It might be common that the number of air change is an indispensable parameter in the Class 1000 clean room, the so-called air change rate, in fact it means the multiple of the amount of clean air entering the clean room relative to the volume of the clean room, stating as times/h. KEL will tell you more about “How to Calculate the Air Change Rate and Air Flow rate of the Cleanroom", hope it can help everyone!

HOW TO CALCULATE THE AIR CHANGE RATE OF THE CLEANROOM:
The air supply flow of the laminar flow clean room is generally determined according to the indoor cross-sectional wind speed.
The cross-sectional wind speed of Class 100 vertical laminar flow clean room is no less than 0.25m/s and cross-sectional wind speed no less than 0.35 m/s.

The clean room is generally estimated by the number of air changes:
*Class 1000 clean room not less than 50 times/h;
*Class 10000 clean room not less than 25 times/h;
*Class 100000 clean room is not less than 15 times/h.
*Class 10000 air changes times ≥ 25 times per hour (usually 27-28);
*Class 100000 air changes times > 15 times per hour (usually 17-18).

However, the air flow cannot be blindly designed only according to the number of air changes, the residual heat and humidity of the clean room and the process should be considered. Otherwise, the air flow may be able to meet the temperature and humidity requirements at the beginning, and the system will not work well after running for a period of time.

Calculation of air flow of Class 100 and Class 10: room area X (0.3~0.5) m/sx3600s = air flow (M³/H); (Class 100000, Class 10000, Class 1000) air change times = air flow + volume)

According to the design data, the number of air changes in the clean room (take Class 1000000 as an example) is 15~20 times/h. If a clean room is 100㎡, 3m high, and there are 10 people. Then according to the personnel fresh air = 40*10=400CMH, according to the number of air changes 20*100*3=6000CMH. These two data are very different, then need to refer to the data for calculating the number of air changes, whether 6000CMH is fresh air flow or total supply air flow (fresh air flow + return air flow).

1. If it is a fresh air flow system, then the data calculated by the number of air changes is the same as air supply flow.

2. If it is a fresh air flow + return air flow system, then the fresh air flow is determined by personnel or infiltration + exhaust air flow, if calculated according to the fresh air flow of the personnel as 400CMH, the total supply air flow is 6000CMH, then the return air flow is 5600CMH, the 400CMH air flow is the sum of exhaust air flow and infiltration exhaust air flow. In addition, the load of the clean room is mainly based on the heat dissipation of the equipment and the temperature rise of the motor, accounting for about 80% of the total load, even more than 1000w/㎡.