Dusting of workplaces with fresh air is carried out. Air showers, their purpose and scope. Structural solutions for air showers

The intensity of a person's thermal exposure is regulated based on the person's subjective perception of the radiation energy. According to the requirements of regulatory documents, the intensity of thermal radiation of technological equipment operating from heated surfaces, lighting devices should not exceed:

− 35 W/m 2 when irradiating more than 50% of the body surface;

− 70 W/m 2 for irradiation of 25 to 50% of the body surface;

− 100 W/m 2 for irradiation of not more than 25% of the body surface.

From open sources (heated metal and glass, open flame), the intensity of thermal radiation should not exceed 140 W / m 2 with exposure of no more than 25% of the body surface and the mandatory use of personal protective equipment, including face and eye protection.

Sanitary standards also limit the temperature of the heated surfaces of equipment in the working area, which should not exceed 45 ° C, and for equipment in which the temperature is close to 100 ° C, the temperature on its surface should not exceed 35 ° C.

In a production environment, it is not always possible to meet regulatory requirements. In this case, measures should be taken to protect workers from possible overheating:

− remote control of the technological process;

− air or water-air showering of workplaces;

- arrangement of specially equipped rooms, cabins or workplaces for short-term rest with the supply of air-conditioned air to them;

− use of protective screens, water and air curtains;

− use of personal protective equipment, overalls, footwear, etc.

One of the most common ways to deal with thermal radiation is shielding radiating surfaces. There are three types of screens:

1. Opaque - such screens include, for example, metal (including aluminum), alpha (aluminum foil), lined (foam concrete, foam glass, expanded clay, pumice), asbestos, etc. In opaque screens, the energy of electromagnetic vibrations interacts with screen substance and turns into thermal energy. Absorbing radiation, the screen heats up and, like any heated body, becomes a source of thermal radiation. In this case, the radiation from the screen surface opposite the shielded source is conditionally considered as the transmitted radiation of the source.

2. Transparent - these are screens made of various glasses: silicate, quartz, organic, metallized, as well as film water curtains (loose and flowing over the glass), water-dispersed curtains. In transparent screens, radiation, interacting with the screen substance, bypasses the stage of conversion into thermal energy and propagates inside the screen according to the laws of geometric optics, which ensures visibility through the screen.

3. Translucent - these include metal meshes, chain curtains, screens made of glass reinforced with a metal mesh. Translucent screens combine the properties of transparent and opaque screens.

According to the principle of operation, the screens are divided into:

− heat-reflecting;

− heat-absorbing;

− heat-removing.

However, this division is rather arbitrary, since each screen has the ability to reflect, absorb and remove heat at the same time. The assignment of the screen to one or another group is made depending on which of its abilities is more pronounced.

Heat-reflecting screens have a low degree of blackness of the surfaces, as a result of which they reflect a significant part of the radiant energy incident on them in the opposite direction. Alfol, sheet aluminum, galvanized steel, and aluminum paint are widely used as heat-reflecting materials in the construction of screens.

Heat-absorbing screens are called screens made of materials with high thermal resistance (low coefficient of thermal conductivity). Refractory and heat-insulating bricks, asbestos, and slag wool are used as heat-absorbing materials.

As heat-removing screens, water curtains are most widely used, freely falling in the form of a film, irrigating another screening surface (for example, metal), or enclosed in a special casing made of glass (watercolor screens), metal (coils), etc. .

The effectiveness of protection against thermal radiation with the help of screens is estimated by the formula:

where Q bz - intensity of thermal radiation without the use of protection, W / m 2, Q s - intensity of thermal radiation with the use of protection, W / m 2.

The ratio of heat flux attenuation, t, by a protective screen is determined by the formula:

where Q bz− emitter flux intensity (without using a protective screen), W/m 2 , Q− intensity of the heat radiation flux of the screen, W/m 2 .

The transmittance of the heat flux screen, τ, is equal to:

τ = 1/m. (2.8)

Local supply ventilation is widely used to create the required microclimate parameters in a limited volume, in particular, directly at the workplace. This is achieved by creating air oases, air curtains and air showers.

The flow of air directed directly at the worker allows to increase the removal of heat from his body to the environment. The choice of air flow rate depends on the severity of the work to be performed, as well as on the intensity of exposure, but it should, as a rule, not exceed 5 m/s, since in this case the worker experiences discomfort (for example, tinnitus). The effectiveness of air showers increases when the air sent to the workplace is cooled or when finely sprayed water is mixed into it (water-air shower).

An air oasis is created in separate areas of working rooms with high temperatures. To do this, a small working area is covered with light portable partitions 2 m high and cool air is supplied to the enclosed space at a speed of 0.2 - 0.4 m / s.

Air curtains are designed to prevent the penetration of outside cold air into the room by supplying warmer air at a high speed (10 - 15 m / s) at a certain angle towards the cold stream.

Air showers are used in hot shops at workplaces under the influence of a radiant heat flux of high intensity (more than 350 W / m 2).

The flow of air directed directly at the worker allows to increase the removal of heat from his body to the environment. The choice of air flow rate depends on the severity of the work to be performed, as well as on the intensity of exposure, but it should not, as a rule, exceed 5 m/s, since in this case, the worker experiences discomfort (for example, tinnitus).

The effectiveness of air showers increases when the air sent to the workplace is cooled or when finely sprayed water is mixed into it (water-air shower).

The essence of the invention: in the case there is a fan, the outlet pressure fitting connected with it with a nozzle having a longitudinal section and an outlet end. Folding paws with fixators of their position are installed on the body. The box is formed by two U-shaped parts, hinged at the outlet end of the nozzle, located on the nozzle and connected to each of the parts of the box by a mechanism for their synchronous movement. The longitudinal section of the nozzle has a constant cross section, a rectangular shape and a length of 0.3-0.7 of the width of the longitudinal section. The water inlet fitting is installed at the outlet end of the nozzle. The body is round. 2 w.p. f-ly, 5 ill.

The invention relates to ventilation systems, namely to mobile installations of local water-air showering. Local ventilation installations are known, containing a fixed housing, a fan and an outlet pipe with a nozzle located in it. The disadvantage of this device is that it is stationary and cannot be used during repair and commissioning for local temporary ventilation of workplaces. Known installation of water-air showering, containing a movable housing located in it a fan associated with the outlet pressure pipe with a nozzle and a fitting for supplying water to the nozzle. The disadvantage of this device is the inability to control the size of the ventilated place and the intensity, since the outlet end of the nozzle has a round constant cross section and the difficulty of transporting the body to the ventilated place. The aim of the invention is to increase productivity and labor efficiency by facilitating transportation, providing regulation of the size of the cooling-ventilating flow exiting the nozzle and bringing the fan closer to the cooling zone. To achieve this goal in the installation, the nozzle is made with a section of a constant section of a rectangular shape, the length l of which is selected from the condition l = (0.3 ... 0.7) h, where h is the section width, the water supply fitting is installed near the outlet end of the section constant section, the body is made round and the device is equipped with hinged paws mounted on the body with fixators of their position, two U-shaped parts forming the box, hinged near the outlet section of the constant section of the nozzle so that the axis of the hinges is parallel to the base of the box parts and perpendicular to the axis of the nozzle, located on the nozzle and connected to each of the parts of the box by a mechanism for their synchronous movement. In addition, the length l of the box parts is selected from the condition l = (2.5...4)h, and each of the parts is made wedge expanding in length, while the opening angle is chosen not more than 15 °, and the walls of the box parts are made of variable height , increasing from the outlet end of the section of constant section of the nozzle, while the maximum wall height is selected within (0.55...0.65)h. The execution of the case is round with folding legs allows transportation to any area of ​​repair work, and due to the maximum approach of the unit to the cooled area, increase the cooling efficiency. The fitting is located in the zone of maximum high-speed flow, which allows you to effectively spray water and evenly distribute it in the stream. The execution of the nozzle of a rectangular shape and supplying it with a box with the specified dimensions and adjustable width provides an effective supply of the cooling flow to a given place, the creation of a flat curtain and regulation of the flow depending on the requirements for cooling the work area. Figure 1 shows the proposed installation, side view, in a state of transport; figure 2 - the same, in working condition; figure 3 - nozzle with minimal disclosure of parts of the box, side view; figure 4 - the same, at maximum disclosure; figure 5 - the same, top view. The installation comprises a round body 1, a fan 2 located in it with an outlet pressure pipe 3 with a nozzle 4 and hinged paws 5 mounted on the body 1 with locks 6 of their position. Nozzle 4 is made with section 7 of constant section of rectangular shape with height b, width h and length l, and length l = (0.3...0.7)h. The installation contains a fitting 8 for supplying water to the nozzle 4, installed near the outlet end 9, and two U-shaped parts 10 forming a box, fixed near the outlet end 9 of the section 7 using hinges 11, the axis a-a of which is parallel to the base 12 of the parts 10 and perpendicular to the axis b-b of the nozzle 4. The length L of the parts 10 of the box is selected from the condition L = (2.5...4)h. Each of the parts 10 is selected wedge expanding in length with an opening angle of not more than 15 about. The height b of the walls of the parts 10 is made variable with a maximum height of 0.55...0.65 of the height b. In addition, the installation contains a mechanism for synchronous movement of parts 10, made, for example, in the form of a rack 13 fixed in section 7, a screw 14 associated with it, a nut 15 mounted on the screw 14 and two rods 16, one end of each of which is pivotally connected to the nut 15 and the other with the corresponding part 10. The installation works as follows. With the legs 5 retracted into the body 1 and the nozzle 4 disconnected, the installation is transferred or rolled to a predetermined place, as close as possible to the cooled zone in which work is performed. After that, the paws 5 are folded back and they are fixed with latches 6. The body 1 is fixed in this case in a stable position. An outlet pressure pipe 3 with a nozzle 4 is fixed on the fan 2, and a pipeline of the water supply system is fixed on the fitting 8. Then, depending on the distance from the nozzle 4 to the cooled zone, its size and the conditions around the cooled zone and the requirements and intensity of cooling, the position of the parts 10 is set. , i.e. the closer the parts 10 turn to each other by the mechanism of synchronous movement of the parts 10. At the same time, the screw 14, turning, moves the nut 15 and the rods 16 or reduces or separates the parts 10, turning them around the axis a-a of the hinges 11. Turn on the fan 2 and supply water through fitting 8. Water, entering the nozzle 4 in the zone of maximum air velocity, mixes with it and exits the box. Getting into the cooling zone and evaporating there, it, together with the ventilating air flow, cools the space, including the work zone. The correct choice of the opening angle, depending on the expected conditions and the size of the cooling zone within 15 °, allows you to select the conditions for supplying the air flow with the necessary movement parameters and in the required quantities.

Claim

1. INSTALLATION OF WATER-AIR SHOWERING, containing a housing, a fan located in it, an outlet pressure fitting connected to it with a nozzle having a longitudinal section and an outlet end, a fitting for supplying water to the nozzle, characterized in that the installation is equipped with folding paws mounted on the housing with their locks position, a box formed by two U-shaped parts hinged at the outlet end of the nozzle, located on the nozzle and connected to each part of the box by a mechanism for their synchronous movement, while the longitudinal section of the nozzle has a constant cross section, a rectangular shape and a length of ( 0.3 ... 0.7)h, where h is the width of the longitudinal section, and the water supply fitting is installed at the outlet end of the nozzle, and the body is made round. 2. Installation according to claim 1, characterized in that the U-shaped parts of the box have a length of (2.5 ... 4) h, where h is the width of the nozzle section, and each of the parts of the box is made wedge-shaped with an opening angle wedge no more than 15 o . 3. Installation according to claim 1, characterized in that the walls of the U-shaped parts of the box are made of variable height, increasing from the outlet end of the nozzle, while the maximum height of the walls is (0.55 ... 0.65) b, where b - height of the longitudinal section of the nozzle.

Class 36d, 1a, USSR

Iatenaa-teiaeeekav

P. V. Uchastkin

VENTILATION SHOWER UNIT FOR WORK

INSIDE HOT PRODUCTION EQUIPMENT

In some cases, it becomes necessary to carry out work inside hot production equipment. These include repair work in the furnaces of powerful electric steam boilers.

: stations, hot open-hearth furnaces, as well as work on production operations inside furnaces for heating and firing various products, etc.

These works are carried out under conditions of high temperature (up to 100), which is caused by the need to reduce the downtime of the specified production equipment. These works are very heavy and do not allow their long-term maintenance.

L7H Lightening of the dust During such works, a mobile ventilation shower unit is offered. The principle of operation of the installation is aimed at creating a low temperature zone in the hot space by supplying air with a lower temperature than the temperature inside the hot equipment.

A distinctive feature of the proposed installation is the method of protecting the air shower torch from excessive new! singing temperature while mixing in the surrounding grief: .ci o Air.

Known designs of such installations do not provide protection for the suffocating 1ra kel a From on Grs VYA1. For the indicated shortcoming, it was proposed to install water-spray nozzles on the shower head. which create a curtain of finely sprayed water on the periphery of the air torch. Sucking from the surrounding space to the main jet, hot air meets atomized water on its way. An intense IIcoapeHIIe of water occurs, resulting in a decrease in the ambient air temperature, which leads to a significant decrease! !o temperature in the suffocating flame.

To move the torch, it is proposed to use a flexible air duct, at the end of which is a 11PIHI Pe11.7PH d31INRU1oshi1 pump. H!OH:Ioå can be mounted on a stand so that it can be rotated as needed! direction. No. 84128

Figure 1 (Fig. 1) shows a diagram of a ventilation shower installation in operation, in Fig. 2 - installation without hose, side view; in fig. 3 - "the same, front view.

The 4th unit of the installation consists of a centrifugal fan 1 medium pressure and an electric motor 2. The fan impeller is mounted on the motor shaft. The fan and the electric motor are mounted on a trolley 3, which has three wheels: two of them are mounted on a common axis, the third is swivel. Turning the wheel 1 II cT c H Il P H Il o M o IH H P g H o B T II H . T Ya kos o f O R vI;1 0 H H e x o I O B o l l I B c T H telekkn provides it with good maneuverability. The fan inlet is protected with mesh. For winding the rubber plya11GYA 4, a coil b is used.

On the frame of the trolley, a starting device 6 of the electric motor is mounted, consisting of two package switches. One of the switches is used to turn the motor on or off, the other to switch phases, so that with any connection to the electric current network, the direction of rotation of the electric motor necessary for the fan is ensured.

The air duct 7 is made in: 1de of a flexible metal sleeve and has a length of 6 liters. For more convenient use, it consists of two links connected “into us” with the help of cuffs and locks. At one end of the air duct there is a square flange for connection to the fan outlet, and at the other end there is a transition pipe with a round flange and tightening locks for connection with a shower head 8. The latter is a transition outlet, inside which 10 guide vanes are installed. The nozzle is articulated with a tripod 9, there is a round flange around which o "can freely rotate 360. On the upper part of the nozzle, a tap 10 pipes for supplying water and water sprayers 11 with a diameter of 0.6 l1m are fixed.

To prevent clogging of water sprayers, a l2 mesh filter is placed on the rubber hose. The hose has an inner diameter of 10 mm, at one end it has a union nut for connection with a tube of water sprayers, and on the other - a nut for connecting to a faucet on the water supply.

The worker must be in the area of ​​the airflow coming out of the nozzle, so that the head and upper body are in the flow.

When moving the worker, the choking flow is directed to a new location by turning the nozzle around the axis.

The unit allows you to reduce the temperature at the workplace by

30 - 50C. If usually after 5 - 10 l1in stay inside the furnace of a boiler or an open-hearth furnace, the body temperature of a worker reached 39, then when working with the proposed installation and for from 30 11k to one hour, the body temperature was 37. ,1", invention

1. Ventilation shower installation for work inside hot production equipment, characterized in that, in order to prevent the temperature increase of the showering air torch from mixing ambient air with it, water spray nozzles are installed on the periphery of the shower nozzle ycxaHoBle, creating a water curtain around the air torch, providing a decrease in the temperature of the sucked air. No. 84128

2. Installation according to claim 1, characterized by the use of a flexible air duct, at the end of which a shower nozzle is attached, in order to bring the shower torch closer to the place of work.

3. Installation according to paragraphs. 1 and 2, characterized in that the showerhead is mounted on a stand with the possibility of turning it to direct the showering torch. No. 84128

11dp. to the stove 30j. (II – 61)

oum format. 70 108)i;

CBTI at 1 (office for Ivobrstspii and discoveries of the prp Council of Ministers of the USSR

Moscow, Center, M. Cherkassky lane, 216.

Volume It, 35 ed. l.

Price 7 kop.

Printing house, Sapunova Ave., 2, Editor N.I. Mosin Tskred A.A.

Local mechanical supply ventilation.

Air showers, their purpose and scope

An air shower is a local air flow directed at a person. With the help of such a flow, i.e. jets of air, it is possible to create local air conditions most favorable for human work in a limited area or areas of production. Such areas where air showers are needed are primarily:

1. fixed jobs
2. places of long stay in the premises of workers
3. rest areas for workers

in fig. 1 shows, as an example, a schematic diagram of an air shower at a heating furnace, when outside air is supplied for air showering.

1 - heating furnace with an open or opening opening 2

3 - fixed workplace at opening 2

4 - showering air distributor for supplying a jet of air to the workplace 6

5 - underground channel for supplying fresh air to the air distributor.

The condition of the air jet 6 at the fixed workplace 3 that creates an air shower must meet certain hygienic and physiological requirements. Air showers must be performed in the following cases:

1. in those cases when it is impossible to obtain normalized parameters of air in the room by means of general exchange ventilation.
2. when the achievement of certain parameters of the internal air in the room due to general exchange ventilation is, although possible, but at the same time requires huge volumes of air.

In many cases, when work is carried out in an environment of tangible thermal radiation, and the means of general ventilation will be insufficient, in order to maintain the required temperature and relative humidity in the workplace and eliminate the violation of thermoregulation between the human body and the environment, air showers must correct the air conditions . The industrial premises in which, first of all, an air showering device is necessary include:

- metallurgical and engineering plants, where air showers are needed for industrial furnaces, rolling mills, presses and hammers and other technological units.

– glass

– bakeries and other enterprises.

With the help of air showering, the following parameters of the air environment at fixed workplaces can be adjusted:

1. air temperature,

2. air speed,

3. humidity,

4. concentration of hazards in the workplace.

Due to the movement of air leaving the suffocating air distributor, heat transfer from the human body increases, and this circumstance is very important, especially in cases where a person works in an environment of tangible thermal radiation.

A jet of fresh air from a showering air distributor must be sent to meet the workers and, first of all, the exposed parts of the body exposed to radiation should be blown. If it is necessary to increase the heat transfer from the human body in air showers, air with a lower temperature is used compared to the air temperature in the room. In addition, sometimes, in order to increase heat transfer from the human body, a jet of emitted air is sprayed into lava.

In this case, water droplets fall on the open parts of the human body, on his clothes, evaporate and cause additional cooling of the person.

If an air shower is used indoors to localize the released dust or to combat increased gas contamination, then the air outlet velocity from the suffocating air distributor should not be significant so that the dust lying on the surface of the building structure does not roil.

In practice, this speed should be 1-1.5 m/s. The width of the shower jet S should be approximately 1.2-1.5 m. Except for the case when air showers serve large areas. According to SNiP 41-01-2003 "Heating, ventilation and air conditioning, air showering of permanent jobs with outside air must be provided in the following cases:

1. when irradiating a person at a fixed workplace with a radiant heat flux with a surface density of ≥140 W/m2 or more.

2. in open technological processes accompanied by the release of harmful substances and the impossibility of constructing shelters or local exhaust ventilation, while providing for measures to prevent the spread of harmful emissions to permanent workplaces.

When showering with outside air in industrial premises, the design temperatures and air speeds should be provided for:

1. when irradiating a worker with a radiant heat flux with a surface density of 140 W / m 2 or more according to Appendix E of SNiP 41-01-2003, depending on the category of work performed and the surface density of the heat flux.

2. In open technological processes associated with the release of harmful substances according to Appendix B of SNiP 41-01-2003.

Table 6. 2 of the designer's handbook edited by Pavlov and Schiller shows the data of the LIOT Institute on the numerical values ​​of the intensity of thermal exposure of certain types of industries working at workplaces, for workshops of machine-building plants (forging, foundry, thermal and others) when designing and calculating air showering intensity exposure of workers can be taken according to the instructions for the design of heating and ventilation of the corresponding listed shops. Developed by the SantekhNIIProekt Institute.

Detailed data on the intensity of exposure of working shops of machine-building plants are given in the reference book Torgovnikov B.M. "Design of industrial ventilation".

According to SNiP 41.01-2003, when showering workplaces with outdoor air, the design parameters of outdoor air should be taken as follows according to SNiP 23.01-99 *.

1. parameters A for the warm period of the year,

2. parameters B for the cold period of the year.

Air supply by air showering systems of workplaces should be provided through rotary horizontal planes of air distributors that ensure minimum turbulence of the outgoing jet and the possibility of changing and directing the jet of the vertical plane at an angle of at least 30 0 .

Installations of air showering of workplaces can be:

1. stationary see fig.1

2. mobile or portable.

Suffocating installations supplying outdoor air are stationary and are classified by type as supply air installations from which they are separated only by devices for supplying fresh air.

The showering air in stationary installations is supplied to certain workplaces with the help of air distributors, which, at the exit, give a concentrated jet leaving at a given relatively high speed (up to 3.5 m / s).

Currently, unified showering air distributors (UDV) are recommended for preferred use in stationary air shower installations. They are designed and can be used in the following versions:

1. with bottom air supply and without humidification and with humidification.

2. with top air supply without humidification and with humidification

Figure 2 shows the design of a unified showering air distributor with an upper air supply and humidification UDV UV.

1- air distributor housing

4- swivel

5- pneumatic nozzle

The air distributor consists of a body 1 in which guide vanes 2 and devices 6 are located that provide kinematic connection of the guide vane unit 2 with the guide grille 3.

Changing the direction of the choking jet in the horizontal plane is carried out by turning the choking air distributor around the axis, for which it has a hinge 4. In the vertical plane, the direction of the jet by turning the guide grille 3 can change from a horizontal position by an angle of up to 45 0 . To humidify the air, nozzles 5 with pneumatic spraying of water are installed on the guide grille. The nozzles can be moved both horizontally and vertically on the guiding grid and thus optimal humidification conditions can be created.

As an air distributor in air showering installations, a rotary showering air distributor (RPD - rotary showering branch pipe) can be performed, see fig. 3.

The PPD air distributor consists of 3 links:

- top link

– mid-level

–lower link

2- support rollers

4 - hinge

The lower link 5 has a compressed rectangular output section and is connected to the middle link by an axis 4, around which it can be rotated down by an angle of up to 25 0 .

In a predetermined position, the lower link 5 is fixed by two clamps located on the side surfaces of the middle link, the middle link rotates around the vertical axis on three rollers 2, which rest on the fixed flange of the upper link.

The showering air distributor is attached to the air duct on a flange connection and for this purpose the air duct must be securely attached to the external structures.

Air distributors PD (showering pipe) were developed by Professor V.V. Batulin with an upper air supply and a lower air supply. Accordingly, figures 4 a and 4 b.

1 - air duct from the ventilation system

4- swivel joint

5- handle for changing the positions of the guide grid

The air distributor rotates around the vertical axis with the help of hinge 4. To cool and humidify the supply air, nozzles FP-1 and FP-2 with pneumatic water spray can be used, see Fig. 2. NPO (scientific and production division) "Proektpromventilation" has developed a rotary adjustable air distributor VP with a round or rectangular connecting pipe, the design of which is shown in Figure 5.

1 - fixed part of the fan

2 - rotary part of the fan

3 - metal flexible sheet

4 - dividers

5 – RV fan grille installed in the outlet section of the fan

6 - hinge.

VP fans can be mounted vertically with top air supply, or horizontally with side air supply.

The second type of shower installations are mobile (portable) installations. Air treatment in them usually consists in mixing atomized water with the air flow coming out of the axial fan in the design.

Figure 6 shows a schematic diagram of a mobile shower installation.

1 – axial fan (usually MTs series) with electric motor 2;

3 - support structure:

4 - pneumatic nozzle.

Of the fan showering units, called water-air showers, the units of the design VA, PAM, developed respectively by the Sverdlovsk (SNOT) and Moscow (MIOT) Institute of Labor Protection, are the most common.

Working on recirculated room air, these units are characterized by a simple design, provide significant cooling of the supplied showering air, and in addition provide its partial washing from dust.

The calculation of the HP is based on the patterns of movement of a free jet of supply air and the head in determining the following parameters:

1. the flow rate of the supplied supply air;

2. speed of air outlet from the shower diffuser

3. constructive dimensions and standard size accepted for installation of the air distributor.

Air showering is the most effective measure for creating the required meteorological conditions (temperature, humidity and air velocity) at permanent workplaces. The use of air showers is especially effective in case of significant thermal radiation or in open production processes, if the technological equipment that emits harmful substances does not have shelters or local exhaust ventilation. Air showering is a jet of air directed to a limited workplace or directly to the worker.

The mobility of air in the workplace during air showering reaches from 1 to 3.5 m/s. Showering is carried out with special pipes, while the jet is directed to the irradiated areas of the body: head, chest. The size of the blown area is m. Showering can be carried out with external untreated air, adiabatically cooled air or isohumidity cooling. In some cases, it is allowed to use recirculated air, while there should be little thermal radiation and no harmful emissions.

The cooling effect of air showering depends on the temperature difference between the body of the worker and the air flow, as well as on the speed of air flow around the cooled body. When the jet coming out of the hole is mixed with the surrounding air, the velocity, temperature difference, and concentration of impurities in the cross section of the free jet change. The jet must be directed in such a way as to prevent, as far as possible, hot or fume-laden air from being sucked in. For example, when a fixed workplace is located near an open furnace opening, a showering device should not be placed near the opening with the direction of the jet towards the worker, since in this case it is impossible to avoid the suction of hot gases, as a result of which superheated air will flow to the worker. When calculating air showering systems, design parameters A for warm and design parameters B for cold periods of the year should be taken. To calculate year-round air showering, the warm period is taken as the calculation period, and only the supply air temperature is determined for the cold period.

Systems supplying air to the air shower nozzles are designed separately from systems for other purposes. The distance from the place of air outlet to the workplace should be taken at least 1 m. Calculation procedure

1. They are set by the air parameters at the workplace, they indicate the installation location of the nozzle, the distance from the nozzle to the workplace, and are also set by the type of shower nozzle. 2. We determine the air velocity at the outlet of the nozzle depending on the normalized air mobility in the room , where is the normalized air mobility, is the distance from the nozzle to the workplace, m, is the coefficient of change in speed, is the section of the selected nozzle. 3. We determine the minimum temperature at the outlet of the branch pipe , where is the normalized temperature, is the coefficient of temperature change. 4. We determine the air flow required for supply to the nozzle.