Question 1: What is the quality of air that is blown from an ISO 7 zone through an ISO 35H HEPA filter? Is this air suitable for ISO 5?
Question 2: What about the particle concentration in the sizes 0.1 µm, 0.2 µm and 0.3 µm? These are not even defined in ISO Class 7. Are these also separated to the extent that it later corresponds to ISO Class 5?
Answer 1: This is an easy math problem. The air in an ISO7 class cleanroom has a maximum of 352,000 particles of size 0.5µm.
If you send this air through a HEPA filter (ISO 35H), which has a minimum filtration efficiency of 99.95% at the MPPS point, you will only have a maximum of 176 particles of 0.5 µm after the filter. This in turn corresponds to cleanroom class ISO 4 (limit value is 352P).
Attention! You only have this cleanroom class just after the filter! As soon as the outflowing air mixes with the room air, the cleanroom class is undefined again.Answer2: Smaller particles are separated even better. (The MPPS point is 0.3ym)
