How To Calculate CleanRoom Purification According The HEPA Filter Box Air Flow

                                       How To Calculate Clean Room Purification According The HEPA Filter Box Air Flow    

 According to the GBJ73-84 Standard, the HEPA filter units air speed multiply the area is HEPA filter units totally air flow. 

The clean room totally air flow divide by the clean room volume can get the air change times. 

But according to the 5.1.4 item: the clean room should have enough fresh air, 

the figure depened on the max air flow:

1: The10%-30% totally air flow in turbulence clean room,

 2-4% totally air flow in laminar air flow clean room.

2: Compensation indoor air flow out and keep the clean room positive pressure fresh air.

3: Ensure the clean room worker each person at each hour more less than 40 sqm.

All of this can read out the square meter area for each person,

 the fresh air flow, the air change times, and clean Room height inversely relation,

 according to the clean room parameter make the  person number, 

 when design the clean room draw 

, the designer should considerate the fresh air filter in each room

air changer times, clean room height, the clean room area and so on.

There is follow formula:

     Class 100:  clean room height is 2.5m, the air change times is 300 times/hour, fresh air should be 4%

                        The area for each person =40sqm3÷4%÷300÷2.5m=1.33sqm

    Class 10,000: clean room height is 2.5m, the air change times is 25 times/hour, fresh air should be 20%

                          The area for each person =40sqm3÷20%÷25÷2.5m=3.2sqm

    Class 100,000: clean room height is 2.5m, the air change times is 15 times/hour, fresh air should be 20%

                         The area for each person =40sqm3÷20%÷15÷2.5m=5.33sqm