ISO & GMP Cleanroom Validation & Requalification
ISO & GMP Cleanroom Validation & Requalification
ISO Cleanroom specialises in the cleanroom validation process, providing comprehensive testing and reporting for your facility to the ISO 14644 series of classification standards. Our documentation meets the strict requirements of both ISO 14644 and EU GMP Annex 1 guaranteeing your cleanrooms are audit-ready and fully compliant with all regulatory bodies. We provide a complete qualification scope, with the exception of microbial airborne and surface contamination testing.

Cleanroom Validation States and Scope
Cleanroom validation tests are performed in three distinct operating states to measure performance under different conditions:
- As-built: The cleanroom structure is complete but is empty of equipment. Your installer will often test this state to prove the installation. However, you may wish to consider third-party validation for enhanced, independent assurance.
- At-rest: The room is populated with all required equipment but is not operational (no personnel or moving parts). This provides important baseline data.
- Operational: The cleanroom is fully running, operating in accordance with its defined process. This is the critical state most customers are interested in, providing the most relevant assurance for final cleanroom validation.
Validation vs. Monitoring
It is crucial that cleanroom validation is not confused with the continuous monitoring of the cleanroom, which must take place at a regularity specific to your process. We are able to provide assistance in formulating your monitoring plan if required. EU GMP specifically calls for monitoring in two states, at rest and in operation, as well as measuring the time taken for the cleanroom to return to the at rest levels once the activity has finished.
Required Testing Scope
Cleanroom Qualification is the overall process of assessing your facility’s compliance with its intended use. The scope of your cleanroom validation is determined by your classification and regulatory requirements.
Need help defining your testing scope?
ISO 14644 Core Requirements
To meet the requirements for BS EN ISO 14644 Parts 1, 2, 3, 4, and 7, all validated cleanrooms require testing for:
- Airborne Particle Count
- Airflow Measurement (Volume and Velocity)
- HEPA/ULPA Filter Integrity Test.
Additional EU GMP Annex 1 Requirements
If your process requires EU GMP qualification, Annex 1 specifies additional tests (where relevant to design/operation) that may be included in the cleanroom validation: Air Pressure Difference Measurement, Airflow Direction and Visualisation, Temperature and Relative Humidity Measurement, Recovery Testing, and Containment Leak Testing. We do not offer Microbial Airborne and Surface Contamination testing.
We believe that the gold standard is not just to test for compliance but to monitor your cleanroom regularly through all three operational states to give a complete picture of the health of your cleanroom.
— TONI HORSFIELDValidation and Requalification Intervals
To maintain compliance, cleanroom validation must be performed at regular intervals.
Test | Classification/Airflow Type | Maximum Time Interval | Relevant Standard |
Particle Count | ≤ ISO Class 5 | 6 months | ISO14644-1 2015 |
> ISO Class 5 | 12 months | ISO14644-1 2015 | |
Filter Leak Test | Unidirectional Airflow and ≤ ISO Class 5 | 6 months | ISO14644-3 2019 |
Non-Unidirectional and > ISO Class 5 | 12 months | ISO14644-3 2019 | |
Airflow | Unidirectional Airflow | 6 months | ISO14644-3 2019 |
Non-Unidirectional | 12 months | ISO14644-3 2019 |
Commissioning and Periodic Review Tests
These optional tests are recommended at commissioning and every 4 years (or following significant changes): Containment Leak, Airflow Visualisation, Recovery Time, Particle Deposition, and Segregation.
Required test | Classification | Maximum time interval | Test procedure |
Containment leak | All cleanrooms | 12 months | ISO14644-3 2019 |
Airflow visualization | All cleanrooms | 12 months | ISO14644-3 2019 |
Recovery time | All cleanrooms | 24 months | ISO14644-3 2019 |
Particle deposition | All cleanrooms | 24 months | ISO14644-3 2019 |
Segregation | All cleanrooms | 24 months | ISO14644-3 2019 |
Customer Monitoring Tips
Cleanroom validation should not be confused with the continuous monitoring required to suit your process. We can assist in formulating your monitoring plan. Key monitoring includes Air Pressure and Particle Count (suggested daily) and Environmental controls (Temperature, Humidity, Light).
Required Test | Classification | Maximum Time Interval | Relevant Standard |
Air Pressure | All Cleanrooms | Suggested Daily Monitoring | ISO14644-2 2015 |
Particle Count | All Cleanrooms | Suggested Daily Monitoring | ISO14644-2 2015 |
Environmental Controls; Temperature, Humidity, Light Levels, ESD | If required suggest regual monitoring | ISO14644-2 2015 |
Taken from BS EN ISO 14644-2:2015. National annex. Guidance on maximum time intervals for periodic testing of cleanrooms and clean zones.
Detailed Test Methods
Particle counting test
We use a Light Scattering Air Particle Counter (LSAPC) with a flow rate of 50 LPM. Our counters are calibrated yearly and measure from 0.3μm to 10μm. The calibration certificate is included within your cleanroom validation report.
Air Pressure Test
It is necessary to show that the air flows in the correct direction between rooms in a suite of cleanrooms (i.e., from clean to less-clean areas). A pressure differential of 5 Pa,10 Pa, or 15 Pa is typically required (depending on the design and number of rooms) with the cleanest area at the highest pressure. While your cleanroom may have pressure gauges installed, we advise checking these instruments. ISO Cleanroom uses a calibrated electric micromanometer to measure and verify these critical pressure differentials.
Air Flow testing
Air volume supply rates (m3/s) or air velocity rates (m/s), depending upon the design of your cleanroom, will be measured using an array of instruments. Duct velocities will be measured by a static pitot tube. The average air velocity of filters is measured using calibrated vane anemometers or airflow measuring hoods (balometer).
Filter integrity test
Your HEPA and ULPA filters are tested by the manufacturer; however, cleanroom validation requires us to ensure the filter has not been damaged in transit or during installation, and that there is a successful seal to the filter housing. Damage can also occur during the filter's life if large particulate (e.g., from maintenance operations) impacts the filter. We have both a calibrated photometer and LSAPC and can conduct the test via either method, depending on your process's sensitivity to outgassing.
Containment Leak Test
This test is specifically designed to detect the intrusion of unfiltered air into the cleanroom from the outside. Typical weak spots are wall joints, doors, ceilings, and windows. These seals can degrade over time, especially in spaces with large temperature variations. We have both a calibrated photometer in combination with the Laskin nozzle aerosol generator and LSAPC’s that can conduct this test. The choice of tests depends entirely on your process's sensitivity to outgassing.
Recovery Test
The recovery test is used to verify that the installation can return to a specified cleanliness level within a finite time, after being exposed briefly to a source of airborne particulate challenge. We would use either the Laskin generator to create a cold oil aerosol challenge or microspheres, depending on your process's sensitivity to outgassing
Airflow Visualisation tests
The airflow visualisation test demonstrates the air direction and/or pattern, which is compared directly to the design of the cleanroom or clean air equipment. This is shown using the Laskin generator to create a cold oil aerosol, which can then be photographed and filmed to provide auditable evidence of the flow for your cleanroom validation. For cleanrooms sensitive to outgassing, a taper or streamer can be used instead.
Cleanroom Validation FAQs
Cleanroom validation is the periodic, comprehensive testing that verifies the installation meets regulatory standards (ISO 14644/GMP). Monitoring is the continuous measurement that takes place at a frequency suited to your process and operational requirements.
Our reports meet the full requirements of both the ISO 14644 series of classification standards and EU GMP Annex 1, ensuring your facility is audit-ready and fully compliant with all relevant regulatory bodies.
For cleanrooms classified as ISO Class 5 or those with unidirectional airflow, particle counting and airflow testing must be performed every 6 months. For classifications above ISO Class 5 or with non-unidirectional airflow, the interval is 12 months.
Cleanroom validation can be performed in three states: As-built (bare structure, empty), At-rest (equipment installed but not running), and Operational (fully running with personnel and processes). Most customers require the critical Operational state.
The test demonstrates air direction and patterns by creating a visible challenge using a Laskin generator (cold oil aerosol). The flow is photographed or filmed for audit evidence. In cleanrooms sensitive to outgassing, a taper or streamer may be used instead.
The test confirms that the filter has not been damaged during transport or installation and that it seals correctly to the housing. Damage can also occur during the filter’s service life from large particulate impacts.
It is necessary to maintain a pressure differential, typically between adjacent rooms, to ensure air flows correctly from cleaner areas to less clean areas, with the cleanest area at the highest pressure.
Our technicians who carry out all cleanroom validation and testing are accredited Professional CTCB-I (Cleanroom Testing and Certification Board - International) specialists. This certification demonstrates their form competence and expertise in meeting international standards and is repeated every 5 years.
Ensure Compliance & Protect Your Process. Book your cleanroom validation today.