HOW TO STERILE AIR IN CLEAN ROOM?

Using ultraviolet germicidal lamps to irradiate indoor air can prevent bacterial contamination and thoroughly sterilize.

Air sterilization in general-purpose rooms: For general-purpose rooms, a radiation intensity of 5 uW/cm² per unit volume of air for 1 minute can be used for sterilization, generally achieving a sterilization rate of 63.2% against miscellaneous bacteria. For preventive purposes, a sterilization intensity of 5 uW/cm² is typically used. For environments with stringent cleanliness requirements, high humidity, or harsh conditions, the sterilization intensity may need to be increased by 2-3 times. The ultraviolet rays emitted by germicidal lamps are similar to those emitted by the sun. Exposure to these ultraviolet rays over a period of time at a certain intensity can cause a tan on the skin. Direct exposure to the eyes can cause conjunctivitis or keratitis. Therefore, strong germicidal rays should not be applied to exposed skin, and direct viewing of an active germicidal lamp is prohibited. Typically, the work surface in pharmaceutical clean room is 0.7 to 1 meter above the ground, and most people are under 1.8 meters tall. Therefore, for rooms where people stay, partial irradiation is recommended, irradiating the area between 0.7 meters and 1.8 meters above the ground. This allows for natural air circulation to sterilize air throughout clean room. For rooms where people stay, to avoid direct UV exposure to eyes and skin, ceiling lamps emitting UV rays upward can be installed, 1.8 to 2 meters above the ground. To prevent bacteria from entering clean room through entrances, high-output germicidal lamps can be installed at entrances or in passageways to create a germicidal barrier, ensuring that bacteria-laden air is sterilized by irradiation before entering clean room.

Air sterilization in sterile room: According to common domestic practices, the following procedures are used to activate and deactivate germicidal lamps in pharmaceutical clean room and sterile rooms in food clean room. The on-duty personnel turn on the germicidal lamp half an hour before work. When staff enter clean room after showering and changing clothes, they turn off the germicidal lamp and turn on fluorescent lamp for general lighting. When staff leave sterile room after get off work, they turn off fluorescent lamp and turn on germicidal lamp. Half an hour later, the on-duty personnel disconnect germicidal lamp master switch. This operating procedure requires that the circuits for germicidal and fluorescent lamps be separated during design. The master switch is located at the entrance to clean room or in duty room, and sub-switches are installed at the entrance of each room in clean room. When the sub-switches of the germicidal lamp and the fluorescent lamp are installed together, they should be distinguished by seesaws of different colors: in order to increase the outward emission of ultraviolet rays, the ultraviolet lamp should be as close to the ceiling as possible. At the same time, a polished aluminum reflector with high reflectivity can be installed on the ceiling to enhance sterilization efficiency. Generally, sterile room in pharmaceutical clean room and food clean room have suspended ceilings, and the height of the suspended ceiling from the ground is 2.7 to 3 meters. If the room is top-ventilated, the layout of the lamps must be coordinated with the layout of the supply air inlet. At this time, a complete set of lamps assembled with fluorescent lamps and ultraviolet lamps can be used. The sterilization rate of the general sterile room is required to reach 99.9%.