📌 Good Practices for Air Handling Unit (AHU) in Pharmaceuticals

1. Design & Installation

• AHU must be designed as per GMP & cleanroom classification requirements.

• Install HEPA/ULPA filters at terminal locations for sterile areas.

• Provide air locks and pressure differentials to avoid cross-contamination.

• Use smooth, cleanable surfaces to avoid microbial/particulate accumulation.

2. Operation & Monitoring

• Maintain differential pressure (10–15 Pa) between areas of different grades.

• Monitor and record temperature, RH, and differential pressure regularly.

• Ensure uniform air distribution via proper ducting and diffuser design.

• Validate and requalify AHUs at defined intervals.

3. Filter Management

• Pre-filters, fine filters, and HEPA filters must be maintained and replaced as per schedule.

• Perform integrity testing of HEPA filters (DOP/PAO test).

• Ensure no bypass or leakages at filter joints.

4. Cleaning & Maintenance

• Establish SOPs for periodic cleaning of AHU components (filters, coils, ducts, drain pans).

• Use sanitized condensate drain pans to prevent microbial growth.

• Calibrate and maintain instruments (differential pressure gauges, sensors).

• Keep a preventive maintenance schedule for motors, fans, and belts.

5. Documentation & Compliance

• Maintain logbooks for cleaning, filter changes, calibration, and maintenance.

• Implement alarm systems for critical parameters (DP, temp, RH).

• Ensure compliance with EU GMP Annex 1, US FDA, and WHO guidelines.