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Fan Filter Units in Retrofit Isolation Rooms

Posted by Price Industries on March 31, 2020 at 1:46 PM
Price Industries

Application of Fan Filter Units in Airborne Infectious Isolation Rooms 

Two surgeons washing their hands in a hospital sink

Airborne infectious isolation rooms (AIIRs) are used for patients with easily communicable airborne diseases. When there is a shortage of AIIRs, existing patient rooms (or hotel rooms in temporary care facilities) can be converted to negative pressure isolation rooms. Price Fan Filter Units (FFUs) can be used in three configurations to retrofit these existing spaces.

Ceiling-Mounted Reverse Flow FFU

Ceiling-mounted exhaust-flow fan filter unit
In this, the most permanent and involved application, a reverse flow FFU is installed in the ceiling near the patient. Air is drawn from the room, HEPA filtered and then exhausted through existing exhaust/return ductwork.

Portable Reverse Flow FFU

Portable exhaust-flow fan filter unit
A reverse flow Fan Filter Unit can be placed on the floor of the patient room and plugged into a standard wall socket, drawing air in through the face of the unit and exhausting HEPA-filtered air out through ductwork that is directed to a room exhaust/return grille, to an adjacent space or out a window. It is important that any openings for ductwork are sealed for leakage to maintain room pressurization.

Portable Supply Flow FFU

Portable standard fan filter unit

A supply flow FFU can be placed on the floor of a patient room and plugged into a standard wall socket, drawing air through the back of the unit and expelling HEPA-filtered air out through the face of the unit. The FFU should be positioned in an opening in a doorway or wall that is sealed to prevent leakage past the FFU. Alternatively, the FFU can be placed in the doorway between two adjacent rooms (possibly hotel rooms) to create a negative pressure space where the patient is located.

For more information about Fan Filter Units or Critical Environments products, please contact us at or visit

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Topics: HVAC, Engineering, Design Engineering, Training, Tech Tip, Catalog, Engineering Update, Critical Environments, Filtration

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