10/08/2026
Your cleanroom can pass the airflow test and still fail it.
Air velocity and air changes per hour are two different measurements. A room can pass one and fail the other, and that's one of the easiest ways for a result to look fine until an auditor looks closer.
The right scope. The right operating state. The right acceptance criteria, written down before anyone picks up a probe. That preparation is what separates a test that holds up in an audit from one that gets rejected.
Velocity, air changes, smoke patterns, HEPA integrity, and particle counts each answer a different question. Together, they're the difference between a room that looks compliant and one you can prove is compliant.
The standards and SOPs you already work to (ISO 14644, USP 797/800, your site's own protocol) don't change. This guide gives you a clear sequence to follow them.
💡 In this step-by-step guide, you'll learn:
✅ How to define scope, room class, and operating state (at-rest vs. in operation) before you test
✅ How to measure air velocity and air changes per hour, including grid layout and calculation
✅ How to run a smoke study and a HEPA filter integrity scan without missing a leak
✅ How to interpret pass/fail results, troubleshoot failures, and document everything for auditors
Get the full eight-step breakdown of how to perform cleanroom airflow testing.
Read now: https://appliedphysicsusa.com/how-to-perform-cleanroom-airflow-testing-step-by-step/
