It checks if the HEPA filters are working correctly and free from leaks, ensuring only clean, particle-free air enters the cleanroom.

What is the PAO Test?

The PAO Test evaluates whether a HEPA filter is properly sealed and functioning by introducing test particles and checking for any leaks.

This keeps the cleanroom environment safe for sensitive products, research, and manufacturing processes.

How the Test is Done:

1️⃣ Spray Test Particles

A special aerosol (such as PAO) is sprayed upstream, just before the HEPA filter.

2️⃣ Check for Leaks

A Photometer or sometimes a Particle Counter is used downstream of the filter to detect if any particles are leaking through.

3️⃣ Pass or Fail?

Pass – If almost no particles are detected after the filter (leakage < 0.01%).

Fail – If too many particles pass through, the filter has a leak and needs repair or replacement.

Equipment Used:

Aerosol Generator – Generates fine aerosol particles (PAO) to test the performance and integrity of the HEPA filter.

Photometer – Measures the concentration of aerosol particles before and after the HEPA filter to detect any leaks.

Particle Counter – Sometimes used for precise particle measurements in critical environments.

Important Terms:

Photometer – Measures aerosol particle concentrations before and after the HEPA filter to detect any potential leaks.

HEPA (High-Efficiency Particulate Air) Filter – Designed to capture 99.97% of airborne particles measuring 0.3 microns or larger.

Why the PAO Test Matters:

• Ensures no leaks that could allow contaminants into the cleanroom • Verifies HEPA filter performance and installation quality

• Supports GMP, ISO 14644, and FDA compliance

• Protects products, patients, and sensitive operations

Need HEPA Integrity Testing?

Aimtech Systems LLP specializes in professional HEPA Filter Integrity (PAO) Testing with:

• Validated, calibrated equipment

• Comprehensive, audit-ready reports

• Experienced cleanroom validation teams