Analysis and comparison of galvanized steel duct and double-sided color steel duct

Update:27 Aug 2020

Due to the close integration of the duct production, in […]

Due to the close integration of the duct production, installation and construction of the ventilation and air conditioning system with the site, this task has been completed by the engineering construction unit for a long time. However, attracted by the huge market, many manufacturers have developed various new materials for air ducts hoping to get involved in this industry. In recent years, a wide variety of composite air ducts have appeared on the market, and some air ducts have also been promoted in ventilation and air conditioning projects due to their outstanding characteristics. For example: aluminum foil composite air duct is used as the soft connection between the air duct and the tuyere; the application of FRP air duct in the detoxification system. However, due to the immature technology, the composite air duct has many technical defects and has not been widely promoted. Galvanized steel duct is always in the leading position with its mature technology and good combination with the site. Now a kind of double-sided color steel plate composite air duct has appeared on the market, which overcomes some defects of the composite air duct. It has also been promoted to a certain extent, but there are still some processes that need to be improved. The performance of galvanized steel duct and double-sided color steel duct is now compared as follows:

From the above table, it can be seen that the performance of the double-sided color steel plate composite air duct is not much different from that of the galvanized steel plate air duct, which can already meet the performance requirements of ventilation and air conditioning. However, the following defects still exist in the process:

1. The performance of the plate: the plate is uniformly processed by machinery, the thickness of the steel plate is about 0.3mm, which cannot be adjusted according to the pipe diameter, and there is no additional reinforcement measures, the strength is slightly insufficient when applied to the large pipe diameter air duct. In addition, due to the separation of the inner and outer surfaces of the double-layer color steel plate, the inner layer steel plate bears greater pressure, and the deformation and the outer plate surface are uneven, which will affect the overall performance of the air duct. The steel plate thickness and reinforcement method of the galvanized steel duct can be flexibly adjusted according to the specifications.

2. Flange form: Double-sided color steel plate composite air pipe adopts PVC combined flange, this flange is easy to age, there are joints, which affects the amount of air leakage and water easily penetrates into the insulation layer from the joints. The flange protrudes into the air duct, increasing the resistance along the way. In addition, this type of flange cannot directly interface with the fan and unit, and the connection between the double-sided color steel plate duct and the tuyere is not easy to handle. The galvanized steel plate air pipe flange is an angle steel flange frame, and the inner wall of the air pipe is flat, making the resistance less than the double-sided color steel composite air pipe. The connection with the fan, unit and tuyere also has mature technology.

3. Insulation form: double-sided color steel plate composite air duct adopts sandwich insulation. The material, thickness, fullness of the middle insulation layer, and the environmental protection and flame retardant properties of the glue cannot be visually inspected. If the insulation layer penetrates into moisture, it will cause the insulation material to rot, and the rotted insulation material cannot be replaced. In addition, the double-sided color steel plate composite wind pipe flange has joints and no insulation, which affects the insulation effect. The outer layer of the double-sided color steel air duct is a smooth metal plate, which is easy to form condensation under hot and humid climate conditions, especially when the sandwich insulation is partially damaged. The galvanized steel air duct has already formed a mature heat preservation method, and the craftsmanship and quality are guaranteed. The application of wooden supports also overcomes the common "cold bridge phenomenon". Now in the selection of insulation materials for ventilation and air conditioning, rubber-plastic insulation boards are the most suitable insulation materials. The double-sided color steel plate has not yet produced air ducts of this kind of insulation material.

In addition to the above performance defects, the production, installation and on-site construction of the double-sided color steel plate composite air duct still have the following problems to be solved:

1. The production of air duct: the double-sided color steel plate composite air duct is produced by the manufacturer in a unified manner. It is off-site and cannot be monitored by the supervision. In addition, the manufacturer serves multiple units at the same time, without specificity, and cannot arrange production according to the project schedule. Too much production at one time, if there is a change in engineering, it will cause a lot of waste. If manufacturers have too many production tasks, they will not be able to guarantee the timely arrival of materials and affect the progress of the project.

2. Transportation and storage of the air duct: Due to the large volume of the air duct, the transportation cost is extremely expensive. Excessive attendance at one time requires a lot of storage space, and a lot of manpower and material resources will be wasted in handling and storage.

3. Timeliness of response to engineering changes: Due to changes in the requirements of the owner and the need for professional cooperation, local changes often occur in the project. Air ducts are produced by manufacturers, and it is difficult to adjust them in time due to factors such as message transmission and production planning arrangements. There will be phenomena such as waste of produced materials, and failure of materials to enter the site in time after changes, affecting the construction progress of the project.

The galvanized steel sheet ducts are processed on-site and are manufactured on-the-fly, specifically for this project. Overcome all the above problems.

In summary, there are still many shortcomings to be perfected in the double-sided color steel composite air duct technology and production form, and this new technology has not yet been widely promoted, and there are still many uncertainties. Therefore, galvanized steel ducts are still suitable for large-scale ventilation and air conditioning systems.