Cross-contamination is one of the most important aspects to avoid in the pharmaceutical industry. All manufacturing procedures, from receipt of the raw materials to the final product, are designed to avoid cross-contamination, even the architecture of the plant is designed to meet the same goal.
One of the most common questions that comes up when designing the critical HVAC system for pharmaceutical production areas is to determine whether or not the air that is supplied to the areas can be returned. Logically, it is known that returning a certain amount of air achieves a considerable energy savings. Unfortunately, returns are not always allowed, but if the same product is manufactured within the same areas and dust is not produced at high volume, it is possible to return it. However, if the products manufactured are diverse or a lot of dust is produced, it is convenient to extract the air with other equipment independent of the injection and to discharge it to the atmosphere, but not before filtering it to remove any pollutant toxic to the environment.
According to the manufacturing process, the defined characteristics to be met, as the maximum number of total particles per cubic meter of air to enlist the maximum number of viable particles allowed, in both dynamic and static conditions, with a particle size of 0.5 and 5μm, as well as the monitoring frequency. It is also defined the minimum differential pressures that must exist between areas, either of the same or different classification, and the flow direction that air must have. In addition to this, the minimum air changes per hour and the ranges of temperature and relative humidity within the areas, as well as the necessary entrance dress.
The HVAC system must be designed to meet these requirements. Although they are quite demanding, they are not impossible. The important thing is to correctly understand the requirements for each classification.
A very significant feature of HVAC systems within the pharmaceutical industry is the filtration of both air entering the areas as well as extraction and collection of powders. The type of filter, its efficiency or if it is terminal, that is to say, placed at the level of ceiling, are vital for the installations and equipment.
The HVAC system must be designed and integrated in such a way as to comply with the classification of the required area according to the standards. Those corresponding to ISO Class 5, 6 and 7 must have, at least, 99.97% HEPA terminal filters of 0.3 μm. In the case of ISO-8 class, they must have at least 95% efficiency filters and ISO-9 class must have at least efficiency filters of 85%.