03 Dec Cleanroom Air Filtration: Types of Filters and What They Do
It’s no secret that a major part of keeping cleanrooms pristine and spotless comes down to air filtration. In any cleanroom, air filters work together to trap particles of a wide range of sizes. Whether you’re working within a compounding pharmacy, semiconductor fabrication plant, or some other contamination-controlled space, air filtration is indispensable. In this article, we’ll cover the most common types of cleanroom air filters, as well as how they work together to keep cleanrooms clean.
Common Types of Cleanroom Air Filters
As we mentioned already, cleanroom air filters work together to remove particles of different sizes. Here’s a look at the most common types:
Pre-Filters
You can think of pre-filters as the first line of defense in a cleanroom air filtration system. They are placed before the more expensive filters so that they can capture the largest particles. This lessens the burden on the more advanced/sensitive filters placed closer to the cleanroom, and extends their lifespan.
Typically, these filters need to be replaced every two or three months.
HEPA Filters
The HEPA (high-efficiency particulate air) filter is the gold standard for most cleanrooms and is found in the majority of cleanroom systems. You may hear that they trap 99.99% of particles 0.3 micrometers in size, but this number is actually the least efficient particle size, known as the most penetrating particle size (MPPS). In other words, HEPA filters are even better at capturing particles smaller and larger than 0.3 micrometers.
In practice, these filters can last for two or three years, but may need to be replaced sooner or later, depending on how well they are taken care of, the number of particles in the space, the cleanliness level required, and other factors.
ULPA Filters
Finally, there are ULPA (ultra-low particulate air) filters, which remove 99.999% of particles at 0.12 micrometers (again, keep in mind that this is the MPPS, so they are even more efficient than stated!). Though not as ubiquitous as HEPA filters, they are still used in many cleanrooms, especially in spaces that require a very high level of cleanliness, as in ISO 5 and stricter environments.
You may be wondering: If ULPA filters are even better at catching particles than HEPA filters, why not use them in most cleanrooms instead?
Well, there are a few reasons for this. First of all, they are more expensive than HEPA filters. And perhaps most importantly, they reduce airflow, which increases operational costs by a lot. Also, ULPA filters aren’t necessary in many cases, because most cleanrooms only need to filter particles of specific sizes, which HEPA filters can handle on their own.
(If you want a full account of the differences between HEPA/ULPA filters, check out our article here.)
The Bottom Line
Cleanroom air filtration is the most important factor when it comes to keeping out contamination. Pre-filters catch the big particles so that more advanced, sensitive filters can last longer. HEPA filters are the gold standard for cleanrooms, while ULPA filters are there when they need to meet the strictest standards. Together, they make sure cleanrooms stay pristine and ready for the work they were built for.
Ready to create a contamination-free environment? Contact the experts at Allied Cleanrooms for a custom quote on modular cleanrooms today!