Air shower His appointment and use of the use of the air shower call the air flow to limited workplace or directly to humans. In many cases, when the work is carried out in the situation of tangible heat radiation, and the means of general ventilation turn out to be insufficient to maintain the required temperature and humidity of the air and eliminate the violation of the thermoregulation of the normal heat exchange between the human body and the air showers should be adjusted somewhat ...
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Plan
24.1. Air shower, its appointment and application area.
24.3. Calculation of air shower.
The air shower is called the flow of air aimed at a limited workplace or directly to humans.
In contrast to the overall ventilation, which puts its task to support certain conditions aerial In the whole room, the local influx is aimed at creating local air conditions on a limited area of \u200b\u200bthe room. Such areas are or places of the longest staying in them workers, or resting.
Thus, the purpose of the air soul is that in space, a limited area of \u200b\u200bthe flow of the flow, maintaining special, different from the air conditioning conditions in the whole room. These conditions should satisfy certain, predetermined hygienic and physiological requirements.
Air evocation is used to create in permanent workplaces of the required meteorological conditions during thermal irradiation and in open production processes, if the technological equipment that emitting harmful substances does not have shelters or local exhaust ventilation.
The air shower is arranged in the following cases:
In many cases, when the work is carried out in the situation of tangible thermal radiation, and the means of general ventilation turn out to be insufficient, in order to maintain the required temperature and humidity of the air and eliminate disruption of thermoregulation (normal heat exchange between the human body and the environment), the air souls must be somewhat Adjust the air conditioning conditions. Here you need to include metallurgical and engineering plants (where the souls are needed in industrial furnaces, rolling mills, molotov, presses, etc.), glass plants, dyeing factories, bakeries, etc.
The same adjustment the air souls must serve with the currently used natural ventilation (aeration) of modern workshops. This may occur in cases where a natural inflow due to aeration by the arrangement of the supply holes (fraamug, etc.) cannot sufficiently serve jobs (forge, foundry, thermal and other trains).
The role of air shower when aeration is particularly important and due to the fact that a natural inflow is introduced without preliminary preparation (without heating or cooling, etc.), while for air shower such preliminary preparation can be carried out at low cost .
In industrial shops designed taking into account aeration, air flow consumption for air shower is a slight percentage of natural air exchange.
Finally, in hot shops in areas with high outdoor temperatures, when the overall ventilation (natural or mechanical) supports in the workshops air temperature 3-5 ° above the outer, aerial souls, suitable in the workplace, create conditions close to comfortable, and the outer air for them is subjected to pretreatment (cooling).
When designing air evidence, measures must be taken, preventing the production of industrial harmful discharge into closely located permanent jobs. The air jet should be aimed so that it is possible to succeed with it with hot or contaminated air gases.
For air searches, workplaces should include air distributors providing minimal turbulization. aerial jet and having devices to change the direction of the jet in the horizontal plane at an angle 180about and B. vertical plane at an angle 30.about .
When designing an air stroke with outdoor air, the calculated parameters should be received.BUT For warm period of year andB. For the cold period.
Air stroke during thermal irradiation should provide on the places of permanent stay of the operating temperature and the speed of air movement in accordance with the application of Table. G.1 SP 60.13330.2012.
Air souls are classified for several features:
The concentrated feed applies only when the workplace is strictly fixed.
When the air soul device, air is subjected to a different processing. Air flow temperature, relative humidity, gas concentration, air speed can vary.
When dealing with radiant heat, it is enough to increase the airflow speed until the ambient temperature exceeds 30about . At T\u003e 30 Increasing the flow rate can not provide normal well-being of the body.
The systems supplying air to air souls are designed separately from other purposes.
The distance from the place of release of the air to the working meta should be taken at least 1m with a minimum diameter of the pipe 0.3 m, and the air flow should be directed:
If it is impossible to achieve a normalized air temperature in the stitching jet at the workplace with an increase in air movement speed, the nozzles of the thin spraying of water should be installed in the flow of the air supply at the outlet from the air-dispersion device or apply adiabatic air cooling during centralized processing it in the supply chambers. Installations with application artificial cold require significant operational and capital costs, so artificial air cooling should be applied only in cases where the normalized air temperature in the workplace is below the temperature of the supply air obtained by its adiabatic cooling.
When designing air evidence systems, the air distributors of the UDV should be used. Air distributors are usually installed at a height of at least 1.8m on the floor (up to their lower edge). To squeeze a group of permanent jobs, air distributors of VGK and VSP can be used.
Unified duplicating air distributors UDB are recommended to preferred use. They are designed in the following versions: lower air supply without moisturizing UVN and with moisturizing the full; Upper air supply without moisturizing UDVV and with wetting UDVUV. The fragrance of fixed jobs can be carried out by fragrant nozzles of various types: PPD, PDN, PDV, PD, VP.
With thermal irradiation of permanent jobs with heated surfaces intensity from 140 to 350 W / m2 It is envisaged to install fans - fans. When using fans - fans, it is necessary to maintain the allowable GOST 12.1.005-88 air temperature increasing speed by 0.2 m / s more specified in this GUTE. For this purpose, fragrance of workplaces in the inner air is carried out by PAM-24 rotary aerators. The distance from the aerator to the workplace is determined by the specific conditions, the maximum distance is 20m.
In the premises of public, administrative and domestic and production buildingsBuilded B.lV climatic area, as well as in substantiation and in other climatic areas, with excess of explicit warmth more than 23 W / m3 should be provided in addition to the general supply ventilation The installation of ceiling fans to increase the speed of air movement at workplaces or in separate areas during the warm period of the year. For this purpose, the ceiling fans of the military-industrial complex MPK-15 "Union", "Zangezur-3", "Zangezur-5" are used. Replacing the ceiling fans should not be limited by areas with a hot climate. They are rational to apply in areas with temperate climates.
The achievement of normalized air parameters is determined by the calculation of the limit (axial) values \u200b\u200bof the air jet parameters at a permanent workplace.
For the calculated values \u200b\u200bat a permanent workplace, it is recommended to accept:
The temperature of the air mixture in the air jet is equal to normalized by Appendix Tab. G.1 SP 60.13330.2012, with thermal irradiation intensity 140 W / m2 and more. For intermediate values \u200b\u200bof radiant density surfaces heat flux The temperature of the air mixture in the stitching jet should be determined by interpolation.
The minimum concentration of harmful substances in the air jet is equal to PDC on Appendix 2 GOST 12.1.005-88;
The speed of movement of the air jet - the corresponding temperature of the air mixture in the fragrant jet by Appendix E SNIP41- 01 - 2003 with thermal irradiation intensity 140 W / m2 or more.
When calculating, the scenario-solid scenario is determinedF O. , air outlet speed and air distributor aircraftL O. . Temperature of supply air at the outlet of the air distributort O. Must be less than or equal to normalized.
The calculation is made from the condition of ensuring the normalized air parameters at a permanent workplace according to the following formulas:
a) during heat dissipation andt norms\u003e t o obtained with adiabatic air cooling or without cooling,
; (24.1)
, (24.2)
where, H. - distance from the air distributor to the workplace, m; T, P. - respectively, the speed and temperature coefficients of the air distributor (accepted by reference literature);
b) during heat dissipation andt norms< t o obtained during adiabatic cooling,
; (24.3)
; (24.4)
T O \u003d T norms, (24.5)
those. Requires non-articular air cooling;
c) for gas and dust-findings are calculated by formula (24.2), and
, (24.6)
where, PDK. - the maximum permissible concentration of harmful substances in the workplace in accordance with Annex 2 GOST 12.1.005-88;Z RZ and Z o - The concentration of harmful substances in the air of the working area and in the supply air at the outlet of the air distributor.
If valid are givent, P, F O and X It should be determined by: at the formula (24.4);t O. under the formula (24.5); under the formula (24.2);t o with the formula
. (24.7)
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Air evocation is the most effective event for creating the required meteorological conditions in permanent workplaces (temperature, humidity and air velocity). The use of air shower with significant heat radiation or with open production processes is particularly effective if the technological equipment that emit harmful substances does not have shelters or local exhaust ventilation. Air stroke is a jet of air aimed at a limited workplace or directly on the worker.
Air mobility in the workplace during air stroke reaches from 1 to 3.5 m / s. Decoration is carried out by special nozzles, while the jet is sent to the irradiated areas of the body: head, chest. The size of the area of \u200b\u200bthe area is m. The stroke can be carried out by outer unprocessed air, adiabatic-cooled air or isolating cooling. In some cases, it is allowed to use recycling air, and there must be a slight thermal radiation and no harmful discharge.
The cooling effect of air scenario depends on the difference in temperature of the body of the working and air flow, as well as from the speed of flowing in air of the cooled body. When mixing the jet, leaving the hole, with the ambient air, the temperature difference and the concentration of impurities in cross section Free jet change. The jet should be directed so that it is possible to sue hot or air polluted air polluted. For example, when finding a fixed working place near an open bake opening, there should be no stitching device near the opening with the direction of the jet to meet the worker, since in this case it is impossible to avoid suction of hot gases, as a result of which the superheated air will be applied to the worker. When calculating the air stroke systems, the calculated parameters are made for warm and calculated parameters B for cold periods of the year. To calculate the air stroke of the year-round operation for the calculated period, the warm period is taken, and for the cold period, only the temperature of the supply air is determined.
Systems supplying air to air stroke pipes are designed separately from other destination systems. The distance from the place of release of air to the workplace should be taken at least 1 m. Calculation procedure
1. Place air parameters in the workplace, the location of the nozzle is planned, the distance from the nozzle to the workplace, and are also set by the type of stroke pipe. 2. 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, - the coefficient of changes in the speed - the cross section of the selected pipe. 3. Determine the minimum temperature at the outlet of the nozzle, where the normalized temperature is the temperature change coefficient. 4. Determined air consumption required for feeding the pipe.
Appointment of air shower. The air shower is called the flow of air aimed at a limited workplace or directly to the worker. Especially efficiently the use of air shower with thermal irradiation of the worker. In such cases, the air shower is arranged on the site of the longest residence of a person, and if the paper provides for short-term breaks for recreation, on the place of rest. To blow the air to the top of the body, as the most sensitive to the effects of thermal exposure.
The speed and temperature in the workplace at the use of the air shower is prescribed depending on the intensity of the thermal irradiation of the person, the duration of the continuous stay of it under the irradiation and ambient temperature.
Air stamp should be provided for permanent workplaces with an irradiation intensity of 350 W / m2 or more. At the same time, a stream of air can be directed to a person with a speed of O \u003d 0.5 ... 3.5 m / s and a temperature of 18-24 ° C, depending on the period1 of the year and the intensity of physical exertion.
Constructive execution of air shower. The air coming out of the stubbing nozzle should wash the head and body torso with a uniform speed and have the same temperature.
The axis of the air flow can be directed to the human breast horizontally or from above at an angle of 45 ° when providing in the workplace of the specified temperatures and air movements, as well as in the face (respiratory zone) horizontally or from above at an angle of 45 ° while ensuring permissible concentrations of harmful discharges.
The distance from the stubborn nozzle to the workplace should be at least 1 m with a minimum diameter of the pipe 0.3 m. The width of the working platform is received equal to 1 m.
By design, fragrant installations are divided into stationary and mobile.
Faurity unit type VA-1. The unit consists of cast-iron beds, on which the axial fan No. 5 of the MC type is mounted with an electric motor, a shell with a collector and a grid, a confusion with guide shovels and a fairing, a pneumatic nozzle of the type FP-1 or FP-2 and pipelines with reinforcement and reinforcement and flexible hoses For supplying water and compressed air. The unit is made with a rotation of the fan around the axis of the bed to 60 ° and the trunk lifting vertically by 200-600 mm.
In addition to the type of fan aggregates, a rotating PAM.-24 unit is used in the form of an axial fan with a diameter of 800 mm with an electric motor on the same shaft. The productivity of the unit is 24,000 m3 / h with long-range jets 20 m. The unit is equipped with a pneumatic nozzle for spraying water in the air flow.
Stationary fragrant installations Fixed to stroke pipes both untreated and treated (heated, cooled and moistened) outer air. Mobile installations are served by air of the room. In the air flow supplied, water can be sprayed. In this case, water droplets, falling on the clothes and open parts of the human body, evaporate and cause additional cooling.
Frashing fixed jobs can be carried out by fragrant nozzles different types. Nozzles have a suppressed output section, a hinge compound to change the direction of air flow in the vertical plane and the rotary device to change the flow direction in the horizontal plane in the range of 360 °. Regulation of the direction of the air flow in nozzles is carried out in the vertical plane by turning the guide blades, and in the horizontal plane using the rotary device. PD pipes can be used both with nozzles for pneumatic spraying of water, and without them. Nozzles should be installed at an altitude of 1.8-1.9 m from the floor (to the bottom edge).
Calculation of air shower. When combating thermal irradiation for air-sowing systems, the calculated parameters of the outer air category B are taken, and in other cases, the calculated parameters of the outdoor air category A for the warm period of the year and category B for the cold period of the year.
The calculation of the separation unit (according to the method of Dr. Tehn. Sciences P. V. Perekkina) reduces to the definition of the cross-sectional area of \u200b\u200bthe stubble pipe FO from the condition of ensuring the normalized air parameters in the workplace. The calculation is carried out in the following order.
Local mechanical supply ventilation.
Air souls their appointment and application
The air shower is called a local air flow air. With this stream, i.e. Air jets, you can create local the most favorable human conditions of the air in a limited area or production sites. Such areas where the air shower device is needed primarily:
in fig. 1 as an example is shown schematic scheme The air shower devices at the heating furnace when the outer air is supplied for air evidence.
1 - Heating furnace with open or opening opening 2
3 - Fixed workplace at opening 2
4 - fragrant air distributor for submission to the workplace of air jet 6
5 - the underground channel for supplying the air-operated air to the air distributor.
The condition of the air jet 6 at a fixed workplace 3, which creates the air shower must comply with certain hygienic and physiological requirements. Air souls must be performed in the following cases:
In many cases, when the work is carried out in the situation of tangible heat 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 thermoregulation violation between the human body and the environment of the air souls must adjust the conditions of the air media . To the production premises in which, in the first place it is necessary, an air stroke device can be attributed:
- Metallurgical and engineering plants, where air souls are necessary in industrial furnaces, rolling mills, presses and molotov and other technological aggregates.
- Glass
- Bakery and other enterprises.
Using air evidence you can adjust the following parameters Air Wednesday at fixed workplace rooms:
1. Air temperature,
2. Air movement speed,
3. Humidity,
4. Concentration of harm in the workplace.
Due to the movement of the air from the scented air distributor increases the heat transfer from the body of a person and this circumstance is very important especially in cases where the human work occurs in the situation of tangible thermal radiation.
The jet of the supply air from the fragrant air distributor must be sent to the meeting working and blow at the same time the open parts of the body exposed to irradiation. If it is necessary to increase the heat transfer from the human body in air souls, air with a lower temperature is used compared with the indoor air temperature. In addition, sometimes to increase heat transfer from the body of a person, the jet of the released air is sprayed into Lava.
In this case, the water droplets fall on the open parts of the human body, on his clothes, evaporate and cause additional cooling of the person.
In the event that the air shower is used in the room for localization of the distinguished dust or to combat increased gas data, the air exit rate from the fragrant air distributor should not be significant in order for dust lying on the surface building construction, not climbed.
Practically, this speed should be 1-1.5 m / s. The width of the scented jet s must be about 1.2-1.5 m. Except for the case when the air souls serve large on the area area. According to SNiP 41-01-2003 "Heating, ventilation and air conditioning, air strokes of permanent jobs by external air must be provided in the following cases:
1. When man irradiated at a fixed workplace with a radiant heat flux with a surface density of ≥140 W / m 2 or more.
2. With open technological processes accompanied by the release of harmful substances and the inability of the shelter or local exhaust ventilation, providing for measures to prevent the proliferation of harmful discharge on permanent jobs.
When evoking the outer air of the production premises, the estimated temperatures and air velocities should be provided:
1. When irradiated with a radiant heat flux with a surface density of 140 W / m 2 and more on Appendix E SNiP 41-01-2003, depending on the category of work performed and the surface density of the heat flux.
2. With open technological processes associated with the release of harmful substances by annex in SNiP 41-01-2003.
Table 6. Two directories of the designer edited by Pavlova and Schiller are given the data of the LITIA Institute in the numerical values \u200b\u200bof the intensity of thermal exposure in the workplaces of certain types of industries, for machine-building factories (forge, foundry, thermal and other) when designing and calculating air evidence intensity Exposures of working can be taken on instructions on the design of heating and ventilation of the corresponding listed workshops. Developed by the Institute "Santekhniyproekt".
Detailed data on the intensity of irradiation of working workshops of machine-building factories are given in the directory of BM merchants. "Design of industrial ventilation."
According to SNIP 41.01-2003, when srooping jobs by outside air, the calculated parameters of the outer air should be taken in the following SNIP 23.01-99 *.
1. Parameters and for the warm period of the year,
2. Parameters b for the cold period of the year.
The air supply of air stroke systems of workplaces should be provided through the rotary horizontal planes of air distributors providing minimal turbulence of the outgoing jet and the possibility of changing and directions of the jet of the vertical plane at an angle of at least 30 0.
Installations of air searches of jobs can be:
1. Stationary see Fig.1
2. Mobile or portable.
Fragrant installations The feeding the outer air is carried out stationary and in the type refer to inlet installations From which they are sent only to devices for supplying air.
The fooling air in stationary installations is fed to certain jobs with air distributors, which are given by the concentrated jet exiting the resulting relatively high speed (up to 3.5 m / s).
Currently, unified scenario air distributors (UDV) are recommended to preferred use in stationary air stroke installations. They are designed and can be applied in the following versions:
1. With the lower supply of air and without moisture, and with moisture.
2. With the upper air supply without moisturizing and with moisture
Figure 2 shows the structural execution of a unified fragrant air distributor with the upper air supply and humidification of UDV Uv.
1- Air distributor housing
4- hinged connection
5- pneumatic nozzle
The air distributor consists of a housing 1 in which the guide blades 2 and the device 6 provide the kinematic bond of the guide blades 2 with the guide lattice 3.
The change in the direction of the stroke jet in the horizontal plane is carried out by turning the separating air distributor around the axis for which it has a hinge 4. In the vertical plane, the direction of the jet due to the rotation of the lattice guide 3 may vary from the horizontal position at an angle to 45 0. For humidification of air on the guide grid, nozzles 5 with pneumatic spraying of water are installed. Nozzles can move both horizontally and vertically the guide lattice and thereby can be created. optimal conditions For moisturizing.
As an air distributor in the air stroke installations, a swivel-scented air distributor can be performed (PPD - a swivel cutting nozzle) See Fig. 3.
The PPD air distributor consists of 3 x links:
- Upper Star
-The average level
-Nigal link
2- Supported rollers
4 - hinge
The lower link 5 has a suppressed rectangular output section and is connected to the middle axis 4, around which it can be turned down at an angle to 25 0.
In a given position, the lower link 5 is fixed by two clips on the side surfaces of the middle link, the average link is turned around the vertical axis, which rely on the fixed flange of the upper link.
To the duct stirming air distributor attached to flange connection And for this purpose, the air duct must be securely attached to outdoor designs.
The air distributors of the PD (dusting pipe) were developed by Professor V. V. Batulin with an upper air supply and with the lower air supply. Accordingly, Figures 4 A and 4 b.
1 - Air duct from the ventilation system
4- rotary hinge
5- Point to change the positions of the guide lattice
Around the vertical axis, the air distributor rotates with the help of a hinge 4. For cooling and moisturizing the supplied air supply air, the nozzles of FP-1 and FP-2 can be used with a pneumatic spraying of water, see Fig. 2. NGOs (Scientific Production Division) "ProjectPromventilation" has developed a rotary adjustable air distributor VP with a connecting pipe of a round or rectangular cross section of which is shown in Figure 5.
1 - fixed part of the fan
2 - Swivel Fan
3 - Metal flexible sheet
4 - dividers
5 - fan grille RV, installed in the output section of the fan
6 - hinge.
VP fans can be installed vertically at the upper air supply, or horizontally with lateral stern.
The second type of fragrant installations is mobile (portable) installation. The air processing in them is usually mixed to the stream of air emerging from the existing axial fan of sprayed water.
Fig. 6 shows a schematic diagram of a mobile fragrant installation.
1 - axial fan (usually MC series) with electric motor 2;
3 - supporting design:
4 - pneumatic nozzle.
From fan-sowing units, called water souls, the aggregates of the design of the VA, PAM, developed by Sverdlovsk (SNOT) and Moscow (Miot) by the Institute for Labor Protection, are most common.
Working on the recycled air of the room, these aggregates are characterized by a simple design, give a significant cooling of the separated scenario air, and also provide its partial washing from dust.
The calculation of the VD is based on the patterns of the movement of the free jet of the supply air and the title in the definition of the following parameters:
1. Consumption of the supplied air supply air;
2. The speed of air outlet from the fragrant air distributor
3. Constructive sizes and sizes adopted to install the air distributor.
The air shower is a local, directional air flow. In the air soul zone, conditions are created other than the conditions in the entire amount of the room. With the help of the air shower, the following air parameters can be changed at a place of finding a person: mobility, temperature, humidity and concentration of one or another harmfulness. Usually the air shower area are: fixed jobs, the most long stay of workers and recreation sites. In fig. 3.19 schematically shows the air shower used to create the necessary conditions in the workplace.
Fig. 3.18. Onboard suction: A - simple; b - tilted; B - Garden
Fig. 3.19. Air shower: A - vertical; b - inclined; B - Group
3.0 m / s, the temperature may vary from 16 to 24 ° C. If the air shower is used to combat dust, the air velocity should not be higher than 0.5-1.5 m / s, in order to prevent the dust raising by raising the floor.
A large influence on the efficiency of the air soul is the design of the air-powered nozzle (supply nozzle). It is advisable to have this device turning and at the same time to envisage the ability to change the angle of inclination of the stream axis by introducing rotary blades. In fig. 3.20 depicted in suction nozzles of the design of V. V. Baturin, made taking into account these two requirements.
Classification of ventilation and air conditioning systems
Fig. 3.20. Infection nozzles of the design of V. V. Baturin: A - at the upper subport; B - with lower air supply
For the air shower, the outer air or air taken from the room can be used. The latter, as a rule, passes the appropriate processing (most often cooling). The outer air can also be processed to give it the necessary parameters.
Summer installations can be stationary or mobile.
Spaning adiabato water reduces air temperature. In fig. 3.21 and 3.22 show the urgent souls of this type of construction of the Moscow and Sverdlovsk Institutions of labor protection.
In air curtains, as well as in air souls, uses the main property of the influenza torch - its relative range. Air curtains are arranged to prevent air flow through technological openings or gates from one part of the building to another or outdoor air in production facilities. In fig. 3.23 depicted air curtain diagrams designed to prevent or sharp decrease in penetration through the gate of cold outdoor air in the workshop. The air supplied for the curtain can be preheated, and then curtains are called air-thermal.
Air curtains designed to prevent the penetration of cold air should be provided at the gate that open more often than five times or at least 40 minutes in shift, as well as technological openings of heated buildings, falconed in areas with calculated outdoor temperature for designing heating system- 15 ° C and below when the ability of the gateway device is excluded. If the air temperature decreases(on technological or sanitary- hygienic considerations) unacceptable curtains can be designed for any duration of the opening and any calculated outdoor air temperature. At the same time, technical- economic Justification of this decision.
Fig. 3.21. Water-high shower type Miot small model:
Fig. 3.22. Mobile fan aggregate SIOT-3:
Fig. 3.23. Air curtains: but - operating principle; b - different air supply methods:
I - air supply from below; II - side air supply on one side; III - same on both sides
1 - water supply pipeline
from water supply; 2 - casing; 3 - electric motor; 4 - axial fan; 5 - drain pipe; 6 - Stand 1 - axial fan; 2 - electric motor; 3 - nozzles; 4 - metal fairing; 5 - Stand on wheels; 6 - Pipeline for water supply from water supply
In the case of a short-term (up to 10 minutes), the opening of the gate is usually allowed to reduce the air temperature in the workplaces protected from airborne by air breaking through the gate, shirms or partitions. The degree of reduction depends on the nature of the work performed: with easy physical work - up to 14 ° C, the operation of moderate gravity is up to 12 °, heavy operation - up to 8 °. If there is no permanent jobs in the area of \u200b\u200bthe gate, a decrease in temperature in the working area of \u200b\u200bthis area to + 5 ° is allowed.
Currently the necessary conditions The air environment in the workplace is quite often created using a device of special ventilated cabins. In such cabins, conditions are supported different from the conditions in all production premises. This is achieved most often in the cab in a specially cooked air: in hot shops - cooled, in cold, unheated premises - Heated. Ventilated cabins can be attributed to local ventilation systems. Naturally, their use is possible when the workplace is strictly fixed, for example, at the control panel. In fig. 3.24 shows a ventilated cabin for a crane control, developed by the Leningrad Institute for Labor Protection.
Community ventilation systems can be inlets and exhaust (Fig. 3.5, 3.6, 3.9). When using general systems, the task is to create the necessary air conditioning conditions throughout the size of the room or in the scope of the working area. In contrast to local systems, in this case, all the harm it is distributed throughout the extent. Consequently, the main task to be solved in the design of the systems under consideration is that the airborne content of one or another harmfulness is not exceeded the validity of the maximum permissible concentration, and the meteorological parameter values \u200b\u200bresponded to the relevant requirements.
Often the room is equipped with a supply and exhaust second systems ventilation (Fig. 3.10).
The general method of creating a given air environmental conditions has wide use and in combination with air conditioning systems.
Fig. 3.24. Ventilated cabin
In the present course, this method is paid very much attention, as it is the main object for
