Cleanroom certification is the measured proof that a controlled environment meets its specified ISO cleanliness class — particle counts taken at defined locations, HEPA filters scanned for integrity, air change rates confirmed, pressurization relationships verified, and temperature and humidity documented. dL Flow Tech is an independent, NEBB-certified firm that has certified cleanrooms and controlled environments for pharmaceutical, hospital, and laboratory applications across the Hudson Valley since 1982. Certification is what transforms a room that looks clean into one that demonstrably is.
Schedule cleanroom certification: Call (845) 265-2828 or send your cleanroom specifications for a proposal.
What is cleanroom certification?
Cleanroom certification is the documented testing process that confirms a controlled environment meets the cleanliness class it was designed for. It follows the ISO 14644 series of standards, which classify cleanrooms from ISO Class 1 (the fewest allowable particles per cubic meter) through ISO Class 9, with each class defined by a specific particle-size and concentration limit.
Certification involves more than counting particles. A cleanroom that achieves its ISO classification while losing pressurization relative to adjacent spaces, or whose HEPA filters have microscopic penetrations, is not protecting what it was built to protect. A rigorous certification tests the full set of parameters that together determine whether the room actually performs its function.
ISO cleanroom classifications
| ISO Class | ≥0.1 µm particles/m³ | Typical Application | US FED 209 Equivalent |
|---|---|---|---|
| ISO 5 | 100,000 | Aseptic fills, semiconductor fab | Class 100 |
| ISO 6 | 1,000,000 | Pharma manufacturing | Class 1,000 |
| ISO 7 | 10,000,000 | Hospital pharmacy, sterile processing | Class 10,000 |
| ISO 8 | 100,000,000 | General pharma, electronics assembly | Class 100,000 |
What a full cleanroom certification covers
Airborne particle counting (ISO classification)
Using a calibrated optical particle counter, we sample air at the number of locations and sample volumes ISO 14644-1 requires for the room's area, at each of the particle sizes defined for the target ISO class. The particle counts determine the room's actual ISO classification and whether it meets the specification.
HEPA filter integrity testing
HEPA filter integrity testing (PAO/DOP scan test) challenges each installed HEPA filter with a standardized aerosol upstream, then scans the downstream face and frame with a photometer. A HEPA filter rated at 99.97% efficiency can still fail the scan if it has a microscopic penetration, a frame seal failure, or an installation leak around the housing. Particle counts can pass while a filter has a pinhole that would be catastrophic in a pharmaceutical or sterile environment — the integrity scan finds it.
Air change rate and airflow verification
We measure the actual air change rate the room is receiving and compare it to the design specification. For unidirectional (laminar) cleanrooms, we measure face velocity across the filter bank. For turbulent (non-unidirectional) rooms, we measure total supply airflow. Air change rate is directly tied to particle dilution and removal — the mechanism by which the room achieves its ISO class.
Room pressurization
Cleanrooms are typically maintained at positive pressure relative to adjacent spaces to prevent particle ingress when doors open. Pharmaceutical cleanrooms have cascading pressure differentials between classification zones. We measure the differential pressure at rest with all systems running and confirm it meets the specification, and verify that the pressure relationship is maintained under normal traffic patterns.
Temperature and humidity
Many cleanroom processes specify environmental limits. We measure and document temperature and relative humidity across the room and confirm the HVAC system is holding conditions within specification.
Additional tests available
- Recovery testing — how quickly the room returns to classification after a particle challenge or door opening event.
- Containment leakage — measuring actual air leakage through the room envelope under pressurization.
- Airflow visualization — smoke or tracer visualization to confirm unidirectional flow pattern and identify recirculation zones.
- Vibration and noise — for process-sensitive environments where vibration or acoustic criteria apply.
Hospital and pharmaceutical cleanroom certification
Hospital sterile compounding pharmacies — under USP 797 — must meet ISO 5 at the critical work zone and ISO 7 or ISO 8 in the buffer and anteroom. The certification requirements are defined in USP 797, and facilities are expected to maintain documentation of environmental monitoring and certification. Our certification report format is designed to support USP 797 and Joint Commission review.
For pharmaceutical manufacturing under FDA 21 CFR 211 and EU GMP, cleanroom certification is a GMP requirement. We produce certification documentation consistent with regulatory expectations and can support audit-readiness review.
Service area
dL Flow Tech performs cleanroom certification from New York City north through the Hudson Valley to Albany — Dutchess, Westchester, Orange, Putnam, Rockland, and Ulster counties, the five boroughs, and the Capital Region.
Certification due — or a new cleanroom to qualify? Call (845) 265-2828 or send your cleanroom specs and we'll scope the certification.
Frequently asked questions
- What is ISO 14644 cleanroom classification?
- ISO 14644 is the international standard that defines cleanroom classes based on airborne particle concentration. ISO Class 1 is the cleanest; ISO Class 9 is the least restrictive. Certification involves particle counting at defined locations to confirm the room meets its specified class.
- How often does a cleanroom need to be certified?
- ISO 14644-2 recommends testing at least every 12 months for ISO Class 5 and above, and every 24 months for ISO Class 6–9. FDA guidance for pharmaceutical cleanrooms typically requires more frequent monitoring. Any significant HVAC modification triggers retesting.
- What tests are included in a full cleanroom certification?
- A full certification typically includes airborne particle counting, HEPA filter integrity testing, air change rate measurement, room pressurization, and temperature/humidity. Recovery testing, containment leakage, and airflow visualization can be added based on requirements.
- What is HEPA filter integrity testing?
- HEPA filter integrity testing challenges each installed HEPA filter with a test aerosol and scans downstream for penetration. A HEPA filter can pass a particle count but fail an integrity test due to a pinhole, a frame leak, or an improper installation — the scan finds penetrations the particle counter misses.
- What is the difference between "at rest" and "in operation" certification?
- ISO 14644 recognizes three occupancy states: as-built, at-rest (equipment installed, no personnel), and in-operation. In-operation certification is most meaningful for regulatory compliance; at-rest is common for routine periodic re-certification.
About the Author
Dennis LaVopa
Founder & NEBB-Certified TAB Supervisor · dL Flow Tech, Inc. · Since 1982
Dennis founded dL Flow Tech in 1982 after years as a field TAB engineer. He holds NEBB certification as both firm supervisor and individual practitioner, and has personally directed TAB on hundreds of healthcare, laboratory, institutional, and commercial projects across the Hudson Valley and New York metro. His signature appears on every certified dL Flow Tech report.
