Don't Just Measure Average—Map the Whole Air Flow in Cleanroom

One of the biggest misconceptions we run into on cleanroom projects? That “as long as the average is in the 0.3–0.5 m/s range, we’re good.” Sorry—but that mindset is how contamination sneaks in unnoticed.

At our firm, we know that uniform airflow is just as critical as the target velocity itself. In unidirectional (laminar) cleanrooms—especially ISO Class 5 or stricter—a single dead zone or high-velocity jet can disrupt the entire protective airflow blanket, allowing particles to settle or swirl unpredictably. That’s why we never rely on a single reading or a rough average. Instead, we evaluate ity the right way: with a systematic, grid-based measurement using calibrated anemometers.

Here’s how we do it: during commissioning, we lay out a measurement grid across the critical work plane—typically every 1 to 2 feet—depending on room size and classification. At each point, we record wind speed multiple times to account for minor fluctuations. Then we calculate the standard deviation and compare max/min values. Industry best practice (and many regulators) expect wind speed variation to stay within ±20% of the mean, and we aim even tighter—±15%—for high-risk areas.

We once audited a “validated” cleanroom where the average was 0.42 m/s—perfect on paper. But our grid scan revealed a 0.15 m/s dead spot near a piece of equipment. No wonder their environmental monitoring kept flagging particle excursions in that corner.

And it’s not just about the numbers. We pair wind speed maps with smoke studies to visually confirm flow patterns. Because data tells you what, but smoke shows you why.

Bottom line: uniformity isn’t a luxury—it’s foundational. A cleanroom with uneven flow isn’t just inefficient; it’s deceptive. It looks compliant while quietly failing its core mission. And in our business, that’s a risk we never sign off on.

 Suzhou Pharma Machinery Co.,Ltd.

2026/01/16

Mia