Airlock system plays a vital role in pharmaceutical industries to protect clean rooms from contaminants and to prevent cross-contamination.
An airlock is produced by creating differential pressure between two areas and differential pressure is produced by HVAC.According to WHO a differential pressure of 10-15 pascals should be maintained.
Purpose of Airlock
The main purpose of the airlock system is to prevent cross-contamination.
-In a sterile area prevent the entry of less clean air to high clean area.
-In a sterile area prevent the entry of microbes from the less clean area to the high clean area.
-In oral solid dosage forms, manufacturing areas prevent the outflow of powders.
Personnel Airlock (PAL)
The airlocks which are used for the entry of personnel into the cleanroom is called personnel airlock (PAL).
Material Airlock(MAL)
The airlock which is used for transferring of materials is called Material air Lock (MAL).
Design of Air Lock
The airlock is a closed room between two cleanrooms of different classes
-Air lock is usually with two doors one door open in one clean room like in class C and other door opens in another class area like in class D.
-Both doors of airlock should not be opened simultaneously. First of all open one door and enter into airlock from Class D then close that door and open other door to enter into Class C.
-Interlocking system should be installed in airlocks to prevent the opening of both door at the same time.
-An alarm system should be installed which give an alert if both doors are opened at the same time. The doors of air lock should be opened towards higher pressure side.
Principle of Air Lock
As it is a general role that air moves from an area of higher pressure towards the area of lower pressure.
Types Of Air Locks
There are three types of an airlock system
-Bubble Airlock
-Sink Air Lock
-Cascade Air Lock
Bubble Air Lock
In bubble airlock pressure inside the airlock is high or positive and in adjacent sides, the pressure is less or negative.
Sink Air Lock
In sink airlock, the pressure inside airlock is negative and in adjacent areas pressure is positive so air moves from higher pressure area to lower pressure area mean from adjacent rooms to the airlock.
Cascade Airlock
In cascade airlock system pressure increases or decreases in ascending or descending order for example from 30 Pa to 20 Pa to 10 Pa or 10 Pa to 20 Pa to 30 Pa. So air moves from higher pressure to lower pressure side and prevent cross-contamination.
Note:
-monitoring of air pressure is required in all areas because any drop or increase in the pressure of any area may result in cross-contamination.
-for sterile areas inside is maintained at positive pressure, so air moves from the high clean area to outside low clean area.
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