Ventilation planning is an important phase of construction. The microclimate and durability of the building depends on the efficiency of the ventilation system. Especially responsible it is necessary to approach the choice of air ducts. It should be understood which types of ventilation pipes are suitable for existing working conditions.
To deal with the issue, it is necessary to evaluate the properties of the materials from which they are made, as well as the features of the operation of products of different shapes and degrees of flexibility. This is what the article will discuss in this article, where we will examine in detail the characteristics of pipes from various materials, providing the material with thematic photos.
The content of the article:
- Ventilation Duct Requirements
Types of materials and their operational properties
- View # 1 - plastic ducts
- View # 2 - galvanized products
- View # 3 - Stainless Steel Pipes
- View # 4 - black steel products
- View # 5 - Sandwich Pipe
- View # 6 - Technical Textiles
- Features of rigid and flexible ventilation channels
- Comparison of round and rectangular section
- Conclusions and useful video on the topic
Ventilation Duct Requirements
Design and calculation of ventilation - Responsible work, requiring from the contractor knowledge of building codes and understanding of the principles of air exchange processes. Equally important are the parameters of the building itself and the climatic features of the region.
Regardless of the air circulation pattern (natural or forced inducement), a network of ventilation ducts is established.
The productivity and reliability of the ventilation system largely depends on the correct choice of the geometric dimensions of pipes and the material of their manufacture.
Air ducts must meet several requirements:
- Tightness. This property is necessary to maintain thrust, as well as prevent the mixing of oncoming clean and exhaust air flows. Particular attention is paid to the connection of individual elements of the ventilation line.
- Noiseless operation. The level of aerodynamic hum should be within the limits of sanitary standards. Allowable noise system - 25-35 dB.
- Corrosion Resistance. Through the home pipeline is the release of air masses of varying degrees of humidity. Water vapors can accumulate on the walls of the ventilation channels, causing rust formation.
- Compact and light weight. The total footage of the highways of the ventilation system is large enough not to “overload” the building and clutter the space are selected pipes with a minimum size that provides unimpeded circulation.
- Fire safety. The material of pipe fittings should not easily ignite and emit harmful vapors during combustion.
In addition to the main characteristics, the compliance of ventilation pipes with additional parameters is welcomed: ease of installation, good thermal insulation properties and smoothness of the ducts.
An important parameter of the outlet pipes is high ring stiffness. The external part of the ventilation duct, which rises above the roof, is subject to considerable wind load.
Types of materials and their operational properties
Most domestic ventilation pipes are made from metal or plastic. The product range includes dozens of different positions. The alternative options for the arrangement of ventilation systems include products from technical textiles and sandwich pipes.
View # 1 - plastic ducts
The category of plastic pipes for ventilation has considerably pressed through traditional galvanization and is increasingly being used to create networks of air ducts of private households.
The range of polymer products allows you to choose pipes for the organization of the internal and external parts of the ventilation system. The device of a plastic highway in small buildings is quite justified.
The main arguments for the ventilation of polymer pipes:
- absolute non-susceptibility to corrosion, which cannot be said about galvanized brothers;
- ease of installation and processing - plastic can be cut with a hacksaw, and dock individual elements by heating the ends, ensuring complete tightness of the duct;
- lightweight - in this matter polymers out of competition;
- surface smoothness and lack of welds - resistance to moving air flow is reduced, which allows the use of smaller fans;
- low cost
Treatment of plastic pipe products with an antistatic agent minimizes the build-up of dust and reduces the number of cleanings. Due to the physical properties of the material, the pipeline practically does not “buzz”. Dimensions: length - 3-12 m, diameter - 16-1600 mm.
The listed advantages of plastic, along with low cost, make polymer products most in demand for ventilation. However, there are also negative sides.
The weak side of the plastic is low fire resistance. Therefore, the polymer duct is applicable within a single fire zone, compartment or department. For the arrangement of industrial ventilation plastic is prohibited
Preferring plastic pipelines, one should take into account the specific polymer features.
The construction market offers the following types of ventilation pipes:
- Polyvinyl chloride. Advantages of PVC ducts: resistance to UV rays, availability, operating temperature range from -10 ° C to +70 ° C. A popular application is exhaust pipes that provide ventilation in the kitchen and bathrooms.
- Polypropylene. Material technical performance exceeds PVC. Properties: boundary heating temperature +85 ° C, resistance to aggressive substances. There is a fire-resistant variety (PPS) with flame retardant additives. Polypropylene is covered with an antistatic that minimizes the accumulation of dust.
- PTFE. Fluorine-containing polymers differ in heat resistance (from -60 ° C to +200 ° C), resistance to UV exposure, and immunity to alkalis and acids.
- Polyethylene. Maintains negative temperatures up to -50 ° C and heating up to +80 ° C. The material retains the primary qualities under the action of ultraviolet.
Products with polyurethane have similar characteristics with PVC pipes. The difference of the latter is high temperature resistance (up to +270 ° C).
We recommend to get acquainted with the nuances plastic pipe selection for ventilation arrangement.
The shape of the flow section of plastic pipes is a circle, square, rectangle. Possible rigid or flexible structure. Corrugated ducts may represent a symbiosis of steel frame, aluminum foil and plastic layers
View # 2 - galvanized products
Galvanized pipe products are distinguished by their versatility - air ducts are used for arranging industrial, administrative buildings and housing facilities.
Galvanized steel is made of carbon steel of different grades and is subjected to hot or diffuse galvanizing. This treatment protects the steel from oxidation - the pipes are not afraid of contact with water.
Permissible working environment of galvanized ventilation pipes: air temperature - up to +80 ° C, humidity - up to 60%. Galvanization meets all the requirements for air exchange systems. Restrictions in the application - transportation of aggressive gas mixtures.
Summary of the advantages of galvanized steel:
- Low weight explains the ease of assembly of the ventilation system - there is no need to build a complex supporting structure that increases the cost of the engineering network. An additional plus is the convenience of transporting pipe fittings.
- Mechanical strength - galvanized steel withstands point pressure, mechanical impact with sharp objects and point loads. The resistance to bending pressure is higher in the pipeline with stiffeners.
- Due to the zinc treatment, the air duct does not corrode even under conditions of stable high humidity. Galvanized pipes are suitable for organizing ventilation exhaust to the outside.
- Under the influence of high temperature, galvanizing retains its original size and shape. The fire resistance of pipes for high-rise buildings is 90 minutes.
- The operational life of a galvanized duct varies from 20 to 25 years.
Additional arguments for galvanized steel: reasonable price, the possibility of producing pipes and fittings of different configurations.
The range of galvanized rolled steel includes many items. The main criteria for classification: the shape of the duct, the diameter and thickness of the wall, as well as the degree of tightness
Based on the form and principle of manufacture, galvanized pipes for ventilation are divided into the following types:
- round longitudinal;
- spiral wound.
Rectangular products are made on the machines of the tunnel assembly. The standard length of the pipe cut is 1.25 m, the minimum size of the cross section is 10 * 10 cm. Rectangular air ducts are equipped with stiffeners.
Round longitudinal welding is characterized by simple manufacturing technology. Galvanized sheet steel is cut, rolled into a pipe on a roll mill and fed to a faltserokatny machine to connect the ends.
The main feature of longitudinal longitudinal ducts is high aerodynamic performance, ensuring quiet circulation of air masses without sound vibrations. Cut length - up to 2.5 m
Spiral-wound products are made of galvanized strip (width - 137 mm), twisted into a spiral. Edge docking - lock joint with external seam.
The design of the pipe determines a number of positive qualities of "spiral" ducts:
- significant stiffness;
- savings on the purchase of shaped elements;
- easy installation;
- acceleration and low noise during air transportation - in the spiral channel, the turbulence of the flows is amplified.
The arrangement of ventilation systems with spiral-wound pipes is cheaper compared to the use of rectangular products.
“Spiral” cuts of 3 m and 6 m are on sale. Custom-made pipes can be made of arbitrary footage and can be equipped with additional stiffening ribs
The wall thickness is normalized and depends on the diameter:
- 0.5 mm - for air ducts with a section up to 315 mm;
- 0.7 mm - products with a diameter of 350-800 mm;
- 0.9 mm - pipes of standard size 900-1250 mm;
- 1.2 mm - air ducts with a section of 1400-1600 mm.
According to the class of tightness according to SNiP, galvanized pipes are divided into dense (П) and normal (Н). The difference criterion is the method of execution of the weld.
In dense constructions, the joints after welding are rolled by a press and covered with a sealant. This duct can withstand pressures up to 1.5 MPa and is suitable for use in buildings with a high risk of explosion. Normal ventilation products are mounted in household systems.
View # 3 - Stainless Steel Pipes
Pipes from a stainless steel have in their arsenal all of the listed advantages of rolled steel. The addition of chromium to the alloy makes the metal rust-proof. Correction of the composition by adding additional alloying elements gives the stainless steel specific qualities.
Depending on the chemical composition of the range of corrosion-resistant steel is divided into several grades: C1 - martensitic (chromic) steel, F1 - ferritic steel, A1-A5 - austenitic steels with nickel
For the construction of ventilation systems are used pipes of austenitic steel, characterized by:
- corrosion resistance to many working environments;
- good processability;
- strength and ductility;
- heat resistant - up to +500 ° C;
- chemical inertness to toxic and radioactive substances;
Products made of chrome-nickel stainless steel are more expensive than galvanized ducts. Externally, the products are similar to what unscrupulous manufacturers sometimes use.
There are several ways to detect fakes.
- Spectral analysis. Requires special devices that determine the chemical composition of the metal.
- Visual inspection. On galvanizing, the presence of characteristic “divorces” - crystallization patterns is permissible.
- Electromagnetic Differences. Most stainless steel alloys are not magnetised, whereas a magnet is well attracted to steel.
- Chemical reaction. As a result of interaction with hydrochloric acid, zinc begins to bubble (hydrogen is released), and zinc gradually disappears. For the experiment, one drop of acid is enough.
It should also be borne in mind that the pipe rolling of galvanized steel has a faint bluish tint.
If a stainless steel is not subjected to mirror treatment, then it, compared with galvanization, has a more matte surface
View # 4 - black steel products
Products from the "black" rolled products are used in smoke removal, aspiration and ventilation systems. This is a good option for exhaust vent pipes. Regarding stainless steel and galvanized steel has improved rigidity, fire resistance and heat resistance.
For the purpose of additional corrosion protection, air ducts on the outside and inside are coated with a red-brown primer. At the individual order delivery without the priming layer is possible
Characteristics of pipe fittings made of black steel:
- wall thickness - 1.2-1.5 mm;
- footage - 1.25-2.5 m;
- docking pipes flanged way;
- execution options - rectangular, round section.
The cost of “black” rolled products is higher than galvanized air ducts of the same size, but lower as compared to stainless steel.
View # 5 - Sandwich Pipe
Insulated air ducts are mounted when creating the ventilation of fireplaces, stoves, heating boilers. Pipes ensure the proper level of fire safety of the system and heat preservation in the room.
The device is a sandwich pipe: two metal "sleeves", between which there is a thermal insulation layer. The material of the outer pipe - galvanized steel / stainless steel, the inner - black steel / stainless steel
Basalt fiber is often used as a heat insulating filling.
- low thermal conductivity - up to 0.05 V * m / K;
- hydrophobicity - moisture absorption up to 2%;
- tensile strength - maintains pressure up to 10-60 kPa;
- biological resistance - material does not give in to rotting, does not promote reproduction of fungi;
- fire safety - melting point about 1100 ° C;
- vapor permeability and sound insulation - partial "absorption" of vertical sound vibrations.
Basalt is chemically inert and does not react with metals - the risk of rust is reduced to zero. The choice of a sandwich pipe for exhaust ventilation depends on operating conditions.
When heating with the use of solid fuel, air ducts are made of heat-resistant stainless steel; when heated with a gas-cooled carrier, a main line from ordinary steel is acceptable.
Advantages of sandwich pipe ventilation systems:
- universality of use;
- ease of assembly;
- pipeline layering prevents condensation;
- duct insulation.
The disadvantages of insulated pipes include: a large weight (2-2.5 times the metal, several times - polymers) and high cost.
View # 6 - Technical Textiles
Fabric air distribution system proposed by Danish developers 20 years ago. The novelty has partially replaced metal channels in the food, electronic, chemical industry, catering, swimming pools, concert and exhibition halls.
There are two types of textile pipes:
The purpose of the airtight systems is the transportation and removal of air masses. Production material - polyamide.
Air-permeable channels (textile diffusers) evenly distribute the supply air in the room through perforated holes and exhaust adapters. Material "sleeves" - polyester
Fabric systems are free from the shortcomings of metal ducts. Among the significant advantages of textiles include:
- No drafts. A draft is often observed in the air supply zone from the metal / plastic channel. Through the textile pipe is "scattered" supply of air jets.
- Noise absorbing qualities. Fabric "extinguishes" the aerodynamic noise of the fan and air flow.
- Ease of cleaning. Textiles act as a barrier, partially filtering the supplied air. The material accumulates dust, but is easy to clean - washable (50 cycles) and disinfect.
- Condensate protectionbut. Due to vapor permeability, no condensate forms on the surface of the fabric piping. Microorganisms do not develop in dry canals.
The optimal air flow rate for a textile pipe is 5-8 m / s, for other types of pipes are also provided air flow ratesthat should be considered when designing ventilation and choosing duct material.
At pressure decrease the form "sleeves" keeps at the expense of the thin sewn rings. The service life of the duct is 10 years. Fire-hazardous premises are equipped with textile pipes with additional fiberglass - the limiting temperature is +300 ° C.
Features of rigid and flexible ventilation channels
According to the degree of flexibility distinguish rigid and flexible air ducts. The choice between two positions depends on the complexity of the system being built and the operating conditions. When installing a rigid network, turns and transitions are made using the connecting corner elements.
We recommend to get acquainted with the main types of fittings for steel pipes and technology to perform various connection options.
Flexible duct "adapts" to any vector of the direction of the line. In some cases, a combined version is used - the corrugated pipe is joined to a rigid
Flexible air ducts are made of various materials. But, regardless of the material of manufacture, corrugated air ducts, in comparison with rigid channels, they have some drawbacks: low sound insulation, reduction in air flow rate due to corrugated walls.
It is the composition of the pipe that determines its technical and operational properties:
- Aluminum Corrugation: corrosion resistance, endurance to temperature fluctuations (-30 ° C / + 270 ° C), tightness, bending radius - 0.76 d, chemical inertness, refractoriness.
- Polyester reinforced steel frame. Characteristics: low cost, moisture resistance, low flammability, temperature range is -20 ° C / + 65 ° C, low weight. The disadvantage is the accumulation of static electricity.
- Polyester film with aluminum foil it has high strength (allowable pressure - up to 2400 Pa), good aerodynamic properties.
- Heat insulation corrugation provides a reduction in heat loss and prevents condensate.
Regardless of the type of ventilation pipe chosen, it is important to be able to install it correctly. Installation diagrams and detailed installation instructions for flexible and rigid ducts we reviewed here.
Comparison of round and rectangular section
Many wonder what form of pipe to choose: round or rectangular? If we estimate the throughput, the round products win - the air masses meet less resistance, which means that the circulation is faster.
In rectangular pipes, the corners remain unused, therefore fittings with an increased cross-sectional area are selected. However, such a highway takes up less space - wide and flat models are easier to hide behind a hinged ceiling or above cabinets.
The oval-section pipe combines the strengths of rectangular and circular ducts: good throughput and the ability to “hide” the ventilation system
Also, the section is an important parameter that is used when calculation of duct areanecessary for the arrangement of the ventilation system. Correctly performed calculations will allow you to purchase the required amount of material without overpaying for extra pipes.
Conclusions and useful video on the topic
Characteristic features of plastic, asbestos-cement, corrugated aluminum and steel galvanized pipes for ventilation of basements and cellars:
The organization of the ventilation system requires a competent approach to the choice of the main structural elements - ventilation pipes. Products for galvanization, stainless steel and plastic meet most of the requirements for air ducts of private houses..
Form is not of fundamental importance. Her choice depends on the characteristics of the path of the ventilation network.
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