Ventilation Duct

How to Install Ventilation Duct

How to Install Ventilation Duct

Install Ventilation Duct

Install Ventilation Duct Ventilation duct mainly refers to the ventilation duct of central air conditioning system, which we often ignore it, but it is an important part of air conditioning system. It is a kind of metal or composite pipe for ventilation and air conditioning engineering of industrial and civil buildings. It is a municipal infrastructure to make the air circulate and reduce the concentration of harmful gases.

Classification of Usage

Divided into: supply and return air pipe of the purification system, ventilation pipe of central air conditioning, industrial supply, and exhaust air pipe, suction and exhaust air pipe of the environmental protection system, mine gas drainage pipe, mine rubber-coated cloth air duct, etc. Install Ventilation Duct

Classification of Shape

Divided into: round duct, rectangular, spiral duct. Install Ventilation Duct

Classification of Processing Technology

Divided into: angle iron flange duct, TDF flange duct. Install Ventilation Duct

spiral duct

Application

The air duct is mainly used in industrial and construction engineering, and its application fields mainly involve: purification system of the dust-free workshop in electronic industry, purification system of the aseptic workshop for medicine and food, central air conditioning system of hotels, shopping malls, hospitals, factories and office buildings, exhaust duct for dust removal, smoke extraction and oil absorption in industrial pollution control, supply duct for the industrial environment or post comfort, air duct for air-conditioning, air-conditioning system for air-conditioning and air-conditioning Gas drainage system for coal mine gas drainage, air supply and return system for coal mine environment control, etc. Install Ventilation Duct

Air Duct Construction

  1. For more complex civil buildings, in the design stage, each type of work (HVAC, water supply and drainage, power supply and lighting, and Architecture) should first negotiate the space separation, and determine the elevation range of each kind of pipe. In general, they should not go beyond the limits set for themselves. In case of the crossing of individual pipe sections, it is necessary to negotiate with other projects. Install Ventilation Duct
  2. The principle to solve the collision and coordination of various ventilation pipes is generally: “small pipes give way to large pipes, and pressure gives way to no pressure”. For example, if the water pipe collides with the air pipe, the water pipe should be turned. If the cold and hot water pipes collide with the downpipe, the cold and hot water pipes should be changed. Install Ventilation Duct
  3. Before construction, the Engineer in charge of the main equipment shall draw the pipelines and single lines of each type of work on a plan. One-color pen for each type of pipe. Integrate the elevation of each intersection to see if there is any contradiction, find it in time, and solve the problem before installation. Install Ventilation Duct
  4. In order to reduce investment, save space and reduce floor height, some pipes without slope requirements can be laid through beams (such as water pipes, fire spray pipes, etc.). Install Ventilation Duct
duct installing

Common Problems of Air Duct Installation

  • The material does not meet the quality requirements

This kind of problem is a headache. If the material does not meet the requirements, the air duct will leak when the system is running, which will cause the loss of air conditioning load and affect the service life of the air duct. Install Ventilation Duct

rectangular duct
  • Noise in duct

This phenomenon may be caused by the uneven surface, uneven thickness, obvious indentation, crack, sand hole, scar and corrosion of the plate, or the plane sinking of the ventilation duct, the side protruding outward, and obvious deformation.

  • The warping angle, twist and elbow angle of ventilation duct are not accurate Install Ventilation Duct

This is due to the inaccurate setting out of plate cutting; The length and width of the sheet metal on the opposite side are not equal; The width of the undercut at the four corners of the ventilation duct is not equal; The setting position of bite seam is wrong, and the force of manual bite seam is different; Taking no corresponding reinforcement measures. In this case, the relative plane of the rectangular duct is not parallel, and the two ends are not parallel; The angle is not straight; The diagonals are not equal; Install Ventilation Duct

The bite is not tight. The final direct result is that the air duct connection is uneven, the installed air duct is not straight, the flange gasket is not tight, the system air leakage, resulting in air conditioning load loss, and shortens the service life. Install Ventilation Duct

Precautions for Air Duct Installation

rectangular air duct

1. Check the quality of materials before installation

Carefully measure the thickness of the steel plate. Before the installation of the air duct, the factory certificate and material quality certificate of the material must be checked first, and then the appearance of the material must be checked; Then measure the thickness of the steel plate. Prevent rework due to non-conforming materials. Install Ventilation Duct

2. Hoisting safety should be guaranteed

The hoisting of the clean air duct is the same as that of the ordinary ventilation duct, and the suspender, cross arm, expansion bolt, and lower skid of the insulation air duct are required to meet the relevant specifications and quality acceptance standards. Install Ventilation Duct

Install duct

3. Pay attention to unfold the blanking steps

The construction personnel should strictly check the sheet metal, and control the length, width, and diagonal of each sheet metal within the allowable range; After blanking, the two sheets on the opposite side of the air duct should overlap to check the accuracy of the size; The reserved size of sheet bite must be correct to ensure the same width of bite; The biting seam sets at the four corners. When the biting seam is closed by hand, the center of both ends of the biting seam shall be tightened with a wooden hammer, and then the biting seam shall be uniformly compacted along the whole length. Install Ventilation Duct

4. Do a good job of light leakage inspection

After the ventilation duct assembles on the ground, the light leakage inspection should carry out before the heat preservation. According to the site conditions, the light leakage inspection can be carried out according to the internal or external light leakage, and the sealant shall be added at the light leakage, and the heat preservation can be carried out only when there is no light leakage. Install Ventilation Duct

Air duct install

5. Air leakage test

For the supply and return air main pipe and branch pipe of purification system with higher grade, besides light leakage inspection, air leakage test shall be conducted after ground assembly. For the smaller system, it can be tested after the installation of the air duct, and for the larger system, it can be carried out after the segmented assembly on the ground as far as possible, so as to find problems and deal with them in time. Install Ventilation Duct

6. The cushion material should be selected well

The gasket at the flange connection of the ventilation duct shall be made of airtight, dust-free, elastic, and non-aging materials, such as closed cell sponge rubber plate, soft rubber plate, etc. the thickness of the gasket shall be 5-8mm. The joint shall be processed into ladder shape, and direct butt joint is strictly prohibited. Install Ventilation Duct

It can be summed up in one sentence, how to correctly install the air duct is extremely important, the following describes some of the installations of air ducts in more comprehensive detailed steps, reduce the loss caused by installation problems.

  • Ensure foundation works are completed before installation

The installation of the ventilation duct must be carried out after the completion of these foundation works; Before installation, the appearance quality shall be inspected, and the dust on the inner and outer surface and the debris in the pipe shall be removed. Install Ventilation Duct

Air duct

● Prefabricated ventilation duct

If it is not to be installed temporarily, it should not be placed at will. All pipe orifices should be wrapped up with a plastic cloth and stacked indoors according to the system number as far as possible. If the conditions do not allow it, it must be stacked outdoors, and pay attention to place the cushion wood under the air duct, and there should be reliable rainproof, windproof sand, and sunproof shelter measures above.

● Clean the ventilation duct

The air duct should be cleaned with neutral detergent which has no corrosion to the surface of the board, no dust after drying, and no harm to the human body. First, clean with a cleaning solution, then clean with clean water, and finally wipe the watermark with a clean white cloth. If it is not installed, for the time being, it can also be dried naturally, but after drying, the air outlet should be sealed.

● Keep the ventilation duct clean and tidy

The installation personnel shall wear clean work clothes, gloves, and work shoes. The air duct and its components that have been cleaned and sealed shall not be disassembled before installation. When installing, remove the end sealing film, and then connect the connector; If there is a pause in the middle of the installation, the port should be re-sealed, so as to ensure the purification of the air conditioning system.

● No other pipelines shall be laid in the ventilation duct

The power line of the axial flow fan, electric heater, and other equipment installed in the ventilation duct system shall be protected and insulated. The fixed cable of the outdoor riser is strictly prohibited to be pulled on the lightning rod or lightning protection network. When the air duct passes through the wall or floor, it shall not be installed in the wall or floor.

The distance between the air duct and the wall should not be less than 200 mm, and the distance between the air duct and the floor should not be less than 150 mm. When the air duct passes through the fireproof and explosion-proof floor or wall that needs to be closed, the embedded pipe or protective sleeve with the wall thickness of not less than 1.6 mm shall be set, and the flexible material that is non-combustible and harmless to the human body shall be used between the air duct and the protective sleeve.

Install Ventilation Duct
  • The installation of ventilation duct shall meet the design requirements

The location of the reserved holes in the building structure should be correct, and the holes should be more than 100 mm larger than the outside size of the air duct. The connection interface between the air duct and the air duct of the building structure should be inserted along the airflow direction, and sealing measures should be taken. Flexible short pipe with a length of 150-300 mm shall be set at the joint of the ventilation duct and fan, fan case, air handling machine, etc., or according to the design requirements.

The flexible short pipe should not be used as reducing connecting pipe for alignment and leveling. The length of the flexible short pipe located in the structural deformation joint should be more than 100 mm larger than the width of the deformation joint. The installation slope of the air duct conveying condensate or moisture vapor shall meet the design requirements. It is not suitable to set longitudinal joint at the bottom of air duct, and the joint of air duct should be sealed.

  • Connection of ventilation duct flange

The gasket material should be used instead of thick paper, paperboard, asbestos rope, lead oil hemp fiber, and linoleum paper. The joint of gasket material shall be reduced as far as possible. The joint of gasket material shall be connected in trapezoid or tenon shape and shall be glued firmly. The width of gasket material after the flange is compressed evenly shall be level with the inner wall of the air duct. The joint between the air duct and the enclosure structure such as the ceiling and partition wall of the cleanroom shall be tight.

  • The ventilation duct system should have good grounding measures

When passing through the auxiliary production room, it must be tight, and no interface shall be set. When the temperature of conveying air is higher than 80 ℃, protective measures shall be taken for the air duct according to the design regulations. The air duct measuring hole shall be set at the position convenient for measurement and observation; For the measuring hole on the air duct in the ceiling, the movable ceiling plate or inspection door shall be reserved at the corresponding position. When metal flange and metal reinforcement are used for insulation air duct, measures shall be taken to prevent condensation of the cold bridge at its exposed parts.

  • The ventilation duct system should be checked for air leakage

This is the last link of the installation of air conditioning, but it is the most important link, so the owner must not ignore this link in the acceptance of air conditioning, and should carefully check to prevent air leakage after the installation of the air duct.

HVAC syetem
  • Common sense of air duct maintenance

After the installation of the air ventilation duct, the open parts such as the air duct mouth and the filter mouth that are not installed for the time being shall be properly wrapped with plastic cloth in time to prevent the dust from entering the cleaned air duct, thus causing secondary pollution in the duct.

1 thoughts on “How to Install Ventilation Duct

  1. Avatar of Jason Jason says:

    I’m a member of the air duct installation engineering team. I’m glad to see this kind of article in advance. It’s great

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