Cleanrooms and equipment

In a high-cleanliness downflow cleanroom, which is closest to the typical number of times the room's air is replaced per hour (air changes per hour)?

  1. ASeveral hundred
  2. BOne
  3. CFive to ten
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Answer: A. Several hundred

Downflow cleanrooms blow air from the entire ceiling at about 0.3 to 0.5 m/s, so a room a few meters high works out to several hundred air changes per hour. Ordinary offices have only a few air changes per hour, and cleanrooms use a great deal of energy just to move air.

  • A. Correct. It is far more than in ordinary buildings.
  • B. Once is not enough to remove particles.
  • C. That is close to ordinary buildings and too few for high cleanliness.
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