Designing the ventilation of industrial premises is a rather difficult task. Creating schemes is carried out taking into account the specifics of the enterprise. Let's consider further what ventilation of industrial premises represents . Its types and requirements for it will also be described in the article.
Classification
The main objective of the ventilation system of industrial premises is the operational "capture" of all impurities and their removal. These or those installations are selected depending on specific working conditions. The air in the units can move mechanically or naturally. There is also a classification according to the principle of operation. Ventilation can be supply, exhaust or mixed. Each group has its own subgroups of equipment. So, the supply ventilation can be local. It is presented in the form of an air shower, veil or oasis. General ventilation of industrial premises provides dispersed or directed flow.
Natural filtration
The supply and exhaust ventilation in the production room is functioning due to the difference in pressure and temperature in the street and in the workshop. In this case, the driving force will be the heat or wind pressure. Due to the pressure drop, the expanded masses are forced out of the workshop. In their place, cold, clean ones, are tightened. In the windward area, a high pressure region forms. It enhances the flow of outside air. On the leeward side, pressure is always reduced. This contributes to the outflow of waste mass. Ventilation systems and equipment , the functioning of which is based on physical laws, are used, as a rule, in enterprises with intense heat generation. However, far from always a powerful exchange will ensure the formation of appropriate working conditions for employees. The stronger the temperature difference between the ceiling and the floor, the higher the workshop itself, the more efficiently the natural ventilation of production rooms works. If there are gaps in windows and walls, doors or gates often open, drafts may appear. This helps to reduce the temperature in the workshop. In the summer, in areas remote from windows and doors, ventilation standards are substantially violated.
Aeration
A flexible duct is used for it. Aeration is carried out according to the principle of natural draft. In some cases, during the construction of a building, the calculation of the ventilation system of the production room is not carried out, the installations are not mounted. In such cases, channels and shafts that function from heat pressure can be placed in the workshop. A flexible duct is covered by a deflector. The wind blows over it, due to which a rarefaction region is formed. Such ventilation bends are widely used on agricultural and livestock farms, in small bakeries, and forges. They are installed on the highest portion of the roof. Aeration is considered one of the most effective methods of natural ventilation. Often it is used in enterprises where a large amount of heat, poisons and gases is generated.
Device
Natural ventilation of industrial premises involves the arrangement of three levels of openings with window panes having a specific design. The first 2 rows are located from the floor at a height of 1-4 m. Light-aeration lamps equipped with adjustable window panes are mounted in the roof. In summer, clean streams pass through the lower transoms, while dirty streams go up. When calculating the system, the area of openings and windows is determined. The worst conditions for the operation of the installation is considered to be calm weather. It is taken as a reference point. In the wind, such ventilation of industrial premises works efficiently. However, with a certain force and direction of the wind, reverse thrust may appear. As a result, air mixed with gases and dust is sent to the rooms where people are. To prevent the spread of harmful substances, lights with wind protection are installed. In summer, the supply masses are cooled by spraying cold water into them. It comes from the nozzles that are located at the vents. With this cooling, humidity rises slightly.
SNiP: ventilation and air conditioning
The Rules establish a number of requirements for buildings that use a natural filtration scheme. In particular, it is necessary that the perimeter of the structure is open for air access. The Rules also indicate that workshops with a height of not more than 1 floor or buildings located on the last floors are aerated. In multi-span rooms, the installation of natural ventilation is significantly difficult. If the width of the workshop is more than 100 m, clean flows to its center are practically not received. In such cases, special Baturin lights (non-inflated) are mounted. They have separate channels for inflow and exhaust. However, in the winter, such an installation can provoke an undesirable drop in temperature in the workshop. To prevent such consequences, forced ( artificial) ventilation of industrial premises is mounted.
Advantages and disadvantages of aeration
The ventilation elements are controlled mechanically. One of the main advantages of the aeration scheme is the low cost of components. In this case, the installation can provide a sufficiently powerful air exchange. Meanwhile, she has several drawbacks. First of all, the functioning of the system depends on weather conditions. In addition, as mentioned above, it does not provide delivery of clean flows to remote sections of the workshop. Another disadvantage is the complexity of management. Aeration is not used in enterprises where technologies that imply the spread of harmful substances are used.
Forced ventilation of industrial premises
It allows you to bring the performance of flows supplied to the shop, to the normative. The required parameters are defined in SNiP. Forced ventilation and air conditioning have the following advantages:
- The operation of the units is not related to temperature readings outside the workshop.
- You can remove streams, as well as submit them from any site.
- The calculation of the system is accurate.
- Allowed to change the multiplicity in any range. It is calculated based on the diameter and speed of the grinding / grinding wheel.
Most popular installations
Currently, exhaust ventilation is widespread. The installation restricts the spread of contaminated streams and removes them directly from the source. The quality of ventilation depends on the correct selection of equipment, the degree of discharged atmosphere, the shape of the receivers. The key elements of the installations are:
- Suction.
- Fan.
- Challenge
- Filters
- Exhaust duct.
The entire volume of dirty streams should be picked up by the receiver and passed on to other elements.
Suction Specifics
Air inlets are closed and open. The latter include:
- Protective cover.
- Exhaust hood.
The protective casing eliminates the flow of dust, which is formed, for example, in the carpentry workshop during polishing, grinding, etc. It is equipped with a visor and is installed across the movement of particles. An exhaust umbrella reduces the area of distribution of hot air containing harmful impurities and rises by the principle of convection, and removes it. It must be sized to completely cover the source. The umbrella can be equipped with overhangs. They are made of dense canvas or hard sheets. It is more convenient to use open umbrellas. In them, overhangs do not interfere with the access of enterprise employees. In hazardous production, the velocity of the stream entering the umbrella is from 0.5 m / s, if it is without impurities, then 0.15-0.25 m / s.
Side / articulated telescopic suction
They are installed directly at the workplace in galvanic or pickling baths. Air moves over them and draws in harmful pairs of acids and alkalis before they begin to spread throughout the workshop. With a small (up to 70 cm) bath width, single-sided suction pumps are installed, if this parameter is greater than the specified value, double-sided elements are mounted. In addition, the latter are equipped with designs that ensure the blowing of fumes from the surface of the liquid. The volume of flow passed through these plants will depend on the level of vapor toxicity and temperature. Equally important is the size of the surface of the liquid. Since fumes quickly destroy metal, the suction is made of PVC and other stable materials. Articulated telescopic receivers are quite common. Ventilation pipes for this type of hood are equipped with retractable elements. They can be brought directly to the source of pollution. In workshops with soldering irons and welders, the suction is installed directly in the tools.
Closed Type Receivers
These include:
- Cabins.
- Fume hoods.
- Cameras.
- Boxing shelters.
The latter are used in enterprises with especially toxic and radioactive substances, where workers carry out all manipulations with gloves or using mechanical devices. Cabinets are mounted in workshops with intensive emission of harmful gases. Ventilation pipes for exhaust with a completely isolated source of pollution are considered the most effective.
Electrical installations
The ventilation systems of forced-type industrial premises are equipped with special units. They are electric fans. As a rule, axial or radial models are installed. The latter are also called "snails" because of the shape of the hull. A wheel with blades is built into it. In the process of movement, the flows enter the body, change direction and are fed into the tap under pressure. Absorbed masses are often saturated with aggressive and dangerous compounds, and sometimes with explosive substances. Depending on impurities, enterprises install fans:
- Standard. They are designed to capture streams with a low dust content, the temperature of which is up to 80 degrees.
- Corrosion-resistant type. Such plants are used to trap the vapors of acids and alkalis.
- Spark proof. They are used for explosive mixtures.
- Dusty. These plants are designed to filter streams containing particles in an amount greater than 100 mg / m 3 .
Axial fans include inclined blades mounted in a cylindrical housing. In the process, the flows move parallel to the axis. These units are usually installed in mines, emergency channels, etc. The advantage of such devices is that they can supply air in opposite directions.
Dust collectors
Current norms and standards define the requirements for ventilation of industrial premises . Installations must operate so that the content of harmful impurities is within the permissible value. Accordingly, one of the key parameters is the efficiency of cleaning. In some cases, a dust collector is sufficient to filter the air. In this situation, the cleaning is called single-stage. If air pollution is significant, multi-stage filtration is organized. The type of treatment plant will depend on the form, chemical composition and volume of impurities. The simplest design of a dust collector is considered to be a dust precipitation chamber. It significantly reduces the intensity of the flow, due to which harmful impurities settle. However, such an installation can only be used for primary filtration. Dusting chambers can be labyrinth, simple, with a chipper.
Cyclones
They are inertial dust collectors and are used to filter air with a particle content of more than 10 microns. The cyclone is made as a cylindrical metal container, tapering downward. Air is supplied from above. Under the influence of centrifugal force, dust particles hit the walls and fall. Purified air comes out through the pipe. To increase the amount of trapped dust, water is sprayed inside the housing. These units are called cyclone washers. Recently, rotoclones and rotary dust collectors have gained the most popularity.
Filters
They are also used to purify air. Filters can run on electricity. In this case, positively charged particles are attracted to the negative electrodes. High voltage passes through the filter. For the subsequent cleaning of the electrodes from dust, periodic automatic shaking is carried out. Caught dust is sent to drives. In practice, coke and gravel filters are also used. Fine and medium cleaning devices are made of special material. It can be synthetics, felt, porous fabrics, nets. They capture not only dust, but also small particles of oils. However, such materials quickly clog up and require regular cleaning or replacement. If necessary, filter the air from explosive compounds or gases, as well as aggressive substances, ejection systems are used. They have 4 cameras: diffuser, neck, confuser and for discharge. Streams enter them under high pressure. The direction is set by the compressor or fan. The dynamic pressure in the diffuser is converted to static. After that, the flow goes out.
Alternative option
Before directing the air into the room, it must be processed: warm or cool, filter. In some cases, hydration is also required. For these purposes, forced ventilation is used. It consists of:
- The fence.
- Taps.
- Filters.
- Heaters.
- Fans.
- Distributors.
Installation of installations is carried out according to certain rules. A supply chamber is provided for the fan, filter and heater. Receivers should be located at a height of 2 meters from the ground, in places remote from sources of pollution. In some cases, installation on the roof of the structure is allowed. When choosing the installation location, the wind direction should be considered. On the outside, the air intakes are covered with umbrellas, blinds or grilles. Filters in installations can be of various types. As a rule, devices made of nonwoven materials are used. In winter, air heating is carried out using heaters or heaters. The heat carrier is electricity or water. For humidification, special irrigation chambers are installed. They spray fine air fraction. Similarly, cooling is carried out.
Local setting
These include air showers. They represent clean flows directed to work areas. The purpose of such a shower is to enhance the heat transfer of the employee's body to prevent overheating. Installations can be mobile or stationary. Hot shops are equipped with showers, as well as rooms with infrared radiation greater than 350 W / m2. Norms depend on temperature, severity of work, and also radiation intensity. The average t in the shower is +18 ... + 24 degrees. The flow moves at a speed of 0.5-3.5 m / s. Its indicator is directly proportional to the radiation intensity and air temperature.
Oases and curtains
These devices are often used in large enterprises. The oases serve the site of the workshop, fenced off from the rest of the area using light screens. Within its limits, air moves at a certain speed and has a given temperature. Curtains are used to prevent overcooling of workers and cooling the shop through openings or open doors. They can be without heating or with it.
Preventive surveillance
Such sanitary control of ventilation systems of industrial premises is performed when:
- Reconstruction, planning, construction or change of technology / profile of an enterprise, site, workshop.
- Running mounted or repaired sewage treatment plants.
- The introduction of new technological units, processes or chemicals that can have a harmful effect on the environment or humans.
Reconstructed or newly built ventilation systems are launched by the commission in the prescribed manner. It includes a representative of the sanitary and epidemiological service. Evaluation and inspection of the ventilation system can be carried out after the completion of all construction and installation activities.In this case, before inspection, it is necessary to establish all technological processes in accordance with the regulations. During the inspection, production facilities should operate with the planned load, ventilation devices should reach the specified performance. Preventive supervision is carried out in the form of:
- Making conclusions on design materials on the correct selection of a ventilation scheme. The documents for verification are working and technical drawings.
- Observations of the installation of ventilation units.
- Participation in the reception and execution of conclusions on the compliance of the units with the current sanitary and hygienic requirements.
Current survey
It is carried out in the form of selective control:
- State of the environment in the areas where the intake devices are located. Inspection can be carried out directly at the workplace.
- Work, condition, operation of ventilation systems.
The frequency and volume of the sample examination is determined by the sanitary doctor. In this case, the degree of probable negative impact of the production environment at a particular enterprise on personnel is taken into account.