What Is The Ventilation Duct

What Is The Ventilation Duct What is the common ventilation duct in the ventilation and air conditioning system? What are their unique features? About the problem of pipeline material, this article goes to understand in detail, and next we will tell customers how to choose air duct machines.
What Is The Ventilation Duct
Advantages of iron sheet air duct
1. It has high strength and can withstand the wind pressure of 3000pa, which can meet the use of a high, medium, and low-pressure air system. What Is The Ventilation Duct
2. It can be processed on-site, with low transportation cost and convenient adjustment, without affecting the construction period. What Is The Ventilation Duct
Defects of iron sheet air duct
1. It is easy to rust and has a short service life, which is not conducive to improving the indoor air quality. In a humid environment, the service life is only 5-7 years, and after 4-5 years, the inside of the air duct is full of rust. What Is The Ventilation Duct
2. High air leakage rate and high energy consumption. The iron sheet air duct is connected by bite and flange, and its air leakage rate is about 10% (permitted by national standards). What Is The Ventilation Duct
3. The ventilation is noisy. The thin wall of the iron sheet duct will produce noise under the action of wind speed and pressure. What Is The Ventilation Duct
4. Large weight increases the load of the building. The weight of iron sheet air duct is more than 10kg per square meter. What Is The Ventilation Duct
5. High thermal conductivity. The iron sheet air duct adopts external insulation, which increases the project cost and affects the construction period. If the external insulation is not in place or damaged, it will produce a cold bridge. Condensate damage to the ceiling will damage the following objects. What Is The Ventilation Duct
6. The production and installation cycle is long. The iron sheet air duct should be constructed by large-scale machinery, with undercut and flange, and the speed is slow.
7. High maintenance costs. The iron sheet air duct should be maintained and treated with rust prevention. What Is The Ventilation Duct
8) It’s not beautiful. The iron sheet air duct is not smooth and beautiful after external insulation. What Is The Ventilation Duct
9. Occupy the ceiling space. The iron sheet air duct, together with the height of the flange and the thickness of the insulation material, occupies a large ceiling space (generally 40-60 mm). What Is The Ventilation Duct
Aluminum foil composite glass fiber duct
Aluminum foil composite glass fiber duct is made directly from the heat preservation material of iron sheet air pipe – superfine glass wool. In 1992, super air duct (glass fiber duct) entered the domestic market. Although it has been operated for more than ten years, the market share is still quite small, even the share is shrinking. What Is The Ventilation Duct
Advantages of aluminum foil composite glass fiber duct
- Sound absorption. Because it is directly made of superfine glass wool, the material is relatively loose and has good sound absorption performance.
- Lightweight. It weighs about 3 kg per square meter. What Is The Ventilation Duct
Defects of Aluminum foil composite glass fiber duct
1. The strength is poor. Due to the direct use of ultra-fine glass wool production, poor pressure bearing capacity can only be used in low-pressure, small ducts. Finished product protection requirements are high, easy to be broken by the later hydropower and decoration projects. It can’t be cleaned. What Is The Ventilation Duct
2. I’m afraid of dampness. Ultrafine glass wool has high water absorption. If the surface is not sealed properly, especially after slotting, it will absorb a lot of water and reduce the heat preservation performance and strength. What Is The Ventilation Duct
3. The fiber is easy to disperse. If the surface of superfine glass wool is not sealed in place, especially after slotting, it will lead to fiber dispersion and affect human health. What Is The Ventilation Duct
4. Large wind resistance. The absolute surface roughness is 0.9-1.1 mm. Generally, the unit power is required to be increased by 10% to increase energy consumption. What Is The Ventilation Duct
Aluminum foil polyurethane duct
Aluminum foil polyurethane air duct is a kind of air duct made of polyurethane in the middle and composite aluminum foil on both sides. One of the main characteristics of aluminum foil polyurethane air duct is lightweight, but its biggest deficiency is that the fire performance can not meet the national requirements. The national “code for fire protection of high rise buildings” and “code for fire protection of civil buildings” both stipulate that the ventilation duct materials must be made of class non-combustible materials. Aluminum foil polyurethane air duct can only reach B 1 level at the highest, and its accessories and glue are organic materials, and can only reach B 1 level at the highest, which is not in line with national standards. The poor strength and pressure bearing capacity of the aluminum foil polyurethane air duct are also its major shortcomings. What Is The Ventilation Duct
Aluminum foil composite phenolic duct
Phenolic duct is made of phenolic as thermal insulation material and composite aluminum foil on both sides. What Is The Ventilation Duct
The phenolic duct has the advantages of lightweight and obvious disadvantages, such as poor strength, easy pulverization, easy delamination of aluminum foil and phenolic, a large number of strong acids used in the foaming process, organic glue containing formaldehyde, which is not environmentally friendly. What Is The Ventilation Duct
Color steel plate air duct
The color steel plate air duct is divided into single-sided color steel and double-sided color steel. The single-sided color steel is to move the original superfine glass wool from the outside to the inside, that is, a layer of color steel from the outside and a layer of superfine glass wool from the inside. The double-sided color steel is to make a layer of iron sheet protection outside the insulation cotton of the iron sheet air duct. There is no great innovation compared with the iron sheet air duct in technology, but it is actually the iron sheet air duct. The improvement point is that PVC insert is used to replace the bite and flange, and the thermal insulation cotton and color steel plate are formed at one time without secondary thermal insulation. What Is The Ventilation Duct
Advantages of double sided color plate air duct
1. The airtightness is improved. Because PVC inserts are used to replace the bite and flange, the air leakage rate of the iron sheet air duct is reduced.
2. There is no need for secondary insulation, which improves the construction efficiency. What Is The Ventilation Duct
3. The color steel plate air duct improves the service life. What Is The Ventilation Duct
Defects of double sided color plate air duct
1. The use of PVC inserts instead of bite and flange makes the iron sheet air duct nondescript. It not only reduces the fire resistance and fire resistance of the air duct (PVC inserts can only reach B1 level) but also makes the advantages of good toughness of the iron sheet completely lost. In order to improve the tightness, it is more reasonable to think about the construction quality or plugging of the iron sheet air duct. What Is The Ventilation Duct
2. Glass wool is easy to disperse inside, which affects human health. Both single side and double side color steel plates need to be slotted to make an air duct. The sealing after slotting is a big problem, and it is difficult to seal in place. What Is The Ventilation Duct
3. The air duct is not easy to clean. The interior of one side is glass wool, which is not easy to clean. The interior of two sides is color steel plate. Under the action of cleaning brush, the paint layer will be damaged, which will affect the service life. What Is The Ventilation Duct
4. Compared with the iron sheet air duct, the strength is greatly reduced. The thickness of the color steel plate is only 0.3mm, which is 0.2mm less than the thinnest 0.5mm of the iron sheet air duct. The air duct needs to be reinforced, and the spacing between supports needs to be reduced, which increases the cost. What Is The Ventilation Duct
5. The finished air duct leaves the factory, which makes the iron sheet air duct easy to make and adjust on site. What Is The Ventilation Duct
6. PVC flange strength is not high, no metal bite and flange strength is high, is a weak point of strength. What Is The Ventilation Duct
Glass magnesium duct
- Glass magnesium air duct saves energy and reduces the operating cost of the system (energy saving air duct). The energy saving effect of glass magnesium air duct is quite obvious, which is more than 10% more than that of iron sheet air duct. For air duct, the main indexes to distinguish the performance of air duct are the resistance along the way, air leakage rate and insulation performance. The smaller the resistance, the lower the air leakage rate and the better the insulation performance, the better the performance of the air duct is. Glass magnesium air duct has excellent performance in these aspects: What Is The Ventilation Duct
- Good insulation performance, reduce heat conduction energy consumption. Glass magnesium air duct directly composite insulation materials, do not need secondary insulation, the air duct thermal conductivity is small, excellent insulation performance, reduce the loss of heat conduction in the process of cold and hot air transmission, in line with the national “code for energy conservation design of public buildings”. At the same time, glass magnesium air pipe has improved the external insulation of iron sheet air pipe, and changed it to internal insulation, which makes the insulation material protected by an inorganic layer, and avoids the damage to the insulation materials or other pollutants in the construction of other types of work, so as to make the insulation effect stable and long-term.
- The air leakage rate is low, and the air delivery efficiency is improved. Glass magnesium air pipe is made of adhesive structure, without flange connection, which greatly improves the airtightness of air pipe. Compared with iron sheet air pipe, it reduces air leakage of bite and flange, reduces air leakage rate of the air pipe, and improves air transmission efficiency. The air leakage rate of the glass magnesium air pipe is only 1/10 of the iron sheet air pipe. What Is The Ventilation Duct
- The glass magnesium air duct plate is manufactured mechanically with a smooth and flat surface, small friction coefficient, and low wind resistance, and the absolute roughness of the air duct surface is less than 0.2 mm. What Is The Ventilation Duct
- Glass magnesium duct can bring clean air (environmental protection duct) and improve indoor quality (IAQ). Glass magnesium duct can improve indoor air quality without rust, mildew, dust, bacteria, and fungi, dust and fiber, odor, granular and gaseous pollutants, and biological aerogel. What Is The Ventilation Duct
- Glass magnesium air duct has good sound insulation performance, with average sound insulation of 21db. Meanwhile, the insulation material has the function of vibration reduction and sound absorption, which can isolate and reduce the noise generated by air vibration and machinery, eliminate the noise caused by contraction and expansion of iron sheet air duct, and keep the indoor environment quiet.
- High quality and high performance products of glass magnesium duct
- Excellent fire performance. Glass magnesium duct is made of non-combustible inorganic materials and thermal insulation materials by high-tech process. It is a class of non-combustible material tested by national quality supervision and inspection center of fire protection building materials( Composite overall Grade A ).
- Super high strength performance. Glass magnesium duct has high strength, bearing capacity greater than 1000 N, can withstand 3000 pa wind pressure, can meet the use of a high, medium, and low-pressure air system. High strength also reduces the requirements of finished product protection in the construction process, so that the product is not easy to be damaged.
- Excellent moisture-proof and water-resistant performance. Glass magnesium duct is not afraid of water and does not rust and corrode in a humid environment. Even if immersed in water, it can still maintain high strength, with wet strength as high as 80%. What Is The Ventilation Duct
- It can effectively improve the net space of the ceiling. The glass magnesium duct adopts the non-flange connection process, which saves the height of the flange and can improve the indoor net space.
- The weight of the glass magnesium duct is 7 kg per square meter, which is 30% lighter than that of the iron sheet duct. It can effectively reduce the building load. What Is The Ventilation Duct
- Beautiful appearance. Glass magnesium air duct is connected by flange, with a flat bottom and beautiful appearance. The outer wall can be painted with any paint to facilitate secondary decoration.
- No cold bridge, more energy-saving. Glass magnesium duct adopts no cold bridge construction technology, there is no cold bridge node, more energy-saving. What Is The Ventilation Duct
- On-site assembly and installation, high construction efficiency, save time. Glass magnesium duct adopts on-site assembly and installation technology, does not need large machinery and equipment, on-site adjustment is fast, high efficiency can save time.
- The weight of glass magnesium duct is less than that of other composite ducts.
In addition to the above ventilation ducts, the following ventilation ducts are also commonly used in HVAC systems:
- Materials and types of ventilation pipes used in HVAC engineering
- Galvanized iron sheet air duct. This is a kind of ventilation pipe which is used earlier and still used at present. It is made of galvanized iron sheet and is suitable for gas transmission with small moisture content. However, due to its early appearance, there are many imperfections, such as ease to rust, poor anti-corrosion ability, lack of noise attenuation and heat preservation function, so it is necessary to set up an additional muffler and heat preservation protective layer, As a result, the production cycle is long, and the installation is inconvenient, there will still be large noise when using, and the service life is short. What Is The Ventilation Duct
- FRP air duct. Glass fiber reinforced plastic air duct is a kind of ventilation duct made of relatively new magnesium oxychloride material, which is strengthened by glass fiber cloth. It is made after hydration reaction and curing. This kind of pipe has the characteristics of fire resistance, corrosion resistance, high hardness but heavyweight, and also does not have the function of noise elimination and heat preservation. It needs to add a muffler and heat preservation protective layer to ensure the better operation of the HVAC system. Therefore, more time and energy are needed in the production and installation, and it is not easy to change and modify once the design is completed, It brings some trouble to the user process. What Is The Ventilation Duct
- Composite fiberglass duct. Composite fiberglass duct, also known as the new super duct, is a new type of ventilation duct with scientific and technological content with the continuous progress of science and technology in recent years. Centrifugal fiberglass board is used as the main material, and anti-moisture aluminum foil cloth is set outside the pipe, glass fiber cloth is used inside, and glue spraying is carried out. The composite fiberglass duct is light in the material, small in volume, easy to install, space-saving, easy to modify, fire-resistant and moisture resistant, and can eliminate noise, heat preservation, reduce air leakage, easy to use, long life, high cost performance, which has good application advantages in the current ventilation duct. What Is The Ventilation Duct
- Application performance of ventilation duct
- Thermal insulation performance
The wall of the super air duct is a centrifugal fiberglass board with low thermal conductivity (0.029 w / m / k at 24 ℃ and 0.04 w / m / k at 70 ℃). In particular, the outer composite aluminum foil has a high heat reflection ability, and its strength and toughness are much better than aluminum foil, so it is not easy to break. Because the air duct wall is the insulation layer, the pipe adopts a tenon joint, T-shaped inner frame butt joint, and iron sheet plug joint (or outer flange connection), so that all parts of the air duct are evenly insulated without cold bridge phenomenon, and has good thermal insulation performance. However, the galvanized iron sheet air duct and the inorganic glass fiber reinforced plastic air duct have no heat preservation performance, so the heat preservation layer and the heat preservation protective layer should be added. What Is The Ventilation Duct
2. Fire performance
Super air duct is based on non-combustible glass fiber cotton board, using self-made flame retardant adhesive (national patent), aluminum foil cloth, and glass fiber cloth are compounded on both sides of the substrate. Therefore, the finished duct belongs to non-combustible material, which conforms to grade A of GB8624-1997 “classification method for flammability of building materials”, and has good fire performance. The galvanized iron sheet air duct and inorganic glass fiber reinforced plastic air duct are non-combustible materials, but whether their thermal insulation materials burn depends on the material. Originally, polystyrene board was used as an interlayer, because it would produce toxic gas under the effect of an external fire source, so it was gradually eliminated. At present, non-combustible insulation materials such as centrifugal glass wool are usually used as the interlayer. Due to strength and other problems, the product quality is not very stable. What Is The Ventilation Duct
3. Noise elimination performance
The wall of super air duct is a kind of porous sound absorption material, which has good sound absorption effect for medium and high frequency sound waves. Some data show that the noise elimination capacity of super air duct can reach 18 dB / M ~ 21 dB / m when the medium frequency is 1 000 Hz ~ 2 000 Hz and the pipe diameter is 500 mm ~ 320 mm. It is a very good pipe type noise eliminator, which can eliminate the primary noise from air-conditioning equipment and the noise from valve body, valve body and air-conditioner With the extension of the pipe, the effect of the secondary noise produced by the pipe fittings is more obvious, so the special muffler can be omitted. However, the galvanized iron sheet air duct and the inorganic glass fiber reinforced plastic air duct have no noise elimination performance, so the muffler should be added. What Is The Ventilation Duct
4. Moisture resistance
There are no perishable materials and components in the materials used for the super air duct. The outer surface of the air duct is made of moisture-proof aluminum foil cloth. Its moisture permeability is 0, and it has a strong anti-corrosion ability. The water absorption rate of fiberglass board is not more than 2%. When the pipe is in a humid environment for a long time, its noise elimination and heat preservation properties will not change. Because it is a porous material, it is necessary to prevent the pipe interior, pipe end, an incision from being soaked by water for a long time. The galvanized iron sheet air duct is easy to be affected by moisture, corrosion, and rust, which is more serious when conveying air for air conditioning with large moisture content. Especially when the air duct is made, the galvanized layer at the iron sheet bite is damaged, and it is not easy to make up an anti-corrosion treatment. There will be condensation at the place where the cold bridge is produced, which will cause corrosion to the pipeline, thus affecting its overall life. Due to the restriction of raw material ratio, the stability of moisture-proof ability of inorganic FRP air duct is poor. What Is The Ventilation Duct
5. Air leakage
According to the specification, the air leakage volume of air duct shall be calculated according to the percentage of system air volume according to the length and air tightness of the duct. The air leakage rate of air duct should be 10% (for general air supply and exhaust system). The super air duct is connected by slotting, tenoning and gluing, and the joint is sealed by aluminum foil tape. The air leakage of the non reinforced air duct is basically 0, the air leakage rate of the reinforced air duct is not more than 1%, and the air leakage rate of the system is not more than 2%. When the static pressure in the pipe is 500 PA, the air leakage per unit area of the air duct is less than 118 m3 / h · m2.
6. Weight
The volume weight of super duct is 64 kg / m3, and the weight per unit area is 2.8 kg / m2 (thickness) δ= 25 mm, including the weight of hanger bracket (1.5 kg), which is the lightest of all kinds of duct materials. The volume weight of galvanized iron sheet air duct is 7 870 kg / m3, and that of inorganic glass fiber reinforced plastic air duct is 2 100 kg / m3.
7. Friction resistance
The inner wall of the super air duct is made of the glass fiber cloth, and the surface roughness is 0.2 mm, which is slightly larger than the measured value of the iron sheet air duct. When the wind speed in the air duct is less than 15 m / s, the resistance along the way is less than 7% compared with that of the iron sheet (including the resistance increased by the reinforced strut in the air duct), In general ventilation and air conditioning duct, the resistance along the way only accounts for about 10% of the local resistance (the local resistance of super duct and galvanized iron duct is basically the same), so the increased ventilation resistance of glass fiber duct is less than 1% compared with iron duct, which has no obvious impact on the whole duct system and can be ignored. The friction resistance of the inorganic FRP duct is larger than that of the iron sheet duct, which is close to that of the composite fiberglass board duct.
8. Shielding capacity of fiberglass duct
The inner wall of the composite fiberglass duct is made of composite fiberglass cloth, which has the ability of shielding fiber from flying. Under the condition of 15 m / s wind speed in the duct, the fiber in the inner wall of the duct does not fall off, which fully meets the national health standards and ensures the indoor air quality and environment.
- Application effect and Prospect of ventilation pipe
- Galvanized iron sheet air duct. As a kind of traditional ventilation pipe, it is generally suitable for HVAC projects with low requirements for environmental conditions. It is suitable for conveying dry and non-corrosive gas. In use, because of the large noise and the insulation effect can not last for a long time, in the long run, it may be gradually replaced by ventilation pipes of new materials.
- FRP air duct. It is a kind of ventilation pipe that is later than galvanized iron sheet air duct. It has the characteristics of fire prevention and corrosion resistance. It is suitable for outdoor overhead HVAC engineering and corrosive environment. Its appearance has been favored by many consumers. However, in view of the actual moisture-proof effect of FRP air duct, and the overall quality performance has not reached the expected effect, And because its price is calculated by weight, this unreasonable pricing method makes the more expensive price of FRP air duct not directly proportional to its actual value, so the number of users has declined in recent years. With the further development of the market economy, the material and price of the FRP air duct must be changed in order to obtain long-term survival and development space.
- Composite fiberglass duct. It is a new type of ventilation pipe that appears and uses in recent years. It has been gradually accepted by people and occupies a larger market share. Its overall performance is more advantageous than the previous ventilation pipe, and its design is more scientific and reasonable, more humanized. It is not only easy to install and use, but also has better performance, economic applicability, noise elimination, heat preservation, and space-saving, It can be widely used in different environments, and has a long service life, so it has a long-term development space. With the continuous progress of science and technology and the continuous improvement of people’s understanding, it will become a kind of universal ventilation pipe and occupy a larger market space.
In a word, the composite fiberglass board air duct has the advantages of noise elimination, heat preservation, fire prevention, moisture resistance, small air leakage, stable performance, economic applicability, etc. in different places, according to different requirements, all kinds of air ducts will have their uses. It has the advantages of light material, easy handling and hanging, convenient modification on-site, easy construction, convenient assembly, fewer connection points to be sealed, saving installation space, high thermal efficiency, quiet operation, long working life, optimal performance-price ratio, and low comprehensive cost. Strengthen the research and application of new materials and new technology of air ventilation pipe, so that we can better adapt to the market and grasp the market.
Good article, hope to see more like this