
08 Oct What is a HEPA Filter? Definition and Benefits
Imagine losing millions of dollars over a few specks of dust. In many manufacturing industries, small particles can ruin entire batches of products, lead to recalls, and worse. As a result, cleanrooms, and an important part of them, HEPA filters, have been instrumental in preventing these disasters. In this article, we’ll discuss what a HEPA filter is, how they benefit cleanrooms, and more.
What is a HEPA Filter?
A high-efficiency particulate air (HEPA) filter is an advanced air filter that can remove extremely small particles from the air. They are able to capture at least 99.97% of airborne particles as small as 0.3 microns. This size, which is known as the most penetrating particle size (MPPS), is the hardest for them to capture. (In fact, HEPA filters can capture particles smaller than 0.3 microns even more efficiently.)

A HEPA filter is essentially a web of randomly arranged fibers. Such fibers can be made of materials like borosilicate glass or synthetic materials like polypropylene. The filter’s effectiveness in trapping particles has a lot to do with the diameter of these fibers, their density, and the overall thickness of the filter. Many elements work together to trap these particles, and the physics of this can be complex. Mechanisms such as interception, impaction, and diffusion, all help to make sure that particles do not pass through.
How Do HEPA Filters Benefit Cleanrooms?
HEPA filters are almost universally required in cleanrooms, and have become an essential part of creating a clean space. Here are a few reasons why they are so widely used today.
Particle Control
The purpose of any filter is to remove particles. HEPA filters are simply very effective in carrying this out. In cleanrooms, dust, bacteria, or mold can cause major issues in many manufacturing industries (such as semiconductors or pharmaceuticals), so the high efficiency of them reduces the risks of trouble.
Regulatory Compliance
Further, many companies simply need to make their products in cleanrooms to satisfy regulators. As you might imagine, industries such as healthcare, biotechnology, and pharmaceuticals have to operate under strict rules so that their products do not harm patients. The exact regulations will differ depending on the industry, but ISO, cGMP/GMP, USP 797/800, and others are commonplace.
Workplace Safety
A corollary to the above, but still worth pointing out, is that HEPA filters also protect cleanroom workers/personnel. The particles that they are exposed to may be dangerous, as they are in pharmaceutical compounding where workers are expected to handle dangerous drugs. HEPA filters are an important part of compliance (with USP 800 and other regulations), as they help prevent hazardous material from recirculating within the workplace.
The Bottom Line
HEPA filters are the most essential feature of modern cleanrooms. They are perhaps the most important piece of the equation, and are integral to keeping cleanrooms clean. Through various mechanisms, they effectively remove tiny particles, help cleanrooms reach compliance, and protect both products and workers. HEPA filters have become the backbone of air quality in cleanrooms.
Interested in adding a cleanroom to your location? Reach out to the experts at Allied Cleanrooms to get a free quote on a new buildout.
FAQs About HEPA Filters in Cleanrooms
1. How often do HEPA filters need to be replaced in a cleanroom?
The replacement schedule for HEPA filters will depend on the environment and type of use. However, they are usually replaced every 3 years in cleanrooms, but some can last 8 years or more. You’ll want to test/monitor your filters from time to time to make sure they are working properly, which is how you can make the decision about whether or not they need to be replaced.
2. Can HEPA filters remove viruses from the air?
Yes, absolutely. Strangely enough, many viruses travel into cleanrooms via other particles (in droplets, dust, aerosols, etc.). As a result, HEPA filters are able to remove many virus-containing particles effectively.
3. How do HEPA filters compare with ULPA filters?
HEPA filters capture at least 99.97% of particles as small as 0.3 microns, but ULPA filters are even more efficient, and can trap 99.999% of particles down to 0.12 microns
So why not just use ULPA filters, then?
Well, ULPA filters create more airflow resistance, and as a result, require more energy to operate (making them expensive!). HEPA filters are a better balance between efficiency and cost. (If you’re interested in learning more, check out our article on the differences between HEPA/ULPA filters here.)