Due to the worldwide Coronavirus (COVID-19) outbreak, our customers have immediate needs for isolation rooms, also known as negative pressure rooms, to protect non-infected people from infectious air particles. Reverse-flow, or exhaust, motorized HEPA fan filter units (FFU’s) are used to create negative pressure isolation rooms by removing infectious air particles from a room, through a high efficiency particulate air (HEPA) filter, and then typically exhausting the filtered air out of the building.
Technical Air Products has been manufacturing cleanrooms and related products for over 25 years. The same components, walls and ceiling grid we manufacture for cleanrooms are also used for negative pressure isolation rooms. The main component, the motorized HEPA FFU that we manufacture for positive pressure cleanrooms, can be reconfigured to become an exhaust FFU to turn an existing room into a negative pressure isolation room.
Negative Pressure Isolation Rooms
The intent of an isolation room is to control the airflow in a room to minimize the chance for cross-infection, of non-infected people within a facility, from airborne infectious particles.
This is accomplished by:
- Maintaining different air pressures between adjacent rooms.
- Air filtration, using HEPA or ULPA filters.
- Controlling airflow patterns to best suit the application.
- Exhausting infectious air particles from the room, diluting with large volumes of air.
Types of Isolation Rooms
- Positive air pressure rooms – Where a patient with a compromised immune system is protected from airborne infectious particles (Class P).
- Negative air pressure rooms – Where others are protected from any airborne transmission from a patient who may be an infection risk (Class N).
- Negative air pressure rooms with Anterooms, with interlocked doors, which are used for quarantine isolation (Class Q).
An anteroom, also called a gown room or airlock, functions as:
- A controlled area in which the transfer of supplies, equipment and people can take place without contaminating surrounding areas.
- A controlled negative pressure room where personnel can put on or take off their personal protective equipment (PPE) prior to entering into, or exiting from, the isolation room.
- An additional barrier against the potential loss of pressurization of the isolation room.
Isolation Room Design
When designing an isolation room, make sure the anteroom has enough space for storage and application of PPE. The door into the anteroom from the isolation room should be self-closing, and should swing into the anteroom.
The anteroom provides access to the isolation room for staff and visitors. For Class N isolation rooms, due to the negative pressure relationship between the isolation room and the surrounding area, separate doors can be provided for the ingress and egress of the patient’s bed directly in and out of the isolation room. It is imperative that the isolation room keeps negative pressure to the anteroom, and the anteroom keeps negative pressure to the surrounding area, to ensure infectious particles do not escape from either room into the surrounding areas when any of the doors are open. Magnehelic gages should be installed to ensure negative pressure relationships are held.
A dedicated exhaust system should be provided from the isolation room. To maintain negative pressure, the exhaust system needs to remove more air than what is being supplied into the room. The exhaust air ducts for isolation rooms should be independent from the building’s air exhaust system. This will reduce the risk of contaminated air finding its way back into non-contaminated areas through a back-draught situation.
Mobile HEPA Fan Filter Unit
High Efficiency Particulate Air filters, or HEPA filters, have been used for years in cleanrooms and healthcare facilities to control the spread of airborne particles, including viruses and bacteria. For over 25 years, Technical Air Products has manufactured motorized HEPA fan filter units (FFU). FFU’s are individually powered fan units that draw “dirty” air through HEPA filters, to deliver clean air to, or from, a critical environment.
HEPA filtered FFU’s are most widely used to provide clean air in positive pressure rooms. Positive pressure cleanrooms keep contaminated air from surrounding areas out. However, FFU’s can also be reconfigured to exhaust air out of a room, through the HEPA filter, to protect surrounding areas from contaminated air particles in the room. When more air is exhausted out of a room than is supplied to the room, a negative pressure relationship is created, which helps ensure that contaminated air in the room is isolated and does not spread outside of the critical environment.
Typically, positive pressure cleanrooms, or negative pressure isolation rooms, are designed that way from the beginning, and are never used for both. FFU’s are usually installed in the ceiling of a room and can be part of a more extensive HVAC system. However, there are times when customers need to convert standard rooms in their facility into either positive or negative pressure critical environments. This has become even more of a need recently, as the COVID-19 pandemic has forced us all to change the way we operate and live.
With that in mind, Technical Air Products has designed mobile versions of our proven HEPA fan filter units, providing our customers more flexibility to react to ever-changing critical environment needs. Our mobile FFU’s can each deliver over 600 cfm of clean air to any room. They are a perfect tool for reducing the amount of airborne contaminants circulating in a room, protecting the health of its occupants. Or, add an optional ducted hood over the HEPA filter and exhaust air out of the room, creating a negative pressure isolation room to keep people in surrounding areas safe from infectious air particles in the room.