How to evaluate the manufacture of ventilation ducts. Air ducts. Methods for the production of galvanized air ducts

AIR DUCTS AND TYPICAL PARTS FOR VENTILATION SYSTEMS

METAL AIR DUCTS

Air ducts and fittings for them are manufactured of certain sizes and types established by VSN 353-86 "Design and use of air ducts from unified parts", "Temporary normal for metal circular air ducts for aspiration systems", TU 36-736-78 "Metal air ducts" and SNiP 2.04.05-86 "Heating, ventilation and air conditioning".

When transporting air with temperatures up to 80 ° C and relative humidity up to 60%, air ducts made of hot-rolled or galvanized sheet steel, cold-rolled steel strip, thin sheet cold-rolled steel, fiberglass, asbestos-cement pipes and ducts are used (air ducts made of asbestos-cement structures are not allowed supply ventilation). If the temperature or relative humidity of the air transported through the ducts is higher than the specified limits, use galvanized sheet steel, sheet steel of increased thickness (up to 1.5 ... 2 mm), sheet aluminum, plastic pipes and sheets (only at high relative humidity) , fiberglass, asbestos-cement pipes.

In the event that the air mixture contains chemically active gases, vapors or dust, metal-plastic, thin sheet steel of increased thickness (up to 1.5 ... 2 mm) with a protective coating corresponding to the transported medium (perchlorovipil enamels and varnishes) are used for the manufacture of air ducts , plastic and asbestos-cement pipes, boxes and sheets, fiberglass. In some cases, air ducts made of thin-sheet corrosion-resistant, heat-resistant and heat-resistant steels or titanium are used to move an aggressive environment.

Round air ducts. Round-section air ducts are made with diameters, mm: 100, 125, 160, 200, 250, 315, 355, 400, 450, 500, 560, 630, 710, 800, 900, 1000, 1120, 1250, 1400, 1600, 1800 and 2000; for aspiration and pneumatic conveying systems, diameters are additionally used, mm: PO, 140, 180, 225 and 280.

For ducts made of roofing sheet steel, the outer diameter of the duct is taken as the standardized diameter.

The wall thickness of round ducts, through which air moves with a temperature of no more than 80 ° C, depends on their diameter.

Air duct diameter, mm. ... Up to 200 250 ... 450 500 ... 800

Duct wall thickness, mm ................ 0.5 0.6 0.7
Air duct diameter, mm. ... 900 ... 1250 1400 1G00 1800 ... 2000

Duct wall thickness, mm ................ 1.0 1.2 1.4

Air ducts made of metal-plastic with one- or two-sided coating are made as spiral-lock with a diameter of 100 ... 800 mm, hook and longitudinal. The manufacturing technology of air ducts from a metal layer does not differ from their manufacture from a steel sheet or mite.

Straight sections of round air ducts are taken in lengths of 2500, 3000, 4000, 5000 and C000 mm.

Shaped parts of circular section are shown in Fig. 27. Bends with one link and two glasses and zero bends (Fig. 27, a, b) with an average radius R-D are used for general ventilation systems; for aspiration and pneumatic conveying systems, bends are used consisting of five links and two glasses (Fig. 27, c) with an average radius R \u003d 2D with a branch diameter of more than 315 mm, or of three links and two glasses with a branch diameter of 315 mm or less.

Stamped bends (Fig. 27, d), which have high aerodynamic properties, are used for general ventilation systems and.

Branching nodes (tees) shown in fig. 27, d, f, -z, i, l, are used only for general ventilation systems, and in Fig. 27, g, k, m - for aspiration systems and pneumatic transport.

Unified axial transitions (Fig. 27, n) are standardized in length.

Flexible corrugated metal air ducts (TU 400-2-157- 86) are made of the following materials:

Low-carbon steel mite, cold rolled or galvanized (GOST 503-81 *) with section ОЛхЮОmm;

Cold-rolled strip with a section of 0.1 X 100 mm made of corrosion-resistant and heat-resistant steel (GOST 4986-79 *);

aluminum rolled soft foil (GOST 618-73 *) 0.1 ... 0.15 mm thick, 100 mm wide.

The bending radius of flexible corrugated air ducts depends on the nominal diameter (Table 34).

Rectangular air ducts... Air ducts rectangular section are made with side dimensions, mm: 100X150, 150X150, 150X200,

250X250, 300X150, 300X250, 400X250, 400X400, 500X250, 500X400, 500X500, 600X400, 600X500, 600X600, 800X400, 800X500, 800X000, 800X800, 1000X500, 1000X600, 1000X800, 1000x1000, 1250X000,

1250X800, 1250X1000, 1250X1250, 1600X800, 1600XY00, 1600X1250, 1600X1600, 2000XY00, 2000X1250, 2000X1600, 2000x2000, 2500XX1250, 2500X1600, 2500x2000, 2500x2500, 3150X1600, 3150x2000, 3150X2500, 4000x31.

Figure: 28. Shaped parts of rectangular ducts:
a, b - bends with a central angle of 90 and 45 °, o - bend assembled from panels, d..g - unified branch nodes (tees), h - unified transition, f - back of the head, 2 - sidewall. 3 - sheiki, 4 - base, 5 - passage, 6 - unified transition, 7 - branch, 8 - plug

The wall thickness of rectangular ducts, through which air is mixed with a temperature of up to 80C, depends on their cross section.

The largest side of the duct section, mm (inclusive) ............ 250 1000 2000

Duct wall thickness, mm ... 0.5 0.7 0.9

To ensure the rigidity of straight sections of air ducts, the standard length of which is 2500 mm, with a cross-sectional side from 400 to 1000 mm, ridges are performed with a step of 200 ... 300 mm along the perimeter of the duct or diagonal bends (zngs). With a cross-sectional side of more than 1000 mm, in addition, external or internal stiffening frames are installed. Diagonal steel corners are usually used as external stiffening frames, and circular or oval inserts made of steel strip with a pitch of 1250 mm are used for internal ones. Stiffening frames should be securely connected to the duct by spot welding or rivets. If the size of one side of the duct is more than 2000 mm, its rigidity is ensured by assembling it from separate panels.

Shaped parts of rectangular section are shown in Fig. 28. Bends of rectangular ducts (Fig. 28, a, b) have a constant neck radius of 150 mm with a bend width of up to 2000 mm. With a larger width, the bend is assembled from panels (Fig. 28, c).

Rectangular branch nodes (tees) (Fig. 28, d ... g) are assembled from straight sections, branch pipes and unified transitions; sometimes stubs are added to them.

Unified transitions (Fig. 28, h) one-sided with a normalized height of 300, 400, 500, 700 and 900 mm are used to change the cross-sections of air ducts and branches.

The ventilation system is one of the integral parts of any room - residential, industrial, warehouse, retail, office, etc. The internal microclimate depends on the high-quality and efficient ventilation, and, therefore, the level of comfort of a person's stay there. Therefore, the correct choice and installation of the air duct is the basis for high-quality air exchange.

In this article, we will consider the main types and properties of these products, their advantages and disadvantages, as well as application features.

The air duct is one of the main elements of the ventilation system, the purpose of which is to redistribute air, ensuring both its inflow into the room and its exhaust. At the same time, ventilation can be both natural and forced - with the help of special devices.

Air ducts are used not only for ventilation, but also to ensure the circulation of air masses when:

• Air heating.
• Air conditioning.
• Air transportation for technological purposes.

Depending on their purpose, a variety of materials for air ducts can be used - black or galvanized steel, aluminium foil, reinforced steel wire, polyester film, composite materials or plastic. The most demanded in household use are plastic ventilation ducts.

The advantages of plastic ducts

A ventilation box made of plastic is one of the most affordable and effective solutions when equipping a ventilation system in rooms of any type. Most often, ventilation boxes are made from a type of plastic such as polyvinyl chloride. It has a number of positive aspects, which leads to many reasons to use this particular type of ventilation ducts.

A ventilation box made of polyvinyl chloride has its main advantages:

• Mechanical strength.
• Environmental safety.
• Elasticity.
• Resistant to chemically active and organic liquids.
• Resistant to temperature shocks.
• Low specific gravity.
• Possibilities of finding the desired shape.
• Ease of installation.
• Ease of maintenance.
• Wide range of colors.
• A variety of shapes and sizes.
• Affordable prices.
• Disassembly options for cleaning or repair work.

A person is faced with the question of the correct organization of ventilation during the construction of a small house in the country, and during the construction of industrial workshops, and during the arrangement of office buildings. For each case, you can choose the best option ventilation, but the use of galvanized steel air ducts can be considered a universal solution in any situation.

On the advantages of galvanizing

In general, they can be made from the following materials:

• plastic - the price of such a solution is minimal, but the scope is also limited to private construction;

• aluminum - they are corrosion resistant, but aluminum is a rather ductile metal, so such ventilation ducts do not tolerate possible loads;
• made of galvanized steel - practically have no drawbacks;
• from scrap materials. For example, an air duct can be built even from ordinary thick boards that fit well to each other.

Note! Plank ventilation ducts can be recommended exclusively for airing outbuildings, for example, cellars or basements in the country.

Galvanized ventilation ducts can be used practically without restrictions. They will cope with the transportation of hot air or vapors of aggressive substances without any problems. In addition, steel is able to withstand high temperatures while maintaining sufficient strength.

Plastic is completely unable to withstand prolonged exposure to elevated temperatures, and it will not be able to oppose anything to the effects of chemicals. The only advantage of this material is its low weight and ease of installation.

Ventilation pipes made of galvanized steel can withstand, without reducing their technical and operational indicators:

• temperature about + 80ᵒС - no time limit;

Note! For the safety of personnel, air ducts transporting hot air are usually equipped with a heat-insulating layer.

• within a short time, the air temperature may rise to + 200ᵒС. even in the event of a fire at the enterprise, the ventilation system will prevent smoke from the territory;
• galvanized pipes for ventilation do not require additional protection from moisture. The thin zinc coating prevents corrosion.

Note! Even if the integrity of the zinc layer is violated, for example, by cutting in a self-tapping screw, the steel still remains protected. The fact is that steel and zinc form a galvanic pair, and as a result of a chemical reaction, a thin oxide film covers the cut.

Methods for the production of galvanized air ducts

The technology directly depends on the shape of the pipe cross-section.

Ventilation pipes can be:

• round section - optimal aerodynamic performance;

• square or rectangular section - slightly worse aerodynamics, but easier to install thanks to flat surfaces.

The raw material for the manufacture of galvanized air ducts is thin galvanized sheet steel. As a rule, sheet thickness does not exceed 1.0 mm, this provides a balance between acceptable weight and sufficiently high rigidity.

The production of galvanized ventilation is carried out according to one of 2 methods:

• in the case of a circular cross-section, either spiral-wound technology is used, or simple rolling of sheet metal with subsequent folding of the edges;
• for profile air ducts, only one technology is used - the galvanized sheet is passed through a series of rollers, which give it the desired shape. Then the edges of the future ventilation duct are connected.

Spiral wound technology

It is characterized by extremely high productivity, the machine processes approximately 60 m of strips per minute. The production of galvanized ventilation using this technology consists in the fact that the machine simply bends the steel strip so that a round-section pipe is obtained.

At the same time, adjacent turns are overlapped, due to strong tension, the edge of the strip is slightly deformed and a tightness of the joint is achieved.

In addition to high productivity, pipes produced using this technology are characterized by high rigidity. The screw seam plays the role of a stiffener, so that under equal conditions such air ducts will withstand a greater load than its longitudinal seam counterpart.

Straight seam pipes

Galvanized ventilation pipes produced using this technology in terms of technical and operational indicators almost do not differ from spiral-wound pipes. Unless they have a little less rigidity.

The entire technical process can be divided into 3 stages:

• strips of the required length are cut;
• it is passed through a series of rollers;
• joining the adjacent edges of the metal.

As for the profile pipeline, quite often everything is prepared at the ends of the section for the subsequent flange connection. The same technology is used to manufacture ventilation ducts from galvanized steel.

Galvanized ventilation elements

When installing a ventilation system, you will need not only galvanized ventilation ducts, but also a number of shaped elements. For example, bends for different angles of rotation, plugs, grilles, tees, etc. Without these elements, installation is simply impossible.

Bends

This is one of the most common types of shaped elements, it is used when it is necessary to ensure a smooth rotation of the duct. The main characteristic of the retraction is the angle of rotation; variants are available that provide a rotation angle from 15ᵒ to 90ᵒ.

Note! Galvanized ventilation will perform significantly worse if the duct is turned at a large angle many times. This reduces the air flow rate.

As for the production of elbows, a strip of variable width is used for this. Due to the unequal width when folded, its ring width is different. The entire bend consists of several such rings, by adjusting the strip width, it is theoretically possible to obtain any bend angle, but for convenience they are produced in 15ᵒ increments.

Ventilation box

Strictly speaking, a ventilation box is simply a vertical rectangular or square duct in which several smaller ducts are located. Depending on the operating conditions, plastic, aluminum or galvanized ventilation ducts can be used.

If you mentally dissect this structure across, then the observer will see not 1, but 3 channels. The largest one is a common ventilation duct, and two smaller ones provide removal of unpleasant odors from the underlying apartment. Typically 1 bend is used in the kitchen and 1 in the bathroom or restroom.

Given the small area of \u200b\u200bkitchens and bathrooms in most apartments, many people think about how to minimize the area of \u200b\u200bthe box and make it invisible. Galvanized ventilation ducts can help with this.

Note! Residents of multi-storey buildings are often mistaken, considering the ventilation box as their property, and demolish it. If it comes to trial in court, then the would-be builders will have to restore the destroyed with their own hands.

Other fittings

In addition to the bends during the installation of ventilation, you may need such shaped elements as:

• transitions or wefts - used to offset the duct. In parallel with the displacement due to the reduction in diameter, the air flow rate can be adjusted;

• plugs - used if necessary to close the free end of the pipe;
• gates - regulating devices;
• fire dampers;
• crosses and tees - are used to create complex nodes of the ventilation network;

• nipples - used when installing pipes;
• galvanized steel ventilation grilles - used to protect against insects, small animals and debris from the ventilation duct.

About mounting technology

As for attaching the channel to the walls or ceiling, you can do with ordinary clamps or even just hang the pipe on a metal tape. In industrial buildings, a bracket is embedded in the wall for laying the air duct, and the pipe rests on it.

Note! If the air velocity is high, then fastening the duct with clamps or with a metal tape will not provide sufficient rigidity. The pipe will rattle, so a more secure mount is needed.

Special attention should be paid to the tightness of the joints of individual sections.

The connection can be done in several ways:

• nipple... The nipple itself is a section of a pipe of a slightly smaller diameter, it is simply inserted into the duct with effort and rotated. The instructions for making a sleeve connection look the same, and the only difference is that the diameter of the sleeve is larger than the diameter of the duct;

• flanged - joint strength is achieved by simply tightening the bolts;

• folded - a reliable joint is provided due to joint deformation of the metal of different pipe sections.

Materials used in the manufacture of air ducts, the main technological processes and the types of machines needed to carry out this production cycle.

1. Dependence of the duct wall thickness on its cross-sectional area.

2. The main types of machines required for the manufacture of steel galvanized air ducts.
· Guillotine.
· Bending machine.
· Folded rolling machine.
· Folding machine.
· Stiffening machine.
· Pucklevochny machine.
· ZIG machine.
· Apparatus for the production of work on spot welding.
· Spiral-wound machine.
· The machine for the manufacture of bends of circular section Gariloker (GORELOCKER).
· Rolling machine.

1. Materials used for the manufacture of galvanized steel air ducts.

Galvanized steel air ducts are mainly made of sheet with a thickness of 0.5 - 1.2 mm, depending on their standard sizes, for example:
rectangular duct, ranging from 100x100 mm, and up to 500x200 mm, is made of galvanized steel sheet 0.5 mm thick;
rectangular duct, ranging from 500x300 mm, and up to 800x200 mm, is made of galvanized steel sheet 0.7 mm thick;
rectangular air duct, ranging from 800x300 mm, and up to 1000x1500 mm, is made of galvanized steel sheet 1.2 mm thick.

The grade of the used steel is ST-3, ST-6.

2. The main types of machines required for the manufacture of steel galvanized air ducts:

Each machine is designed to perform one unique or several related technological operations for the processing of galvanized steel sheet, gradually turning it into a semi-finished product, a set of shaped products and, finally, a ready-to-use air duct consisting of a system of air ducts and ventilation equipment.

Guillotine.

The machine is designed for cutting steel sheet across the entire width of the coil and nothing else. Structurally, it is a workbench on which a knife with a counterweight or an electric drive is mounted.

Bending machine.

The machine is designed to bend steel sheet to the required angle (from 00 to 3600). Structurally, it is a frame with two movable and fixed guides. The movable guide bends the sheet. The drive can be manual or electric.

Folded rolling machine.

It is intended for the production of several types of locks connecting the edges of the steel sheet, and, accordingly, for connecting different sections of longitudinal seam ducts: single lock, double lock. Structurally, it is a frame with a rolling mechanism and an electric motor.

Folding machine.

This device is designed to tighten (settle) the corner at the junction of the extreme edges of two steel sheets, that is, to close the lock and obtain a tight connection between two adjacent sections of the longitudinal seam duct.

Stiffening machine.

It is intended for the manufacture of stiffening ribs, which serve to reduce the vibration of the duct walls during the passage of air and, accordingly, reduce noise. Air ducts, the walls of which are equipped with stiffening ribs, do not rattle during operation and “keep their shape” better.

Pucklevochny machine.

Serves for processing the joints of the air duct with the flange and giving them the necessary rigidity, strength and tightness. In fact, the machine pushes the flange and air duct sheets, ensuring the strength and immobility of their connection to each other.

ZIG machine.

It is intended for the production of correct angles on the edges of sheets at the points of connection to the air duct sections of the following shaped products made of galvanized steel sheet: bends, semi-bends, reductions and tie-ins. In fact, the machine produces flanging and tightening of the edges of parts previously cut from galvanized steel sheet on other types of machines, for example, GORELOCKER.

Spot welding machine.

Carries out welding operations for joining steel sheets by spot welding. It is used for the manufacture of cross-section transitions of galvanized steel air ducts, mixing and distribution chambers of central and duct air conditioners, sections of silencers and adapters.

Spiral winding machine.

It is used in the manufacture of exclusively circular air ducts. The thickness of the steel sheet used for the manufacture of spiral-wound air ducts directly depends on the cross-sectional area of \u200b\u200bthe air duct - the larger the area, the thicker the sheet.

The circular air duct, starting from a diameter of 100 mm and up to a diameter of 500 mm, is made of galvanized steel sheet 0.5 mm thick;
a circular air duct, starting from a diameter of 500 mm and up to a diameter of 900 mm, is made of galvanized steel sheet 0.7 mm thick;
a circular air duct, from a diameter of 900 mm to a diameter of 1250 mm, is made of galvanized steel sheet 1 mm thick.

The maximum allowable cross-sectional area of \u200b\u200bthe air duct that this machine can digest is 1.13 m2, with a diameter of 1250 mm.

Garilocker (GORELOCKER).

The machine of this type is designed for cutting galvanized steel sheet into segments, and further production of bends and semi-bends with a diameter from 100 mm to 1250 mm inclusive.

Rolling machine.

This device is designed for the production of round longitudinal seam air ducts. Allows to manufacture fittings and inserts with a length of 50 mm. up to 1250 mm. inclusive: adapters and cross-section transitions (from rectangular to round, and vice versa). It is possible to manufacture a straight section of the air duct, however, its length will be limited to 1250 mm.

The above machine park is used in the production of galvanized steel air ducts and fittings of the following types:
- Straight-seam galvanized steel air ducts of square cross-section with a length of 10 cm to 2.5 m inclusive;
- Longitudinal steel galvanized circular air ducts with a length of 5 cm to 1.25 m inclusive;
- Spiral wound galvanized steel air ducts with a length from 50 cm to 5 m inclusive.
- Cross-section transitions (designed to connect air ducts of various diameters and cross-sectional shapes).
- Elbows (Designed to rotate the air duct by 900, can be either round or square).
- Semi-bends (Designed to rotate the air duct by 450, can be either round or square).
- Tees (Designed for dividing the air duct into two parts of the same section, in a non-standard version, it can be divided into equal parts with a transition to a larger section, for example (100x100 / 100x100) / 200x100).
- Adapters (Designed for attaching grilles of both ceiling and wall types. Non-standard detail requiring the development of an individual drawing. Structurally, the adapter is a steel box with a cut-in from the top or side).

Reduction (Shaped part designed for transition from a main pipe to an air duct of a smaller diameter. Reductions are used both rectangular and circular. Structurally, they are divided into straight inserts and saddle inserts. The insertion length cannot be more than 20 cm).

We remind: Here you can buy wholesale components and spare parts for industrial ventilation systems: fastening of air ducts, air conditioners, rectangular and round air ducts, traverse, mounting bus, galvanized corners, bracket for connecting flanges, mounting tape, perforated, tape clamp, aluminum tape, brackets, grilles and anemostats, sheet and roll insulation, galvanized metal sheets. And also we produce wholesale trade fasteners: threaded stud, self-tapping screws, screws, bolts, screws, nuts, washers, rivets, drop-in anchors. Deliveries go all over Russia, from a warehouse in Moscow.

Air duct production

Boxes for ventilation and air conditioning systems are used in the construction of any channel systems. The material for their manufacture is selected depending on the actual operating conditions, the parameters of the working environment, as well as on the purpose. For manufacture of air ducts use low-carbon steel, "galvanized" or "stainless steel", as well as different kinds plastic.

Air ducts for ventilation from "galvanized" are used in air exchange systems with a working environment of up to + 80C (possibly a short rise to + 200C) and humidity up to 60%. Galvanized steel air ducts can be used in areas with any climate in accordance with GOST 15150, provided that they are not aggressive working media (air and gas-air). Galvanized air ducts do without additional protective coating, since the top zinc layer protects the metal from corrosion even in places of damage (due to galvanic steel-zinc pair, which forms an oxide film under the influence of atmospheric oxygen).

Stainless steel air ducts are designed to work with overheated air and aggressive gas-air mixtures. Working environment temperature - up to + 500C (short-term increase up to + 70C is allowed). Steel according to GOST 5632-72 (heat- and corrosion-resistant) is used as a blank material for the production of stainless steel air ducts.

"Black" air ducts are made of low-carbon steel. Workpiece thickness - from 1.2 to 15 mm. "Black" ventilation ducts tolerate high temperatures and exposure to open flames well (they are weakly susceptible to deformation - the ventilation system ducts will not depressurize, and the fire will not spread to neighboring rooms).

For aspiration systems and smoke extraction "black" ventilation ducts are the right choice. Ventilation systems made of plain carbon steel are mainly in demand for production areaswhere excessive gas, dust, etc.

Air ducts can be round or rectangular in cross section... The production of rectangular air ducts is a classic of ventilation systems, but thanks to progressive technologies, the market is increasingly giving way to circular air ducts, since they are more technologically advanced in manufacturing, have better aerodynamic characteristics and are convenient to install. Today the production of round air ducts is "gaining momentum", becoming more and more popular.

For the installation of air ducts in a single line, various shaped components are used, which are conventionally subdivided into typical (corners, turns, splitters, "ducks", transitions, etc.) and atypical (adapters for ventilation grilles or reducers for air exchange systems).

In some cases, air ducts made of polymers (plastic) can become an excellent alternative to their metal counterparts. Among the advantages of plastic air ducts, it is necessary to highlight a low specific weight, ease of installation (no need for special tools and devices), and a reasonable price. But plastic air ducts are not suitable for moving chemically aggressive gas-air mixtures.

There are rigid, semi-rigid and flexible plastic air ducts. Rigid air ducts can be circular or rectangular, while flexible and semi-rigid air ducts have only a circular cross-section.