With regard to industry, ventilation of industrial premises is a complex of measures, equipment and organizing its maintenance, haunting the goal of maintaining a stable air exchange and moving air flows in the premises.

Ventilation systems are set to maintain regulatory meteorological parameters in rooms of different functionality. Classify the types of ventilation of industrial premises can be as follows:

• The method of organizing air exchange is natural and forced (mechanical) ventilation.
• Purpose: Supply or exhaust ventilation.
• Service area: general or local system.
• Structurally: Channel or Breakless ventilation system.

Types of industrial ventilation

Such natural ventilation of industrial premises is based on natural airproof, on the appearance of which the following factors affect:

• The difference between the outer air temperatures and indoor temperature (aeration).
• The difference in atmospheric pressure between the lower level indoors and the hood, which is mounted on the roof.
• Wind speed and pressure.

The organization of the work of natural ventilation of the premises will not require significant injections to the equipment. Installing natural ventilation is the simplest of the existing systems and does not require supplying electricity. Disadvantages - dependence on the values \u200b\u200bof temperature, pressure, directions and wind speeds. The exact calculation of natural ventilation of industrial premises is made by formulas:

Air Flow Exchange Options

The current ventilation norms of industrial premises are reflected in SNiP 41-01-2003 of 26.06.2003. According to these prescriptions, general ventilation should ensure air exchange in the entire premises. Properly installed generally exchange ventilation of industrial premises removes spent masses throughout the size of the room, and the supply equipment supplies clean air back.

• Turning air force

Assimilation of excess moisture, heat and dilution of harmful discharge and impurities - the tasks of the influencing general ventilation. All this allows you to observe sanitary and hygienic standards and standards for comfortable stay on the work area.

If it is cold in the room, then the intake sociable ventilation solves the problems of mechanical motivation, purification and heating of air mass.

• Extraction of general type

The simplest device for organizing a secrets exhaust ventilation system is a fan with an air vent in the window or in the exhaust channel. With the length of the air duct, more than 30-40 m and the pressure decreases greater than 30-40 kg / m2 axial fan should be replaced with the central one. Community ventilation systems of industrial premises often work in a pair with other ventilation systems (more often it is natural or mechanical ventilation), since due to the heterogeneity of harmful impurities and different conditions for their formation, the use of some single system is ineffective.

• Air ducts when venting

Using ventilation systems suggests in some cases for efficient air movement, the availability of a network of air ducts, that is, channel systems. In the absence of ventilation channels, such a system is called vagueless. For example, the fan is installed in the ceiling or in the wall, with the presence of a system of natural ventilation, etc. Any ventilation system has 4 main properties: functionality, volume of serviced areas, method of moving air masses and constructive design.

The main purpose of exhaust ventilation is to eliminate the exhaust air from the served room. Exhaust ventilation, as a rule, works in a complex with a supply, which, in turn, is responsible for the supply of clean air.

In order for the room a favorable and healthy microclimate, you need to make a competent project of the air exchange system, perform the appropriate calculation and make the installation of the necessary aggregates for all the rules. Planning, you need to remember that the condition of the entire building and the health of people who are in it depends on it.

The slightest mistakes lead to the fact that ventilation ceases to cope with its function as it is necessary, the fungus appears in the rooms, finishing and building materials are destroyed, and people begin to root. Therefore, the importance of the correct calculation of ventilation can not be underestimated by no means.

The main parameters of exhaust ventilation

Depending on which functions perform the ventilation system, the existing settings are customized to:

1. Exhaust. We are necessary for the fence of the exhaust air and his leads from the room.
2. Inlets. Provide fresh clean air from the street.
3. Cut-exhaust. At the same time, you remove the old edge air and serves a new one in the room.

Exhaust installations are mainly used in production, in offices, warehouse and other similar premises. The disadvantage of exhaust ventilation is that without the simultaneous device of the supply system, it will work very badly.

In the event that more air will be pulled out of the room than it comes, drafts are formed. Therefore, the supply and exhaust system is the most efficient. It provides the most comfortable conditions and in residential premises, and in industrial and work type premises.

Modern systems are equipped with various additional devices that purify air, heated or cooled it, moisturizes and evenly distribute indoors. The old air without any difficulty is displayed through the hood.

Before entering into the arrangement of the ventilation system, it is necessary to approach the process of calculating it. Directly the calculation of ventilation is aimed at determining the main parameters of the main system nodes. Only by defining the most appropriate characteristics, you can make such ventilation that will fully fulfill all the tasks set before it.

In the course of the calculation of the ventilation, such parameters are defined as:

1. Consumption.
2. Operating pressure.
3. Califer power.
4. Air duct area.

If you wish, you can additionally calculate the cost of electricity flow to work and maintain the system.

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Step-by-step instructions for determining system performance

Calculation of ventilation begins with the definition of its main parameter - performance. Dimensional ventilation unit - m³ / h. In order to calculate the flow of air flow, you need to know the following information:

1. The height of the premises and their area.
2. The main purpose of each room is the main purpose.
3. The average number of people who will be simultaneously in the room.

To make the calculation, the following devices will need:

1. Roulette for measurements.
2. Paper and pencil for records.
3. Calculator for computing.

To calculate, you need to know such a parameter as the multiplicity of air exchange per unit of time. This value is set by SNiP in accordance with the type of room. For residential, industrial and administrative premises, the parameter will differ. It is also necessary to take into account such moments as the number of heating devices and their power, the average number of people.

For household premises, the multiplicity of air exchange, which is used in the calculation process is 1. When calculating the ventilation for administrative premises, use the value of the air exchange, equal to 2-3, depending on the specific conditions. Directly the multiplicity of air exchange indicates that, for example, in the domestic room, the air will be fully updated 1 time in 1 hour, which is more than enough in most cases.

The calculation of performance requires the presence of data such as the magnitude of the air exchange by the multiplicity and number of people. It will be necessary to take the greatest value and, already pushing out from it, choose the appropriate power of exhaust ventilation. Calculation of the multiplicity of air exchange is performed according to a simple formula. It is enough to multiply the area of \u200b\u200bthe room to the height of the ceiling and the value of the multiplicity (1 for household, 2 for administrative, etc.).

To calculate air exchange by the number of people, multiplying the amount of air, which consumes 1 person, to the number of people indoors. As for the volume of the consumed air, on average, with minimal physical activity, 1 person consumes 20 m³ / h, with an average activity, this indicator rises to 40 m³ / h, and with high already 60 m³ / h.

To be clearer, it is possible to give an example of calculating for an ordinary bedroom having an area of \u200b\u200b14 m². There are 2 people in the bedroom. The ceiling has a height of 2.5 m. Completely standard conditions for a simple urban apartment. In the first case, the calculation will show that the exchange of air is equal to 14x2,5x1 \u003d 35 m³ / h. When calculating the second scheme, you will see that it is already 2x20 \u003d 40 m³ / h. It is necessary, as already noted, take more importance. Therefore, specifically in this example will be calculated by the number of people.

Under the same formulas, oxygen consumption is calculated for all other premises. Finishing will remain folded all the values, get overall performance and select ventilation equipment based on this data.

Standard values \u200b\u200bof ventilation systems are:

1. From 100 to 500 m³ / h for ordinary residential apartments.
2. From 1000 to 2000 m³ / h for private houses.
3. From 1000 to 10,000 m³ / h for industrial premises.

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Determination of the power of an air heater

In order for the calculation of the ventilation system to be implemented in accordance with all the rules, it is necessary to take into account the power of the air heater. This is done if the complex will be organized in the complex with exhaust ventilation. A calorior is installed in order for the air from the street warmed up and enter the room is already warm. Relevant in cold weather.

The calculation of the power of the air heater is determined taking into account such a value as the air flow rate, the necessary temperature at the outlet and the minimum temperature of the incoming air. The last 2 values \u200b\u200bare approved in SNiP. In accordance with this regulatory document, the air temperature at the calorfer outlet should be at least 18 °. The minimum temperature of the external air should be specified in accordance with the residence region.

The composition of modern ventilation systems includes performance regulators. Such devices are designed specifically so that the air circulation rate can be reduced. In the cold time, this will reduce the amount of energy consumed by an air heater.

To determine the temperature to which the device can heat the air, an easy formula is used. According to it, you need to take the value of the power of the unit, divide it to air flow, and then multiply the value obtained by 2.98.

For example, if the air flow at the facility is 200 m³ / h, and the calorifer has a power of 3 kW, then substituting these values \u200b\u200bin the resulting formula, you get that the device will heat the air with a maximum of 44 °. That is, if in winter it is on the street there is a -20 °, then the selected air heater will be able to heat oxygen to 44-20 \u003d 24 °.

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Operating pressure and air duct

The calculation of ventilation implies the mandatory definition of parameters such as the working pressure and the cross section of the air ducts. An efficient and full-fledged system includes air distributors, air ducts and fittings. When determining the operating pressure, such indicators should be taken into account:

1. Form of ventilation pipes and their cross section.
2. Fan parameters.
3. Number of transitions.

The calculation of the suitable diameter can be performed using the following ratios:

1. For a residential building building on 1 m of space, a pipe with a cross-section area of \u200b\u200b5.4 cm² will be enough.
2. For private garages - pipe with a cross section of 17.6 cm² for 1 m² of area.

With a pipe cross section, such a parameter as the air flow rate is directly connected: in most cases, the speed is obtained within 2.4-4.2 m / s.

Thus, performing the calculation of ventilation, whether it is a exhaust, supply or supply-exhaust system, you need to take into account a number of essential parameters. The efficiency of the entire system depends on the correctness of this stage, so be careful and patient. If you wish, you can additionally determine the cost of electricity to work as a suitable system.

Ventilation in the manufacturing workshop is a complex complex of interrelated processes and devices aimed at creating a high-quality air exchange within the production room.

The ventilation system of the workshop plays a much more important role than a similar system in any other room. The main emphasis is that this is a whole system of engineering development, which is designed to ensure uninterrupted air filtration from harmful and toxic impurities and its functional circulation, without disturbing the course of technological processes, but contributing to favorable conditions for their successful implementation.

Types of ventilation of industrial shops

Depending on the method of moving air, ventilation of production workshops can be:

• natural;
• mechanical.
  

In the first case, the air exchange occurs due to the temperature difference and the difference in the pressure of the air flow. This type of ventilation may be unorganized (based on elementary physical phenomena - for example, draft) and organized (aeration). To do this, use special descripts (for example, boxing boxes), allowing to adjust the magnitude and strength of the air flow.

Mechanical ventilation allows the preliminary treatment of supply air (cooling, heating, moisturizing) and filtering the contaminated air before emissions into the atmosphere.

* When creating a workshop ventilation project and determining air exchange rates for natural and mechanical ventilation, SNiP 41-01-2003 is guided.

As an engineering and technological object, ventilation of industrial workshops can be divided into 2 species, according to the method of organizing air exchange:

• local type;
• community type.

In the first case, the main task of local ventilation lies in localization and subsequent removal of harmful and toxic substances and emissions directly at the place of their occurrence. In practice, the source of pollution is hidden from all sides of the so-called. Shields, forming a kind of cap. Inside such shelter, there is a vacuum during the suction of the air masses because the pressure is inside below atmospheric. Such a measure prevents the admission of harmful impurities into the room. The local ventilation system of the workshop effectively copes with the purification of air, and its organization is quite budgetary.

In cases where local ventilation cannot localize contamination sources in full, we will use a common ventilation type. Its goal is to complex air purification in all industrial premises (or significant part), by diluting the concentration of harmful impurities, dust and dirt, thermal emissions, and so on.

Community ventilation perfectly copes with heat absorption and, mainly applied in cases where there is no emission of harmful impurities into the atmosphere of industrial premises. If the specificity of production implies emission of gases, harmful vapors, carcinogens and dust, the ventilation of a mixed type is used: generally exchange + local suction.

In some cases, enterprises whose production is associated with significant dusting or emissions of toxic impurities, completely refuse to communicate with secrecy ventilation. This is explained by the fact that a powerful general system can simply disseminate these harm and dust throughout the workshop.

The key concept of building ventilation systems is to remove the maximum amount of harm in local suns (and this is the main basis on which industrial exhaust ventilation is built), and the remaining impurities to dilute the influx of fresh air by reducing their concentration to the maximum permissible level.

Classification of ventilation of industrial workshops according to the method of action:

• supply ventilation workshop;
• exhaust ventilation shop;
• supply-exhaust ventilation shop.
  

Supply ventilation in the workshop exhaust ventilation in the workshop

The supply system of ventilation workshop is aimed at ensuring the free inflow of fresh air in volumes, which will be enough for the full functioning of production. In the supply-type supply systems, mainly channel fans, which produce air intake from outside, followed by its passage through the calorifers, where heating and moisturizing occurs (if required).

Such systems are able to fully ensure the enforcement of air masses in the workshop. At the same time, air pressure increases in comparison in atmospheric pressure indicators, which contributes to the natural (inorganized) extrusion of the exhaust air to the street through the slots, outputs or holes.

Local supply ventilation can be several species and include such equipment as:

• air shower (pure air flow, directed to the workplace: stationary and mobile)
• air and thermal curtains (heated and without)
• oasis (servicing whole areas of the workshop, where the air moves with the calculated speed and temperature)

The exhaust system removes contaminated / wet / hot / toxic air, and its replacement for clean occurs inorganized - through window and doorways, etc. Such ventilation of the workshop is very relevant in technological processes involving a large allocation of heat, moisture, harmful evaporation and With a significant staff involved in the production of employees.

All types of exhaust ventilation plants of production workshops consist of several components:

• sUPPM (open type - consisting of protective casing, exhaust umbrella, hinged-telescopic / side suns, air actors; or a closed type - to which exhaust cabinets can be attributed (for industries with high release of toxic gases and poisonous vapors), cameras, shelter boxes (To work with especially poisonous and radioactive substances), cabin)
• fan (centrifugal or axial);
• exhaust channel;
• filter;
• duct

Supply-exhaust ventilation of the workshop removes dirty air with the simultaneous supply of fresh air masses. The distribution of threads can occur in 2 ways:

• by mixing;
• by displacing.

For the first variant in the ceiling or wall space, the installation of high-speed diffusers, through which the street air is forcibly enters the room. Inside, it is naturally mixed with spent and removed through a diffuse valve.

In the second version, at the level of the floor, the installation of air distributors, through which the forced inflow of fresh air occurs. Cool air is distributed at the bottom of the room, and warm rises upstairs and naturally displaces through the ventilation grids.

Features of calculations and ventilation devices in the workshops of various purposes

The design of the ventilation of the workshop is a complex engineering task, to solve which it is necessary to perform thorough calculations that are largely dependent on its purpose.Production ventilation should delete all the harmfulness, including hot air, explosive impurities and poisonous discharge, water pairs - everything that is allocated during the production process, equipment and personnel.

The calculation of the ventilation system of the workshop is performed separately for each of the types of pollution:

By excess heat:

Q \u003d Q U + (3.6V - CQU * (TZ - TP) / C * (T 1 - T P), where

Q U. (m 3) - the volume that is given to the local suction,

V. (Watt) - Number of heat that highlights products or equipment,

from (KJ) - heat capacity \u003d 1.2 kJ (reference data),

T Z. (° C) - T contaminated air drawn from the workplace,

T R. (° C) - T inlet air masses,

T 1 - T air removed by ventilation of the general type.

For explosive or toxic production:

With such calculations, the key task is to dilute toxic emissions and evaporation to the maximum permissible level.

Q \u003d QU + (M - QU (KM - KP) / (KU - KP)where

M. (mg * hour) - the mass of toxic substances allocated in one hour,

K M.(mg / m 3) - the content of toxic-in-in in air, departed by local systems,

To R. (mg / m 3) - the number of poisoning things in the supply air masses,

K U.(mg / m 3) - the content of toxic-in-in in air, assigned by generally exchange systems.

By excess moisture:

Q \u003d q U + (W - 1,2 (O M -O P) / (O1-OP)), where

W. (mg * hour) - the number of moisture, which enters the placement of the workshop for 1 hour,

O. M (gram * kg) - the volume of steam assigned by local systems,

O R. (gram * kg) - index of humidity of the supply air.,

O 1. (gram * kg) - Number of steam, allocated by the general system.

According to the highlights from the staff:

Q \u003d n * mwhere

N. - number of employees,

M. - air flow at the rate of 1 person * hour (according to SNiP is 30 m 3 per person in a ventilated room, 60 m 3 - in an unbelievable).

Calculation of exhaust ventilation shop

It is possible to determine the number of exhaust air according to the following formula:

L \u003d 3600 * V * swhere

L (m 3) - air consumption,

V. - airflow speed in the exhaust device,

S. - Square of the exhaust type installation.

Features of ventilation of workshops of various focus

Ventilation of the mechanical shop

Harmfulness: thermal discharge from electric motors, personnel, pairs of aerosols and cooling fluids, oils, emulsions, dust - emery and mechanical.

Local suction: over grinding / rippling machines, machines without cooling, tanks for emulsions, baths for washing parts.

Community: air flow from above; The calculation of air in excess moisture and heat is at least 30 m 3 per 1 person.

Harmful: Heat from presses, solvent pairs, glue, Woodworking waste - Dust, chips, sawdust

Heating: Air combined with ventilation system

Local Spautions: Outdoor and underground for Woodwashers, Spautions from Machines; Air purification occurs in sleeve filters, cyclones

Secondary: dispersed air flow into the upper zone, through perforated type ducts (mainly)

Harmfulness: evaporation of alkalis, acids, electrolytes, excess heat and moisture, dust, hydrogen cyanide

Heating: Air combined with ventilation system

Local Spautions: Bathing for baths, independent exhaust systems over baths with cyanide and acid solutions, explosion-proof fans, mandatory equipment of baths for baths with acids of various types with backup fans. Mandatory filtering of the populated air masses

Secondary: air ducts from anti-corrosion materials or mandatory anti-corrosion coating of all air ducts; Feed 5% of the inflows in all adjacent premises; 3-fold air exchange in departments for the preparation of solutions and cyanide salts. Mandatory filtering of the pulled air masses.

Harmfulness: fluoride compounds, nitrogen oxide, carbon, ozone

Heating: Air combined with ventilation system

Local Spautions: Description (if possible)

Community: Hood: 2/3 of the bottom zone, 1/3 - from the top. The calculation of air to dilute of harmful emissions from welding to the maximum permissible level.

The calculation is made on the basis of the weight of welding electrodes, which are spent in 1 hour: for manual welding - 1500-4500 m 3 * h per 1 kg. electrodes, 1700-2000 m 3 * h for semi-automatic gas, 2500-5400 m 3 * h - for welding using powder wire.

Ventilation shop cooking

Harmfulness: Evaporation of solvents / diluents, paint particles

Heating: Central, or Air, which is combined with ventilation

Local Spautions: In aggregates degreasing, painting cameras, inkjet installations, drying chambers, tables, stands, dipping baths.

Community: The influx for compensation for local exhaust + 1 bright, secreated exhaust ventilation is not less than 1 bron from the upper zone.

Ventilation in foundry shops

The main task of ventilation of the foundry shop is to cope with a huge amount of heat, which is thrown into production facilities.

Harmful: radiant heat, a huge amount of heat generation, ammonia, sulfur gas, carbon monoxide

Heating: together with ventilation system

Local Spautions: Almost for all types of hot workshop equipment

Community exhaust with mechanical motivation in the upper zone of the workshop + aeration + stirring jobs + secrend \u200b\u200binflow ventilation.

Creating and designing ventilation in industrial workshops of any destination is trusted exclusively by professionals who will ensure compliance with all the necessary standards and fulfill the calculations, taking into account the characteristics of your production.

The air medium inside industrial buildings is polluted much more intense than in apartments and private houses. The types and number of harmful emissions depends on the set of factors - the industries, such as raw materials used by technological equipment and so on. Calculate and design ventilation of industrial premises, removing all the harmfulness, is quite difficult. We will try in an accessible language to state the calculated techniques prescribed in the regulatory documents.

Design algorithm

The organization of air exchange within a public building is either produced in several stages:

1. Collecting the source data - the characteristics of the structure, the number of workers and the severity of labor, varieties and the amount of harm it, localization of selection sites. It is very useful to pee in the essence of the technological process.
2. Selection of the ventilation system and office, scheme development. 3 basic requirements are put forward to project solutions - efficiency, compliance with SNiP (SanPiN) standards and economic validity.
3. The calculation of the air exchange is determining the volume of the supply and exhaust air for each room.
4. Aerodynamic calculation of air ducts (if any), selection and placement of ventilation equipment. Clarifying the flow of inflow and removal of contaminated air.
5. Installation of ventilation according to the project, launch, further operation and maintenance.

Note. For a better understanding of the process, the list of works is greatly simplified. At all stages of documentation development, various coordination, clarification and additional surveys are required. Engineer - the designer constantly works in a bundle with the technologists of the enterprise.

We are interested in paragraphs number 2 and 3 - the choice of the optimal air exchange scheme and the determination of air costs. Aerodynamics, installation of ventkanals and equipment - extensive themes of other publications.

Types of ventilation systems

To properly organize an air renewal of the room, you need to select the optimal ventilation method or a combination of several options. Below on the structural scheme simplifically shows the classification of the existing ventsystems suitable in production.

Let us explain each type of air - Read more:

1. Inorganized natural ventilation includes ventilation and infiltration - air penetration through door shells and other slots. Organized feed - aeration - produced from windows by means of exhaust deflectors and anti-aircraft lights.
2. Auxiliary roof and ceiling fans increase the intensity of the exchange with the natural movement of air masses.
3. The mechanical system implies forced distribution and air selection by fans by means of air ducts. This also includes emergency ventilation and various local suction - umbrellas, panels, shelters, exhaust laboratory cabinets.
4. Air conditioning - bringing the air environment of the workshop or office to the required condition. Before serving, the air is cleaned with filters to the working zone, / dries, heated or.

Heating / Air Cooling With Heat Exchangers - Calorifers

Reference. According to regulatory documentation, the lower part of the volume of the workshop of 2 meters from the floor, where people are constantly being constantly located.

Often, the mechanical supply ventilation is combined with air - in winter, the street stream is heated to the optimum temperature, water radiators are not set. The contaminated hot air is sent to the recuperator, where 50-70% of the warmth of the influx.

To achieve maximum performance at a moderate equipment price allows a combination of listed options. Example: A natural aeration is allowed in the welding workshop, provided that each post is equipped with a forced local hood.

Scheme of traffic flows with natural aeration

Direct instructions for the development of air exchange schemes give sanitary and sectoral norms, nothing to invent and invent. Documents are designed separately for public buildings and various industries - metallurgical, chemical, catering enterprises, and so on.

Example. Working out the ventilation of a hot welding workshop, we find the document "Sanitary rules for welding, surfacing and cutting of metals", read section 3, paragraphs 41-60. There are outlined all requirements for local and general ventilation, depending on the number of employees and consumption of materials.

The supply and exhaust ventilation of industrial premises is selected depending on the purpose, economic feasibility, and according to the current standards:

1. In office buildings it is customary to do natural air exchange - aeration, ventilation. With increased cluster of people, the installation of auxiliary fans is envisaged or an air exchange with mechanical motivation is organized.
2. In the machine-building, repair and rolling shops of large sizes to arrange forced ventilation will cost too much expensive. Generally accepted scheme: Natural extract through anti-aircraft lanterns or deflectors, the inflow is organized from the fraumug's open. And in the winter, the upper windows (height - 4 m), in the summer - the bottom.
3. When highlighting toxic, dangerous and harmful to health vapors, aeration and ventilation is not allowed.
4. In the workplace near the heated equipment, it is easier and more correctly organized by stroking people with fresh air than to constantly update the entire volume of the workshop.
5. In small industries with a small number of pollution sources, it is better to install local suits in the form of umbrellas or panels, and the overall ventilation is to provide natural.
6. In industrial buildings with a large number of jobs and sources of distinguishing, it is necessary to make a powerful forced air exchange. It is impractical to the fallen 50 and more local hoods, except for such events are dictated by norms.
7. In laboratories and work premises of chemical plants, all ventilation is done mechanical, and recycling is prohibited.

Project of generally compulsory ventilation of a three-story building using a central air conditioner (longitudinal section)

Note. Recycling - the return of the selected air part in the workshop in order to save the heat (in summer - cold) spent on heating. After filtration, this part is stirred with a fresh outdoor stream in different ratios.

Since within the framework of one publication it is unrealistic to consider all varieties of production, we have outlined the overall principles of air exchange planning. A more detailed description is presented in the appropriate technical literature, for example, the Tutorial of O. D. Volkov "Design of ventilation of an industrial building". The second reliable source is the Forum of Avok Engineers (http://forum.abok.ru).

Methods of calculating air exchange

The purpose of the calculations is to determine the flow rate of the supplied air. If point drawings are used in production, the amount of air mixture is added to the umbrellas removed to the resulting fractional volume.

For reference. Exhaust devices are very poorly affected by the movement of flows inside the building. Inform the necessary direction helps the supply jets.

According to SNiP, the calculation of the ventilation of the production premises is made in the following indicators:

• excess heat outgoing from heated equipment and products;
• water vapor, saturated shop air;
• harmful (toxic) emissions in the form of gases, dust and aerosols;
• the number of employees of the enterprise.

Important moment. In the utility and various household rooms, the regulatory framework also provides for the calculation of the multiplicity of exchange. You can get acquainted with the methodology and use the online calculator.

An example of a system of local suns acting from one fan. Provided dust capturing with a scrubber and an additional filter

Ideally, the flow of influx is considered in all indicators. The greatest of the results obtained is made for the subsequent development of the system. One nuance: if there are 2 types of hazardous gases, interacting with each other, the inflow is calculated for each of them, and the results are summed up.

We consider consumption for the highlights of heat

Before taking the calculation, you need to prepare for the collection of source data:

• find out the area of \u200b\u200ball hot surfaces;
• find out the heating temperature;
• calculate the amount of heat;
• determine the temperature of the air in the working area and beyond (above 2 m above the floors).

In practice, the task is solved in conjunction with the engineer-technologist of the enterprise, which provides information on the production equipment, product characteristics and the intricacies of the manufacturing process. Knowing the specified parameters, follow the formula:

Decoding designations:

· L - the desired amount of air supplied by the supply installations or penetrating through framugs, m³ / h;

• LWZ is the amount of air taken from the serviced dotted suction area, m³ / h;
• Q - the magnitude of the heat dissipation, W;
• c is the heat capacity of the air mixture, we accept 1.006 kJ / (kg ° C);
• TIN is the temperature of the mixture supplied to the shop;
• TL, TWZ - air temperature above work area and within its limits.

The calculation seems cumbersome, but in the presence of data is performed without problems. Example: The thermal flow indoor Q is 20000 W, the exhaust panels are removed in 2000 m³ / h (LWZ) temperature on the street + 20 ° C, inside - plus 30 and 25, respectively. We consider: L \u003d 2000 + \u003d 8157 m³ / h.

Excess water vapor

The following formula almost repeats the previous one, only heat parameters are replaced by humidity symbols:

• W is the number of water vapors coming from sources per unit time, gram / hour;
• DIN - moisture content in the influx, g / kg;
• DWZ, DL - moisture content of the operating area and the upper part of the room, respectively;
• the remaining designations are as in the previous formula.

The complexity of the technique is to obtain the source data. When the object is built and production works, moisture indicators are not difficult to determine. Another question is to calculate the selection of vapors within the workshop at the design stage. The development of 2 specialists should be engaged in a technologist and designer of the Ventxystem.

Dust and harmful emissions

In this case, it is important to explore the subtleties of the process. The task is to draw up a list of harm, determine their concentration and calculate the flow rate of the pure air. Estimated formula:

• MPO is the mass of a harmful substance or dust allocated per unit of time, mg / hour;
• QIN - the content of this substance in the street air, mg / m³;
• QWZ is an extremely permissible concentration (MPC) of harm in the volume of the serviced zone, mg / m³;
• QL is the concentration of aerosol or dust in the remaining part of the workshop;
• decoding the designations L and LWZ are given in the first formula.

The ventilation algorithm is as follows. The room is directed to the calculated amount of inflow, diluting the inner air and the downstream concentration of pollutants. The lion's share of harmful and volatile substances retract local umbrellas located above the sources, a mixture of gases removes the mechanical extractor.

Number of working people

The technique is used to calculate the influx into office and other public buildings, where industrial pollutants are missing. It is necessary to find out the number of permanent jobs (denoted by the Latin letter N) and use the formula:

The M parameter shows the volume of the air clean mixture allocated to 1 workplace. In the ventilated offices, the value M is taken equal to 30 m³ / h, fully closed - 60 m³ / h.

Comment. Only permanent jobs are taken into account, where employees stay at least 2 hours a day. The number of visitors to the role does not play.

Calculation of the umbrella of local exhaust

The task of local suction is to select harmful gas and dust at the selection stage, directly from the source. To achieve maximum efficiency, it is necessary to correctly select the size of the umbrella depending on the size of the source and the height of the suspension. The calculation technique is more convenient to consider with reference to the drawing of the suction.

Decide alphabetic designations in the diagram:

• A, b - the desired size of the umbrella in the plan;
• h - the distance from the lower edge of the retractor to the surface of the focus of the emission;
• a, b - the sizes of overlapping equipment;
• D - the diameter of the ventilation duct;
• H is the height of the suspension, adopted no more than 1.8 ... 2 m;
• α (alpha) - an angle of disclosure of an umbrella, ideally does not exceed 60 °.

First of all, we calculate the dimensions in terms of simple formulas:

• F - the area of \u200b\u200bthe wide part of the umbrella, is calculated as a x b;
• ʋ - the speed of the air flow in the container of the box, for non-toxic gases and dust we accept 0.15 ... 0.25 m / s.

Note. If it is necessary to suck toxic harm, the norms require increase the rate of exhaust stream to 0.75 ... 1.05 m / s.

Knowing the number of selected air, it is not difficult to choose the channel fan of the required performance. The cross section and the diameter of the exhaust duct is determined by the reverse formula:

Conclusion

Designing ventilation networks - the task of experienced engineers. Therefore, our publication is familiarizing, explanations and calculated algorithms are somewhat simplified. If you want to thoroughly understand the vengeration of premises in production, we recommend to study the appropriate technical literature, there is no other path. Finally, the method of calculating air heating in the framework of the video.