Maintaining positive or negative air pressure is an important metric in cleanrooms located in hospitals, labs and other manufacturing facilities, ensuring a clean, non contaminated air supply. In multipurpose rooms, a well designed ventilation system can switch the flow from positive to negative, and vice versa, depending on the nature of the work being performed. Usually in multipurpose rooms indication lights on a control panel or display can show the airflow direction status; whether positive or negative.
In a positive air environment, the positive air pressure pushes air out of a room by increasing the airflow rate. The supply fan, also known as the intake fan, replaces the old air with freshly pulled in filtered air. Any contaminants are forced out of the room with the old air, ensuring a clean air supply. Positive pressure rooms maintain a high pressure inside the treated area by constantly pushing old air out and in scenarios that must continually filter harmful contaminants out of the environment. In medical settings, positive pressure rooms are referred to as protective environments. Positive air pressure rooms are common in hospital environments such as human and animal nurseries, vitro fertilisation labs and operating theatres.
Positive air pressure can be applied to both cleanrooms and within finished product, ensuring contaminants and dust don’t affect the product performance. As an example, computers feature small fans to blow out debris and dust to avoid build up and product failure, while smaller component manufacturers such as those making PCB boards and other computer chips will benefit from positive pressure room to ensure that the newly manufactured parts are not defective from new. In medical settings, these protected environments allow staff to keep vulnerable patients safe from infections and disease.
In contrast with positive air pressure, negative pressure rooms use lower air pressure to allow outside air into the segregated environment. This traps and keeps potentially harmful particles within the negative pressure room by preventing internal air from leaving the space. In medical settings these rooms are called Airborne Infection Isolation Rooms (AIIR) and their main function is to protect people outside the room, from exposure. Air is more likely to flow into a negative air pressure room than out of it, ensuring contaminants do not leave.
Negative air pressure rooms are used in industries that manufacture pharmaceutical products, do biochemical testing and are also a common solution in infection control efforts, for example hospitals use them in inpatient rooms and to quarantine seriously contagious patients. The following are common areas to build a negative pressure environment within hospitals; waiting rooms, triage areas, bathrooms, autopsy rooms, soiled laundry areas and decontamination spaces.
Both negative and positive pressure environments are an important and necessary part of a wide range of research and medical environments, maintaining clean conditions in the smallest clinic to the largest hospitals.