Resolving Pressure Differential Failure in a Pharmaceutical Grade C Cleanroom

The Challenge:

A pharmaceutical manufacturer was experiencing persistent pressure differential failures between their Grade C manufacturing suite and the adjacent Grade D corridor. Despite multiple HVAC adjustments, the facility could not maintain the required 15 Pa differential — creating a recurring GMP non-conformance and threatening their manufacturing licence.

The Approach:

A comprehensive site assessment was conducted measuring actual supply and extract air volumes against design specifications. The assessment identified a supply-to-extract air volume imbalance of over 5,000 m³/h — meaning the extract system was removing significantly more air than was being supplied, collapsing the positive pressure differential. Further investigation revealed incorrectly sized extract ductwork installed during the original facility construction.

The Solution:

A full HVAC redesign was executed — recalculating supply and extract volumes, resizing ductwork, adjusting AHU configurations, and recommissioning the system to achieve and sustain the specified pressure differentials. The facility was reclassified following recommissioning and returned to compliant operation with full IQ/OQ/PQ documentation.

Key Learning:

Pressure differential failures are rarely resolved by simple HVAC adjustments. A systematic measurement and investigation approach — comparing actual air volumes against design intent — is essential to identify the root cause and implement a durable solution.