Cleanroom Classifications & Standards

Depending on what industry you’re in, and what you’re manufacturing, your cleanroom will have to comply with certain standards. But how do you know what classification your cleanroom has to fit into, and how do you know what equipment you need to meet that classification?

While it’s our job here at Angstrom Technology to make sure that your cleanroom functions exactly to your specifications, it’s good for you to know what those specifications are. For instance, the default standard for medical device packaging is ISO 7 (a class 10,000 cleanroom). See the chart below for more information on classes. So, if you’re building a cleanroom for medical device packaging, you know that your cleanroom has to function at least to ISO 7 standards. From there, you can talk to our cleanroom experts here at Angstrom Technology to figure out exactly what kind of equipment and materials you’ll need to build the proper cleanroom.

If your industry doesn’t have a default classification, or if you think that you might want more contamination control than what is recommended, there’s three basic questions you can ask to determine what standard you’ll have to comply with:

  1. What are your sources of contamination? (Where do particles get in, and how?)
  2. What size particles do you need to filter out? (What particles adversely affect your operation?)
  3. How much circulating air will you need to get rid of that contamination?

Once you determine the answers to these questions, it’ll be much easier to figure out what type of cleanroom you need, and how much contamination you’ll have to control.

Sources of contamination

The point of a cleanroom is to keep the outside from getting in. Once you install a cleanroom, theoretically if no one entered or left, and you changed filters regularly, it would perform to exactly the standards it was set up to. Unfortunately, the world doesn’t function in a vacuum, and you do need employees to go in and out if you want to get anything accomplished. So what are your main sources of contamination, and how do you make sure they don’t disrupt your cleanroom classifications?

Your biggest source of contamination is going to be your employees. Humans regularly shed particles of all kinds, from hair to dead skin, and there’s no real way to stop that from happening. So, any employee that enters a cleanroom will be required to wear a certain amount of protective clothing. Each cleanroom environment will have standardized gowning procedures to make sure that the right amount of particles are kept from contaminating your cleanroom.

Depending on your standards, employees may be required to wear as little as a lab coat and goggles, or as much as a full gowning suit. It’s also good to know that your employees can always wear more than what is prescribed for your environment, if you’re looking to keep your cleanroom a little cleaner.

The other source of contamination is the process. This means the cleanroom itself. You have to know where trouble areas might be in the cleanroom, and if it’s potentially letting in any type of contamination. Once you know where the trouble areas are, you can place return air grill and filtration systems at the optimal locations within your cleanroom, ensuring that your cleanroom functions to its highest capacity.

What particle size has to do with your classification

It’s important to know what specific types of particles you need to filter out. Classifications vary based on both how many particles are allowed per square foot, but also by the size of the particles. 10 particles that are ½ micron in size is a much different amount of contamination than 10 particles that are 5 microns in size. Usually, your industry will specify what size particles are damaging to your product or your process, and will say how many are allowed per square foot for you to be in compliance. You have to factor in both particle size, and the amount of particles allowed to define the right contamination class for your cleanroom.

Air Circulation and Classification

Air circulation is very important to maintaining a proper cleanroom. Each class of cleanroom will have a certain amount of required air based on the size of the cleanroom, and the bigger your space, the more air you’ll have to pump in. Believe it or not, each time you go up a class, say from an ISO 8 to an ISO 7, you’ll have to use twice as much air. That’s why you really want to think about the construction of your cleanroom, and you’ll need to talk to your contractor to make sure you’re creating the most efficient cleanroom possible.

For example, the building you’re using to install your cleanroom has 10 foot ceilings. You’d like to use your existing ceilings for the ceiling of your cleanroom, but consider that by having 10 foot ceilings, instead of 8 foot ceilings, you’re increasing the space in the room by 25%. That means you’ll have to pump in 25% more air to keep that cleanroom clean. So, make sure you’ve thought about all of your options, and you work closely with your contractor before you make a final decision.

Standard Classifications

Classifications are generally recognized on two different scales. First, the International Standards Organization (ISO), and second, the U.S. General Service Administration’s standards, scientifically known as FS209E, and colloquially referred to as Classes. We’ve included a chart below to show what the specific requirements are for each standard, based on both the amount of particles, and particle size. Note that both ISO and FS209E Classes overlap.

Cleanroom Standards Classifications Chart

ISO Recommended Air Change Rates

Another important aspect of contamination control in your cleanroom is the air-change per hour (ACH), also referred to as the air-change rate (ACR). This refers to the amount of times per hour that the air inside your cleanroom is exchanged for new, filtered outside air. For reference, a normal home with an air conditioner changes room air a maximum of twice an hour, while a cleanroom can change air anywhere from 10 to over 600 times an hour. The chart below shows the range of air change and the ceiling coverage recommended based on the ISO class of your cleanroom.

ISO Recommended Air Change Rates

Deciding on the right cleanroom can be very difficult. You have to balance a lot of factors: industry standards, budget, space, and time constraints, and then you have to install it. We know it can be confusing, especially when all the information is new. At Angstrom Technology, we work with you to design a cleanroom that meets your specifications exactly. We’ll talk with you, help you decide what type of cleanroom is right for your project, and we’ll even meet you at the construction site to help design it. If you’re looking for the right cleanroom, it’s time to give us a call!


We’re here every step of the way to ensure you get the perfect cleanroom. Submit your request online and one of our cleanroom experts will contact you with your free quote.


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