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Heating, Ventilation and Air- Conditioning (HVAC) Part 1 (b): Introduction and overview

Supplementary Training Modules on Good Manufacturing Practice. Heating, Ventilation and Air- Conditioning (HVAC) Part 1 (b): Introduction and overview. WHO Technical Report Series, No. 937, 2006. Annex 2. HVAC. Objectives To continue from Part 1(a), now focus on: Air filtration

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Heating, Ventilation and Air- Conditioning (HVAC) Part 1 (b): Introduction and overview

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  1. Supplementary Training Modules on Good Manufacturing Practice Heating, Ventilation and Air- Conditioning (HVAC) Part 1 (b): Introduction and overview WHO Technical Report Series, No. 937, 2006. Annex 2

  2. HVAC Objectives To continue from Part 1(a), now focus on: • Air filtration • The role of HVAC in dust control • HVAC system design and its components (part 2) • Commissioning, qualification and maintenance (part 3)

  3. HVAC Air Filtration • Degree of filtration is important to prevent contamination • Type of filters to be used dependent on the quality of ambient air, return air and air change rates • Manufacturer to determine, select and prove appropriate filters for use considering level of ambient air contamination, national requirements, product specific requirements 4.2.1, 4.2.3

  4. HVAC Levels of protection and recommended filtration *Filter class should be referenced to the standard test method 4.2.1

  5. HVAC Contamination should be prevented through appropriate: • Materials for components and construction • Design and appropriate access to dampers, filters and other components • Personnel operations • Airflow direction • Air distribution component design and installation and location • Type of diffusers (non-induction type recommended) • Air exhaust (normally from a low level) 4.2.4 – 4.2.10

  6. HVAC

  7. HVAC Airflow patterns • Filtered air entering a production room or covering a process can be • turbulent, or • unidirectional (laminar) • GMP aspect • economical aspect • Other technologies: barrier technology/isolatortechnology.

  8. Unidirectional/laminar displacement of dirty air Turbulent dilution of dirty air HVAC Airflow patterns

  9. Airflow patterns Prefilter AHU Main filter 2 3 1 Unidirectional Turbulent Turbulent HVAC

  10. HVAC Airflow patterns (4) Workbench (vertical) Cabin/booth Ceiling

  11. HVAC Unidirectional airflow (UDAF): Provided where needed over product or material to prevent contamination, or to protect operator UDAF in weighing areas • The aim is to provide dust containment • Airflow velocity should not affect balance • Position of material, balance, operator determined and validated – no obstruction of airflow or risk 4.3.1 – 4.3.10

  12. HVAC Annex 5, 7.

  13. HVAC Annex 5, 7.

  14. HVAC Infiltration • Facilities normally under positive pressure to the outside • Prevent infiltration of unfiltered, contaminated air from outside • Some cases - negative pressure (e.g. penicillin manufacture). Special precautions to be taken 4.4.1 – 4.4.4

  15. HVAC Cross-contamination • General aspects and concepts • Displacement concept • low pressure differential, high airflow • Pressure differential concept • high pressure differential, low airflow • Physical barrier concept 4.5

  16. HVAC General aspects • Multiproduct OSD manufacturing, prevent movement of dust between areas where different products are processed • Directional air movement and pressure cascade can be helpful – dust containment • Normally, corridor at higher pressure than cubicles, cubicles at higher pressure than atmosphere 4.5.1 – 4.5.3

  17. HVAC Containment concepts • Pressure cascade regime influenced by: • Product and product group, e.g. highly potent products (in some cases, pressure cascade regime negative to atmosphere) • Processing methods • Building structure should be considered including airtight ceilings and walls, close fitting doors, sealed light fittings 4.5.4 – 4.5.9

  18. HVAC Displacement concept • Air supplied to the corridor, through the doors (grilles) to the cubicles • Air extracted at the back of the cubicle • Velocity high enough to prevent turbulence in doorway • Requires large air quantities (Not preferred method) 4.5.10 – 4.5.12

  19. HVAC Pressure differential concept • Concept can include high pressure differential, low airflow, and airlocks in the design • Airlock types include: Cascade, sink and bubble type • Sufficient pressure differential required to ensure containment and prevent flow reversal – but not so high as to create turbulence • Consider effect of other items such as equipment and extraction systems in cubicles • Operating limits and tolerances 4.5.13 – 4.5.18, 4.5.22

  20. HVAC Pressure differential concept (2) • Calibrated monitoring devices, set to alarm system • Monitoring and recording of results • Doors open to higher pressure • Dust extraction system design • Interlocked with air-handling system • No airflow between rooms linked to same system • Room pressure imbalance 4.5.19 – 4.5.26

  21. HVAC Pressure cascade solids Protection from cross-contamination

  22. HVAC Physical barrier concept • In some cases, impervious barriers are used to prevent cross-contamination • Spot ventilation • Capture hoods 4.5.27 – 4.5.28

  23. HVAC Temperature and relative humidity (RH) • Controlled, monitored and recorded where relevant • Materials and product requirements, operator comfort • Minimum and maximum limits • Premises design appropriate, e.g. low humidity areas, well sealed and airlocks where necessary • HVAC design – also prevent moisture migration 4.6.1. – 4.6.6

  24. HVAC Temperature and relative humidity (RH) (2) • Remove moisture, or add moisture as necessary • Dehumidification • Refrigerated dehumidifiers with cooling media • Chemical dehumidifiers • Humidifiers should not be sources of contamination • Use of pure steam or clean steam • No chemicals added to boiler system if these can have a detrimental effect on product (e.g. some corrosion inhibitors/chelating agents) 4.6.7. – 4.6.11

  25. HVAC Temperature and relative humidity (RH) (3) Humidification systems: Design should be such that the system does not become the source of contamination: • No accumulation of condensate • Avoid evaporative systems, atomizers, water-mist sprays • Suitable duct material, insulation of cold surfaces • Air filters not immediately downstream of humidifiers • Chemical driers – used if not sources of contamination 4.6.12. – 4.6.18

  26. HVAC Dust Control • Dust and vapour removed at source • Point of use extraction – fixed points or movable hood – plus general directional airflow in room • Ensure sufficient transfer velocity to prevent dust settling in ducting • Risk analysis – airflow direction, hazards, operator 5.1. – 5.7

  27. HVAC Dust Control (2) • Normally air supplied through ceiling diffusers, and air extracted from low level – aids flushing effect • Extraction of vapours – consider density of vapour • Handling harmful products – additional steps needed • e.g. barrier technology, glove boxes • totally enclosed garments with air-breathing systems • Fresh air rate supply • comfort, odour and fume removal, leakage, pressure control, etc. 5.8. – 5.14

  28. HVAC Protection of the environment (Exhaust air dust) • Exhaust air from equipment and some areas of production carry heavy loads of dust (e.g. FBD, coating, weighing) • Filtration needed to prevent ambient contamination • Not highly potent material • EN779 F9 filter recommended • Harmful substances (e.g. hormones) • EN1822 H12 (HEPA) filter recommended • In some cases two banks of HEPA filters • Safe change filter housings ("bag-in bag-out" filters) 6.1.1 – 6.1.5

  29. HVAC Protection of the environment (Exhaust air dust) (2) • Filter banks provided with pressure differential indication gauges • Limits indicated, results monitored at regular intervals • Manual, Building Management Systems, Building Automated Systems, System Control and Data Acquisition systems • Automated systems provided with alarm or similar system to indicate OOS 6.1.6 – 6.1.10

  30. HVAC Protection of the environment (Exhaust air dust) (3) • Reverse pulse dust collectors • Should be equipped with cartridge filters with compressed air lance, • Continuous operation – no interruption of airflow • Dust collectors with mechanical shakers • Used in a manner not to become source of contamination • Switched off at times resulting in loss of airflow, and disruption of pressure cascade • Wet scrubbers • Use suitable drainage system for dust slurry • Determine exhaust air quality to verify filtration efficiency 6.1.11 – 6.1.15

  31. HVAC Protection of the environment (Fume removal) • Appropriate design, installation, and operation of fume, dust, effluent control • Wet scrubbers • Added chemicals for increased adsorption efficiency • Deep bed scrubbers • Activated carbon or chemical adsorption granular media • Specific to type of effluent • Type and volume prepared 6.2.1 – 6.2.5

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