Plastic air ducts for ventilation: the calculation, selection and installation

Plastic ducts for ventilation are used for residential and industrial premises stream of fresh air, removal of malodor and excretion of harmful vapors. In our time, especially popular are the channels in plastic because of practicality, durability, ease of installation and relatively low cost. The article discussed in detail the calculation of questions, the selection and installation of ventilation ducts.

Plastic ducts for ventilation: species, size and classification

A wide variety of applications in air ducts of ventilation systems causes a wide range of types and designs. There are several parameters that form the basis of the classification:

• sectional shape: elliptical, rectangular, round;
• performance material: plastic, metal and plastic, steel;

• rigidity;
• Size or diameter of the cross section;
• method and connection type;
• structural design.

In order to meet the broad needs of the consumer and to provide options for designs, the company manufacturers offer a wide variety of plastic ducts. Thus, for a rectangular flat duct typical dimensions range from 100h55 to 204h60 mm circular diameter is 100-200 mm.

Classification shaped section

The most commonly used types of cross sections are circular and rectangular. In some cases where the design imposed severe restrictions on the size and shape of the channel, using elliptic embodiment. Such a section is achieved by treatment with round articles on special machines.

For manufacturing plastic duct circular shape requires less material and their manufacture itself more simple technology. In the case of a rectangular execution costs increased on average by 20-30% during the transition from the circular cross-section. Complication of the manufacturing process due to the fact that the ducts are drawn together from several individual parts.

The main arguments for selecting circular shape are best leaks (which is provided one-piece construction and the absence of welds), high speed air stream flows, reduced noise, reduced weight and ease of installation.

Advantageously rectangular channels should be allocated in the optimal allocation of space. Such a shape takes up less space, easily adapts to the unusual layout, for example, when aligned with the false ceiling.

Useful advice!If the site of the alleged location of the ventilation system imposes restrictions on the cross-duct sizes, you can use the transition elements for changing the cross-sectional shape. In this area the lateral portions fay should be identical.

The classification of the material duct execution

The material which is used for manufacturing various types of air ducts, depending on their application and possible limitations imposed by existing ventilation system.

Widespread both in terms of aggressive transfer of air flow, as well as for use in all types of premises received a plastic or PVC type. Plastic is easy and smooth material that is resistant to the influence of moisture, acids and alkalis. Due tightness thereof is made different connecting elements (elbows, tees, bends) .4.

Galvanized steel ducting used in ventilation systems that operate in a non-aggressive environment (temperature up to 80 ° C). The protective coating has anti-corrosion properties and significantly increases the service life of products, however, increases the price per m2 installation of ventilation ducts.

Metal-plastic type ducts manufactured using two metal layers (often made of corrugated aluminum) and a layer of foamed plastic. This type has a high strength at a low weight. The products have aesthetic appearance and do not require additional insulation. The drawback is the increased cost.

Useful advice! In a domestic environment (especially in apartment kitchen ventilation organization) preferred is the use of plastic wires due to less noise, weight, ease of installation and lower value.

For other types of ducts include polyethylene, vinilplastovye and steklotkannye. These species are characterized by high levels of corrosion resistance, light weight, ability to flex in all planes for unlimited angle.

Classification by stiffness

Because today the most common are hard ducts - the main part of the whole ventilation equipment on the market is focused on the type. Often rigid boxes have a circular or rectangular cross-section. For the manufacture of the sheet material used. The basalt wool can serve as an external insulation.

Flexible ducting for ventilation presents a corrugated (corrugated sleeve) that is made of polyvinyl chloride (PVC). It should be noted excellent ease of transportation and installation. Before you buy a flexible duct, the shortcomings of this type should be taken into account. Thin walls have a low level of noise isolation. Also raised surface corrugations have a negative effect on the air flow rate through the wire.

The latter type - a semi-rigid. He is the intermediary between the flexible and rigid products, combining high strength and elasticity. The disadvantages of such ducts should include a lower air velocity, which imposes limits their use in branched systems.

Useful advice! It is not necessary to limit the choice of only one type of ductwork. A wide range of connecting elements makes it easy to combine hard and flexible ducts. This combination does not affect the performance of the ventilation system as a whole.

Plastic air ducts for ventilation: Methods and types of connections

The most common ways compound is flanged duct portions and flat joints. The basis is the first installation of the flanges which are attached to the portions ventkanala rivets or screws. The tightness in the joints is achieved by means of rubber seals and other.

Wafer connection is made via the band of thin sheet steel and metal strips.

The main types of compound airway tubes are:

• tees (at the interface or junction system);
• knees and elbows (in places the channel turns);
• Adapter (for transition from a rectangular to a circular duct, or conversely, the connection portions of different cross section);
• confusers and diffusers (in places of transition to another dimension). The first narrow channel, and the second - expand.

Advantages and disadvantages of plastic vent pipe for exhaust

Without a doubt, flat plastic ducts are very popular for use in residential non-industrial buildings. Here, the following positive characteristics of such products should be highlighted:

• due to the absence in these elements exposed oxidation, plastic wires do not suffer from corrosion. This feature greatly simplifies the work of designers, abolishing the need to provide additional protection. The oxidation resistance makes the design itself and its installation process easier;
• impairment of PVC vent pipe considerably (sometimes 2-3 times) of metal analogs cheaper;
• smooth inner surface promotes maximum airflow and do not require periodic cleaning;
• the opportunity to cut a piece of wire on site, and a wide range of different fittings greatly simplify the assembly and installation of the construction;
• no toxicity and complete safety for both human and environmental sredy.8.

Along with all these advantages have flexible PVC ducts and one major drawback: a low fire resistance.

calculation of air ducts

Calculation of ventilation ducts is one of the most important stages of designing the air supply system. Before proceeding directly to the selection of cross-sectional area of ​​wires, it is necessary to determine the performance of the ventilation air.

Calculation of performance through the air ventilation system

To start required site plan, which specified area and the purpose of each room. The air supply is provided only in those rooms in which people are long time (living room, bedroom, study). Not supplied with air in the corridors because there falls from the living rooms, and more - in the kitchen and bathrooms. From there, the air flow discharged through ventilation. This scheme prevents the spread of bad odors around the house or apartment.

The amount of air supplied for each type of dwelling calculated using MGSN 3.01.01. and SNIP 41-01-2003. Standard volume to 1 in each room is 60 m³ / h. Bedroom this figure could be reduced by a factor of 2 to 30 m³ / h. It is also worth noting that the calculation takes into account only the people for a long time in the room.

Useful advice!The calculation characteristics of the ventilation system can be carried out manually by the specified formulas. However, there are many online calculators that simplify and accelerate the solution of this problem.

The next step is to calculate the air by the multiplicity. Multiplicity indicates how many times per hour there is a complete renewal of air in the room. The minimum value is one. This value prevents stagnation of the atmosphere in rooms.

From the above, to determine the air flow rate is required to calculate the two parameters of air: at the multiplicity and the number of people, of which the larger value is selected.

The calculation of the number of people:

L = N x L_normwhere

L - Power ventilationM³ / h;

N - the number of people;

L_norm - normalized value of air flow rate on the person (typically - 60 m³ / h, in the sleep state - 30 m³ / h).

Calculation of the ventilation rate:

L = b x S x Hwhere

L - Power supply air m³ / h;

b - the multiplicity of air (living quarters - of from 1 to 2, offices - from 2 to 3);

S - floor space in m²;

H - vertical space dimensions (height) meters.

After calculating the ventilation for each room values ​​are summed for each method. And more will be required ventilation capacity. For example, typical values ​​are:

• rooms and apartments - 100-500 m³ / h;
• cottages - 500-2000 m³ / h;
• offices - 1000-10000 m³ / h

Method of calculating the ducts

To calculate the square ducts is necessary to know the volume of air which must flow in a time interval on them (as per the previous calculation step) and the maximum flow rate. The calculated values ​​of cross section decreasing with increasing speed of the air passage, but the noise level increases. In practice, for houses and flats speed value selected in the range of 3-4 m / c.

Related article:

Air ducts for ventilation. Installation, operation and maintenance of systems

Materials for manufacturing. Types of sections of air ducts. The methods of combining the elements of the system. Cleaning and disinfection of duct systems.

It should be noted that use low-speed wire with a large size is not always possible due to the complexity of placing in ceiling void. Design can reduce the height from the rectangular ducts having similar cross-sectional area at smaller dimensions, compared with the round shape. However, mount the circular flexible ducts faster and easier.

The calculation of the area of ​​the duct using the following formula:

S_c = L x 2,778 / Vwhere

S_c - the estimated size of the wire cross-section, cm²;

L - air flow rate m³ / h;

V - velocity of the air in the wire, m / s;

2,778 - constant for the conversion of various dimensions.

Calculation of the actual cross-sectional area of ​​circular cross section of the duct according to the formula:

Calculation of the actual area of ​​the plastic rectangular ducts by the formula:

S = A x B / 100where

S - actual duct area, cm²;

A and B - the transverse dimensions of the duct of rectangular cross section, mm.

Useful advice!If necessary to make the calculation of the air speed in the duct, you can perform calculations, inverse described for the selected channel cross section area.

The calculation starts with the Main Canal and spend for each branch. The air velocity in the main duct can be increased up to 6-8 m / c. It should be added that in domestic ventilation systems usually use circular channels 100-250 mm in diameter or a similar rectangular cross section area. Very useful for the selection of plastic ducts for ventilation Vents directories.

Note!When choosing a need to focus on compliance with product performance standards set by GOST. Ducts should also have quality certificates.

Organization of air ventilation in the kitchen

When selecting the kitchen hoods to decide exactly how bad odors are removed and evaporation - recirculating air or gas through the outlet to vent. Both the first and the second option has its own advantages and disadvantages. I should add that the majority of modern devices can operate in both modes, but in the absence of ventilation duct work, they will only be able to recycling.

The extracts without air fan draws air and passes through the filter, thereby cleaning it. Consumers who purchased this class of devices, often guided low price and ease of installation. However, their significant drawback is the need for periodic replacement of filters and rather low productivity.

The second embodiment is to work in the air outlet mode devices. When this gas is also absorbed by the fan, is then passed through zhiroulavlivatel and ejected in the ventilation shaft. This approach is more efficient, but requires a more laborious installation and additional cost to the retraction organization. The channel must be sealed, it is also recommended setting the valve to cut off flow of air from outside the room.

After the selection of a plastic duct for drawing in the kitchen you can buy it at a reasonable price directly from the manufacturer.

Mounting options and installation of air duct

The first method is attachment via pins and profile. He is one of the most prevalent in the professional environment, it is carried out by means of the L- and Z- shaped profile. When this profile is fixed to the box by means of screws. In the locking position the pin placed on rubber seals to reduce noise and vibration dampening.

When installing large main ventilation ducts are most commonly used pins and crosshead. Channel is based on the yoke, and pins restrict the possible lateral displacements. Also, the rubber seal can be used for better fixation. This mount leaves duct sealed, which is very important when installing sound- and heat-insulating elements.

Fastening clamp pin and is preferred for round channels mounting. Short sections of flexible duct can be fixed without studs.

Universal mount is punched tape. The method is suitable for rectangular and round plastic duct. In addition to the low cost of installation design has no rigidity and can vibrate noticeably.

Mounting of the flexible corrugated duct

Flexible and semi-rigid channels of small cross-section is usually used in homes as a duct for the kitchen range hoods. Installation is carried out in several stages:

• line marking is carried out according to the design drawings or own schema setup. Are held on the ceiling line to indicate the passage path channels;
• installation of fixtures. To prevent sagging, dowels attached every 40 cm along the guide line, they fixed clamps;

• measuring duct length. Metering hoses need to be carried out at their maximum tension;
• Slicing can use a sharp knife or scissors, and the frame wire cutting pliers have a bite. The insulation is cut only when wearing gloves;
• for building duct lengths - two sleeves are put on the connecting flange and the fixed yoke;
• sleeve end is aligned with the pipe flange or ventilation grille;
• Then hold direct mounting of a flexible duct. The sleeve is held under tension through the set collars to the junction with the central backbone;
• separate outlet is provided for each opening project.

Useful advice!In the case where the ceiling space limits the diameter of the channel you can use the transition from a circular to a rectangular duct with the same sectional area.

Montazh flexible insulated duct

Installation insulated duct held in a similar manner, but there are some nuances when cutting or alignment sleeve need to unscrew layer insulation, more cut / join the inner frame and flange, sealing compound, whereupon the insulation back to the original position again and fasten insulated.

The thermal insulation is connected to the body of the duct tape and aluminum collars. They also isolated by the outer layer.

It should take into account that the flange connection can be a weak point for mounting soundproofed duct. Attenuation increases donning full channel tube (without gaps). For sealing use the same materials.

Installation of plastic air ducts for drawing in the kitchen

After selection in directory plastic rectangular duct for ventilation and acquire all relevant elements can proceed to the assembly. Trial assembly of units held on the floor or a table, which is then hung from the ceiling or attached to the wall. Compound straight sections is performed couplings. Shaped elements joined nipples which, in turn, is obtained by cutting from a straight section of the desired length pieces.

The connecting elements in ventilation systems are made with larger diameter pipes for tight joining direct channels. Therefore docked, for example, a tap tee needed via direct short pipe (pin). Once connected, this site is fully concealed pipes.

Arising in connections and the looseness and gaps can cause air leaks, so they are covered with sealant before docking. It should be remembered that the use of screws and lead to seal failure.

Some contractors are screwed plastic air ducts for drawing to the suspension or bracket screws. In implementing such a method of installation ducts price is reduced, and the process is significantly accelerated. Is correct installation channel yokes that densely cover tube. This mount is equipped with a rubber gasket and is made specifically for fixing the bracket to a wall or hanging hairpin.

Studs required length are attached to the plates overlap anchors or other hardware. Also commercially available plastic brackets and clamps in the form of tabs. These elements greatly simplify and speed up the assembly process.

Organization of the ventilation system - a relatively simple process. Describes a simple method of calculation makes it easy to find the right items, and a wide range of ventilation channels and connecting elements simplifies placement and installation of plastic ducts in a limited space of ordinary premises.