HVAC & PRESSURE DIFFERENTIALS
Answers to the questions our clients ask most often about cleanrooms, laboratories, compliance, and our services — straight answers from people who work in controlled environments every day.
Q: What air change rate does my cleanroom need?
Air change rate requirements depend on your ISO classification. As a general guide — ISO Class 8 requires a minimum of 20 air changes per hour, ISO Class 7 typically requires 60 or more, and ISO Class 5 environments typically require 240 to 480 air changes per hour. Your specific HVAC design should be based on a detailed calculation accounting for your room volume, heat loads, and contamination control requirements.
Q: What pressure differential should be maintained between cleanroom zones?
A differential pressure of 10 to 15 Pascals between adjacent cleanroom zones is the typical standard in pharmaceutical GMP environments — ensuring air flows consistently from cleaner to less clean areas. This differential must be continuously monitored and documented.
Q: Why does my cleanroom keep losing its pressure differential?
Pressure differential failures most commonly result from HVAC system imbalances — where the supply and extract air volumes are not correctly proportioned — door seal failures, inadequately sealed penetrations, or HVAC component failures. A systematic measurement and investigation approach is required to identify and resolve the root cause.
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