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Flow direction of airflow in one-way flow clean room

Apr 04, 2019

There are two types of one-way flow clean rooms: horizontal flow and vertical flow. In horizontal flow system, air flow flows from one wall to another. In the vertical flow system, the air flow is from the ceiling to the ground. One-way airflow is used for situations requiring lower concentration of suspended particles or microorganisms in the clean room.

 

In a one-way flow clean room, air flows in one direction and flows through the whole space at an average speed of 0.3 m/s to 0.5 m/s. The air is supplied to the room by an efficient filter covered with the ceiling of the clean room. The airflow is like an air piston, which flows downward through the room, takes away pollutants and discharges them from the ground. After mixing with some fresh air outside, it is recycled to the high efficiency filter.

 

Suspension pollution from personnel and processes can be removed immediately by this kind of air, and turbulent ventilation system adopts the principle of mixing and dilution. In an empty room without any obstacles, one-way flow can quickly remove pollutants with much lower wind speeds than previously mentioned. But in an operating room, the machine and the people walking around the machine can create obstacles to air flow. Obstacles can turn one-way flow into turbulence, thus forming air masses around obstacles. Human activities can also turn one-way flow into turbulence. In these turbulences, due to the lower wind speed and the smaller degree of air dilution, the pollution concentration is higher.

 

Therefore, the wind speed must be maintained in the range of 0.3 m/s to 0.5 m/s in order to quickly recover the interrupted one-way flow and fully dilute the pollution in the turbulent zone around the obstacle. One-way flow can be correctly represented by wind speed, because the higher the wind speed, the cleaner the room will be. The number of ventilation per hour is related to the volume of the room, such as the height of the ceiling, so it is not suitable to express one-way flow. The air supply volume in one-way flow chamber is many times that in turbulence chamber.www.wxrfcleanroom.com