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.


dwyer digital differential pressure gauge


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.




6 Tips When Considering Installing a Cleanroom

6 Tips When Considering Installing a Cleanroom

#1 Can you afford NOT to have a cleanroom?

You may have been going back and forth trying to decide if it’s worth it to spend your budget on installing a cleanroom, but the question you should really be asking is can you afford not to have one? As products become smaller and smaller, particle contamination can have a bigger effect on your manufacturing process, potentially causing costly product recalls, and even potentially life-threatening situations depending on your industry. Once you take into account the risks of not having a cleanroom, you’ll be better able to decide if it’s worth it or not.


#2 Traditional vs Modular Cleanrooms

Now that you know you really do need a cleanroom you’ll have to decide whether you’re going to need a traditional or modular cleanroom. A traditional cleanroom is built, much like any building is, out of brick or drywall, and coated with an epoxy finish. Though these function well after they are built, a lot of time and effort goes into the construction process. A modular cleanroom is generally prefabricated off site, and then delivered to your business with all of its parts, and conveniently put together with no dust or mess, and a very minimal construction time.


#3 Cleanrooms have Various Cleanliness Standards

Depending on your industry, you’ll have to meet a certain standard of cleanliness determined by ISO international standards. These standards are classified by how many particles of a certain size are allowed to be in your cleanroom to maintain your process safely. The kicker here is, the more stringent your standards, the more you’re probably going to have to spend. Once you know your standards, you’ll have a better idea of a practical budget.


#4 Time to Production

As the adage goes, “time is money.” So you’ll want to consider how long it will take to get your cleanroom set up before you can start production. If you decided to go with a traditional cleanroom, it’s going to take a while before you’ll be up and running, whereas with a modular cleanroom it may only be a few weeks before you can get started. It’s also good to remember that modular cleanrooms can always be extended and added to if you want to expand your operation down the road.


#5 Time to Validation

If you went with a modular cleanroom, you will want to factor in a bit of time for validation. Before you can start production, your cleanroom will have to be validated to ensure that it is performing to the correct ISO standard. It’s also important to note that if you want to keep your cleanroom running well, you should schedule regular validations. That way you know your cleanrooms is performing as it should, and you’ll be protected from any external audits from clients.


#6 Good Cleanroom Protocol

Finally, once your cleanroom is installed and set up, you’ll want to make sure you maintain that through proper protocol. Make sure your employees are properly trained on gowning methods and best practices, and make sure your cleanroom is cleaned thoroughly according to standards. The better you maintain your cleanroom, the better it will function. If you have proper protocol and procedures in place before your cleanroom production begins, you’re sure to be able to start your project as soon as it’s installed and validated.

If you have more questions regarding your cleanroom project, don’t hesitate to call the experts at Angstrom at 1-888-768-6900. With more than 20 years experience installing and maintaining every type of cleanroom, we’re sure to have an answer or solution!