Industrial climate control systems comprise two main categories of airflow systems to consider when trying to combat and contain infectious airborne contaminants: positive air pressure and negative air pressure clean rooms.
Typically found in medical settings, positive and negative pressure cleanrooms prevent the spread of infectious diseases and keep contaminants out of restricted or sterile spaces. These rooms are an essential part of research laboratories and medical facilities.
Positive Air Pressure Cleanroom
First off, what is positive air pressure? In terms of a cleanroom environment, positive air pressure forms when the industrial air filtration system’s intake fans create a greater airflow than its exhaust, producing a positive pressure in the chassis. In layman’s terms, this means that the air pressure inside your cleanroom is greater than the pressure on the outside of it. To achieve this, clean, filtered air must be pumped into the room through the ceiling.
The room design and exhaust system need to be set up so that clean air can exit the room without circulating back in. Doing this allows any particulate matter that originates in the cleanroom to be filtered out while also preventing any germs or contaminants from the surrounding environments to enter the room. If a door was opened in a positive air pressure cleanroom, the clean air would rush out of the room rather than being circulated (much like deflating a balloon).
A positive air pressure cleanroom is used when the facility’s priority is keeping any and all possible contaminants or germs out of the clean room entirely. These rooms are used for industries where the cleanroom is meant to protect products or tools from particulate matter in the air, such as medical equipment manufacturing or microelectronic microchip manufacturing companies. In a hospital setting, a positive pressure cleanroom allows doctors and nurses to keep at-risk patients safe from disease and infection.
Negative Air Pressure Cleanrooms
In contrast to the positive pressure cleanroom, a negative pressure cleanroom uses a lower air pressure to allow outside air into the environment. The air pressure in this type of cleanroom is lower than the pressure outside of the room. In this environment, air enters through filters near the floor, and then is sucked out through filters in the ceiling.
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. Any air that flows out of the room has to first flow out of a filter, ensuring that no contaminants can escape. This keeps potentially harmful particulate matter from leaving the internal air space of the room.
Negative pressure rooms are often used in medical facilities to isolate patients with infectious conditions and protect medical staff and people outside the room from exposure. A negative pressure room in a hospital will contain airborne contaminants such as viruses, bacteria, fungi, yeasts, molds, pollens, gases, VOCs (volatile organic compounds), small particles and other chemicals within the room. These air filtration systems are also used in industries that manufacture pharmaceutical products and do biochemical testing.
Building a Better Cleanroom
Building a positive or negative pressure room requires the use of specialized construction knowledge and climate control equipment. Both positive pressure airflow and negative pressure airflow rooms require a lot of special components to run at optimal levels.
In order to meet minimum safety standards, the airflow must undergo at least 12 changes per hour and must be maintained in order to sustain the desired environment. Depending on the size and purpose of the room, more may be necessary. Here are just some of the essential elements to constructing a positive or negative airflow clean room:
● HEPA filters. These control the movement of airborne contaminants in the room
● Self-closing entryway with an adequate seal
● Thoroughly sealed floors, ceiling, walls, and windows
● Fans and ductwork to move air in the desired directions
● A monitoring system that allows users to adjust pressure when necessary
● Intermediate environment between the pressure room and outside environment for deliveries, observations, and protective gear storage
Some facilities, such as medical device manufacturers or hospitals, additionally incorporate UV radiation into the system to help maintain a sterile environment. Using a UV light in a filtration system sterilizes particles and reduces viruses in the quarantine space, helping to protect healthcare workers who enter the room to service the quarantined patient.
Positive and Negative Pressure Rooms in Hospitals
In medical facilities such as hospitals, positive and negative airflow pressure rooms are an essential part of controlling the spread of infectious diseases. As mentioned before, a positive pressure room allows staff to keep vulnerable patients safe from infections and disease. Positive pressure rooms are usually used in scenarios that must continually filter harmful contaminants out of the environment.
This makes them helpful when treating patients with compromised immune systems because the introduction of any harmful element will be efficiently filtered out. They’re also used in situations that must continually maintain a specific type of atmosphere in a room, such as infant nurseries. Other uses of positive pressure rooms include in vitro fertilization labs and operating theaters.
Conversely, a negative pressure room uses lower air pressure to allow outside air into the segregated environment. Hospitals use them in patient rooms of infected people to ensure infectious germs don’t spread throughout the facility via the HVAC system. They are a common and highly effective solution in infection control efforts.
Hospitals are usually designed with negative pressure environments in most areas in order to keep the staff and public safe from those who are sick. The following areas in most hospitals are usually set up as a negative pressure environment:
● Waiting areas, especially in emergency rooms
● Triage areas
● Bathrooms
● AII (airborne infection isolation) rooms
● Autopsy and dark rooms
● Soiled laundry areas
● Decontamination spaces
The next time you find yourself visiting someone in the hospital, you can rest easy knowing these common areas were designed with your health and safety in mind.
When a hospital manager plans their pressurized cleanroom, they must ensure they satisfy all regulations and requirements. This means making sure that the room fits the space and needs of the facility; that the room conforms to all applicable legal regulations; and that the room fully protects the general public (as well as the patients) from the spread of any and all infectious diseases.
Efficiently installed positive and negative pressure rooms mean the difference between a healthy setting for hospital patients and one compromised by infectious pathogens, and that can be the difference between life and death. And using the best commercial air filter is a critical part of this environment.
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