ISO 14644 cleanroom classification testing for every cleanliness class
Every cleanroom is designed for a cleanliness class. Classification testing proves the room actually achieves it, using particle counts taken at locations and volumes defined by ISO 14644-1.
How ISO 14644 classification works
ISO 14644-1 sets out cleanliness classes based on the maximum number of airborne particles per cubic metre at specified particle sizes. The lower the class number, the cleaner the room. ISO Class 5 zones are often used for critical aseptic or precision work, while ISO Class 7 and 8 rooms serve as supporting or background areas.
Classification starts by working out the number of sampling locations from the room's floor area, as the standard describes. A calibrated particle counter samples a defined volume of air at each location, and the results are compared with the class limits at the particle sizes chosen for that room.
Rooms can be classified in different occupancy states: as-built, at-rest or in-operation. The state must be stated on the report, because particle levels in an operating room with people and equipment are normally higher than in an empty one.
Classification is usually one part of wider clean room certification, alongside filter integrity, airflow and pressure checks.
Your class is a promise; classification proves it
Regulatory basis
Cleanroom classes underpin GMP grades and customer specifications; classification shows you meet them.
Process protection
Particle control protects sterile products, precision components and sensitive research work.
Objective evidence
Defined locations and sample volumes make results repeatable and comparable over time.
ISO 14644 classification scope
- Sampling location calculation from room area
- Particle counts at 0.5 µm, 5.0 µm and other sizes as required
- ISO Class 5 zones and unidirectional flow areas
- ISO Class 6, 7 and 8 rooms
- As-built, at-rest and in-operation states
- Upper confidence limit evaluation where applicable
- Room-by-room classification report
- Trend comparison with previous results
Where classification is required
As-built, at-rest and in-operation explained
As-built testing is done on a complete installation with services connected but no production equipment or people. At-rest testing includes installed equipment, but no personnel present. In-operation testing is carried out during normal activity with the agreed number of people working.
Each state answers a different question. At-rest results show the room's inherent capability; in-operation results show how it performs in real use. Many facilities classify at-rest routinely and confirm in-operation conditions for their most critical areas.
Why rooms fail classification
Typical causes include leaking HEPA filters or gaskets, reduced air changes as filters load, pressure problems that let dirtier air enter, unsealed penetrations, and poor gowning or behaviour during in-operation tests. Classification results combined with HEPA filter integrity testing and differential pressure testing usually pinpoint the cause quickly.
How the work is carried out
Room data
We confirm room area, intended class, particle sizes and occupancy state.
Location plan
Sampling locations are calculated and marked according to ISO 14644-1.
Particle counting
Calibrated counters sample the required air volume at each location.
Classification report
Results are evaluated against class limits and reported room by room.
One accountable team, documented results
NABL-Accredited
Calibration and testing carried out under NABL accreditation and ISO/IEC 17025:2017-compliant procedures.
On-Site & Laboratory Capability
Work carried out at your facility or in our laboratory, by one accountable team.
Serving Since 2022
Serving hospitals, laboratories, pharmaceutical and industrial clients across Tamil Nadu since 2022.
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Frequently asked questions
Classify your cleanrooms to ISO 14644
Share room areas and intended classes, and we will plan sampling locations and a test schedule.