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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


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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)


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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


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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 3 Production area with 100% outside air: Primary plus secondary filter (e.g. EN779 G4 plus F8 filters)

Level 2 and 3 Production 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)


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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


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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.


Unidirectional/laminar

displacement of dirty air

Turbulent

dilution of dirty air

Airflow patterns

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PrefilterAirflow patterns

AHU

Main filter

Unidirectional TurbulentTurbulent

1 2 3

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Workbench (vertical) Cabin/booth Ceiling

Airflow patterns (4)

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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


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Annex 5, 7.


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Annex 5, 7.


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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


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Cross-contamination

General aspects and concepts

Displacement concept

– low pressure differential, high airflow

Pressure differential concept

– high pressure differential, low airflow

Physical barrier concept4.5


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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


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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


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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


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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


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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


Pressure cascade solidsProtection from cross-contamination

Note : Direction of door opening relative to room pressure 15 Pa15 Pa15 P aE30 PaPassage 0 PaAirLock Room 3 Room 2 Room 115 PaAir 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

E3 0 P a

P a s s a g e0 P a

A i rL 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

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Physical barrier concept

In some cases, impervious barriers are used to prevent cross-contamination

Spot ventilation

Capture hoods

4.5.27 – 4.5.28


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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 migration4.6.1. – 4.6.6


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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


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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


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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


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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


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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


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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


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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


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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 prepared6.2.1 – 6.2.5

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