The negative pressure isolation room refers to that under the special device, the air pressure inside the room is lower than outside. In this way, from the perspective of air circulation, only fresh air outside can flow into the room. The air polluted by patients in the room will not leak out, but will be discharged to a fixed place in time through a special channel. In this way, the places outside the negative pressure room will not be polluted to reduce the chances of medical staff being infected in large quantities.
There are two main functions of the negative pressure isolation room for infectious diseases. One is to isolate pathogenic microorganisms by using the negative pressure principle, and at the same time, the indoor air polluted by patients will be discharged after special treatment, which will not pollute the environment. The other is to dilute the concentration of pathogenic microorganisms in the room through ventilation and reasonable air distribution, and make the medical staff in a favorable wind direction to protect the medical staff for safety.
Negative pressure value is a delicate key, too much pressure difference will make patients feel uncomfortable, too little difference will not achieve the effect. Generally speaking, the preparation room should have at least - 6 PA (about - 0.612 mmh2o) and the ward should have - 8 PA (about - 0.812 mmh2o).
The negative pressure environment created by the air conditioning system ensures that the untreated air will not leak out through the door of personnel access. At the same time, all the air in the room will be treated through the high-efficiency filter screen, and all pathogens will be blocked in the filter net, so that the clean air will be discharged to the outside. The filter screen containing a large number of pathogens is directly put into the bag without passing through the external environment, and the bag is sealed and treated as infectious waste. In this way, in addition to avoiding the leakage of pathogens, it can also ensure the safety of filter screen replacement personnel.
Positive pressure room and negative pressure room are the same concept but completely opposite mechanism. The pressure in the room is slightly higher than atmospheric pressure (8 Pa; about - 0.812 mmh2o). The air-conditioning equipment will blow the outside air into the ward through the high-efficiency filter screen, so that the air entering the ward is sterile, while the pressure slightly higher than atmospheric pressure can prevent the unfiltered air outside the room from entering the room.
Positive pressure room is mainly used to avoid infection in patients with low immunity, such as burn ward, patients who have just finished organ transplantation, operation room and so on. The same principle applies to the aseptic room required by the Research Institute and the dust-free room required by the semiconductor factory, while the sterile operating platform commonly used in microbiological research is the miniaturized application of positive pressure room. In order to maintain the sterile state in the room, the filter screen should be highly efficient, and the air-conditioning box should not leak at all. In addition, the disinfection mechanism in the room must be started regularly, the most common is ultraviolet light, and occasionally fumigated with toxic gas.
To build a hospital, operating room, pharmacy room, microbiological research center, semiconductor factory, nurse room, isolation ward etc. it needs the sandwich panel as wall and ceiling, it needs the airtight door to stop air circulation.
There is different cleanliness class for dust free room, which make the doors has the difference of 100% hermetic or non-full airtight. This will depend on the project need to design. Normally the operation room and infectious diseases isolation room has a higher requirement.