Transcript GMP Updated Training Modules

Good Manufacturing Practices: HVAC
Heating, Ventilation
and AirConditioning (HVAC)
Part 2: Air flows,
Pressure concepts
WHO Technical Report Series,
No. 961, 2011. Annex 5
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Objectives
To continue from previous section of Part 1, now focus on:
 Air filtration and air flow patterns
 The role of HVAC in dust control
 HVAC system design and its components (part 3)
 Commissioning, qualification and maintenance (part 4)
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Air Filtration
 Degree of filtration of air is important to prevent contamination
 Type of filters to be used is dependent on:
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Quality of ambient air,
Return air / re-circulation
Air change rates
National requirements
Products and required class of clean room etc.
 Manufacturer to determine, select and install appropriate filters
4.2.1, 4.3.3
for use
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Levels of protection and recommended filtration
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Level of
protection
Recommended filtration
Level 1
Primary filters, e.g. EN779 G4
Level 2
Production area with 100% outside air: Primary plus
secondary filter (e.g. EN779 G4 plus F8 or F9 filters)
Level 3
Production facility operating on re-circulated plus ambient air, where
potential for cross-contamination exists: Primary plus secondary
plus tertiary filters (e.g. EN779 G4 plus F8 plus EN1822 H13 filters)
(For full fresh air system, without recirculation, G4 and F8 or F9
filters are acceptable)
4.2.1 - 2
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Contamination can be prevented by considering:
 Appropriate materials of construction of HVAC components
 Placement of components (e.g. upstream of final filters)
 Design and appropriate access (from outside) to dampers,
filters and other components
 Personnel operations and protection
 Airflow direction
 Air distribution component design, installation and location
 Diffusers (type, design, location)
 Air supply and air exhaust location
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4.2.4 – 4.2.10
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Induction diffuser
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Perforated plate
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Swirl type diffuser
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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.
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Airflow patterns
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Turbulent
Unidirectional/laminar
dilution of dirty air
displacement of dirty air
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Prefilter
Airflow patterns
AHU
Main filter
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1
2
Turbulent
Unidirectional
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3
Turbulent
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Unidirectional airflow (UDAF)
Often used in weighing and sampling areas
(Airflow Protection Booths) and provides:
 Dust containment and product and operator protection
Note: For Airflow Protection Booths (APB):
 Airflow velocity should not affect balance (may be lower than
for Class A areas)
 Position of material, balance, operator determined and
validated – no obstruction of airflow or risk
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4.3
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Airflow patterns
Workbench (vertical)
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Cabin/booth
Ceiling
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Unidirectional airflow (UDAF):
 Sampling and weighing area classification – same as other
processing areas following sampling and dispensing
 Dust containment shown through smoke tests as part of
validation / qualification
 Location and type of return and exhaust grilles
 Cleaning and maintenance
 Will discuss examples in the following figures
4.3.
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Infiltration
 Prevent infiltration of unfiltered, contaminated air
from outside
 Facilities normally under positive pressure to the
outside
 Building structure well sealed
4.4.1 – 4.4.4
 Some cases - negative pressure (e.g. penicillin
manufacture). Special precautions to be taken. See
separate guidelines
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Cross-contamination
 Multiproduct facility – even if in different areas - risk for
cross contamination (dust from area to area)
 Correct direction of air movement and pressure cascade
 Normally, corridors positive to cubicles and cubicles
positive to atmosphere
 Consider building structure, ceilings, walls, doors etc
 Different concepts discussed in following slides
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4.5
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Displacement concept
 Not a preferred method (Found in older facilities)
 Based on low pressure differentials and high airflows
 Air supplied to the corridor – then through the doors
(grilles) to the cubicles
 Air extracted at the back of the cubicle
 Velocity high enough to prevent turbulence in doorway
4.6
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Pressure differential concept
 Used where there is low dust in areas. Alone or in combination
with other control techniques
 High pressure differential, low airflow, and airlocks
 Airlock types include: Cascade, sink and bubble type (See
next slides)
 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
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4.7
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 Essential / critical parameter here is pressure differentials
 Risk assessment may be done
 High enough to achieve containment; low permissible when
airlocks are used
 No flow reversal should take place – therefore appropriate
limits e.g. 5Pa to 20 Pa
 No turbulence
 No overlap (two adjacent rooms)
4.7
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 Adequate room pressure differential indication provided
 Each critical room pressure must be traced back to ambient
pressure (by summation of the room pressure differentials) –
provides actual absolute pressure
 Gauges with appropriate range and graduation scale to enable
accurate reading; analogue or digital; as pressure differentials or
absolute pressures
 Normal operating range, alert and action limits defined and
displayed
4.7
 OOS condition should be easily identifiable
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 Calibrated and qualified monitoring devices, verified at
intervals
 Linked to alarm system
 Monitoring and recording of results
 Doors open to higher pressure, self closers
 Doors interlocked where possible
4.7
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 Dust extraction system design is important as it may
impact on pressure cascade
 Central systems interlocked with AHUs
 No airflow between rooms through common system
 What happens in the case of component failure?
4.7
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Airlocks and Material Pass-though-hatches (PTH)
 Can be used to separate two zones
 Dynamic and passive PTH
 Also designed as bubble, sink or cascade
 See next slides for design principles
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4.7
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What type of airlock
is this?
How does it work?
Any examples of where
It can be used?
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Physical barrier concept
 In some cases, impervious barriers are used to
prevent cross-contamination
 Closed systems
 Pump or vacuum transfer
4.8
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Temperature and relative humidity (RH)
 Consider materials and product requirements as well as
operator comfort in the design of the HVAC
 Where conditions are required, provide for control,
monitoring and recording
 Alert and action limits; minimum and maximum limits
 Premises appropriately designed
4.9
 HVAC design to achieve and maintain conditions in
different seasons
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Relative humidity (RH)
 Low RH areas need well sealed walls and ceilings, and
preferably air locks
 Remove or add moisture as necessary
 Dehumidification
– Refrigerated dehumidifiers - cooling media
– Chemical dehumidifiers
 Humidifiers should not be sources of contamination
– Use of pure steam or clean steam
– No chemicals that can have a detrimental effect
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4.9
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Relative humidity (RH)
 Humidifiers should be well drained - 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
4.9
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Dust Control
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Where possible - dust and vapour
removed at source
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Point of use extraction – fixed points
or movable hood – plus general
directional airflow in room
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Ensure sufficient transfer velocity in
extraction system to prevent dust
settling in ducting
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Calculations and
measurements
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Periodic checks for build up
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Risk analysis – airflow direction
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5.1. – 5.6
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Dust Control (2)
 Normally air supplied through ceiling diffusers, near the door
 Air extracted from low level (rear)
 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
5.7. – 5.8.
– comfort, odour and fume removal, leakage, pressure control, etc.
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Dust collection
6.1.1 – 6.1.2
system
Exhaust air dust
 Exhaust air from equipment and
some areas of production can
carry heavy loads of dust,
vapours and fumes (e.g. FBD,
coating, weighing)
 Filtration may be needed to
protect environment (see
National legislation)
 Location of the inlet and exhaust
points relative to one other
important to prevent
contaminants taken into inlet air
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Exhaust air dust
 Wet scrubbers can also be used
 Contaminated air is collected
 Dust is treated with a mist/spray
/ water
 Clean air is exhausted
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