Methods for Evaluation and Measurements for Cleanroom Certification

 1. Airborne Particle Count Testing

This is the primary method for evaluating the cleanliness of a cleanroom. It involves measuring the concentration of airborne particles using particle counters.

Procedure:
– Particle counters are placed at various locations within the cleanroom.
– The counters measure the concentration of particles at different size ranges (e.g., 0.1 µm, 0.5 µm, 5.0 µm).
– The data collected is compared against the allowable limits defined in ISO 14644-1 for the specific cleanroom class.

2. Airflow Velocity and Uniformity Testing

Ensuring uniform airflow is crucial for maintaining the cleanroom’s cleanliness. This test measures the velocity and uniformity of airflow.

Procedure:
– Anemometers or airflow meters are used to measure airflow velocity.
– Measurements are taken at multiple points to assess uniformity.
– The results are compared to the design specifications and standards.

3. HEPA/ULPA Filter Integrity Testing

High-Efficiency Particulate Air (HEPA) and Ultra-Low Penetration Air (ULPA) filters are critical components in cleanrooms. Their integrity must be verified to ensure they are functioning correctly.

Procedure:
– A challenge aerosol is introduced upstream of the filter.
– A particle counter measures the concentration of particles downstream.
– The filter’s efficiency is calculated and must meet the specified requirements (e.g., 99.97% efficiency for HEPA filters).

4. Air Change Rate (ACH) Testing

The air change rate indicates how frequently the air within the cleanroom is replaced with filtered air. This helps maintain a low concentration of contaminants.

Procedure:
– The volume of the cleanroom and the airflow rate from the HVAC system are measured.
– The ACH is calculated by dividing the total air volume flow rate by the room volume.
– The calculated ACH is compared to the required standards.

5. Temperature and Humidity Control Testing

Temperature and humidity must be controlled within specific ranges to prevent contamination and ensure proper operation of equipment.

Procedure:
– Temperature and humidity sensors are placed at various locations within the cleanroom.
– Continuous monitoring is conducted to ensure conditions remain within the specified ranges.
– Data is logged and analyzed for compliance.

6. Surface Cleanliness Testing

Surface contamination can significantly affect cleanroom performance. Surface cleanliness is assessed to ensure minimal particulate contamination.

Procedure:
– Surface samples are collected using swabs or contact plates.
– The samples are analyzed for particle count and microbiological contamination.
– Results are compared to acceptable limits for the cleanroom class.

7. Pressure Differential Testing

Maintaining pressure differentials between cleanroom areas is essential to prevent cross-contamination.

Procedure:
– Differential pressure gauges are used to measure the pressure difference between adjacent areas.
– The measured values are compared to the design specifications to ensure proper pressure gradients are maintained.

Documentation and Certification
After conducting the evaluation and measurements, the results are documented in a detailed report. This report includes:

– Test procedures and equipment used.
– Measurement data and analysis.
– Compliance with the specified cleanroom class requirements.
– Recommendations for any corrective actions if needed.

Once the cleanroom meets all the specified requirements, a certification is issued, confirming that the cleanroom complies with the cleanliness standards defined in ISO 14644-1. This certification is essential for regulatory compliance and maintaining the integrity of processes conducted within the cleanroom.