The production of air ducts is a profitable business. They are needed in the construction of residential and commercial premises. Air ducts are structures resembling pipes that distribute the flow of incoming and exhaust air. Ventilation pipes are also used for these purposes. The article will discuss air ducts made of galvanized steel and other materials.
How to start an air duct manufacturing business?
We study the range
There are several types of air ducts. They are:
- rigid and flexible;
- round or rectangular;
- steel (stainless or galvanized steel), plastic, aluminum, rubber, fabric (polyester), silicone, fiberglass;
- connecting (able to be fastened together using nipples or fasteners);
- fire retardant.
Manufacturing technology depends on the type of raw materials used in production.
Galvanized steel and aluminum are the materials that make the most labor-intensive of all the ways to produce ventilation ducts, which are used in restaurants, schools, shopping centers, offices. Steel products have the following advantages:
- they are not susceptible to corrosion;
- cheaper than plastic;
- fire resistant;
- amenable to quick dismantling.
Flexible ducts for ventilation are more difficult to produce. They are installed in small buildings where it is necessary to remove harmful substances in the air. They also come in two shapes: round and rectangular. It takes a lot of money to produce them. But they are in the highest demand. Therefore, experienced entrepreneurs say that it is better to start manufacturing ventilation ducts from this particular type.
Weigh the pros and cons
The main advantages can be identified:
- Yield. Despite the fact that this business requires a lot of investment, it brings great profits if developed in the right direction.
- High demand. No building is complete without air ducts. And every year, especially in metropolitan areas, more and more multi-storey buildings are being built. They are also needed by those who make repairs and change the communication system. Therefore, there is always a customer for air ducts.
- Year-round production. Since the business is not seasonal, management can sell goods to other regions.
- High payback. In a year, a skilled entrepreneur will be able to help out the amount that will cover all initial expenses.
The cons include:
- large investment investments;
- high level of competition.
Before opening your own production, you need to assess the market situation in your region, analyze competitors. This business is fraught with many features that can have a negative impact on the enterprise as a whole.
How to choose equipment for the production of air ducts?
The technical equipment of the plant is selected taking into account the area and cross-sectional shape of the pipes, their rigidity. Which air ducts to produce in terms of size and parameters is decided by the owner of the enterprise, based on consumer demand.
Also, the main indicator of the type of manufactured products is installation. So, rectangular ducts lend themselves to this process worse than round ones, which have another significant advantage. They are easier to produce due to the fact that they are connected using snap nipples.
But they also have disadvantages - quality. Rectangular ducts are more reliable ventilation structures. They are used for large cross-sectional areas. When complex installation work is expected in a building with an unusual design, rectangular ducts are also preferred.
Since it is not known which types of products will be more in demand in your area, it is better to purchase two machines that can work with both rectangular and round structures.
Equipment for the production of air ducts:
- guillotine;
- machines that correct the shape of the sheet;
- a machine that is responsible for feeding raw materials to the main line;
- an apparatus capable of unwinding sheets made of metal from rolls;
- CNC system.
The equipment intended for the production of air ducts of various shapes does not differ much from each other. To create round structures, rollers (rolling) are used, and for rectangular structures, machines, bending sheets and applying ribs.
Machines for the manufacture of round air ducts will cost no less than 3 million rubles, and for rectangular ducts - 3.5-5 million rubles.
Documents required for organizing a business
Production of air ducts is a commercial activity, does not require licenses or special permits. For legal work, it is enough to register as an individual entrepreneur or open an LLC. The first option is cheaper and easier in terms of preparing all the necessary papers. But serious companies that are interested in large volumes of finished products very rarely work with individual entrepreneurs. Another disadvantage is that in the event of bankruptcy, an entrepreneur (individual) may lose his personal property, and the founders of an LLC risk only the authorized capital and funds of the company.
In order to draw up IP documents, you need to pay a state fee, write an application, make copies of the TIN and passport, and then transfer all this to the tax inspector. The founders of an LLC need to additionally prepare the statutory documents of the company, resolve the issue with the legal address and form the authorized capital (from 10 thousand rubles).
Regardless of the choice of legal form for your business, you need to choose a code that matches your activity. In this case, it is OKVED 28.1.
What tax regime can duct manufacturers choose?
If we are talking about small volumes of production, then you can work on a simplified regime, which provides for mandatory payments to the state in the amount of 6% of profits or 15% of gross income.
If you decide to organize a large-scale production of air ducts and plan to enter into contracts with large companies, then it is better for you to work on a common basis. In order to organize internal and tax accounting in this situation, a qualified accountant is needed, who must be paid a rather large salary. But a good specialist will always find legitimate ways to reduce the amount of tax payments, often exceeding the monetary reward for their work.
Air duct production technology
The production of air ducts takes place in several stages. Let us consider in more detail the production process of one of the types of round structures made of galvanized steel.
The entire production process is automated. The quality of finished products depends on the condition of the purchased machines.
How much money do you need to start a business?
Setting up this type of business requires a large initial investment. The main costs include:
- Purchase of equipment for the manufacture of air ducts of various shapes - 6-7 million rubles.
- Room rental - 50 thousand rubles.
- Salary - 50 thousand rubles.
If there are no funds to create a full-scale production, then you can start with the manufacture of parts needed for ventilation ducts. These include:
- plugs;
- bends;
- tie-ins;
- nipples.
This will not require large expenses, since all these structures can be made from industrial waste and defective products. Machine tools for their manufacture cost within 50 thousand rubles. Subsequently, you can expand the scope of activities and begin to manufacture various types of air ducts themselves.
To save money, you can hire unqualified staff for the first time. Naturally, you need to take care of the quality of the goods, so you should take into account the abilities of employees.
How much can you earn in the production of air ducts?
This business is very profitable. This allows you to get a large profit at a relatively low initial cost. With well-established production, you can get about 200-400 thousand rubles. per month, given that the market price for one meter of air duct varies between 300-600 rubles. The cost depends on the diameter of the pipe (outer).
With intensive work, the initial costs will pay off in 6-12 months.
The manufacture of air ducts is a great business idea for a novice entrepreneur who is looking for a field of activity in which he would like to realize himself. There is always a risk of burnout, but in this case you should not be afraid of this, because not a single room can do without ventilation.
For the manufacture of air ducts, metal, non-metallic and metal-plastic materials are used, as well as building structures. Materials for the manufacture of air ducts are selected depending on the characteristics of the medium transported through the air ducts.
| Materials for air ducts | ||
| Characteristics of the transported medium | Products and materials | |
| Air with a temperature not exceeding 80°C with a relative importance of not more than 60% | Concrete, reinforced concrete and gypsum ventilation blocks; plasterboard, gypsum concrete and wood concrete boxes; thin-sheet, galvanized, roofing, sheet, rolled, cold-rolled steel; fiberglass; paper and cardboard; other materials that meet the requirements of the specified environment | |
| The same, with a relative humidity of more than 60% | Concrete and reinforced concrete blocks; thin-sheet galvanized, sheet steel, sheet aluminum; plastic pipes and plates; fiberglass; paper and cardboard with appropriate impregnation; other materials that meet the requirements of the specified environment | |
| Air mixture with reactive gases, vapors and dust | Ceramic and pipes; plastic pipes and boxes; blocks of acid-resistant concrete and plastic concrete; metal-plastic; Sheet steel; fiberglass; paper and cardboard with protective coatings and impregnation corresponding to the transported medium; other materials that meet the requirements of the specified environment | |
Note: Air ducts made of cold-rolled and hot-rolled steel sheets must have a coating that is resistant to the transported medium.
Carbon steel of ordinary quality according to the rolling method is hot-rolled, if the workpiece is preheated, and cold-rolled, i.e. without heating the workpiece. According to the thickness, such steel is subdivided into thick sheets - 4 mm thick or more and thin sheets - up to 3.9 mm thick. Sheet steel with a thickness of 0.35 to 0.8 mm is called roofing.
hot rolled steel sheet are produced in sheets 0.4...16 mm thick, 500...3800 mm wide, 1200... ...9000 mm long and in rolls 1.2...12 mm thick, 500...2200 mm wide. They are used for the manufacture of air ducts for general ventilation and aspiration.
Sheet cold rolled steel are produced in sheets with a thickness of 0.35 ... 0.65 mm and in rolls with a thickness of 0.35 ... 3 mm. Used for the production of spiral-seam air ducts.
Galvanized sheet steel produced with a double-sided galvanized coating that protects steel from corrosion, in sheets 0.5 ... 3.0 mm thick, 710 ... 1500 mm wide. Used for the manufacture of only folded air ducts.
Thin sheet cold rolled carbon steel use a width of 100 ... 1250 mm, a thickness of 0.6 ... 2 mm.
Cold rolled low carbon steel strip thickness of 0.05 ... 4 mm, width up to 450 mm is used for the manufacture of spiral lock air ducts.
In the manufacture of air ducts and parts of ventilation systems, structural materials are widely used - sectional and shaped steel, as well as rolled aluminum.
flat steel produced in widths from 12 to 200 mm, thicknesses from 4 to 16 mm. These products are supplied in coils or strips, depending on the size. Flanges and fasteners are made from strip steel.
Angle Equal Shelf Steel profiles No. 2 ... No. 16 are made, which corresponds to the width of the shelf in centimeters; the thickness of such steel is from 3 to 20 mm. Frames, duct flanges are made of steel.
Non-ferrous metals
Aluminum- silver-white, light (ρ = 2700 kg/m3) and ductile metal. Interacting with atmospheric oxygen, aluminum is covered with a thin and durable film of aluminum oxide, which well protects the metal from corrosion. Folded and welded air ducts are made of aluminum.
Sheets of aluminum and aluminum alloys, produced with a thickness of 0.4 to 10 mm, a width of 400, 500, 600, 800 and 1000 mm, a length of 2000 mm, are used for the manufacture of air ducts and individual parts of ventilation systems.
The corners pressed from aluminum and aluminum alloys let out shelf width from 10 to 250 mm. With the same shelf width, the profiles can be of different thicknesses. Separate elements of network equipment are made from the corners.
Aluminum foil is produced with a thickness of 0.05 to 0.4 mm and is also supplied in rolls. Use foil for flexible corrugated air ducts. The height of the corrugation is 4 mm, the distance between the corrugations is 10 mm. Such air ducts are easily bent and serve for connection to local suctions.
Titanium- silvery-white refractory metal with high corrosion resistance (especially to acids), rather ductile, density ρ=4500 kg/m3. The high strength of titanium alloys is maintained at temperatures from -253 to +500 °C.
Commercially pure titanium grade VT1-00 or VT1-0, as well as low-alloy alloys of increased ductility grade ST4-0 or ST4-1 in the form of sheets with a thickness of 0.4 to 4 mm are used for the manufacture of air ducts. Air ducts made of titanium are usually welded.
Copper- viscous metal of a reddish color, heat and electrically conductive, plastic enough, which allows it to be processed by rolling, stamping, drawing. Copper in its pure form, as a rule, is not used in ventilation systems; usually alloys of copper with other metals are used. An alloy of copper and zinc is called brass. Compared to copper, brass is stronger, more ductile and harder, more resistant to corrosion and, when cast, has good mold filling.
Copper-zinc alloys (brass) are produced in seven grades: L96, L90, L85, L80, L70, L68, L62 (the numbers indicate the average percentage of copper in the alloy). Brass is used to make spark-proof ventilation equipment.
metal plastics
metal-plastic- structural material, which is a low-carbon cold-rolled sheet steel coated with a film. The industry produces metal-plastic of two types: with one- and two-sided coating.
Metal sheet with one-sided coating produced in the form of a steel tape with a thickness of 0.5 ... 1 mm, protected on one side with a polyvinyl chloride film with a thickness of (0.3 ± 0.03) mm. Metal-plastic is supplied in rolls with a strip width of (1000 ± 5) mm, weighing up to 5.5 tons. The outer diameter of the roll is not more than 1500 mm, the inner diameter is (500 ± 50) mm.
Double-sided coated metal is a steel tape with a thickness of 0.5 ... 0.8 mm, both sides of which are protected by a film of modified polyethylene with a thickness of 0.45 mm.
The metal-plastic has the properties inherent in metal and plastics; it is plastic, can be processed on the mechanisms that manufacture seam air ducts.
non-metals
Sheets of plasticized polyvinyl chloride) are made from an unplasticized polyvinyl chloride composition with the addition of auxiliary substances (stabilizers, lubricants, etc.) by film pressing or extrusion.
Sheets of unplasticized polyvinyl chloride are produced with a length of at least 1300 mm, a width of at least 500 mm. The thickness of the sheets depends on their brand and is for sheet vinyl plastic: VI - from 1 to 20 mm; VNE and VP - from 1 to 5 mm; VD - from 1.5 to 3 mm.
Sheet vinyl plastic has high mechanical strength, lends itself well to both manual and mechanical processing on conventional metal and woodworking machines. When heated, it acquires plasticity and is easily molded. After cooling the heated vinyl plastic, all its mechanical properties are restored. Viniplast is an electrically insulating material.
Sheet vinyl plastic is used in the manufacture of air ducts as an anti-corrosion material operating at temperatures from -20 to + 00 ° C.
Polyethylene- Synthetic polymer, dense, characterized by high chemical resistance. Apply at temperatures up to 60 ° C. A film for ventilation ducts is made from high-density polyethylene, which is delivered to the construction site in the form of a roll wound around a sleeve. 300...400 m of film up to 4000 mm wide and 30 to 200 microns thick are wound into a roll.
fiberglass- a material formed by interlacing mutually perpendicular strands of glass fiber. Flexible reinforced air ducts are made from fiberglass SPL impregnated with latex using glue and spring wire made of carbon steel with a diameter of 2 ... 2.5 mm.
textile materials
Types of air ducts
1. Round 2. Rectangular
Rice. 1. Details of duct networks:
1 - straight sections of round air ducts (A) and rectangular (b) sections;
II - branch nodes of round air ducts (V) and rectangular (r) sections;
III - bends and half-bends of round (d) and rectangular air ducts (e) sections;
IV - transitions;
1 - tee;
2 - transition;
3 - crosses;
4 - plug
Rice. 2. Unified details of round ducts: A- straight seam straight part; b - spiral locking straight part; shaped parts: V - bend 90 degrees; G- bend 30, 45, 60 degrees; d - symmetrical transition to B == 400 mm; e- asymmetrical transition from above IN= 400 mm; and- internal nipple, designed to connect the straight parts of the air ducts to each other; h - external nipple, designed to connect the fittings of air ducts to each other; And- end cap
Rice. 3. Unified details of rectangular ducts: A - straight part: fittings; b - bend 90 degrees; V- outlet 45 degrees; G - plug; d - duck; e- transition from a rectangular section to a round one; and - transition from rectangular to rectangular
3. Semi-oval
A - minor axis;
IN- major axle
Rice. 5. Shaped parts of semi-oval air ducts:
A - bend 90 degrees:
a1 - vertical;
a2- horizontal;
b - the transition is asymmetric;
V - the transition is symmetrical;
G - nipple internal;
d - plug;
e - tee;
and- insert in a circle;
h - transition from oval to round;
And - transition from oval to rectangular
4. Spiral lock
Rice. 6. Spiral lock air duct
Rice. 7. Installation diagram (A) for the production of spiral lock air ducts:
1 - decoiler,
2 - mechanism for cutting and welding the ends of the tape,
3 - belt degreasing mechanism,
4 - ribbon,
5 - profiling mill,
6 - mold head,
7 - spiral lock pipe
5. Spiral welded
Rice. 8. Spiral welded duct
6. Semi-rigid and textile
Rice. 9. Semi-rigid ducts:
A- schematic diagram of a semi-rigid duct;
b- semi-rigid air duct
Rice. 10. Textile air duct
7. Metal-plastic
Rice. 11. Air duct made of metal-plastic:
A - general form,
b - seam design,
c, g- two-sided and one-sided metal-layer,
1- PVC film,
2 - glue,
3 - steel tape
Seam connections
Rice. 12 Types of seam connections;
a - recumbent fold,
6 - recumbent fold with double cut-off,
c - corner fold,
g - corner seam connection with slotted latches,
d - standing fold,
e-zig connection,
g - rack connection
Rice. 13. Seam connection of round elements on the ridge
Rice. 14. Lying fold
Rice. 15. Standing seam
Rice. 16. Corner rebate
Figure 17. Pittsburgh (Moscow) fold
In the manufacture of air ducts, the sheets are interconnected:
- for welding (butt or overlap)
- on folds
Welded joints
Rice. 1.2.1 Welded joints:
a - butt, 6 - lap
Fig 19. Schemes for welding round ducts:
a - overlap,
6 - along the bent edges on one side,
c - along the bent edges on both sides
Rice. 18. Seam classification:
a - depending on the position of the parts to be welded,
6 - in the direction of efforts,
in - in length,
d - by degree of amplification
Rice. 20. Types of welded joints used in welding metal ducts:
a - a longitudinal seam for round and rectangular air ducts, paintings,
6 - annular seam for round bends,
c - welding of round flanges and fittings of rectangular air ducts,
e - welding of rectangular flanges and fittings,
e - welding of flanges of rectangular and round sections,
g - tacking of flanges of rectangular section,
h - welding of spirally welded air ducts,
and - welding of ventilation ducts
Rice. 21. Scheme of welding a section of a rectangular duct:
a - welding of knots,
6 - tacking the branch to the straight section
Rice. 22. Snap fold
Methods for connecting air ducts to each other
Flange connections
Corner flanges
Rice. 23. Angle steel flange
Flanges made of profiled galvanized tape
Rice. 24. Z-rail flange:
1 - Z-rail;
2 - C-rail;
3 - seal 8 x 15;
4 - inner corner;
5 - decorative corner
Rice. 25. Flange from profile type "tire"
Flat steel flange
Rice. 26. Flange made of strip steel for flanged air ducts with a diameter of 100 ... 375 mm
Sheet steel flange
Rice. 27. Sheet steel flange with flanges
Rice. 28. The position of the closing transverse end
rebate on round air ducts
Wafer connections
Fig.29. Flanged connection of rectangular ducts:
a, b- the sequence of preparation of air ducts;
V- section of the connection;
G- complete connection;
1 - lock profile;
2 - rubber compressor;
3 - kapron corner;
4 - decorative corner;
5 - connecting rail;
6 - stiffening corner
Socket (nipple) connection
Rice. 30. Nipple connection of round ducts
bandage connection
Rice. 31. Bandage connections of links of round air ducts:
a - with rubber seals;
b - with buteprol sealant;
in - on rivets;
g - with inserts during installation:
1 - bandage;
2 - sealant;
3 - steel corners;
5 - branch pipe;
6 - apron;
7 - air duct;
8 - bandage with buteprol sealant;
9 - bottom loop;
10 - buteprol
Telescopic connection
Rice. 32. Telescopic duct connection:
a - on self-cutting screws;
b - using combined rivets;
1 - self-tapping screw;
2 - rivet of one-sided riveting
Rice. 33. Connection of parts with one-sided riveting:
1,2 - details;
3 - rivet body;
4 - rod head;
5 - weakened section of the rod;
6 - riveter or pistol;
7 - collet riveter;
8 - rod.
Plank connection
Fig.34. Plank connection of steel
air ducts:
a - general view;
b - types of slats;
c - T-shaped rails
Production of round ducts
Rice. 2.1. Typical technological layout of the production site for the manufacture of air ducts on a seam connection:
a - straight sections;
6 - fittings;
1- container for metal;
2 - marking table;
3 - guillotine shears;
4 - sheet bending mechanism;
5- rolling mechanisms;
6 - roller tables;
7 - containers for flanges;
8 - spot welding machine;
9 - folding mechanisms;
10- mechanisms for flanging;
11 - workbenches;
12 - painting conveyor;
13 - mechanism for
flanging of rectangular air ducts;
14 - welding transformer;
15 - false-sedimentary mechanism;
16 - cutting mechanism;
17 - mechanism for bending curved edges;
18 - sigmachine;
19 - mechanism for upsetting corner folds;
20 - selenium rectifier
Manufacturing sequence
| Working cycle | Operation | Equipment and tools | Operation sketch |
| Marking and cutting blanks | Trim both sides of a standard sheet at a 90° angle (if necessary) | Guillotine shears | |
| Mark the elements of the ventilation blank | Marking table, templates, scriber, ruler, compasses | ||
| Cut corners of elements | Pneumatic manual scissors | ||
| Rectilinear cutting of elements according to the markup | Guillotine shears | ||
| Curvilinear cutting of elements according to the markup | Die cutting mechanism | ||
| Procurement of semi-finished products | Roll rebate (straight) | Seam rolling mechanisms | |
| Roll curved seam and edge | Mechanism for forming curved edges | ||
| Roll (bend) elements of blanks | Rolling mechanisms | ||
| Sheet bending mechanisms | |||
| Cut out elements from the side to form a ridge and corrugation | Mechanisms for the manufacture of bends, ring templates, rollers | ||
| Assembly of elements | Assemble the ventilation blank, close and upset the fold | Seam upsetting mechanism | |
| Assemble the ventilation blank, close and upset the fold | Locksmith workbench; hammer | ||
| Assemble the ventilation blank on the ridges | Mechanism for making taps | ||
| Collect the elements of the parts on the rail and upset | Locksmith workbench, mallet, hammer | ||
| Flanging | |||
| Install the flanges on the ends of the assembled products and flange on the flange mirror or weld | Semi-automatic welding in environment with 2 | ||
| Coloring | Duct painting and drying | Painting conveyor | |
| Packing and marking | |||
| Stacking in a warehouse or in a container |
Good day!
Not a single residential, office, retail, industrial or warehouse space today. And air ducts made of galvanized steel deservedly occupy a leading position among various ventilation ducts. About what this popularity is due to and how not to get lost in the variety of the presented assortment, we will tell in the next material.
Galvanized air ducts are the most common type of ventilation pipes. Which is easily explained.
Advantages of galvanizing:
- Light weight, due to which the installed structures create insignificant loads on the buildings. In addition, the lightness of the material facilitates the process of delivery to the installation site and engineering work.
- The flexibility of the material makes it possible to give the air duct elements any shape, which not only expands their range, but also improves the aerodynamic characteristics of the line.
- Strength and resistance to open fire and aggressive environments. This significantly expands the scope of use and increases the service life of ventilation pipes made of thin-sheet galvanized steel from 10 years or more.
- Low cost.
Galvanized ventilation ducts are easy to maintain. They do not require preliminary priming, since the metal is not subject to an active corrosion process. Aesthetic appeal allows them not to be painted.
The disadvantages of galvanized steel include:
- Increased noise level, characteristic of any metal structure. However, this problem can be solved either by a well-thought-out wiring scheme that minimizes the number of bends and transitions, or soundproofing.
- Tendency to form and accumulate condensate. As a solution - insulation of the pipeline.
- Susceptibility to deformation as a result of a powerful mechanical impact caused by a strong impact, displacement or fall of the structure. Under normal operating conditions, such difficulties do not arise.
The combination of quality, material cost and a variety of technologies that minimize the disadvantages makes galvanized pipelines the most popular types of air ducts used in the arrangement of ventilation mains.
Types of galvanized air ducts
A variety of galvanized air ducts is due to a number of technical characteristics that products are endowed with in the production process. So the following types of products are distinguished:
- Cross-sectional shape: rectangular or round.
- By type of seam: welded and folded.
- In the direction of the seam: spiral wound and straight seam.
Rectangular and round
| Round steel duct | Rectangular steel duct | |
| Aerodynamics | Uniform air distribution and, as a result, improved aerodynamics. | High aerodynamic drag |
| Air mass movement speed | High. | Low. For large circuit sizes, forced air circulation is required. |
| Noise figure | Good noise-absorbing properties due to the absence of turbulence effect. | Requires good soundproofing. |
| care requirements | The high air velocity prevents dirt and dust particles from settling in the pipeline. | Requires periodic cleaning of the pipeline. |
| Estimated data | The shape of the section makes it difficult to calculate data on the area of the structure. | The rectangular configuration makes calculations easier. |
| Installation | Products are lighter and do not require reinforced fasteners. Save time and low labor costs. | The severity of the structure requires the arrangement of reliable clamps. |
| Price | Cheaper by an average of 30%. Minimum costs for transportation, storage, installation and thermal insulation. | In view of the high aesthetics, there are no costs for masking and decorating the highway. |
The advantage of rectangular air ducts lies in the configuration and variety of the model range, which allows you to adapt the ventilation circuit to the characteristics of any room without compromising the calculated cross-sectional area, playing with the width and height of the pipe.
Straight seam and spiral wound
Longitudinal welded pipes are made by bending a sheet of galvanized steel into a round or rectangular pipe. This technology reduces the cost of products, but it also limits its length, which increases the number of connecting elements of the pipeline.
Spiral-wound (spiral-lock or spiral-welded) air ducts are twisted from a thin metal tape. In this case, the seam goes in a spiral and plays the role of a stiffener, which increases the strength of the pipe, and when using the welding method, ensures its tightness.
Spiral-wound air ducts are characterized by:
- less weight;
- increased tightness;
- a small number of butt elements;
- increased speed of movement of the air mass, tk. the spiral shape creates additional rotation in a closed loop;
- reduced noise level.
However, the ribbed surface provokes the accumulation of dust inside the pipeline.
Tightness and density
Tightness and pressure are indicators that ultimately determine the efficiency and cost of the ventilation circuit. A leaky line reduces the quality of air exchange and entails an unreasonable increase in the capacity of pumping equipment, an increase in energy costs, and also leads to the accumulation of condensate inside the pipes.
There are 3 classes of tightness of air ducts:
- A (low). Air permeability from 1.35 to 0.45 l/sec/m².
- B (medium). Air permeability from 0.45 to 0.15 l/sec/m².
- C (high). Air permeability less than 0.15 l/sec/m².
By the coefficient of internal pressure (density) distinguish:
- H-models (normal pressure). Designed for ventilation and smoke removal systems of objects belonging to the category of fire hazard class "B" and "G". Do not require strong sealing, tk. allow a certain percentage of leakage. Rubber seals are usually used as a sealant.
- P-models (dense). They are installed at facilities equipped with powerful pumping equipment and classified as fire and explosion hazardous. They are characterized by 100% tightness of seam joints and the presence of a hermetic lock at the junction of the elements with each other.
What is better and where is it used?
The protective layer of zinc resists the damaging effects of open air, moisture and ultraviolet radiation. Therefore, galvanized ventilation ducts are actively used both indoors and outdoors for arranging systems:
- natural and forced ventilation,
- conditioning;
- aspiration (removal of small particles contained in the air);
- smoke removal (removal of combustion products);
- removal of exhaust gases;
- transportation of gas mixtures, purifiers and air humidifiers.
Even the organization of a conventional hood in the kitchen is most often carried out by means of steel ducts.
When deciding on the use of one or another type of air duct, one should be guided by the features of the operation of the future design:
- Rectangular air ducts are used to save space in small predominantly residential or service premises (private houses, apartments or offices).
- For aspiration and transportation of harmful gases, round pipes with a welded seam are suitable, providing maximum air speed and complete tightness of the housing.
- In industry, preference is given to round shapes, characterized by both the greatest efficiency and the lowest cost.
Elements of the ventilation system
The ventilation line is always a complex structure, consisting of numerous elements that allow:
- change the direction of the contour depending on the configuration of the premises;
- bypass ledges;
- connect several circuits into a single network.
Branches and boxes
The main elements of the duct that determine its direction are ducts and bends. The former pave the path in a straight line, the latter change the contour geometry at an angle of 15⁰, 30⁰, 45⁰, 60⁰ or 90⁰.
Other shaped elements
Ventilation is a complex and extensive network of channels, which is problematic to mount without the appropriate elements. Such components are usually called shaped products.
These include:
- Adapters connecting circuits of various diameters to each other - confusers and diffusers. The first narrow the highway, the second expand.
- Tees and collar tie-ins, ensuring the adjoining of two mains to each other.
- Crosses used to cross two perpendicular air currents.
- S-shaped adapters (ducks) connecting two circuits that do not match in axis and / or section.
- Round nipples and couplings connecting two round boxes. The first are inserted inside, the second are put on over the pipes.
- Plugs installed at the ends of the circuit.
- The umbrella is roof, preventing hit of an atmospheric precipitation in a ventilating shaft.
- Supply and exhaust grilles and other shaped parts.
Dimensions
GOST
- GOST 14918-80 - air ducts made from steel sheet with a thickness of 0.5 to 1 mm by rolling and designed to transport air with a humidity of not more than 60% and a temperature of less than 80⁰C.
- GOST 5632-72 - air ducts characterized by a high degree of tightness, resistance to corrosion and high temperatures (about 500⁰C) and designed to move hot air and chemical gases.
Size Chart Weights and Diameters
Production of galvanized air ducts
Galvanized air ducts are manufactured on special metal-working equipment from thin-sheet cold-rolled steel in accordance with the standards established by the state (SNIP 41-01-2003 and TU 4863-001-75263987-2006). Cutting of metal occurs in automatic mode according to the parameters set by the program.
- Circular sections are processed by rollers, which give the workpiece the required diameter, followed by rolling the longitudinal edge on a seam-rolling machine.
- Spiral-wound ones are made using a different technology: steel with a width of 137 mm is twisted in a spiral with a seam inward.
The use of high-quality galvanizing prevents the galvanized coating from peeling off the metal at the bending points of the product.
Technological standards prescribe for each type of section to use metal of a certain sheet thickness:
Average cost and where to buy
The cost of air ducts made of galvanized steel depends on the size of its cross section and the thickness of the metal. The price is calculated for 1 m². On average, the cost of 1 m² of a product on the market is about 320 rubles. Installation work will cost an average of 700 rubles. for the same square metre.
Despite the wide representation of air ducts in online stores, it is still worth buying them directly from the manufacturer, who is able to accompany each product with a quality certificate.
How to choose?
The operation of the air exhaust system (SVO) depends on how correctly the area of \u200b\u200bits section is calculated.
S - Sectional area.
P - CBO performance.
v - The speed of movement of the air mass (for residential premises, an indicator of 3-4 m / s is used).
Determination of ventilation performance involves determining the amount of air required for a comfortable stay in the room. It is calculated in 2 ways:
- Air volume required:
P - CBO performance.
A - The number of people in the room during the hour.
n - Air consumption rate according to SNIP 41-01-2003 and MGSN 3.01.01.
- By the frequency of ventilation (ventilation):
P - CBO performance.
V - The volume of the room (with equal data, the entire room)
k - The ventilation rate established by the standards of SNIP 41-01-2003.
shape and diameter
The quality of air exchange, energy efficiency and design of the room depend on the selected configuration and the size of the air duct section. Therefore, the choice of air channels should be approached in detail:
- The smaller the diameter of the duct, the higher the speed of the air mass. It is important to be guided by the principle of the "golden mean", because the higher the speed, the higher the noise level.
- Round air ducts provide faster air movement, are easier to install and are cheaper.
- Rectangular are stronger and harmoniously fit into the design of any room.
Construction and rigidity
Depending on the specifics of the design application, there are:
- rigid, semi-rigid or flexible;
- standard or thermally insulated;
- fire retardant.
The tighter the seams, the stronger the connection and the longer the period of operation.
Material
Galvanized ventilation ducts are made of a standard type and insulated.
- The design of insulated models provides a special insulating layer of mineral fiber, polyurethane, foam elastomer, felt or other materials. They maintain the optimum air temperature inside the circuit, preventing the formation and freezing of condensate on the walls. In addition, they reduce the noise level.
- Zinc coating can be one-sided or two-sided. Due to the formation of condensate inside the circuit, double-sided galvanizing is more practical, because. protects the contour from the internal corrosion process.
Not so long ago, galvanized aluminum ducts appeared on the market, the coating of which is 95% zinc and 5% aluminum. They are characterized by greater ductility and improved anti-corrosion properties.
Fastening
Ways of fixing the air ducts depend on the configuration:
- with a round section, coupling, bandage and nipple connection of elements are used;
- rectangular air ducts are fastened with latches and mounting brackets.
Sometimes welding is used.
Installation rules for galvanized ventilation
The laying of ventilation ducts from thin-sheet galvanized steel is carried out in stages.
The ventilation system is one of the integral parts of any premises - residential, industrial, warehouse, retail, office, etc. It is from the well-equipped ventilation that the internal microclimate, and, therefore, the level of comfort of a person staying there, depends. Therefore, the correct choice and installation of the air duct is the basis of 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.
An air duct is one of the main elements of the ventilation system, the purpose of which is to redistribute air, providing both its inflow into the room and its exhaust from it. Ventilation, at the same time, 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.
- Transportation of air for technological purposes.
Depending on their purpose, a variety of duct materials can be used - black or galvanized steel, aluminum foil, reinforced steel wire, polyester film, composite materials or plastic. The most popular in household use are precisely plastic ventilation ducts.
Advantages of plastic air ducts
A plastic ventilation duct is one of the most affordable and effective solutions for equipping a ventilation system in any type of premises. 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 duct.
The ventilation duct made of polyvinyl chloride has its main advantages:
- mechanical strength.
- Environmental safety.
- elasticity.
- Resistant to chemically active and organic liquids.
- Resistant to temperature fluctuations.
- Low specific weight.
- Possibility of acquiring the desired form.
- Ease of installation.
- Ease of maintenance.
- Wide range of colors.
- Variety of shapes and sizes.
- Affordable prices.
- Possibility of dismantling for cleaning or repair work.
AIR DUCTS AND TYPICAL PARTS OF VENTILATION SYSTEMS
METAL AIR DUCTS
Air ducts and fittings for them are manufactured in certain sizes and types established by VSN 353-86 “Design and use of air ducts from unified parts”, “Temporary normal for metal round-section 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 tape, cold-rolled sheet steel, fiberglass, asbestos-cement pipes and ducts are used (air ducts from asbestos-cement structures are not allowed to be used in supply ventilation systems). If the temperature or relative humidity of the air moving through the air ducts is above the specified limits, use galvanized sheet steel, sheet steel of increased thickness (up to 1.5 ... 2 mm), aluminum sheet, plastic pipes and sheets (only at high relative humidity), fiberglass, asbestos-cement pipes.
In the event that the air mixture contains reactive gases, vapors or dust, metal-plastic, thin-sheet steel of increased thickness (up to 1.5 ... 2 mm) with a protective coating appropriate for the transported medium (perchlorvinyl enamels and varnishes), 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 ducts. Circular 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, 18 00 and 2000; for aspiration and pneumatic transport systems, additional diameters are used, mm: PO, 140, 180, 225 and 280.
For air ducts made of roofing sheet steel, the outer diameter of the air duct is taken as the normalized diameter.
The wall thickness of round air ducts, through which air moves with a temperature of not 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 a one- or two-sided coating are made as spiral locks with a diameter of 100 ... 800 mm, as well as straight-seam. The technology for manufacturing air ducts from a metal layer does not differ from their manufacture from a steel sheet or mite.
Straight sections of round air ducts take a length of 2500, 3000, 4000, 5000 and C000 mm.
Shaped parts of round section are shown in fig. 27. Elbows with one link and two glasses and noluouts (Fig. 27, a, b) with an average radius R-D are used for general ventilation systems; for aspiration and pneumatic transport systems, bends are used, consisting of five links and two glasses (Fig. 27, c) with an average radius R = 2D with a branch diameter of more than 315 mm or 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 ventilation systems.
Branch nodes (tees), shown in fig. 27, e, e, -h, i, l, are used only for general ventilation systems, and in fig. 27, g, j, 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 from the following materials:
Cold-rolled or galvanized low-carbon steel sheet (GOST 503-81 *) with a section of OLxYuOmm;
Cold-rolled strip with a cross section of 0.1 X 100 mm from 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 ducts depends on the nominal diameter (Table 34).
Rectangular ducts. Rectangular air ducts are made with side dimensions, mm: 100X150, 150X150, 150X200,
250X250 300X150 300X250 400X250 400X400 500X250 500X400 500X500 600X400 600X500 600X600 800X400 800X500 800X 000, 800X800, 1000X500, 1000X600, 1000X800, 1000x1000, 1250X000,
1250X800 1250X1000 1250X1250 1600X800 X X1250, 2500X1600, 2500x2000, 2500x2500, 3150X1600, 3150x2000, 3150X2500, 3150X3200, 4000x2500, 4000x3150.
Rice. 28. Shaped parts of rectangular air 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, / - back of the head, 2 - sidewall. 3 - neck, 4 - base, 5 - passage, 6 - unified transition, 7 - branch, 8 - plug
The wall thickness of rectangular air ducts, through which air with a temperature of up to 80 ° C is mixed, 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 section side from 400 to 1000 mm, ridges are made with a step of 200 ... 300 mm along the perimeter of the duct or diagonal bends (bends). With a section 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 round or oval steel strip inserts with a pitch of 1250 mm are used as internal frames. The stiffening frames must be securely connected to the duct by spot welding or rivets. With a size of one side of the air duct more than 2000 mm, its rigidity is ensured by assembling it from separate panels.
Shaped parts of rectangular section are shown in fig. 28. Branches of rectangular air ducts (Fig. 28, a, b) have a constant neck radius of 150 mm with a branch width of up to 2000 mm. With a larger width, the outlet 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 ducts and branches.