In the health care, micro-electronics, micro-chip manufacturing, optics, food processing and other environmentally sensitive applications, the need for high end air filtration or HEPA filtration is high.For example, all hospital and out-patient surgery suites require 100% HEPA filtered air all the time whenever a patient is in surgery.

However, did you know that not only does the surgery room require HEPA filtration but it must operated under a negative pressure system?

The concept of negative and positive air pressure as a means to control an enclosed environment has been around for a long time. While we don’t always notice it, we all see this working on a day-to-day basis in the everyday world.

Remember the last time you opened the door to an office building and you had to pull real hard to get the door to open. Or, just the opposite. You opened the door to a building and when it opened up it blew your hair back. The first example is negative pressure, the second positive pressure.

A building or any enclosed room or structure can become negative when the air handling (heating/cooling) system has a design flaw where more return air is being pulled to the air handler than supply air.

This can happen mechanically for a number of reasons but suffice it to say that when this in-balance of air occurs any opening, crack, or communication point in the structure will draw in air, dust, dirt and any small airborne particulate from the outside or an adjoining space.

The opposite in-balance can also occur where there is more supply air than return air creating a positive pressure environment. In this case the room or enclosure maintains a much cleaner environment since the positive pressure prevents any outside contaminants from entering the room.

For applications such as surgery rooms and micro-chip manufacturing, the rooms must not only be HEPA filtered but be under constant positive pressure.

When a patient is in surgery and the body cavity is open the possibility for infection from any airborne pathogen is extreme. Even with all the air being HEPA filtered, if the room itself was not under positive pressure the ability for small, sub-micron contaminants to enter the room is great.

Micro-chip manufacturing has a similar problem. The micro-chips are actually layers upon layers of silica and if even a tiny, sub-micron particle falls in between the layers, the chip is ruined. Again, positive pressure is required in this application.

In applications where a harmful contaminants, highly infectious bacteria and viruses or harmful gases are present, negative pressure systems are applied to keep the contaminants from leaving the room or enclosed area.

Pure Air Systems HEPA filtration units are powerful and can be used to make a room negative or positive by themselves. They can also be used in conjunction with any HVAC system to accomplish this goal. The ability to both provide HEPA filtered air and produce the desired pressure in the room for the specific application make these systems unique in the market place today.

For more information on positive and negative pressure and the overall capabilities of the HEPA systems go to: www.pureairsystems.com




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About the Author: Don Musilli

My name is Don Musilli. I started Pure Air Systems in 1985 and then sold it in 2006. I continue to consult for PAS and write their blog and control their Twitter account. I also, on occasion, make changes to the website. The company is now almost 26 years old and has been a major player in offering commercial grade, high performance HEPA and Carbon based filtration systems for the commercial, institutional, industrial and residential markets.

I currently reside in Englewood, Florida where I write blogs and do social media marketing for a number of clients.


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