Cleanroom HVAC Systems Explained

Cleanroom HVAC Systems Explained

In cleanrooms, air is crucial – how it’s filtered, how it’s heated and cooled, and how it’s circulated. Because of this, knowing how HVAC and filters work together is crucial to maintaining cleanroom air decontamination and meeting cleanroom standards. Before you install a new cleanroom, here’s what you need to know about your cleanroom’s HVAC system:

Dedicated vs. Integrated HVAC

When it comes to cleanroom HVAC systems, the first decision is whether to have a dedicated HVAC system or to incorporate your building’s existing HVAC. This depends on the necessary level of environmental control, the size of your cleanroom, and the other energy requirements of your facilities. Using an existing HVAC system can help you save money at the outset, but for very large cleanrooms or factories, a dedicated system might be more efficient and keep a reasonable load on each system so that they can run efficiently. Additionally, while you can combine a filtration system with an existing HVAC system very efficiently, for extremely stringent cleanroom standards, dedicated HVAC may be your best bet.

Filtration systems

Filtration is also an important consideration here. There are three basic types of filters used in cleanrooms: prefilters, HEPA filters, and ULPA filters. Prefilters are used with both HEPA and ULPA filters as a first step in the filtration process, removing large particles.

HEPA filters are High-Efficiency Particulate Air filters, and they filter out 99.99 percent of particles 0.3µm or larger.

ULPA filters are Ultra Low Particulate Air filters, and filter out 99.999 percent of particles larger than 0.12µm.

Purity Testing

Once your HVAC and filtration systems are in place, you must regularly test the air purity of your system. Testing should occur initially in three phases: as-built testing (when all services are connected and working), at rest (when all equipment is installed and in place), and performance qualification (occurring regularly while the cleanroom is in operation).  

Are you designing a new cleanroom or updating an existing one? Angstrom Technology has the products and expertise you need.

What’s the Difference Between Positive and Negative Air Pressure Cleanrooms?

What’s the Difference Between Positive and Negative Air Pressure Cleanrooms?

If you’re considering a cleanroom, you’re probably trying to gather as much information as possible. What type of cleanroom is right for you? What industry standards do you have to meet? Where will your cleanroom go? You get the picture. Well, one piece of information that might be useful to you is understanding the difference between positive and negative air pressure cleanrooms. As you probably already know, airflow plays a leading role in keeping your cleanroom to standard, but what you may not have known is that air pressure can have a big effect on that as well. So here’s a broken down explanation of each positive and negative air pressure.

Positive Air Pressure Cleanrooms

This means that the air pressure inside your cleanroom is greater than the pressure outside of it. This is achieved by pumping clean, filtered air into the cleanroom, generally through the ceiling.

Positive pressure is used in cleanrooms where the priority is keeping any possible germs or contaminants out of the cleanroom. In the event that there was a leak, or a door opened, clean air would be forced out of the cleanroom, rather than unfiltered air being allowed into the cleanroom. This works somewhat similarly to deflating a balloon; when you untie a balloon, or pop it, air rushes out because the air pressure in the balloon is higher than the pressure of the ambient air.

Positive pressure cleanrooms are used primarily for industries where the cleanroom functions to keep the product clean and safe from particulates, like in the microelectronic industry where even the tiniest particle can damage the integrity of the microchips being manufactured.

Negative Air Pressure Cleanrooms

In a negative air pressure cleanroom, the air pressure in the room is lower than the pressure outside of the room. Generally this is achieved by filtering air out of the room. In most situations, air enters through filters near the floor, and then is sucked out through filters in the room ceiling.

Negative air pressure is used in cleanrooms where the goal is to keep any possible contamination from escaping the cleanroom. Windows and doors have to be completely sealed, and by having a lower pressure, air outside the cleanroom is likely to flow into it, rather than out of it. Think of it like an empty cup that you set in a bucket of water. If you push the cup into the water rightside up, water flows into the cup, because it has lower pressure than the water. The negative pressure cleanroom is like the empty cup here.

Negative air pressure cleanrooms are used in industries that manufacture pharmaceutical products, do biochemical testing, and also in hospitals to quarantine seriously contagious patients. Any air that flows out of the room has to first flow out of a filter, ensuring that no contaminants can escape.

If you have any more questions regarding negative and positive air pressure cleanrooms, take a look at our Dwyer Digital Differential Pressure Gauge or if you’re looking to purchase a cleanroom for your business, give the experts at Angstrom a call today! We custom design all of our cleanrooms, so that they meet your exact specifications and standards. Call us at 888-768-6900, or contact us online.



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