Air lock: Air lock is a system formed in the form of a small room which has entry in and exit doors, entry doors are kept open while exit doors are kept closed. Air flow is controlled in the room so that it prevents contamination of air of inside clean room of higher level of particle control and passage outside. Facility of crossover bench for stage gowning, hand disinfection is provided in air locks. When such air lock system is placed just before the entry of a clean room. Separate airlocks are provided for Material and Man. PAL means Personal Air lock and MAL means
PAL and Material Air Lock. Air locks are provided with HEFA filtered air supply with pressure to prevent the cross contamination.
Clean up time: Clean up time is the time period required in a clean room at when a AHU is started air in the room starts getting filtered, and replaced with HEPA filtered air so that the particle count in the clean room comes to the rated count of the classification.
For an example, a class 10000 area is at rest in morning and before AHU is started its count will be higher than the rated value, after AHU is started air in the clean room starts getting filtered through HEPA filter the particles get filtered and part of air is exhausted and part of fresh air is filtered and supplied so that the particle count in the room drops and is maintained to the level of acceptance as per rated class of the clean room, time period required to attain this is called as Clean up time.
While describing the class of filter one must not use term as 3-micron filter or 5 micron or 10-micron filter As per WHO Guidelines On HVAC system, it may lead to wrong filter getting installed. Therefore, Filters nomenclature should be adapted as EN 779 and EN 1822