example, CO2, which is present in bicarbonates, and H2O, which is contained in hydrated salt molecules. The difference (TDS - R180) is proportional to the bicarbonate content of the water used. In drinking water, R180 values ​​are recommended, not exceeding 1500 mg / l.

Fig. 2

Natural water sources are classified as follows:

• R180 200 mg / l - low mineralization;
• R180 200-1000 mg / l - average mineralization;
• R180 1000 mg / l - high mineralization

Specific conductivity at 20 ° С(Specific conductivity at 20 ° C, σ20)
Specific conductivity of water characterizes the resistance to the flowing electric current, being dependent on the content of electrolytes dissolved in it, which are mainly inorganic salts in natural water. The unit of measurement for conductivity is μS / cm (μS / cm). The specific conductivity of pure water is extremely low (about 0.05 μS / cm at 20 ° C), increasing significantly depending on the concentration of dissolved salts. It should be noted that the conductivity is strongly temperature dependent, as shown in Fig. 2. Consequently, the specific conductivity is indicated at a standard temperature of 20 ° C (less often 25 ° C) and is indicated by the symbol σ20. If σ20 is known, then the values ​​of σt ° C corresponding to the temperature t, expressed in ° C, are determined by the formula: σt ° Cσ20 = 1 + α20 t - 20, (2) where: α20 is the temperature coefficient ( α20 ≈0.025). Knowing σ20, the values ​​of TDS and R180 can be roughly estimated using empirical formulas: TDS ≈0.93 σ20, R180 ≈0.65 σ20. (3) It should be noted that if the TDS estimate in this way has a small error, then the R180 estimate has a much lower accuracy and significantly depends on the bicarbonate content in relation to other electrolytes.

Fig. 3

Acidity and alkalinity(Acidity and alkalinity, pH)

Acidity is determined by H + ions, which are extremely corrosive towards metals, especially zinc and carbon steel. Neutral water has a pH value of 7. At lower values, acidic properties appear, and, conversely, at higher values, alkaline ones. The acidic environment dissolves the protective oxide film, which contributes to the development of corrosion. As shown in fig. 3, at pH values ​​below 6.5, the corrosion rate increases significantly, while in an alkaline medium at pH above 12, the corrosion rate is also slightly increased. Corrosion activity in an acidic environment increases with increasing temperature. It should be borne in mind that at pH< 7 (кислотная среда) латунный сплав теряет цинк, в результате чего образуются поры и латунь становится ломкой. Интенсивность данного вида коррозии зависит от процентного содержания цинка. Алюминий ведет себя иным образом, поскольку на его поверхности образуется защитная пленка, сохраняющая устойчивость при значениях pH от 4 до 8,5.

Chlorides(Chlorides, Cl-)

Chloride ions present in water cause corrosion of metals, especially zinc and carbon steel, interacting with metal atoms after the destruction of the surface protective film formed by a mixture of oxides, hydroxides and other alkaline salts formed due to the presence of dissolved CO2 in water and the presence of impurities in the atmospheric air ... The presence of electromagnetic fields, typical for isothermal (steam) humidifiers with immersed electrodes, enhances the above effect. Chlorides are especially active with insufficient water hardness. It was previously stated that the presence of calcium and magnesium ions has a passivating effect, inhibiting corrosion, especially at elevated temperatures. In fig. 4 schematically shows the inhibitory effect of temporary hardness in terms of the corrosive effect of chlorides on zinc. In addition, it should be noted that a significant amount of chlorides intensifies foaming, which negatively affects the operation of isothermal humidifiers of all types (with immersed electrodes, with electric heating elements, gas).

Fig. four

Iron + Manganese(Iron + Manganese, Fe + Mn)

The presence of these elements causes the formation of suspended suspension, surface deposits and / or secondary corrosion, which implies the need to remove them, especially when working with adiabatic humidifiers using reverse osmosis water treatment, since otherwise rapid membrane clogging occurs.

Silica(Silica, SiO2)

Silicon dioxide (silica) can be contained in water in a colloidal or partially dissolved state. The amount of SiO2 can vary from trace amounts to tens of mg / L. Typically, the amount of SiO2 is elevated in soft water and in the presence of an alkaline environment (pH 7). The presence of SiO2 has a particularly negative effect on the operation of isothermal humidifiers due to the formation of a hard, difficult-to-remove sludge consisting of silicon dioxide or formed calcium silicate. Residual chlorine (Cl-) The presence of residual chlorine in water is usually due to the disinfection of drinking water and is limited to minimum values ​​for all types of humidifiers in order to avoid the appearance of strong odors entering the humidified rooms along with moisture vapor. In addition, free chlorine, through the formation of chlorides, leads to corrosion of metals. Calcium sulphate (Calcium sulphate, CaSO4) Calcium sulphate, which is present in natural water, has a low degree of solubility, which makes it prone to sediment formation.
Calcium sulfate is present in two stable forms:

•  anhydrous calcium sulfate, called anhydrite;
• Two-water calcium sulfate CaSO4 2H2O, known as chalk, which, at temperatures exceeding 97.3 ° C, dehydrates to form CaSO4 1 / 2H2O (hemihydrate).

Fig. five

As shown in fig. 5, at temperatures below 42 ° C., the dihydrate sulphate has a reduced solubility compared to anhydrous calcium sulphate.

In isothermal humidifiers at a water temperature corresponding to the boiling point, calcium sulfate can be present in the following forms:

• Hemihydrate which at 100 ° C has a solubility of about 1650 ppm, which corresponds to about 1500 ppm in terms of calcium sulfate anhydrite;
• Anhydrite, which at 100 ° C has a solubility of about 600 ppm.

Excessive amount of calcium sulfate precipitates, forming a pasty mass, which under certain conditions tends to harden. A summary of the limit values ​​of the feed water parameters discussed above for various types of humidifiers is presented in the following series of tables. It should be borne in mind that isothermal humidifiers with immersion electrodes can be equipped with cylinders designed to operate on standard water and water with a reduced salt content. Electric heater type isothermal humidifiers may or may not have a Teflon-coated heating element.

Isothermal (steam) humidifiers with immersion electrodes The humidifier is connected to a water supply network with the following parameters:

• pressure from 0.1 to 0.8 MPa (1-8 bar), temperature from 1 to 40 ° C, flow rate not lower than 0.6 l / min (nominal value for the supply solenoid valve);
• hardness no more than 40 ° fH (which corresponds to 400 mg / l CaCO3), specific conductivity 125-1250 μS / cm;
•  lack of organic compounds;
• the parameters of the feed water must be within the specified limits (Table 2)

Not recommended:
1. Use of spring water, industrial water or water from refrigeration circuits, as well as potentially chemically or bacterially contaminated water;
2. Adding disinfectants or anti-corrosion additives to the water, which are potentially harmful substances.

Humidifiers with electric heating elements The feed water used for the humidifier must not have an unpleasant odor, corrosive agents or excessive amounts of mineral salts. The humidifier can operate on tap or demineralized water having the following characteristics (Table 3).

Not recommended:
1. Use of spring water, technical water, water from cooling towers, as well as water with chemical or bacteriological contamination;
2. Adding disinfectant and anticorrosive additives to the water. humidifying the air with such water can cause allergic reactions in others.

Gas humidifiers
Gas humidifiers can operate on water with the following characteristics (Table 4). To reduce the frequency of maintenance of the steam cylinder and heat exchanger, namely cleaning, the use of demineralized water is recommended.

Not recommended:
1. Use of spring water, industrial water or water from refrigeration circuits, as well as potentially chemically or bacterially contaminated water;
2. Adding disinfectants or anticorrosive additives to the water. they are potentially harmful substances.

Adiabatic (spray) humidifiers (atomizers), compressed air humidifiers adiabatic type MC can operate both on tap water and on demineralized water, which does not contain bacteria and salts found in ordinary water. This makes it possible to use this type of humidifier in hospitals, pharmacies, operating rooms, laboratories and other special rooms where sterility is required.

1 Adiabatic (spray) humidifiers(atomizers) running on water high pressure
HumiFog humidifiers can only be operated with demineralized water (Table 5). For this purpose, as a rule, water treatment is used, corresponding to the following parameters. The first three parameters are of paramount importance and must be respected under all conditions. If the specific conductivity of water is below 30 μS / cm, it is recommended to use a pump unit made entirely of stainless steel.

2 Adiabatic centrifugal (disc) humidifiers
DS direct humidifiers do not use water as such. With their help, existing steam is supplied to the humidification section of central air conditioners or to supply air ducts... As is obvious from consideration of the above information, in some cases it is desirable, and in some of them it is obligatory, appropriate water treatment by replacing, transforming or removing certain chemical elements or compounds dissolved in the feed water. This prevents premature failure of the used air humidifiers, extends the service life of consumables and materials such as steam cylinders, and reduces the amount of work required for periodic maintenance. The main tasks of water treatment are to reduce to a certain degree corrosive activity and the formation of salt deposits in the form of scale, sludge and solid sediments. The nature and degree of water treatment depend on the ratio of the actual parameters of the available water and those required for each of the humidifiers discussed above. Let us consider sequentially the main methods of water treatment used.

Water softening

Fig. 6

This method reduces the hardness of the water without changing the amount of electrolyte dissolved in the water. In this case, the replacement of the ions responsible for the excess rigidity is carried out. In particular, calcium (Ca) and magnesium (Mg) ions are replaced by sodium (Na) ions, which prevents the formation of lime deposits when the water is heated, because, unlike calcium and magnesium carbonates, which form a variable component of hardness, sodium carbonate remains dissolved in water when elevated temperature. Usually the process of water softening is carried out using ion exchange resins. When using sodium ion exchange resins (ReNa), the chemical reactions are as follows, constant hardness:

2 ReNa + CaSO4 → Re2Ca + Na2SO4, (4) variable hardness:
2 ReNa + Ca (HCO3) 2 → Re2Ca + NaHCO3. (5)

Thus, the ions responsible for excessive hardness (in this case Ca ++) and the dissolution of Na + ions are fixed on the ion-exchange resins. Since ion exchange resins are gradually saturated with calcium and magnesium ions, their effectiveness decreases over time and regeneration is required, which is carried out by backwashing with a dilute sodium chloride solution (table salt):
ReCa + 2 NaCl → ReNa2 + CaCl2. (6)
The formed calcium or magnesium chlorides are soluble and are carried away with the rinsing water. At the same time, it should be borne in mind that softened water has increased chemical corrosivity, as well as increased specific conductivity, which intensifies the electrochemical processes taking place. In fig. 6 shows a comparative view of the corrosive effects of hard, softened and demineralized water. Please note that despite the patented Anti Foaming System (AFS), the use of softened water in isothermal humidifiers of all types can lead to foam formation and eventually malfunction. As a result, water softening during water treatment in air humidification systems is not so much of an independent importance as it serves as an auxiliary means of reducing water hardness before its demineralization, which is widely used to ensure the operation of adiabatic humidifiers.

Polyphosphate treatment
This method allows for a while to "bind" hardness salts, preventing them from falling out in the form of scale for some time. Polyphosphates have the ability to form bonds with CaCO3 crystals, keeping them in suspension and, thereby, stopping the process of their aggregation (the formation of chelate bonds). However, it should be borne in mind that this mechanism is operational only at temperatures not exceeding 70-75 ° C. At higher temperatures, it has a tendency to hydrolysis and the effectiveness of the method is sharply reduced. It should be borne in mind that the treatment of water with polyphosphates does not reduce the amount of dissolved salts, therefore, the use of such water, as in the previous case, in isothermal humidifiers can lead to foaming and, therefore, to their unstable operation.

Magnetic or electric air conditioning
Under the influence of strong magnetic fields, allotropic modification of salt crystals occurs, which are responsible for variable hardness, as a result of which the salts of scale-forming agents turn into a finely dispersed sludge that does not deposit on surfaces and does not tend to form compact forms. Similar phenomena take place when using electrical discharges, which reduce the ability of precipitated salts to aggregate. However, to date, there are no sufficiently reliable data on the efficiency of such devices, especially at high temperatures close to the boiling point.

Demineralization
The methods of water treatment considered above do not change the amount of chemicals dissolved in water and, therefore, do not completely solve the problems that arise. When operating isothermal humidifiers, they can reduce the amount of solid deposits formed, which is most related to water softening methods. Demineralization, carried out by the extraction of substances dissolved in water in one way or another, has a limited effect for isothermal humidifiers with immersed electrodes, since their principle of operation is based on the flow of an electric current in a salt solution. However, for all other types of air humidifiers, demineralization is the most radical method of water treatment, especially for adiabatic air humidifiers. It can also be fully applied for isothermal humidifiers with electric heating elements and gas humidifiers, when using other methods of water treatment discussed above, reducing the amount of formed solid deposits, create concomitant problems associated with an increase in the concentration of strong electrolytes during water evaporation. One of the negative aspects associated with the lack of water demineralization is the formation of a finely dispersed salt aerosol when moisture is supplied to the serviced premises. This applies to the greatest extent to enterprises of the electronic industry ("clean" rooms) and medical institutions (eye microsurgery, obstetrics and gynecology). With demineralization, this problem can be completely avoided, except for the use of isothermal immersion electrode humidifiers. The degree of demineralization is usually estimated by the specific conductivity, which is approximately proportional to the total concentration of dissolved electrolytes in the following ratios (Table 7).

In nature, water with a specific conductivity of less than 80-100 μS / cm is almost never found. Ultra-high demineralization is necessary in exceptional cases (bacteriological laboratories, crystal growth chambers). In most practical applications, however, a fairly high and very high degree of demineralization. The greatest degree of demineralization (up to theoretically achievable) is provided by distillation of water, incl. double and triple. However, this process is costly, both in terms of capital costs and operating costs. In this regard, the following two methods of demineralization have received the greatest application for the purpose of water treatment with air humidification:

Reverse osmosis
In accordance with this method, water is pumped under high pressure through a semipermeable membrane with pores having a diameter of less than 0.05 μm. Most of the dissolved ions are filtered on the membrane. Depending on the membrane used and other characteristics of the filtration process carried out, from 90% to 98% of the ions dissolved in the water are removed. Achieving higher demineralization efficiency is problematic. The possibility of carrying out the reverse osmosis process completely automatically, as well as the absence of the need for the use of chemical reagents, make it especially attractive for the purposes under consideration. The process is quite economical, consuming electricity in the amount of 1-2 kWh per 1 m3 of treated water. The cost of equipment is constantly decreasing due to the increase in its production volume due to the constant expansion of the scope of use. Reverse osmosis, however, is vulnerable if the treated water is very hard and / or contains a large number of mechanical pollution. In this regard, in order to increase the service life of the membranes used, preliminary water softening or polyphosphate treatment or magnetic / electric conditioning and filtration are often required.

Deionization
In accordance with this method, layers of ion exchange resins (columns of ion exchangers) are used to remove solutes, which have the ability to exchange hydrogen ions for cations and hydroxyl ions for dissolved salt anions. Cationic ion exchange resins (cation exchangers, polymeric acids) exchange one hydrogen ion for a cation of a solute that comes into contact with the resin (eg Na ++, Ca ++, Al +++). Anionic ion exchange resins (anion exchangers, polymeric bases) exchange one hydroxyl ion (hydroxyl group) for the corresponding anion (eg Cl-). Hydrogen ions, liberated by cation exchangers, and hydroxyl groups, liberated by anion exchangers, form water molecules. Using calcium carbonate (CaCO3) as an example, chemical reactions look like this, in a cation exchanger column:

Fig. 7

2 ReH + CaCO3 → Re2Ca + H2CO3, (7) in the column of anion exchanger 2 ReH + H2CO3 → Re2CO3 + H2O. (8) As the ion exchange resins consume hydrogen ions and / or hydroxyl groups they must be subjected to a regeneration process using a hydrochloric acid (hydrochloric) acid cation exchanger column treatment:

Re2Ca + 2 HCl → 2 ReH + CaCl2. (9) The anionite column is treated with sodium hydroxide (caustic soda): Re2CO3 + 2 NaOH →  (10) → 2 ReOH + Na2CO3. The regeneration process ends with flushing, which ensures the entrainment of salts formed as a result of the considered chemical reactions... In modern demineralizers, the water flow is organized "from top to bottom", which prevents the separation of the gravel layer and ensures continuous operation of the unit without deteriorating the quality of cleaning. In addition, the ion exchanger layer acts as a filter for water purification from mechanical impurities.

The efficiency of demineralization by this method is comparable to distillation. At the same time, the operating costs inherent in deionization are significantly lower compared to distillation. Theoretically, water demineralized by the considered methods (reverse osmosis, deionization) is chemically neutral (pH = 7), but various substances with which it subsequently contacts are easily dissolved in it. In practice, demineralized water is slightly acidic due to the demineralization process itself. This is due to the fact that the residual amounts of ions and gas impurities lower the pH. In the case of reverse osmosis, this is due to the differential selectivity of the membranes. In the case of deionization, the indicated residual amounts are explained by the depletion or violation of the integrity of the ion exchanger columns. When high acidity water can dissolve metal oxides, opening the way for corrosion. Carbon steel and zinc are particularly susceptible to corrosion. The typical phenomenon is, as noted earlier, the loss of zinc by the brass alloy. Water with a specific conductivity of less than 20-30 μS / cm should not come into contact with carbon steel, zinc and brass. Finally, Fig. 7 shows a diagram interconnecting the considered indicators of water quality, methods of air humidification and water treatment methods. For each humidification method, black rays determine a set of water quality indicators, the quantitative values ​​of which must be ensured within the specified limits. Colored rays determine the methods of water treatment recommended, if necessary, for each of the considered methods of air humidification. At the same time, the priorities of the recommended water treatment methods have been determined. Colored arcs also, taking into account the priorities, identified auxiliary water treatment methods, recommended for preliminary reduction of water hardness, subject to further processing by reverse osmosis. The most critical in terms of the content of dissolved salts in water is the ultrasonic method of air humidification (HumiSonic, HSU), for which the priority is the use of a distillate, or at least the use of deionization or reverse osmosis. Water treatment is also mandatory for atomizers operating on high pressure water (HumiFog, UA). In this case, the use of reverse osmosis provides satisfactory results. More expensive water treatment methods such as deionization and distillation are also possible. Other methods of air humidification allow the use of tap water without its preparation, if their quantitative values ​​are within the specified limits throughout the entire set of specific indicators of water quality. Otherwise, it is recommended to use water treatment methods in accordance with the identified priorities. As for direct-acting humidifiers (UltimateSteam, DS), they are fed with ready-made steam and in the one shown in fig. 7 of the scheme have no formal links with water quality indicators and water treatment methods.

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Description of the problem

The correct humidity level in a cleanroom production environment is essential to maintain production standards, research and minimize waste.

Even small changes in humidity levels can cause accelerated drying of surfaces, substances and materials, as well as lead to the accumulation of static charges, which can cause equipment malfunction or failure.

Accurate humidity control often cannot be achieved with the standard humidification equipment we use in the office or at home, in which case specialized humidification systems are used.

Laboratory humidifiers

The moisture index refers to the amount of water vapor in the atmosphere.

Humidifiers are tools that increase moisture levels.

There are many types of humidifiers depending on the needs and requirements.

A laboratory humidifier is an essential device used in various laboratories to maintain the desired humidity level.

In such rooms, it is very important to be able to accurately adjust the humidity, as well as the uninterrupted operation of the device, since any deviations or failures can lead to distortion in its operation, which is unacceptable.

Below are some of the important benefits of a laboratory humidifier.

Improves atmospheric conditions

Laboratory humidifiers increase the humidity level in the laboratory, which is necessary for a series of tests or tasks. Some tests require controlled atmospheric conditions and required humidity levels. By improving air quality, these humidifiers aid in carrying out experiments and tests in the desired atmospheric conditions.

Reduces static electricity

During the winter season, when the air is dry, there is a high chance of experiencing static electricity from touching certain objects.

When metal furniture and doorknobs are charged with static electricity, it can be very annoying. In addition, static charges can damage electrical laboratory instruments.

The use of laboratory humidifiers avoids all of these problems, and also provides controlled and favorable air humidity in medical and clinical laboratories.

Reduces the likelihood of illness

People tend to get sick and become more susceptible to a number of problems, such as colds and flu, when humidity levels drop significantly. In such a situation, it becomes necessary to raise the humidity level to a favorable level in order to avoid susceptibility to infection.

Often wooden furniture and wooden appliances become unusable due to low humidity levels. By using laboratory humidifiers, the problem can be drastically reduced.

Thus, laboratory humidifiers prevent wear and tear on wooden appliances and furniture, as well as protect people from disease.

Increases work efficiency

Often, doctors and other laboratory workers work long hours, which can lead to fatigue.

This can affect working efficiency, especially if the humidity level drops to a significant level.

By increasing the level of humidity, laboratory humidifiers help reduce the amount of fatigue in the lab.

Solution options

In small spaces, it can be most optimally used ultrasonic humidifiers, they have a number of advantages:

• Ease of operation and maintenance;
• Reliability of construction and simplicity of technology;
• High quality fine mist;
• Eliminate the possibility of oil getting into the sprayed water.

High pressure fog generators (humidifiers)

The most advanced technology in agriculture. Its principle is based on spraying water through nozzles and their instant evaporation. Their advantages:

• Low unit costs of electrical energy;
• Uniform humidification of the entire room;
• Possibility of installing a system of pipelines and nozzles according to your wishes;
• The system of pipelines and nozzles is easily disassembled without the use of special tools;
• The generated fog cools the room.

High pressure humidifiers. The system of pipelines and nozzles is assembled and mounted under the ceiling, the pipelines are connected with collet clamps, without the use of special tools. This allows the humidification system to be assembled according to the customer's individual dimensions.

The system can be controlled remotely using an external control module with a remote humidity sensor. Simple assembly instructions allow you to assemble your humidification unit yourself. The pump is connected to a 220 V network, and water is supplied to it.

When using ultrasonic duct humidifiers, fog is fed into the room through the duct. It is most efficient to install a steam duct directly below the ventilation, as shown in the figure. This contributes to the most effective humidification of the entire volume of the room.

In the high pressure pump, it is necessary to periodically check the oil level and, if necessary, top up to the required level.

You can use regular machine oil. Do not operate the pump without oil.

Over time, the nozzles will become clogged with salt deposits, so they need to be soaked in a special solution.

Options

Upgrade possible already installed system high pressure humidification in the future, by connecting additional pipe sections with nozzles or installing a more powerful pump.

This can be done in case of expansion of production, when the current capacity of the system is not enough to maintain the set humidity level.

In a room with mushrooms, sanitary and hygienic conditions must be maintained, therefore, together with a humidification system, it is possible to install air ozonizers.

Final Words

With the benefits of a laboratory humidifier, more and more laboratories are using a humidifier to maintain proper humidity, improve work efficiency, and achieve accurate test results.

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In order not to be mistaken and choose best moisturizer air for an apartment or for a children's room, you need to know about the advantages and disadvantages different types humidifiers.

Ultrasonic humidifiers

The main problem that the owner of such a device may face is the formation of a white coating. Output - use distilled or purified water(filter with reverse osmosis).

Advanced models are equipped with replaceable filters. However, sometimes they do not help either. If the water hardness in the tap is excessive (value above 21 dH), it is better to either abandon ultrasonic devices in favor of steam or traditional humidification, or use only distilled water, which can be bought quite inexpensively at a car dealer.

You can find out what kind of water you have at the water utility or use aquarium test strips.

Steam humidifiers

The most effective in terms of increasing humidity (almost up to 100%), but:

1. Control is required. Waterlogging (above 65-70%) is good for plants, but not for people and furniture. To help a hygrostat or weather station;
2. Hot steam. At the exit, it is already cooling down, but it can be dangerous for children. But the humidifier can be used as an inhaler;
3. Increased energy consumption. Evaporates water like an electric kettle.

"Air washers" with natural humidification

They are the most economical ones and are complemented by an air purification function. But waiting for a quick effect and creating high humidity (like in steam rooms) is not worth it. As well as superfine cleansing. But there is no plaque and waterlogging.

A little about the functions:

Built-in hygrostat

It should be understood that its readings are approximate and reflect the humidity of the air in the immediate vicinity of the humidifier. Would you like to be more precise for the whole room? Then you need a separate device.

Ionizer

There is no need to wait for some tangible effect. This is not a Chizhevsky chandelier, it is small and simple Little dilutes a large number of positive ions with negative ones for more comfortable breathing.

Choose the humidifier that works best for your conditions, and then your purchase will be a success!