Lựa chọn HAVC

Lựa chọn HAVC

1. HVAC | Slide 1 of 31 May 2006
Heating, Ventilation and Air-
Conditioning (HVAC)

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

2. HVAC | Slide 2 of 31 May 2006
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 | Slide 3 of 31 May 2006
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 | Slide 4 of 31 May 2006
HVAC
Levels of protection and recommended filtration
*Filter class should be referenced to the standard test method 4.2.1
Level of
protection
Recommended filtration
Level 1 Primary filters, e.g. EN779 G4*
Level 2 and 3Production area with 100% outside air: Primary plus
secondary filter (e.g. EN779 G4 plus F8 filters)
Level 2 and 3Production area with recirculated plus ambient air with a risk
of cross-contamination: Primary plus secondary plus tertiary
filter (e.g. EN779 G4 plus F8 plus EN1822 H13 filters)

5. HVAC | Slide 5 of 31 May 2006
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 | Slide 6 of 31 May 2006
HVAC

7. HVAC | Slide 7 of 31 May 2006
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/isolator technology.

8. HVAC | Slide 8 of 31 May 2006
Unidirectional/laminar
displacement of dirty air
Turbulent
dilution of dirty air
Airflow patterns
HVAC

9. HVAC | Slide 9 of 31 May 2006
Prefilter
Airflow patterns
AHU
Main filter
Unidirectional TurbulentTurbulent
1
2 3
HVAC

10. HVAC | Slide 10 of 31 May 2006
Workbench (vertical) Cabin/booth Ceiling
Airflow patterns (4)
HVAC

11. HVAC | Slide 11 of 31 May 2006
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 | Slide 12 of 31 May 2006
HVAC
Annex 5, 7.

13. HVAC | Slide 13 of 31 May 2006
HVAC
Annex 5, 7.

14. HVAC | Slide 14 of 31 May 2006
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 | Slide 15 of 31 May 2006
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 | Slide 16 of 31 May 2006
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 | Slide 17 of 31 May 2006
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 | Slide 18 of 31 May 2006
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 | Slide 19 of 31 May 2006
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 | Slide 20 of 31 May 2006
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 | Slide 21 of 31 May 2006
Pressure cascade solids
Protection from cross-contamination
Note : Direction of door opening relative to room pressure 15 Pa
15 Pa15 P a
E30 PaPassage 0 PaAirLock
Room 3 Room 2 Room 115 Pa
Air LockAir Lock
N o t e : D i r e c t i o n o f d o o r o p e n i n g r e l a t i v e t o r o o m p r e s s u r e
1 5 P a
1 5 P a1 5 P a
E
3 0 P a
P a s s a g e
0 P a
A i r
L o c k
R o o m 3 R o o m 2 R o o m 1
1 5 P a
A i r L o c kA i r L o c k
HVAC

22. HVAC | Slide 22 of 31 May 2006
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 | Slide 23 of 31 May 2006
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 | Slide 24 of 31 May 2006
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 | Slide 25 of 31 May 2006
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 | Slide 26 of 31 May 2006
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 | Slide 27 of 31 May 2006
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 | Slide 28 of 31 May 2006
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 | Slide 29 of 31 May 2006
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 | Slide 30 of 31 May 2006
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 | Slide 31 of 31 May 2006
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