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The Roles of Housekeeping and Vacuum Filtration in Meeting ISO Cleanroom Standards

June 23, 2017

Did you know that a person walking in a cleanroom at a rate of 2 mph (not exactly a brisk pace) can produce 5 million particles 0.3 microns or larger per minute? Even just standing motionless produces 100,000 particles/minute. And every one of those particles is a potential source of contamination.

Cleanrooms are used in many industries where sterile, contaminant-free environments are required. This includes the usual suspects — e.g., pharmaceutical manufacturing, biotech, semiconductors, electronics — as well as other industries, like food processing.

Let’s look at current cleanroom standards and how proper housekeeping and appropriate vacuum filtration can help you meet them.

ISO 14644-1: Classification of air cleanliness

ISO 14644-1 is the most commonly used standard for cleanroom airborne particulate cleanliness. There are nine ISO classifications, based on the number of particles of different sizes allowed per cubic meter of air.

ISO Class

Maximum # of particles per m3

0.1 microns 0.2 microns 0.3 microns 0.5 microns 1 micron 5 microns
ISO 1 10 2
ISO 2 100 24 10 4
ISO 3 1,000 237 102 35 8
ISO 4 10,000 2,370 1,020 352 83
ISO 5 100,000 23,700 10,200 3,520 832 29
ISO 6 1,000,000 237,000 102,000 35,200 8,320 293
ISO 7 352,000 83,200 2,930
ISO 8 3,520,000 832,000 29,300
ISO 9 35,200,000 8,320,000 293,000

To put these numbers in perspective, if you live in a typical city, the air outside corresponds roughly to ISO 9. Medical device packaging areas typically use ISO 7, and operating rooms must be clean to ISO 5 or better. ISO 5 is also the level mandated by the FDA’s cGMP for sterile drug products produced by aseptic processing. As you can imagine, ISO 1 facilities are rare. This one in South Carolina was built for manufacturing…wait for it…cleanroom cleaning products.

Housekeeping and filtration for cleanrooms

Keeping particle levels this low isn’t easy, especially when the particles are so tiny (the platelets in your blood are about 5 microns, so you can imagine how small 0.3 microns is). But it’s essential because even these microscopic particles can cause big problems if they get onto a computer chip or make their way into a drug capsule. The best way to prevent these problems is by keeping your surfaces, machinery, and other equipment as dust-free as possible.

Typically, cleanrooms are kept clean by using both an ambient air filtration system and a regular housekeeping regimen. That regimen will include activities like changing the tacky mats, wiping equipment and surfaces with disposable dusting cloths, clean doors and trim with approved solutions, and mopping the floors.

But regardless of whatever other equipment and processes you use, a HEPA-filtered vacuum should be part of your cleaning arsenal.

Here’s why — HEPA filters are individually tested and certified to guarantee that they capture 99.97% of ultrafine particles, down to and including 0.3 microns. This is especially important because these small particles can remain even after you’ve cleaned with other methods. For example, even dusting cloths designed for cleanrooms can leave fibers behind — fibers that only HEPA-filtered vacuums can pick up.

All of Nilfisk’s cleanroom vacuums are built with a graduated multi-stage filtration system. What this means is that the air travels through a series of progressively fine filters, to trap progressively smaller particles. The HEPA filter actually comes last, on the exhaust outlet, to ensure that once the particles are captured, they’re also retained. This graduated system protects the HEPA filter from excessive wear and tear so it will work better and last longer. For highly critical areas, you can also use a ULPA filter, which is even finer, capturing 99.999% of particles, down to and including 0.12 microns. Using this technology, we can support you with vacuums approved for use in cleanrooms up to ISO 4.

Nilfisk was the first company to engineer cleanroom-packaged vacuums. Learn more about how we can support you.

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