Air handling Unit.

The design, installation, commissioning and qualification of clean rooms heating, ventilation and air conditioning (HVAC) systems is often one of the largest considerations in the design of a new pharmaceutical or biotechnology manufacturing facility. With high running costs (energy associated with the movement, cooling and heating of air) and the potential to impact upon safety and product quality, getting them right is important for business, safety and good manufacturing practice (GMP) criticality. The design of the HVAC system will be based upon the clean room suite that it serves, and will be affected by factors such as the number of rooms served, the layout of the rooms, the equipment within the rooms and, most critically from a qualification perspective, the environmental conditions that the rooms must achieve. The air handling unit helps maintain each room's clean environment by providing an appropriate volume of clean air to each room at the correct temperature and humidity.

The air is filtered by pleated paper filters called high efficiency particulate air (HEPA) filters which, depending upon the classification of the rooms, are located either within the air handling unit or where the air enters each room. Cooling and heating coils are also located within the air handling unit, increasing or decreasing the air temperature to ensure that the room temperatures remain within specification.

Reliable operation of the air handling unit within established limits is critical,1 not only to prevent product quality from being compromised by poor air conditioning, but also for the following reasons:

• to prevent cross contamination of products
• to maintain operator safety, where the HVAC is being used for this purpose
• to maintain product safety, where the HVAC is being used for this purpose.