In cleanrooms, one of the most common airflow terms people hear is ACPH. You may see it in a report, hear it during a certification, or have it listed in a design document. But what does it actually mean? ACPH stands for Air Changes Per Hour. In simple terms, it estimates how many times the total volume of air in a room is replaced, supplied, or exchanged in one hour. If a cleanroom is operating at 30 ACPH, that means the airflow system is supplying enough air to theoreticall

If you work around cleanrooms, pharmacies, hospitals, laboratories, or biological safety cabinets, you’ve probably heard the phrase: “The HEPA filters passed integrity testing.” But what does that actually mean? For many people, HEPA leak testing feels a little mysterious. A technician wheels in equipment, introduces some kind of fog or aerosol into the system, scans the filters with a probe, and eventually places a certification sticker on the equipment or room. To the avera

If you’ve ever watched a technician roll into your cleanroom with what looks like a high-tech suitcase on wheels and start “vacuuming the air,” you might’ve wondered: Are they cleaning? Measuring? Hunting invisible dust gremlins? The answer is: yes… kind of. They’re performing a non-viable particle count , one of the most important (and most misunderstood) tests in cleanroom certification and monitoring. And despite the intimidating name, the concept is actually pretty simple