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Technical Problem In Hvac Duct Cleaning System Production And Installation

  • source:metmac;
  • Time:09/16/2020

1. The cleaning system is in charge of too many splicing seams

1.1. Form of expression: The air duct of the clean system has horizontal splicing seams and large sides<the bottom edge of 800TLm has longitudinal stitching seams.

1.2. Harmfulness: increase the amount of dust in the system air duct and increase the air filter

Load, and shorten the service life of the filter and reduce the cleaning effect.

1.3 Analysis of the causes

① If the ducts are not manufactured in accordance with the "Construction and Acceptance Specifications", they should be reduced as much as possible.

Less splicing. The width of the bottom edge of the rectangular duct is within 800TLm, and there should be no seams;

Above 80oTLm, minimize the longitudinal stitching. But there must be no horizontal seams;

② One-sided reduction of loss to save materials;

③. The air pipe cutting has not been considered comprehensively.

---1_5

 

2. The air filter box is not tight

2.1. Form of expression: air filter box leakage; filter box and filter frame. The frame is not tight.

2.2. Harmfulness: Due to the lack of tightness of the filter box, leakage to the external environment is caused. Wind not only increases cold and heat energy loss, but also reduces the cleaning effect; in addition, due to the joint between the filter frame and the filter box is not tight, so that the air flow reduces the cleanliness of the clean room.

2.3. Analysis of the causes:

① The connection method of the box body plate is improper. The bite form can adopt corner bite and joint

Angle bite, try to avoid using snap bite

② The box body and the filter frame are not connected tightly. The box and filter frame adopt

When the bolts are tightened, the gap must be fitted with a sealing gasket to prevent the void without the filter.

Airflow

③ The verticality and horizontality of the frame are poor;

④ The connection gap of the box body plate, the gap between the box body and the frame is not sealed

---2_4

 

3. The cleaning system is not tight

3.1 Forms of expression: air pipe bite seam, flange connection, air pipe of the clean system

Air leakage at corners, exposed movable parts of the air volume control valve, etc.

3.2. Harmfulness: Because the connection parts are not tight, the air leakage of the system is excessive large, not only increases the loss of cold and heat sources, but also affects the cleanliness of the clean room.

3.3. Analysis of the causes:

① Improper selection of air duct bite form

② No sealing measures are taken for the gaps of the air duct

③ Improper selection of flange gasket material, thickness and connection form

④ The flatness of the flange, the spacing of bolt holes and rivet holes do not meet the requirements

⑤ The shaft hole of the air volume control valve is not tight

⑥ The flange of the duct has a small amount of flanging.

---3_5

4. The installation quality of the high efficiency air filter does not meet the requirements

4.1 Form of expression: damage to the body of the high-efficiency filter, and the tuyere frame of the high-efficiency filter the frame or the high-efficiency filter frame is not tightly connected, and there is leakage after inspection

4.2. Harmfulness: The cleanliness of the clean room cannot meet the design requirements.

4.3. Analysis of the causes

① The high-efficiency filter is not transported and stored vertically according to the factory signs

② Before installing the high-efficiency filter, check the straightness of the filter frame or the end face of the edge

The permissible deviation of the flatness of the end face is ≯1mm each, if the flatness of the end face is out of tolerance, cannot modify the frame of the filter.

③ The airflow direction of the high-efficiency filter installation does not match the arrow marked on the outer frame;

④. The high efficiency filter combined with corrugated board is installed vertically without vertical ground

⑤ The connection between the high efficiency filter and the frame is poorly sealed.

---4_5

5. The enclosure structure of the fabricated clean room is not tight

5.1. Form of expression: air leakage at the joints of the wall panels, ceilings and other parts of the clean room, the indoor static pressure is low.

52. Harmfulness: The air volume of the clean room leaks due to the imperfect enclosure structure, and the room the internal static pressure is low, which affects the accuracy of cleanliness.

5.3 Analysis of the causes

① The external dimensions of the wall or top plate have large deviations

② The grooves on both sides of the wall panel are not tightly sealed

③ The roof and the frame are not tightly sealed

④ The connection between the wall plate and the top plate is not sealed

⑤ The ceiling or wall panel, lighting fixtures, transmission windows and other parts are not sealed

⑥ The holes of various pipelines passing through the wall and ceiling are not sealed;

 

6. Poor blowing effect in air blowing room

6.1. Form of expression: the two doors of the air shower room are not interlocked, and the nozzle airflow is uneven

Even when the staff enters the shower room, there is a sense of vibration and cold wind.

6.2. Harmfulness: The blowing effect of the air blowing room is poor, which reduces the personal purification effect

As a result, it affects the cleanliness of the clean room.

6.3 Analysis of the causes

①. The foundation (or ground) of the air shower room should be flat and padded with thickness

Rubber plate ≤5mm

② After the installation of the air shower room, the various actions specified in the technical documents have not been tested Adjust the inspection to make it meet the requirements of various indicators. Such as fan start, electric heater

Into the heating of the blowing air, the interlocking of the two doors and the test adjustment of the time relay, etc.;

③ The angle of the nozzle should be adjusted. To ensure the airflow from the nozzle (on both sides

(Tangential direction) blow to the body of the person being blown, and the blow angle of the nozzle is generally adjusted to: The top is down 20, and the two sides are horizontally offset by 10.

 

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