How to Test Cleanroom Air Quality | ISO 14644 Particle & Airflow Guide
Why Cleanroom Air Quality Testing Is Important
Cleanrooms rely on strict contamination control. Even small increases in airborne particles, humidity, or airflow changes can cause production defects, product recalls, and equipment failures. Routine air quality testing helps facility managers:
- Ensure compliance with ISO 14644 cleanroom standards
- Maintain consistent product quality and reliability
- Detect early-stage contamination issues
- Keep HVAC and filtration systems working efficiently
- Meet customer and regulatory requirements
Key Parameters to Test in a Cleanroom
Cleanroom air quality testing focuses on multiple environmental factors. Each parameter directly affects contamination levels and the overall cleanliness grade.
1. Airborne Particle Count
This is the most important cleanroom indicator. A calibrated particle counter measures particles of 0.3 µm, 0.5 µm, and larger sizes. ISO 14644-1 defines maximum allowable limits, depending on your cleanroom class.
2. Airflow Velocity and Volume
Proper airflow ensures continuous dilution and removal of contaminants. Technicians use an anemometer or balometer to check:
- Air velocity at FFUs and HEPA filters
- Total air volume changes per hour (ACH)
- Laminar vs. turbulent airflow stability
3. Filter Integrity (HEPA/ULPA Leak Test)
HEPA and ULPA filters must be tested annually or after installation. A photometer or aerosol generator identifies potential filter leaks or damaged seals that could allow contamination into the cleanroom.
4. Differential Pressure
Cleanrooms depend on positive or negative pressure to control contamination flow. Testing ensures proper pressure gradients between rooms and prevents cross-contamination.
5. Temperature and Humidity
Environmental stability is crucial for electronics, battery manufacturing, pharmaceuticals, and precision assembly. Sensors verify that temperature and humidity remain within acceptable ranges.
6. Air Cleanliness Recovery Time
This tests how quickly the room returns to acceptable particle levels after simulated contamination. It verifies filtration effectiveness and airflow performance.
7. Microbial Contamination (Viable Particles)
For pharmaceutical or life science cleanrooms, microbial sampling is required. Settle plates or air samplers are used to detect bacteria and fungi levels.
Step-by-Step: How to Test Cleanroom Air Quality
- Review the required cleanroom classification according to ISO 14644 or GMP guidelines.
- Prepare calibrated testing instruments such as particle counters, photometers, and pressure meters.
- Measure airborne particles at predefined testing points based on room size and standard requirements.
- Test HEPA/ULPA filters for integrity and leakage.
- Check airflow velocity and volume at supply outlets and return grilles.
- Measure room pressurization to confirm proper gradients.
- Verify temperature and humidity stability with calibrated sensors.
- Record data and compare it with ISO standards to determine compliance.
How Often Should You Test Cleanroom Air Quality?
Testing frequency depends on your industry and cleanroom class:
- ISO 5–7: Every 6 months
- ISO 8–9: Every 12 months
- HEPA filter tests: Annually or after system modification
- Pharma/GMP: Monthly or per regulatory requirement
More frequent testing is recommended for critical production lines such as semiconductor wafers, optical lenses, pharmaceutical filling, or precision assembly.
Professional Cleanroom Testing Services
If your facility requires professional validation or re-certification, Farclean provides complete cleanroom testing and measurement services, including:
- ISO 14644 particle testing
- HEPA/ULPA filter leak detection
- Airflow balancing and verification
- Pressure control validation
- Environmental monitoring system support
Our engineering team helps you maintain stable cleanroom performance and ensures full compliance with international standards.
