A global pharmaceutical manufacturer operates a tablet and oral solid dosage (OSD) formulation plant in Visakhapatnam, Andhra Pradesh. The facility is served by 126 air-handling units supporting controlled manufacturing areas, where airflow, static pressure, and room-to-room pressure differentials are validated parameters. At this scale, ventilation is not a utility. It is part of the controlled manufacturing environment, and any change to it carries revalidation consequences under cGMP.
The challenge
Every one of the 126 AHUs ran a belt-driven fan at a single fixed output, regardless of what its rooms needed. Filter loading raises system resistance over time, so airflow drifts and ACPH moves away from its validated value between manual checks. Door openings and leakage disturb the pressure differential between clean and less-clean zones in the same way, and a fixed-speed fan cannot respond to either.
Manual rebalancing cannot keep pace with 126 independent drift points. In the gap between a parameter drifting and someone catching it, particle recovery time after an intervention or cleaning cycle becomes inconsistent. The retrofit also carried a hard boundary: the same airflow, the same static pressure and the same pressure cascade had to be retained, because any material change would raise revalidation concerns in an operating plant. The real question was how to hold ACPH constant, maintain a stable pressure cascade, and ensure repeatable particle recovery across the whole fleet without changing the validated operating conditions.Results infographic: 126 AHUs, 338 EC fans, same airflow and pressure cascade, 51% energy reduction.
The solution
AAD Tech retrofitted 338 EC fans into the 126 installed AHUs, replacing the belt-driven assembly (motor, belt, pulley, VFD, starter and electrical panel) while keeping the AHU casings, coils and filters in place. Each fan is paired with a closed-loop controller. A pressure sensor reads the room condition continuously, the controller compares it with the facility’s validated target, and the EC fan modulates its speed to hold that target. Pressure drops, the fan output rises. Filters load, the system compensates within defined limits. Door events are corrected as they happen, not at the next manual round.Inside the same AHU: belt-driven blower before the retrofit, EC fan array after.
Verification was done unit by unit through signed installation reports. Measured airflow rose on every sampled AHU: 21,337 to 21,444 CFM, 19,510 to 20,128 CFM, 8,461 to 8,606 CFM and 9,959 to 10,437 CFM. Power on the same units fell from 10.67 to 5.22 kW, 8.68 to 4.43 kW, 7.99 to 3.96 kW, and 9.83 to 4.79 kW, representing a 49 to 51 per cent reduction. Because the system responds the same way every time, particle recovery no longer depends on when a technician last rebalanced the unit. The 51% savings are what remain when a fan works only as hard as the room requires.