Importance of Pressure Differential In The Pharmaceutical Manufacturing Industry
The pressure differential is the difference between the atmospheric pressure of one area and that of its surroundings. It is usually measured in pascals using a device called a magnetic pressure gauge.
WHO Guidelines on HVAC Systems
According to the World Health Organization (WHO) pharmaceutical companies must maintain a pressure differential of 10-15 pascals between the manufacturing area and the normal pressure of its surroundings. The aseptic environment of the manufacturing areas must be kept at an increased pressured to ensure the air flows from the aseptic to non-aseptic area. The HVAC system is responsible for creating this increased pressure.
This pressure difference is important as it helps prevent cross-contamination. The dust particles that are produced during the granulation process may enter the air and could contaminate other products. The increased pressure prevents the air containing this dust and any other contaminants reaching the sterile environment.
To maintain the positive pressures in the manufacturing areas and any adjacent corridors, one must activate positive airlocks before entering such corridors to prevent loss of the higher pressure. As well as maintaining the pressure difference, these airlocks also help prevent contaminated air from reaching sterile areas.
Although cross-contamination of one product with powder form is an important issue, the risk of bacterial contamination is higher, and there is a real risk that pharmaceutical products could be contaminated with microbial growth. This is another reason why positive pressures are important in sterile manufacturing rooms.
Recovery tests must be performed regularly to check the pressure differential produced by the HVAC system. Pressure gauges of the HVAC systems and those that monitor the pressures in the room should also be inspected and calibrated regularly.
The building construction must be of a high standard to maintain the integrity of the unit. Airtight windows and doors are required to prevent loss of pressure through gaps in the frames. Alarms that signal a loss of pressure are available to alert staff of any potential problems with the pressure systems.
Pressure differentials may cause difficulty when opening doors, particularly where multi-level differential pressures are used. As such, sliding doors are often the used in this situation to prevent doors sticking, however it is more difficult to seal sliding doors and keep them airtight.