Airlock

Airlock is an enclosed space with interlocked doors, constructed to maintain air pressure control between adjoining rooms (generally with different air cleanliness standards). The intent of an airlock is to preclude ingress of particle matter and microorganism contamination from a lesser controlled area.??

[Reference: Annex 1 Glossary, Page 63]

Types Of Air Locks

The airlock is generally called PAL (personnel airlock) when used for personnel and MAL (Material airlock) when used for transferring materials.

In pharmaceuticals there are basically three types of the airlock used as described below:

1. Cascade Airlock

In a cascade air locking system, pressure increases or decreases in ascending or descending order respectively, (from 30 Pa to 20 Pa to 10 Pa \or\ 10 Pa to 20 Pa to 30 Pa). Thus, air moves from higher pressure to lower pressure, preventing cross-contamination. This type of airlock is commonly used in Tablet manufacturing facilities where higher pressure remains in the corridor to keep drugs inside the cubicle.

2. Bubble Airlock

In a bubble airlock, pressure inside the airlock is high or positive, and is low or negative on adjacent sides. Thus, air moves from the airlock to the primary manufacturing area, and in the same way from the airlock to the corridor. Higher air changes are produced in the airlock, thus producing a bubble as it pushes air outside from the airlock. This type of airlocking system is commonly used in Injectable manufacturing facilities so that air contaminants from outside do not contaminate the product.

3. Sink Airlock

In sink airlocks, the pressure inside the airlock is negative, and is positive in adjacent areas, such that the air moves from higher pressure to lower pressure areas. Higher pressure on both sides of the airlock prevents contaminants from escaping the primary manufacturing area. It is commonly used in the manufacturing of harmful substances such as poison.

Reference: A Cleanroom Hub