Leak Detection Methods and Standards for HEPA Air Filters in Pharmaceutical Cleanrooms
In the pharmaceutical industry, HEPA air filters used in cleanrooms are essential to maintaining environments that meet GMP (Good Manufacturing Practice) requirements. The integrity of these high-efficiency filters has a direct impact on product safety and quality. Therefore, routine leak testing is a critical step in ensuring compliance and maintaining a contaminant-free production space.
Regulatory Standards for HEPA Filter Leak Testing
Leak detection for HEPA air filters in pharmaceutical cleanrooms is governed by several internationally recognized standards, including:
- ISO 14644-3: This standard outlines test methods for cleanrooms and associated controlled environments, including requirements for HEPA filter leak testing.
- GMP Guidelines: GMP regulations require pharmaceutical manufacturers to regularly test air filters to ensure cleanroom air quality remains within acceptable limits.
- EU GMP Annex 1: This document provides detailed guidance on integrity testing of HEPA filters in sterile manufacturing areas, emphasizing routine testing and validation.
Common Leak Detection Method: Aerosol Photometry
Aerosol photometry is the most widely used method for detecting leaks in HEPA air filters. It involves introducing a challenge aerosol upstream of the filter and measuring the downstream concentration using a photometer to identify any potential leakage.
Key Equipment Used for Leak Detection
- Aerosol Generator: Generates a stable aerosol using PAO (poly-alpha-olefin) or DOP (dioctyl phthalate) as the test medium.
- Aerosol Photometer: Measures the downstream aerosol concentration. The GTI Aerosol Photometer 3990/3991 is a commonly used model in the pharmaceutical industry due to its high sensitivity and reliable performance.
Step-by-Step Leak Testing Procedure
1. Preparation
Ensure the cleanroom is operating normally and the HEPA air filters are installed and functioning. Verify that the aerosol generator and photometer (e.g., GTI 3990/3991) are calibrated and ready.
2. Aerosol Injection
Inject the test aerosol into the upstream side of the HEPA filter. Maintain a consistent aerosol concentration between 10–20 μg/L to ensure even distribution.
3. Scanning Inspection
Use the aerosol photometer to scan the downstream side of the filter at a speed no greater than 5 cm/s. Pay close attention to filter frames, seams, and surfaces to ensure no area is missed.
4. Data Recording and Analysis
Record the detected aerosol concentrations. According to industry standards, leakage should not exceed 0.01%. If leaks are identified, mark and document the location and concentration of each leakage point.
Follow-Up and Re-Testing
Any identified leaks must be repaired immediately. After repairs, the filter must undergo a repeat leak test to confirm restored integrity and continued compliance with pharmaceutical cleanroom standards.
About E-FILT
E-FILT is a trusted air filter manufacturer committed to delivering high-performance filtration solutions for pharmaceutical cleanrooms and critical environments. With advanced production technology, strict quality control, and compliance with international standards, E-FILT ensures that every HEPA air filter meets the rigorous demands of GMP-certified facilities. Whether you’re looking for standard HEPA filters or customized filtration systems, E-FILT provides reliable products and expert technical support to protect your cleanroom operations.
