One of the tests conducted to check the normal operation of the purification workshop is the inspection of indoor airflow. This is a component of the entire testing program. In order to dilute or eliminate indoor suspended pollution and prevent the accumulation of pollution indoors, there must be sufficient airflow activity indoors. So it is necessary to detect the airflow.

In turbulent clean rooms, the transportation and mixing of wind are carried out in a turbulent manner. To ensure that pollutants are clearly identified, all parts of the cleanroom must achieve excellent air mixing.

In the unidirectional flow purification workshop, to ensure that the bond area reaches the cleanest level, the air supply comes directly from the high-efficiency filter.

Maintain uniform airflow in the vertical laminar flow direction:

(a) The wind speed at which the signature is blown must not have any speed difference;

(b) The wind speed on the suction surface of the floor return air plate should not have any speed difference. Vortex phenomena occur when the speed is too low or too high (0.2m/s, 0.7m/s), while the airflow is more uniform at a speed of 0.5m/s. Currently, the wind speed in general clean rooms is between 0.25-0.5m/s.

There are many factors that affect the airflow in the clean room, such as process equipment, employees, clean room assembly materials, lighting fixtures, etc. The diversion point of the airflow above the production equipment should also be considered.

The airflow diversion point on the surface of the control panel or production equipment in the purification workshop should be located at 2/3 of the distance between the clean room space and the partition board. This can allow the airflow to flow from the inside of the process area to the work area during operation, while carrying away fine dust; If the diversion point is installed in front of the process area, it will become an improper airflow diversion. At this moment, most of the airflow will flow to the process area, and the dust caused by the operator's operation will be carried to the back of the equipment. As a result, the workbench will be contaminated and the yield will inevitably decrease.

Obstacles such as workstations in the purification workshop will experience eddy currents at their junctions, resulting in poor cleanliness around them. Drilling air return holes on the workstations will minimize the occurrence of eddy currents; The selection of appropriate assembly materials and the completeness of equipment are also important factors in determining whether airflow becomes a vortex phenomenon.

Characteristics of Airflow in Cleanroom

The general requirements for clean air flow organization are as follows:

1. The incoming clean airflow can be evenly distributed or diffused throughout the entire clean area as soon as possible, in order to reduce the pollution of indoor pollution sources such as dust and bacteria on the air and maintain the required cleanliness of the production environment.

2. It can quickly dissipate the dust and bacteria from the pollution source to the clean room, avoiding or reducing eddy currents and dead corners, shortening the residence time of dust and bacteria indoors, and reducing the chance of contact with products.

3. Coordinate the requirements for air conditioning supply such as indoor temperature and humidity uniformity, as well as the quiet requirements for workers. Because the main task of airflow organization is different from that of a typical air-conditioned room, the plan must also be different.

The basis for considering the air conditioning airflow organization plan for quiet air-conditioned rooms and production workshops with normal temperature and humidity accuracy is to choose the largest possible supply air temperature difference in order to reduce the supply air volume, make the system equipment and pipelines smaller, and lower the initial investment and operating costs. So usually, machine dew point air supply is used in summer.

The article originates from Hunan Purification Engineering: http://www.jmyujie.com/