What is an oasis? An oasis is a place in the desert in which there is water and trees grow. And if so, it means that people live here, because there is nowhere else to live in the desert. The desert is barren because of its difficult climate - hot and arid. Vegetation appears only where

OASIS U. If you agree with the assertion that the TRILISTNIK group is a variant of the alternative history of AQUARIUM, then OASIS U can be considered as one of the possible ways of developing CINEMA, do not part its founders Viktor Tsoi and Alexei Rybin at the very beginning

Additional aeration and “surface” thermometer Wintering conditions for fish are significantly improved when a compressor is used for additional aeration of water. For this purpose, you can use a pipe from 1–1 / 2 inches with a length of 1.5–2 m, drilling it through 5–10 cm

Methods to reduce the adverse effects of the industrial microclimate are regulated by the “Sanitary Rules for the Organization of Technological Processes and Hygienic Requirements for Industrial Equipment” and are implemented by a set of technological, sanitary, organizational, and medical and preventive measures.

Consider the main methods:

Thermal insulation;

Heat shields;

Air showering;

Air curtains;

Aerial oases.

Thermal insulation  surfaces of radiation sources reduces the temperature of the radiating surface and reduces both the total heat and radiation. Structurally, thermal insulation can be mastic, wrapping, filling, piece goods and mixed.

Heat shields used to localize sources of radiant heat, reduce irradiation in the workplace and reduce the temperature of the surfaces surrounding the workplace. The weakening of the heat flux behind the screen is due to its absorption and reflectivity. Depending on which ability of the screen is more pronounced, heat-reflecting, heat-absorbing and heat-removing screens are distinguished.

Air shower. The cooling effect of air showering depends on the temperature difference between the working body and the air flow, as well as on the speed of air flow around the cooled body. To ensure the specified temperature and air velocities at the workplace, the axis of the air flow is directed horizontally or at an angle of 45 ° to the human chest.

Air curtains  Designed to protect against the breakthrough of cold air into the room through the openings of the building (gates, doors, etc.). An air curtain is an air stream directed at an angle towards the cold air stream.

Air oases  Designed to improve meteorological working conditions (most often recreation on a limited area). For this purpose, cab schemes with lightweight movable partitions, which are flooded with air with appropriate parameters, have been developed.

Ionic composition of air

The aeroionic composition of the air has a significant impact on the well-being of the worker, and even deviating from the permissible concentration of ions in the inhaled air can even pose a threat to the health of workers. Both increased and reduced ionization are harmful physical factors and therefore are regulated by sanitary and hygienic standards. The ratio of negative and positive ions is also of great importance. The minimum required level of ionization of the air is 1000 ions in 1 cm 3 of air, of which there must be 400 positive ions and 600 negative.

For normalization of the ionic regime of the air, the supply and exhaust ventilation, group and individual ionizers, devices for automatic regulation of the ionic mode are used. As a group ionizer, a Chizhevsky chandelier has recently been used, which provides the optimal composition of aero ions. At most enterprises, this factor is not yet taken into account.

Ventilation. natural ventilation systems

An effective means of ensuring proper cleanliness and acceptable microclimate parameters of the air of the working area is ventilation.

Ventilation called organized and regulated air exchange, which ensures the removal of contaminated air from the room and the supply of fresh air in its place.

From the point of view of aerodynamics, ventilation is an organized air exchange regulated by SNiP P-33-75 "Ventilation, heating and air conditioning" and GOST 12.4.021-75.

The method of moving air distinguishes:

Natural ventilation systems.

Mechanical ventilation systems.

Figure 7.1 - Ventilation systems.

Natural ventilation

Natural ventilation  called a ventilation system, the air in which is due to the resulting pressure difference outside and inside the building.

The pressure difference is due to the difference in the densities of the external and internal air (gravitational pressure, or thermal head ∆Р Т) and wind pressure ∆Р В acting on the building.

Natural ventilation is divided into:

Unorganized natural ventilation;

Organized natural ventilation.

Unorganized natural ventilation  (infiltration or natural ventilation) is carried out by changing the air in the rooms through leaks in the fencing and structural elements due to the pressure difference outside and inside the room.

Such air exchange depends on random factors - the strength and direction of the wind, the air temperature inside and outside the building, the type of fencing and the quality of construction work. Infiltration can be significant for residential buildings and reach 0.5 ... 0.75 room volume per hour, and for industrial enterprises up to 1 ... 1.5 h -1.

Organized natural ventilation  may be:

Exhaust, without organized air flow (duct)

Supply and exhaust, with an organized flow of air (channel and non-channel aeration).

Duct natural exhaust ventilationwithout organized air flow is widely used in residential and administrative buildings. The estimated gravitational pressure of such ventilation systems is determined at an outdoor temperature of +5 0 C, assuming that all pressure falls in the exhaust duct path, while the resistance to air inlet to the building is not taken into account. When calculating the network of ducts, first of all, an approximate selection of their sections is carried out based on the allowable air velocities in the channels of the upper floor of 0.5 ... 0.8 m / s, in the channels of the lower floor and prefabricated channels of the upper floor 1.0 m / s and in the exhaust shaft 1 ... 1.5 m / s.

To increase the pressure in natural ventilation systems, nozzles - deflectors are installed at the mouth of the exhaust shafts. Strengthening traction occurs due to the rarefaction that occurs during the flow around the deflector.

Aerationcalled organized natural general ventilation of the premises as a result of the intake and removal of air through the opening transoms of windows and lamps. The air exchange in the room is regulated by varying degrees of opening of transoms (depending on the outdoor temperature, wind speed and direction).

As a method of ventilation, aeration has found wide application in industrial buildings characterized by technological processes with large heat emissions (rolling shops, foundries, blacksmiths). The supply of outside air to the workshop during the cold season is organized so that cold air does not enter the work area. To do this, the outdoor air is supplied into the room through openings located at least 4.5 m from the floor, in the warm season, the influx of external air is oriented through the lower tier of the window openings (A \u003d 1.5 ... 2 m).

The main advantage of aeration is the ability to carry out large air exchanges without the cost of mechanical energy. The disadvantages of aeration include the fact that in the warm season, the aeration efficiency can significantly decrease due to an increase in the temperature of the outside air and, in addition, the air entering the room is not cleaned or cooled.

The mechanical ventilation system is used to supply fresh, suitably treated air to the room.

Outside air must be taken from unpolluted and ventilated areas. For intake of outdoor air arrange special air intake devices. The openings in the air intake devices through which the outside air is taken in are closed with special grilles protecting them from snow, rain and debris.

The outside air is pretreated before being fed into the room: as a rule, it should be heated in the cold season, and sometimes cooled in the summer. In many cases, the outside air has to be humidified, and before being fed into the room it is often necessary to clean it from dust.

The supply air is processed in the supply chambers (Fig. 8). The figure shows a diagram of a simple supply air chamber for heating air.

Fig. 8. The simplest supply chamber

Air enters the chamber into the air intake shaft 1 through an opening closed by a louvre grill 2. The amount of external air taken in is regulated by valve 3. Then, air enters the air heaters 4, where it is heated. The supply air temperature is regulated by mixing heated air with part of the external unheated air entering through the bypass valve 5 into the room 6, bypassing the heaters. Through the same bypass valve, air enters in the summer when the air heaters turn off.

The treated air from the supply chamber is sucked in by the fan 7 and is pumped by it into the network of air ducts 8, from which the air is discharged into the room in appropriate places and in the required quantity through special devices.

In addition to the general exchange ventilation system, local ventilation systems are also arranged in the form of air showers, air curtains and air oases.

Air shower  It is a concentrated air flow directed to a person working at elevated temperatures or with great physical exertion, when irradiated from heat sources, such as hot surfaces of industrial furnaces, hot metal, etc., increased dust content and air pollution in the room.

The cooling effect of air showering is based on the temperature difference between the air of the soul and the human body, as well as the increased speed of air flow around the body.

Using air showering, it is possible in a space limited by the zone of action of the air flow to change the speed of air movement, its temperature, humidity and the concentration of gases, vapors and dust in it.

Air shower units have various designs.

The main ones are: installations in which air is supplied by a fan through a network of air ducts and discharged in a certain place from several nozzles (Fig. 9); units in which concentrated air flow is supplied to the workplace; mobile air shower units, which can be placed at the right distance from the workplace; fan installations serving workplaces and driving the internal air of the workshop.

Fig. 9. Air shower at the casting site of the iron foundry

The choice of one or another air shower depends on the production conditions.

Examples of fan installations include air-cooling units of the Sverdlovsk Institute of Labor Protection of the All-Union Central Council of Trade Unions (SIOT-3, SIOT-5 and SIOT-6).

SIOT-3 unit (Fig. 10) is a portable fan unit designed for choking workplaces near heating "furnaces, for cooling workplaces near turbines, in drying compartments, etc. It consists of an axial fan with a wheel diameter of 700 mm and electric motors connected on one axis.The unit is mounted on a mobile trolley.

Fig. 10. Portable fan unit for air shower:
   1 - axial fan; 2 - electric motor; 3 - blades; 4 - fairing; 5 - rack; 6 - rollers; 7 - shell; 8 - mesh; 9 - filter; 10 - crane; 11 - a tube; 12 - nozzles

Spray / water is mixed into the air stream, which serves to cool it. The details of the device are shown in the figure.

The SIOT-5 unit is portable and consists of an axial fan with a wheel with a diameter of 500 mm. It is designed to choke the jobs of crane operators, machinery control posts and electrical equipment in hot shops, etc.

SIOT-6 unit is rotary, consists of an axial fan with a wheel with a diameter of 1,000 mm. It is applicable for air-scenting of working platforms of open-hearth, mine, smelting, cage furnaces, etc.

Air curtains. In the cold season, through the opening gates to the workshops, into the vestibules and locks of the front doors of public buildings with a large flow of people, a large amount of cold air enters the front doors of the theaters, which spread along the floor, cooling the lower area of \u200b\u200bthe room.

To combat this phenomenon, ventilation installations are called air curtains.

When the air curtain is installed, warm air is taken from the upper zone of the room or the outside air is specially heated and directed at an angle towards the air tending to break into the room when opening the gate or door.

Air is supplied in the form of a flat jet in the entire width or height of the gate from the channels located below or on the side of the gate.

With a sufficient volume and required speed of the exhaust air, it is possible to stop or significantly reduce the amount of cold air entering the workshop through the gate.

In fig. 11 shows a diagram of the operation of the air curtain at the gates of the workshop

Air oases. An air oasis is a ventilated part of the area of \u200b\u200ba production room, limited by partitions.

Clean air with a lower temperature enters this part of the room through the air ducts than in the rest of the room. As a result of this, the air oasis has a more favorable air environment than the whole room.

Ventilation is a set of measures and devices used in organizing air exchange to ensure a given state of the air environment in rooms and at workplaces in accordance with Construction Norms and Regulations (Construction Norms).

Ventilation systems ensure the maintenance of permissible meteorological parameters in rooms for various purposes.

With all the variety of ventilation systems, due to the purpose of the premises, the nature of the technological process, the type of harmful emissions, etc., they can be classified according to the following characteristic signs:

1. By the method of creating pressure to move air:  with natural and artificial (mechanical) motivation.
2. By appointment:  supply and exhaust.
3. By service area:  local and general exchange.
4. By design:  channel and channelless.

Natural ventilation.

The movement of air in natural ventilation systems occurs:

• due to the temperature difference of the outdoor (atmospheric) air and indoor air, the so-called aeration;
• due to the difference in pressure of the "air column" between the lower level (served by the room) and the upper level - an exhaust device (deflector) installed on the roof of the building;
• as a result of exposure to the so-called wind pressure.

Aeration is used in workshops with significant heat if the concentration of dust and harmful gases in the supply air does not exceed 30% of the maximum permissible in the working area. Aeration is not used if, under the conditions of the production technology, preliminary treatment of the supply air is required or if the influx of external air causes the formation of fog or condensate.

In rooms with large excesses of heat, the air is always warmer than the outside. Heavier outside air entering the building displaces less dense warm air from it.

At the same time, air circulation occurs in the enclosed space of the room, caused by a heat source, similar to that caused by the fan.

In natural ventilation systems, in which air movement is created due to the difference in pressure of the air column, the minimum height difference between the level of air intake from the room and its discharge through the deflector must be at least 3 m. Moreover, the recommended length of the horizontal sections of the air ducts should not be more 3 m, and the air speed in the ducts should not exceed 1 m / s.

The effect of wind pressure is expressed in the fact that on the windward (facing the wind) sides of the building an increased pressure is formed, and on the leeward sides, and sometimes on the roof, a reduced pressure (rarefaction) is formed.

If there are openings in the building’s fences, then atmospheric air enters the room from the windward side and leaves it from the windward side, and the air velocity in the openings depends on the speed of the wind blowing the building and, accordingly, on the magnitude of the resulting pressure differences.

Natural ventilation systems are simple and do not require complicated expensive equipment and the consumption of electrical energy. However, the dependence of the effectiveness of these systems on variable factors (air temperature, direction and wind speed), as well as the small disposable pressure, do not allow us to solve all complex and diverse problems in the field of ventilation with their help.

Mechanical ventilation.

Mechanical ventilation systems use equipment and instruments (fans, electric motors, air heaters, dust collectors, automation, etc.) that allow air to be transported over considerable distances. The cost of electricity for their work can be quite large. Such systems can supply and remove air from the local areas of the room in the required quantity, regardless of the changing environmental conditions. If necessary, the air is subjected to various types of processing (cleaning, heating, humidification, etc.), which is almost impossible in systems with natural motivation.

It should be noted that in practice often provide for the so-called mixed ventilation, i.e., both natural and mechanical ventilation.

Each specific project determines which type of ventilation is the best in sanitary and hygienic terms, as well as economically and technically more rational.

Forced ventilation.

Supply systems are used to supply clean air to the ventilated rooms instead of the remote. Supply air, if necessary, is subjected to special treatment (cleaning, heating, humidification, etc.).

Exhaust ventilation.

Exhaust ventilation removes contaminated or heated exhaust air from the room (workshop, building).

In the general case, both supply and exhaust systems are provided in the room. Their performance should be balanced taking into account the possibility of air entering into adjacent rooms or from adjacent rooms. In rooms, only an exhaust system or only a supply system can also be provided. In this case, air enters this room from the outside or from adjacent rooms through special openings or is removed from this room to the outside, or flows into adjacent rooms.

Both supply and exhaust ventilation can be arranged at the workplace (local) or for the entire room (general exchange).

Local ventilation

Local ventilation is such that air is supplied to certain places (local fresh air ventilation) and polluted air is removed only from the places where harmful emissions are formed (local exhaust ventilation).

Local ventilation.

Local supply ventilation includes air showers (concentrated air flow at increased speed). They must supply clean air to permanent workplaces, lower the ambient temperature in their area, and blow workers exposed to intense heat radiation.

Local oversized ventilation includes air oases - sections of rooms fenced off from the rest of the room by mobile partitions 2–2.5 m high, into which air with low temperature is pumped.

Local ventilation is also used in the form of air curtains (at the gates, stoves, etc.), which create, as it were, air partitions or change the direction of air flows. Local ventilation is less expensive than general ventilation. In industrial premises, when emitting harmful substances (gases, moisture, heat, etc.), a mixed ventilation system is usually used - common to eliminate harmful substances in the entire volume of the room and local (local suction and influx) for servicing workplaces.

Local exhaust ventilation.

Local exhaust ventilation is used when the places of hazardous emissions in the room are localized and their spread throughout the room can be prevented.

Local exhaust ventilation in industrial premises provides for the capture and removal of harmful emissions: gases, smoke, dust and partially generated heat from the equipment. To remove hazards, local suction is used (shelters in the form of cabinets, umbrellas, side suction, curtains, shelters in the form of casings for machine tools, etc.). The basic requirements that they must meet:

• Where possible, the formation of harmful emissions should be completely covered.
• The design of the local suction should be such that the suction does not interfere with normal operation and does not reduce labor productivity.
• Harmful emissions must be removed from the place of their formation in the direction of their natural movement (hot gases and vapors must be removed up, cold heavy gases and dust - down).
• The designs of local suction are conventionally divided into three groups:
• Semi-open exhausts (fume hoods, umbrellas, see Fig. 1). Air volumes are determined by calculation.
• Open type (side suction). The removal of harmful emissions is achieved only with large volumes of suction air (Fig. 2).

The system with local suction is shown in Fig. 3.

The main elements of such a system are local exhausts - shelters (MO), a suction network of air ducts (AC), a centrifugal or axial type fan (B), and a VS - exhaust shaft.

When using local exhaust ventilation to capture dust, the air removed from the workshop must be cleaned of dust before it is released into the atmosphere. The most complex exhaust systems are those in which they provide a very high degree of air purification from dust with the installation of two or even three dust collectors (filters) in series.

Local exhaust systems, as a rule, are very effective, since they allow you to remove harmful substances directly from the place of their formation or discharge, preventing them from spreading indoors. Due to the significant concentration of harmful substances (vapors, gases, dust), it is usually possible to achieve a good sanitary and hygienic effect with a small amount of air removed.

However, local systems cannot solve all the problems facing ventilation. Not all harmful secretions can be localized by these systems. For example, when noxious emissions are dispersed over a significant area or volume; air supply to certain areas of the room cannot provide the necessary conditions for the air environment, the same if the work is carried out on the entire area of \u200b\u200bthe room or its nature is associated with movement, etc.

General exchange ventilation systems - both supply and exhaust, are intended for ventilation in the room as a whole or in a significant part of it.

General exchange exhaust systems relatively evenly remove air from the entire serviced room, and general exchange supply systems supply air and distribute it throughout the entire volume of the ventilated room.

General exchange forced ventilation.

General exchange supply ventilation is arranged to assimilate excess heat and moisture, dilute harmful concentrations of vapors and gases not removed by local and general exhaust ventilation, as well as to provide calculated sanitary and hygienic standards and free breathing of a person in the working area.

With a negative heat balance, i.e., with a lack of heat, general exchange supply ventilation is arranged with mechanical motivation and with heating the entire volume of supply air. As a rule, air is cleaned of dust before being fed.

When harmful emissions enter the air of the workshop, the amount of supply air must fully compensate for general and local exhaust ventilation.

General exchange exhaust ventilation.

The simplest type of general exchange exhaust ventilation is a separate fan (usually axial type) with an electric motor on one axis (Fig. 4), located in a window or in a wall opening. Such an installation removes air from the area of \u200b\u200bthe room closest to the fan, providing only general air exchange.

In some cases, the installation has an extended exhaust duct. If the length of the exhaust duct exceeds 30–40 m and, accordingly, the pressure loss in the network is more than 30–40 kg / m2, then a centrifugal fan is installed instead of the axial fan.

When the harmful emissions in the workshop are heavy gases or dust and there is no heat emission from the equipment, exhaust ducts are laid along the floor of the workshop or are made in the form of underground channels.

In industrial buildings where there are heterogeneous harmful emissions (heat, moisture, gases, vapors, dust, etc.) and their entry into the room occurs under various conditions (concentrated, dispersed, at various levels, etc.), often it is impossible to do with any one system, for example, local or general exchange.

In such premises, general exchange exhaust systems are used to remove harmful emissions that cannot be localized and enter the air of the room.

In certain cases, in industrial premises, along with mechanical ventilation systems, systems with natural motivation, for example, aeration systems, are used.

Channel and channelless ventilation.

Ventilation systems have an extensive network of air ducts for moving air (duct systems) or ducts (ducts) may be absent, for example, when installing fans in a wall, in a ceiling, during natural ventilation, etc. (channelless systems).

Thus, any ventilation system can be characterized by the above four characteristics: by purpose, service area, method of mixing air and design.

Ventilation systems include groups of various equipment:

1. Fans.

• axial fans;
• radial fans;
• diametrical fans.

2. Fan units.

• channel;
• roof.

3. Ventilation systems:

• inflow;
• exhaust;
• supply and exhaust.

4. Air-curtains.

5. Mufflers.

6. Air filters.

7. Air heaters:

• electric;
• water.

8. Ducts:

• metal;
• metal-plastic;
• non-metallic.
• flexible and semi-flexible;

9. Locking and regulating devices:

• air valves;
• apertures;
• check valves.

10. Air diffusers and air exhaust control devices:

• gratings;
• slotted air distribution devices;
• shades;
• nozzles with nozzles;
• perforated panels.