Prevention of cross contamination by HVAC systems

Role of HVAC systems in preventing cross contamination

• HVAC system plays a crucial role in preventing cross contamination by use of appropriate filters
• It should be dedicated, validated and installed at all manufacturing areas
• Materials for various components of HVAC should be selected so that they don’t become source of contamination
• Filter selected by the manufacturer should keep track of regulatory conditions and product requirements
• Good prefiltration improves the life of filters downstream
• Extraction points and air supply should not be disposed or close which may restrict air supply and sweeps away contaminants from working area
• Risk due to recirculation of contaminants should be reduced
• After change of every product dust should be cleaned from the pipes
• The filters should be cleaned away from the air handling units
• Clean filtered air should be supplied from raw material stage to finished product and packing stage
• Contaminants due to air can be controlled by filtration and ventilation
• External contaminants: In order to maintain the cleanroom classification filtration of air should ensure that all contaminants are removed
• Internal contaminants: Pressure differentials should ensure that flow reversal doesn’t occur without causing turbulence
• Ration of fresh air to recirculated air should be justified on installation of recirculation system
• Ventilation filters and dampers should be positioned so they are accessible from outside of manufacturing areas which eases maintenance
• Directional airflow in production and packing areas helps in preventing contamination
• Air velocity between 0.3 to 0.4 m / s removes the particles before they settle on surfaces and also maintains uniformity by overcoming obstructions from people and equipment
• Unidirectional flow of air must be maintained and any discrepancy should be restored
• Laminar air flows have huge supply of air than conventionally ventilated rooms

Related document

http://www.hsa.gov.sg/content/dam/HSA/HPRG/Manufacturing_Importation_Distribution/Overview_Framework_Policies/GUIDE-MQA-023-004.pdf  

Cross contamination, hvac systems, external contaminants, internal contaminants, pressure differentials