Lecture 7. Ventilation

1.Ventilation of industrial premises

2. Purpose and classification of ventilation systems

3.Natural ventilation

4. Artificial ventilation

2.4. Ventilation of industrial premises

2.4.1. Purpose and classification of ventilation systems

Various types of ventilation are used to maintain the required parameters of air purity and microclimate parameters of the production premises. Ventilation is an organized air exchange, which consists in removing polluted air from the working room and supplying fresh outside air instead. Depending on the method of air movement, ventilation can be natural or mechanical.

2.4.2. natural ventilation

Natural ventilation is carried out due to the temperature difference between the air in the room and the outside air (thermal pressure) or the action of the wind (wind pressure). Natural ventilation can be unorganized and organized. With unorganized ventilation, the volumes of air that enter and are removed from the room are unknown. Air exchange depends on the direction and strength of the wind, the temperature of the outdoor and indoor air. Organized natural ventilation is called aeration. For aeration, holes are made in the walls of the building for the entry of outside air, and special devices (lanterns) are installed in the upper part of the building to remove the exhaust air. As a result, it is necessary to calculate the areas of supply and exhaust aeration openings that provide the required air exchange.

2.4.3. artificial ventilation

Artificial (mechanical) ventilation, unlike natural, provides an opportunity to purify the air before it is released into the atmosphere, to capture harmful substances directly near the places of their formation, to process the supply air (clean, heat, humidify) more purposefully supply air to the working area.

General exchange artificial ventilation ensures the creation of the necessary microclimate and the purity of the air environment throughout working area premises. It is used to remove excess heat in the absence of significant toxic emissions, as well as in cases where the nature technological process and features of production equipment exclude the possibility of using local exhaust ventilation. There are four main schemes for organizing air exchange during general ventilation: top-down, top-up, bottom-up, bottom-down.

Rice. 2.4.1. Scheme of the organization of air exchange during general ventilation

It is advisable to use top-down and top-up schemes if the supply air during the cold period has a temperature below the air temperature in the room. The supply air is heated by room air before it reaches the working area. The other two schemes are recommended to be used when the supply air is heated during the cold period and its temperature is higher than the temperature of the indoor air.

If gases with a density exceeding the density of air are emitted in industrial premises, then general ventilation should ensure the removal of 60% of air from the lower zone of the room and 40% from the upper one. If the density of gases is less than the density of air, then the removal of polluted air is carried out in the upper zone.

General exchange supply and exhaust ventilation consists of two units: for supplying clean air and exhausting polluted air. The ratio of these two streams is called the ventilation air balance. This balance can be balanced (if the inflow is equal to the extract), positive (if the inflow prevails) and negative (if the extract prevails).

Local ventilation is also inlet in the form of air showering (when fresh air is supplied to the breathing zone of the worker) or exhaust(when polluted air is removed from the source of emission harmful substances using exhaust hoods, panels, slots, etc.).

Forced ventilation . The scheme of supply mechanical ventilation (Fig. 2.4.2) includes an air intake device 1; air filter 2; air heater (heater) 3; fan 5, air duct network 4 and supply pipes with nozzles 6. If there is no need to heat the supply air, then it is passed directly to the production premises through the bypass channel 7.

Air intake devices must be located in places where the air is not polluted by dust and gases. They must be located at least 2 m from ground level, and from exhaust shafts exhaust ventilation: vertically - below 6 m and horizontally - no closer than 2.5 m.

The supply air is directed into the room, as a rule, by a scattered flow, for which special nozzles are used.

Rice. 2.4.2. Supply ventilation scheme

Exhaust and supply and exhaust ventilation. Exhaust ventilation (Fig. 2.4.3.) consists of a cleaning device 1, a fan 2, a central 3 and exhaust air ducts 4.

Fig 2.4.3. Exhaust ventilation scheme

Air after cleaning must be thrown out at a height of at least 1 m above the roof ridge. It is forbidden to make ejection holes directly in the windows.

In the conditions of industrial production, the supply and exhaust ventilation system is most common with a general inflow into the working area and local exhaust of harmful substances directly from the places of their formation.

In industrial premises where a significant amount of harmful gases, vapors, dust is emitted, the exhaust must be 10% larger than the inflow so that harmful substances are not forced out into adjacent rooms with less toxicity.

In the supply and exhaust ventilation system, it is possible to use not only outside air, but also the air of the premises themselves after its cleaning. This reuse of indoor air is called recirculation and is carried out during the cold season to save the heat needed to heat the supply air. However, the possibility of recycling is subject to a number of sanitary, hygienic and fire safety requirements.

local ventilation

Local ventilation can be supply and exhaust.

local forced ventilation , at which a concentrated supply of supply air of specified parameters (temperature, humidity, speed of movement) is carried out, is performed in the form of air showers, air and air-thermal curtains.

Air showers are used to prevent overheating of workers in hot shops, as well as to form so-called air oases (areas of the production zone that differ sharply in their physical and chemical characteristics from the rest of the room).

Air and air-thermal curtains are designed to prevent the penetration of significant masses of cold outside air into the premises if it is necessary to frequently open doors or gates. The air curtain is created by a jet of air, which is directed from a narrow long slot, at a certain angle towards the flow of cold air. A channel with a slot is placed on the side or at the bottom of the gate or door (Fig. 2.4.4).

Rice. 2.4.4 Air curtains:

a - with bottom air supply, b - with lateral two-way air supply; in - from the side unilateral feed air

Local exhaust ventilation is carried out with the help of local exhaust hoods, suction panels, fume hoods, onboard suction (Fig. 2.4.5) and other devices.

The design of the local suction should ensure maximum capture of harmful emissions with a minimum amount of air removed. In addition, it should not be cumbersome and prevent the operating personnel from working and monitoring the technological process. The main factors in choosing the type of local suction are the characteristics of harmful emissions (temperature, vapor density, toxicity), the position of the worker when performing work, the features of the technological process and equipment.

Fig 2. 4.5. - Examples of local exhaust ventilation

a - exhaust hood, b - suction panel c - fume hood with combined hood d - side suction with overflow

According to the degree of isolation of the local exhaust ventilation area from the surrounding space, open-type exhausts and exhausts from hollow shelters are distinguished (Figure 2.4.6.).

The exhaust ventilation system is one of the most common engineering networks in modern buildings. This applies to private houses, apartments, public and industrial buildings. Exhaust ventilation in a private house in almost all cases consists of exhaust ducts in the wall, even if the developer does not think about the supply system.

The exhaust ventilation system is different types. It is classified according to several factors. In addition to choosing the right type of exhaust ventilation, it is important to correctly select all its elements and equipment layout options. We will try to consider in more detail the principle of operation of ventilation for the hood, the device and installation, as well as the calculation of the exhaust ventilation of the room.

In order for the design of exhaust ventilation to create a high-quality and reliable network suitable for a particular case, it is necessary to know and understand the types and types of exhaust ventilation in a room. They are divided according to several factors. According to the method of setting the air in motion, the exhaust ventilation of the room is:

• with a natural impulse;
• with mechanical motivation.

Also, networks are classified according to how much space they serve. According to this principle, ventilation happens:

• local (local systems);
• general exchange.

natural urge

Networks with natural motivation work under the influence of natural factors. These include the most common exhaust ducts in the wall in our houses and apartments. The air in them moves under the influence of the pressure difference between the room and the outside atmosphere. The main positive factor of natural ventilation hoods is the simplicity of the device and low cost.

Natural exhaust system

But there are also negative properties. First of all, it is dependent on weather conditions. In some cases, natural ventilation in apartment building or a cottage can completely stay. This is possible when the pressure between the outside and inside air equalizes.

Just as the negative properties of natural networks include the difficulty of regulation. It is impossible to change natural factors in such a way as to stop or reduce the speed of air movement. For these purposes, valves and dampers are used. For example, an exhaust ventilation valve, which is placed at the inlet to the channel.

mechanical drive

Mechanical networks appeared later than natural ones. Forced exhaust ventilation consists of a fan that is connected to the mains, as well as additional elements. These elements help regulate the movement of air and perform some other functions.

Their device is more complicated and more expensive than the natural type. First of all, this is due to the need to purchase components, mount them and connect them to the mains.

Mechanical exhaust ventilation system

Exhaust ventilation in an apartment or forced-type house in most cases includes the following elements:

• exhaust ventilation unit. It can be a radial or axial type fan.
• Exhaust pipes for ventilation. They are designed to move air from the working area to the outside.
• performance controllers. They basically adjust the speed of the fan to increase or decrease the amount of air passing through it. Such devices are manufactured different types and are used for ventilation of industrial premises, living rooms, public buildings equally.
• Filters. Their main field of application is industrial ventilation. They are designed to trap harmful contaminants and protect the atmosphere from them.

Industrial ventilation is a set of measures aimed at organizing and maintaining stable air exchange in industrial premises. Operating equipment and production processes are often a source of airborne particles and toxic fumes, which can adversely affect human health. Moreover, the disadvantage fresh air reduces performance and ability to endure physical activity.

The task of ventilation of industrial premises is the removal of exhaust air (exhaust ventilation system) and its replacement with fresh air (supply ventilation system), specially cleaned, heated or cooled, that meets all standards.

When designing ventilation, the following conditions must be taken into account:

• the presence of harmful fumes
• change temperature regime
• increased gas content

Solution

It must be said right away that everything depends on the type of production, therefore, when choosing a ventilation system, you need to build on:

1. Technique, production parameters
2. Required working conditions

Most often for ventilation of large production (120 thousand cubic meters) is usedsupply and exhaust ventilation with cooling or heating water. While not all production facilities are suitable for a system with heat recovery.

Ventilation price (online calculation)

Room/building type:

Select type Office or administrative building Cottage Apartment Commercial premises(shop, shopping center) Sanatorium, hotel Gym, fitness center Warehouse Industrial, industrial premises Cafe, restaurant Swimming pool Server room

Equipment class:

Economy Medium Premium

The total area of ​​all serviced premises:

m 2

Average floor height:

m

Maximum (estimated) number of people in the room/building:

people

Show cost

Air exchange rate

The optimal air exchange rate in industrial premises is determined based on the reference tables of SNiP 2.04.05-91 and is in a fairly wide range: from 3 to 40 times per hour. This means that in one hour the air in the room must be completely replaced with fresh air a given number of times. Also, the norms establish the minimum allowable volume of incoming fresh air. Let us consider in more detail what factors influence these calculations.

Factors that determine proper air exchange in industrial premises:

• Workshop volume and geometry. Both the total volume of the room and its shape play a role. The fact is that the parameters of the movement of air flows around the room depend on the shape, turbulences and stagnant zones can occur.
• Number of employees working in the workshop. The necessary influx of fresh air is determined based on the level of intensity of physical labor. When performing various manipulations that do not require significant physical effort, air exchange of 45 cubic meters per hour per employee is sufficient, and when performing heavy physical work - at least 60 cubic meters per hour.
• The nature of technological processes and air pollution with harmful substances And. For each substance there is a maximum allowable concentration, based on which the intensity of air exchange is determined, which will allow maintaining the concentration within safe limits. The most demanding in terms of multiplicity are dye shops, as well as various industrial sites where volatile and toxic substances are used. In such buildings, the required air exchange can reach 40 times per hour or more.
• The heat generated by the equipment. Excess heat energy must also be effectively removed by the ventilation system, especially if the room is not provided with air conditioning.
• Excess moisture. If processes involve the use of open liquids that evaporate and increase humidity, sufficient exchange must be provided to maintain stable humidity.

IN production shops with an area of ​​more than 50 m2 for each employee, it is necessary to maintain the calculated air temperature in the permanent working area and at least 10 ° C at temporary workplaces;

In cases where the supply ventilation of the production premises cannot maintain the required microclimate indicators in the personnel service area for economic or production reasons, permanent workplaces are equipped with outdoor air showering devices or a local air conditioning system;

The air temperature of the working area at industrial facilities with fully automated production lines operating without attendants is allowed: in summer, at the level of outdoor air temperature, with excess heat - 4 ° C higher than outdoor air temperature; in winter - in the absence of excess heat - 10 ° C, in the presence of excess heat - an economically justified level.

Industrial ventilation requirements

Ventilation and air conditioning of industrial premises is regulated general requirements SanPiN, as well as parameters that are specific to the given workshop of the enterprise. These include:

• mechanical ventilation of industrial premises must comply with the rules fire safety;
• removal of substances hazardous to health, emissions without access to the work area of ​​personnel;
• obligatory hygienic and fire safety certificate of the materials from which the elements of the ventilation system are made;
• anti-corrosion coating of air ducts, or they must be made of materials resistant to such influences;
• the thickness of the coating of ventilation ducts with combustible paint should not exceed 0.2 mm;
• for personnel working areas located directly inside the workshop, the concentration of harmful substances should not exceed 30%;
• humidity, speed indicators of air flow are not standardized in the summer;
• V winter period the temperature indicator of the air inside the workshop with the personnel located there - at least 10⁰ С, in the absence of people - at least 5⁰ С;
• in summer, the temperature indicators of the internal and external air flows are equal, or the internal temperature does not exceed the external temperature by more than 4⁰ С;
• the requirements for industrial ventilation that are not used in the summer of the workshop are not regulated by the temperature indicator;
• the total noise level inside the industrial hall should not exceed 110 dBa, this includes the operating noise of the ventilation system.

The above list is quite general. In practice, the requirements for ventilation of industrial premises are supplemented by individual parameters of production, the design of the workshop, the specifics of products, etc. In addition, it is imperative to take into account how heating and ventilation interact inside the workshop. And it should also be taken into account that lighting and ventilation of industrial premises are also interconnected.

Types of industrial ventilation

The classification of industrial ventilation is carried out according to the criteria of localization, direction and mode of operation. Let's consider in more detail.

According to the principle of operation

• Natural. It is based on the natural circulation of air flows with different temperatures, pressures, and densities. A heavy cold air stream displaces a lighter and warmer one. In an industrial building, this process can occur through natural gaps, leaks in window doorways, or organized supply and exhaust openings, closed with gratings, deflectors.
  Depends on atmospheric conditions, strength and direction of the wind, season (in winter, ventilation is better due to strong draft). This method not suitable for all industries, especially where there are harmful emissions from operating equipment. It can be installed, for example, in agricultural premises.

• artificial ventilation. If production involves by-effect in the form of toxic heat and gas emissions, mechanical ventilation of industrial premises is strictly required. Main function- removal of the exhaust air flow from the working area of ​​the personnel, preventing the penetration of harmful vapors into other rooms, compartments, as well as the supply of fresh outdoor air (purified or unpurified) by the general flow or by address.
  It is organized with the help of mechanical means of supply-removal of air masses (supply, exhaust fans, roof installations). Is over effective way purification, circulation of the air flow inside the industrial workshop.

According to the principle of localization

• General exchange. It is designed for uniform cleaning of the entire workshop from harmful technological heat emissions, normalizing the temperature and humidity index, air speed. Quickly copes with a small percentage of air pollution.
• local ventilation. It is used when there is a localization of a large amount of toxins, vapors, smoke, etc. in a certain place. It is installed directly above the source of increased heat and gas emission. Hoods or a flexible duct connected directly to the equipment may be used. It is used in conjunction with the general ventilation system as an additional air-purifying equipment.
• emergency. Installed and used in the future in case of emergency, for example, fire, excessive release of toxic substances industrial equipment, high level smokeiness, etc.

According to the principle of flow direction

• Supply ventilation units. The principle of operation is based on the displacement of warm exhaust air by a cold influx through organized exhaust openings at the top of the workshop. They can be both natural organization and mechanical.
• Extract ventilation units remove the exhaust air flow along with particles of burning, smoke, toxic fumes, excess heat, etc. Structurally, they can be general or local, most often with forced induction, since it is quite problematic to remove polluted air naturally.
• Air handling unit is used most often, provides the necessary circulation of air masses inside the industrial workshop. Most often with mechanical equipment (supply, exhaust fans).

Equipment for ventilation of industrial premises

The forced ventilation system consists of the following elements:

• air ducts;
• fan;
• air filters;
• air valves;
• air intake grilles;
• noise-absorbing insulation;
• air heater (air heating);
• automatic control unit if necessary.

The mechanical exhaust ventilation device is organized according to the same model, with the exception of the air heater, filters, which are not needed for the exhaust air.

Local exhaust ventilation of industrial premises is organized by exhaust hoods, flexible air ducts connected to a common air exchange system.

In addition, supply and exhaust ventilation can be equipped with a heat recuperator to save energy during the heating of the incoming flow. The supply masses are heated by the heat of the exhaust air, without mixing with it.

Design and installation

To ensure the highest quality ventilation, it is necessary to carry out its design and installation already at the construction stage. This is the only way to take into account all safety measures, to properly design exhaust zones.

But it also happens that it is necessary to install a ventilation system in an already built building. In this case, all the conditions in which the system will be operated, as well as the purpose of the room itself, should be taken into account. The choice of equipment always depends on the explosion and fire hazard of the room.

As is known, general exchange and local ventilation is used for industrial premises. The first is responsible for air exchange and air purification of the entire room. But with the help of local suctions, it is possible to solve only local problems at the place of formation of those very harmful substances. But it is not possible to keep and neutralize such air flows completely, preventing their spread throughout the room. Here additional elements are needed, such as umbrellas.

The choice of equipment for the installation of ventilation of industrial premises is influenced by the type of production and the amount of harmful substances emitted, the parameters of the premises itself, and the design temperature for the cold and warm seasons.

Summing up, I would like to say that such a difficult task as the calculation, design and subsequent installation of ventilation should be performed by qualified specialists who have a wealth of knowledge and years of experience behind them.

Ventilation systems management

Automation control of ventilation systems allows you to optimize the process and reduce operating costs. This approach allows minimizing human participation in management and reducing the risk of the "human factor". Automatic control involves the installation of sensors that record the temperature / humidity of the air, the concentration of harmful substances, the degree of smoke or gas contamination. All sensors are connected to the control unit, which, thanks to the specified settings, turns the equipment on or off. Thus, automation helps to meet the requirements sanitary norms, quickly respond to emergencies and save significant funds.

Ventilation systems are one of the main consumers of electrical and thermal energy, so the introduction of energy saving measures allows to reduce the cost of products. To the most effective measures can be attributed to the use air recovery systems, air recirculation and electric / motors with no "dead zones".

The principle of recuperation is based on the transfer of heat from the displaced air to a heat exchanger, which reduces heating costs. The most widespread recuperators are plate and rotary type, as well as installations with an intermediate coolant. The efficiency of this equipment reaches 60-85%.

The principle of recirculation is based on the reuse of air after it has been filtered. At the same time, part of the air from the outside is mixed in with it. This technology is used during the cold season in order to save heating costs. It is not used in hazardous industries, in the air of which there may be harmful substances of hazard classes 1, 2 and 3, pathogens, unpleasant odors, and where there is a high probability of occurrence emergencies associated with a sharp increase in the concentration of flammable and explosive substances in the air.

Given that most electric motors have a so-called "dead zone", their correct selection allows you to save energy. As a rule, "dead zones" appear during start-up, when the fan is running in idle mode, or when the mains resistance is much less than what is required for its correct operation. In order to avoid this phenomenon, motors with the possibility of smooth speed control and with no starting currents are used, which saves energy at start-up and during operation.

Air exchange calculation example

Ventilation of production and industrial premises is the construction of a system, the main task of which is a set of measures to ensure constant air exchange in workshops and production - the removal of polluted air and its replacement with fresh air.

Unlike home or office premises, industrial facilities are subject to complex technological processes, which are often accompanied by harmful emissions. Therefore, in such working conditions, competently designed and installed system ventilation is vital. It is it that is designed to ensure stable air exchange in industrial premises, which is critically necessary for the health of people working there.

In addition to extracting harmful compounds, the ventilation system purifies, ionizes, heats (in winter) or cools (in summer) the air from the street before supplying it inside the building, and, if necessary, removes excess heat, water vapor and dust particles arising during operation.

Types of ventilation

Ventilation in the production room can be classified as follows.

By way of air circulation:

• Forced or mechanical
• Natural

By work area:

• local
• General exchange

By appointment:

• Supply
• exhaust

By design:

• Drier
• Channelless

Calculation of ventilation of the production room

Working conditions in production are strictly regulated with the help of SNiP and GOST, therefore, the installed ventilation system must provide the necessary microclimate, as well as maintain an acceptable level of contamination, gas contamination and dustiness of the working area, as well as the aeroionic composition of the air.

The ventilation calculation method is selected depending on the technological process in your industrial premises. Traditionally, the production uses general exchange mechanical supply and exhaust ventilation with additional installation local. Often in production, it is necessary to remove not only vapors and impurities, but also mechanical elements from the air. In such cases, an additional filter system is used to remove large particles.

A general exchange mechanical supply and exhaust ventilation system usually includes the following ventilation equipment: galvanized steel air ducts, control sensors and various automatic machines, fans, as well as filters and dust collectors. For each type of harmful substances, MPC values ​​are set, and the task of the ventilation system is to dilute their concentration and remove them with the help of hoods/exhausters.

Features of ventilation of woodworking shops

When ventilating the workshop at such enterprises, chip blowers are used, which trap and remove both fine dust and large wood chips from the room. Further, this air is passed through a filter system or through a cyclone, where impurities are removed into special containers.

If this production also has painting, assembly and drying departments, then in addition to wood dust and shavings, it is necessary to remove glue, solvent fumes, as well as water vapor and excess heat.

Features of workshop ventilation

In rare cases, workshops can get by with natural ventilation, but we would still recommend equipping workplace hood. For framing and art workshops, only supply ventilation is suitable, exhaust ventilation is suitable for small industries associated with harmful emissions / emissions chemical substances or impurities, and for the most comfortable work, supply and exhaust ventilation should be installed.

Features of ventilation of foundries and hot shops

The ventilation of the workshop at these types of production should, first of all, remove excess heat from the room due to increased air exchange, as well as hydrogen sulfide, sulfur dioxide and other harmful impurities released during the heat treatment process. Most often, foundries use both general and local ventilation.

Trust the professionals

Errors in the design of ventilation systems for industrial premises can lead to poisoning, oxygen starvation, overheating / hypothermia, as well as all sorts of chronic diseases of employees, not to mention rapid fatigue and decreased performance.

Company "M-Vent" has great experience in the design and installation of ventilation in various industries. Employees of the company will help you choose the best option in terms of price and efficiency, complete the turnkey project. Trust the professionals.

Thousands of workers annually suffer from occupational diseases, the main cause of which are harmful substances that appear during the production cycle. The impact of high temperatures, dust, various pollution, "accompany" workers in the metallurgical, chemical, mining industries, and more than a dozen industries.

In most modern industrial enterprises, where a significant amount of pollution is released during the production process, along with a general ventilation system, a local type of ventilation is also used. This type of ventilation system helps to reduce the presence of hazards, gases and dust in the place of their production below the WPC, and is appropriate as the main means of their localization.

Types and purpose

Local ventilation can be of two types. Supply - serves to supply air to the devices intended for this: and air showers. These devices, in most enterprises, are used to create “islands” of clean air in workshops with a high emission of pollution. Thermal curtains used to create an air barrier with cold or contaminated air masses when there is a need to open doors frequently. The most widespread in hazardous industries is local exhaust ventilation, designed for local removal of polluted air, in places of its occurrence, in a certain production process. The local exhaust ventilation system prevents the spread of harmful substances throughout the production site. The most demanded equipment for exhaust ventilation, at most enterprises, has become local suction.

Requirements for local suction

The main requirement for local exhaust ventilation systems and suction systems is to prevent the ingress of polluted air into the human respiratory organs and eyes. Besides:

1. They must be simple in design so that personnel can easily assemble and dismantle cleaning devices.
2. A device for removing harmful substances should not be bulky and bulky, as well as interfere with the production process.
3. Pollution and gases that appear during the production process must be removed: volatile substances, vapors - up, and dust, and pollution heavier than air - down.

The main types of air intake equipment used in production

Local suction is a part of any modern enterprise. To date, there are several types of these devices:

Semi-open suction. These are mainly ventilated chambers and fume hoods. These devices provide the highest quality removal of contaminants, while minimum flow air. They are of several types. Devices with a top exhaust are used for the release of substances with high temperature or humidity. Cabinets with a lower intake are designed to eliminate “heavy” polluted air. Portable cabinets with side intake of polluted air are used in the elimination of dusty pollution.

• A fully open polluted air suction device is an exhaust structure that is located outside the source of their emission. To date, the most popular devices of this type are hoods, suction panels and side suctions. The side air intake is mounted if the source of pollution release requires access from different sides. Exhaust hoods are the simplest version of suction. They are mounted in places where harmful substances are released, which tend to rise up. The umbrella is placed at a height of 1.5 m from the floor. The efficiency of devices of this type is achieved by a large volume of exhaust air.
• A completely closed air intake is a part of the equipment and is made in the form of a cover, through the technological openings of which air flows into the device.

Suctions are classified according to the shape of the opening of this device, which are round, square or made in the form of a slot. Round and square holes are most often used in the processes of welding and soldering metals. Ventilation during welding cannot always neutralize all harmful air flows, therefore, a forced general exchange ventilation system is installed in the welding shop without fail, with an inflow of fresh air of at least 40 cubic meters per hour per worker. http://www.youtube.com/watch?v=rDK-xg-Cp_A

Features of the ventilation system of the welding shop

There are many types and methods of welding. It was their diversity that led to the variety of suction options used specifically in welding shops. By design features they can be divided into 4 main groups:

1. Small-sized devices for automatic and semi-automatic equipment. Such ventilation devices are integrated into the welding equipment. These include air intakes in welding holders.
2. Local suctions built into the welding tables. These devices are used in welding and soldering small parts. Local ventilation for soldering and welding can be connected to the general ventilation system.
3. Suction units integrated into welding stands and equipment for welding large parts. This group of devices is integrated into welding and assembly installations and stands.
4. Swivel-lift and portable decontamination devices used for welding operations in various locations. This group of devices includes all portable air receivers of various designs.

The efficiency of air intakes to remove harmful substances requires an accurate calculation of local exhaust ventilation.

Factors affecting the calculation of ventilation of welding production

Advice:
The development of a project and calculations of a ventilation system at any production site is a complex and responsible process that should be handled exclusively by professionals.

This publication will give general information about what affects the calculation of ventilation of a production site with a stationary welding post.

The main factors influencing the calculation of the ventilation system and, accordingly, the selection of the necessary equipment are:

• Required air consumption by the air intake, depending on its design and type of welding.
• Its effectiveness, in a particular workplace.

To calculate the air flow, you can use the formula:

L = 3600 * F * Vo

Where:

L– air exchange
F is the area of ​​the suction hole
Vo is the speed of air movement in the hole

You can use ready-made standard calculations, depending on the design of the air intake.

For example:

The car service station is equipped with a stationary welding station, where an exhaust panel is used as a local suction. In this case, the required air flow is determined on the basis of: 3300 m3/hour per 1 m2 of the panel area.

The efficiency of the device is calculated by the formula:

E = (Lm — Lpr) / Lm

Where

E- device efficiency
Lm- the power that will be required for the intrashop ventilation system, in the absence of a local air intake
Lpr- air flow required to dilute non-localized contaminants to MPC.

Important!
The efficiency of these devices is not the same for various contaminants released during welding and other production cycles.