2022/02/03

The importance of airlocks in the pharmaceutical production

The pharmaceutical production takes place in cleanrooms or clean environments, in other words, in areas whose atmosphere is classified, as the concentration of particles in the air is controlled. These areas can be of two types: cleanrooms and airlocks. In the cleanrooms, manufacturing operations are carried out, whereas the airlocks carry out a supporting role.
If we check the GMP “good practices”, we will observe that the airlocks are defined as a “closed space with two or more doors, standing between two or more environments, for example, from different classified cleanrooms, with the aim to control the airflow between these environments, when you need to access into one of them. An airlock is designed to be used by both people and inputs and/or equipment”.

Types of airlocks

The changing rooms are the airlocks in which the operators put on the clothes they need to access to the classified cleanrooms. In international terminology, these airlocks are commonly known as PAL, in other words, Personnel Airlocks.
The airlocks intended for the transference of materials between two cleanrooms are sort of a no-man’s land between two different environments. The personnel
from one side deposits into the airlock whatever they want to transfer and closes the door. Followed by the other personnel from the other side who open the door and takes it. This is the way the transference is carried out, lacking direct communication between the environments on both ends. Following the same principal mentioned above, these airlocks are called MAL, which stands for Material Airlocks. It is interesting to point out that these airlocks are also known as SAS, which is the airlock denomination in French and oddly enough has the same Latin etymology as the Spanish word “cedazo”, which means strainer.
When we need to transfer small materials and instruments, the airlocks become into the so-called pass boxes, which are small chambers between both cleanrooms. To make the manipulation easier, they are placed at a medium-high position, not at the floor level.

Access protocol and safety measures

The airlocks, both PAL and MAL, are classified as cleanrooms on the highest level with the adjoining one. Thus, we try to avoid the contamination flow from the room at the lowest cleanliness level to the highest one. When it is about people, the contamination transfer is prevented through hygienic practices, such as washing your hands, or in case of higher risk, with showers and putting on clean clothes, which is special and adapted to the type of work to be carried out.
When transferring materials, there are two strategies for contamination control: on the one hand, protecting the materials with a double bag, and then discarding the exterior bag; on the other hand, leaving the materials standing during some time in the airlock, as renewing the atmosphere with filtered air, eliminates any
possible contamination caused when introducing them. In some cases, it is necessary to foresee a decontaminating system. Remember that GMP estates that the pass boxes must not be simple boxes, but filtered air sweeps, and count with disinfection systems when needed.
In consequence, it is easily understood that airlock doors must be latched, to avoid being opened simultaneously and the staff must be trained in order not to leave the doors opened.

Airlock systems

Finally, we should mention that due to the differential pressure (DP), the areas are designed to create airflows that contribute with controlling the contamination. Here, the airlocks also play a very important role.


When the differential pressure in the airlock is in between the two adjoining rooms, an airflow is created from the highest DP to the lowest DP, known as “cascading effect”.
If the DP of the airlock is lower than the one in the adjoining rooms a “sink effect or downturn” is created, as there are airflows towards the airlock.


Finally, when the airflow presents overpressure with respect to the rooms, a “bubble effect” is created, separating both.

Ultimately, the airlocks’ function is to complement the action of the HVAC system to control the airflow and prevent the crossed contamination, especially when we separate two or more rooms that have different classification level. From a technical approach, the crossed contamination control, lays specially on the HVAC system, as it:

  • impulsa aire filtrado “limpio”
  • extrae el aire interior “sucio”
  • y por un adecuado balance de los caudales de aire consigue crear diferenciales
    de presión entre las salas, que se traducen en flujos de aire que arrastran las
    partículas suspendidas en el aire en el sentido que convenga para controlar la
    contaminación cruzada de los productos.

También, resulta necesario un adecuado diseño de los equipos para que no liberen partículas, generadas por ellos mismos o por los productos. Con este fin, las GMP aconsejan utilizar “sistemas cerrados”. Indican que en caso de liberación de polvo, el sistema HVAC debe ser complementado con un sistema de extracción.

Le invitamos a que contacte con nosotros si tiene en mente llevar adelante un proyecto de estas características o para el que necesite asesoramiento.