PHARMACEUTICAL AIR HANDLING SYSTEM

1. PRESENTED BY-
T N PURNIMA
18031S0315
M.Pharm 1st year (II-sem)
Department of Pharmaceutics
Center for Pharmaceutical Sciences, IST,JNTUH
1

2.  Introduction
HVAC system
Air handling unit (AHU)
 Components of AHU
 Construction
 Temperature and humidity control
 Clean room, classification
 Air filtration system
 HEPA filter
 Electrostatic precipitators
 Conclusion
 References
CONTENTS
2

3. • Heating ,Ventilation and Air Conditioning systems are the integral
part of environmental control system design.
• Its goal is to provide thermal comfort and acceptable indoor air
quality.
• Basic components of HVAC:
1. Air Handling Unit
2. Air distribution unit
3. Air filters
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4. • An air handler, or air handling unit (AHU), is a device used to regulate
and circulate air as part of a heating, ventilating, and air-conditioning
(HVAC) system.
• It is a large metal box containing a blower , heating or cooling
elements, filter racks or chambers, sound attenuators, and dampers .
• Small air handlers, for local use, are called terminal units, and may only
include an air filter, coil, and blower; these simple terminal units are
called blower coils or fan coil units.
Terminal units
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5. • A larger air handler that conditions 100% outside air, and no recirculated
air, is known as a makeup air unit (MAU).
• An air handler designed for outdoor use, typically on roofs, is known as
a packaged unit (PU) or rooftop unit (RTU).
Makeup air unit(MAU) Rooftop unit (RTU)
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6. An air handling unit, air flow is from the right to left
AHU components :
1 – Supply duct
2 – Fan compartment
3 – Vibration isolator
4 – Heating and/or cooling coil
5 – Filter compartment
6 – Mixed (recirculated + outside) air duct 6

7. • The major types of components are :
 Filters
 Heating and/or cooling elements
 Humidifier
 Mixing chamber
 Blower/fan
 Balancing
 Heat recovery device
 Controls
 Vibration isolators
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8. Filters
• Air filtration is always present in order to provide clean dust-free air.
• It may be via simple low-MERV pleated media, HEPA, electrostatic, or a
combination of techniques. Gas-phase and ultraviolet air treatments may be
employed as well.
• Filtration is typically placed first in the AHU in order to keep all the
downstream components clean.
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9. • The life of a filter may be assessed by monitoring the pressure drop through
the filter medium at design air volume flow rate.
• This may be done by means of a visual display using a pressure gauge, or
by a pressure switch linked to an alarm point on the building control
system.
• Failure to replace a filter may eventually lead to its collapse, as the forces
exerted upon it by the fan overcome its inherent strength, resulting in
collapse and thus contamination of the air handler and downstream
ductwork.
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10. Heating and/or cooling elements
• Air handlers may need to provide heating, cooling, or both to change the
supply air temperature, and humidity level depending on the location and
the application.
• Such conditioning is provided by heat exchanger coil within the air
handling unit air stream, such coils may be direct or indirect in relation to
the medium providing the heating or cooling effect.
• Direct heat exchangers include those for gas-fired fuel-burning heaters or
a refrigeration evaporator, placed directly in the air stream. Electric
resistance heaters and heat pumps can be used as well.
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12. • Indirect coils use hot water or steam for heating, and chilled water for
cooling. The hot water or steam is provided by a central boiler, and the
chilled water is provided by a central chiller.
• If dehumidification is required, then the cooling coil is employed to over-
cool to that the dew point is reached and condensation occurs.
• A heater coil placed after the cooling coil re-heats the air (therefore known
as a re-heat coil) to the desired supply temperature.
• This process has the effect of reducing the relative humidity level of the
supply air.
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13. Humidifier
• Humidification is often necessary in colder climates where continuous
heating will make the air drier, resulting in uncomfortable air quality and
increased static electricity.
Various types of humidification may be used:
• Evaporative: dry air blown over a reservoir will evaporate some of the
water. The rate of evaporation can be increased by spraying the water onto
baffles in the air stream.
• Vaporizer: steam or vapour from a boiler is blown directly into the air
stream.
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15. • Spray mist: water is diffused either by a nozzle or other mechanical means
into fine droplets and carried by the air.
• Ultrasonic: A tray of fresh water in the airstream is excited by an ultrasonic
device forming a fog or water mist.
• Wetted medium: A fine fibrous medium in the airstream is kept moist with
fresh water from a header pipe with a series of small outlets. As the air
passes through the medium it entraps the water in fine droplets. This type
of humidifier can quickly clog if the primary air filtration is not maintained
in good order.
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16. Mixing chamber
• In order to maintain indoor air quality, air handlers commonly have
provisions to allow the introduction of outside air into, and the exhausting
of air from the building.
• In temperate climates, mixing the right amount of cooler outside air with
warmer return air can be used to approach the desired supply air
temperature.
• A mixing chamber is therefore used which has dampers controlling the
ratio between the return, outside, and exhaust air.
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18. Blower/fan
• Air handlers typically employ a large squirrel cage blower driven by an AC
induction electric motor to move the air.
• The blower may operate at a single speed or be driven by a variable-
frequency drive to allow a wide range of air flow rates.
• Flow rate may also be controlled by inlet vanes or outlet dampers on the
fan.
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19. • Multiple blowers may be present in large commercial air handling units,
typically placed at the end of the AHU and the beginning of the supply
ductwork (therefore also called "supply fans").
• They are often augmented by fans in the return air duct ("return fans")
pushing the air into the AHU.
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20. Balancing
• Un-balanced fans wobble and vibrate. For home AC fans, this can be a
major problem: air circulation is greatly reduced at the vents (as wobble is
lost energy), efficiency is compromised, and noise is increased.
• Another major problem in fans that are not balanced is longevity of the
bearings (attached to the fan and shaft) is compromised. This can cause
failure to occur long before the bearings life expectancy.
• Weights can be strategically placed to correct for a smooth spin .
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21. Heat recovery device
• A heat recovery device, heat exchanger may be fitted to the air
handler between supply and extract air streams for energy savings
and increasing capacity.
These types more commonly include :
• Recuperator, or Plate Heat exchanger: A sandwich of plastic or
metal plates with interlaced air paths. Heat is transferred between
airstreams from one side of the plate to the other. The plates are
typically spaced at 4 to 6mm apart.
• Heat recovery efficiency up to 70%.
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22. • Thermal Wheel, or Rotary heat exchanger: A slowly rotating matrix of
finely corrugated metal, operating in both opposing airstreams.
 When the air handling unit is in heating mode, heat is absorbed as air
passes through the matrix in the exhaust air stream, during one half
rotation, and released during the second half rotation into the supply
airstream in a continuous process.
 When the air handling unit is in cooling mode, heat is released as air passes
through the matrix in the exhaust air stream.
 Heat recovery efficiency up to 85%.
 Wheels are also available with a hydroscopic coating to provide latent heat
transfer and also the drying or humidification of airstreams.
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23. • Run around coil: Two air to liquid heat exchanger coils, in opposing
airstreams, piped together with a circulating pump and using water or a
brine as the heat transfer medium. This device, although not very efficient,
allows heat recovery between multiple supply and exhaust airstreams.
 Heat recovery efficiency up to 50%.
• Heat Pipe: Operating in both opposing air paths, using a confined
refrigerant as a heat transfer medium.
 The heat pipe uses multiple sealed pipes mounted in a coil configuration
with fins to increase heat transfer. Heat is absorbed on one side of the pipe,
by evaporation of the refrigerant, and released at the other side, by
condensation of the refrigerant.
 Heat recovery efficiency up to 65%.
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24. Control unit
• Controls are necessary to regulate every aspect of an air handler, such
as: flow rate of air, supply air temperature, mixed air temperature,
humidity, air quality.
• They may be as simple as an off/on thermostat or as complex as a building
automation system using BACnet or LonWorks,
for example: Common control components include
• temperature sensors, humidity sensors, sail switches, actuators, motors, and
controllers.
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25. Vibration isolators
• The blowers in an air handler can create substantial vibration and the large
area of the duct system would transmit the noise and vibration to the
occupants of the building.
• To avoid this, vibration isolators (flexible sections) are normally inserted
into the duct immediately before and after the air handler and often also
between the fan compartment and the rest of the AHU.
• The rubberized canvas-like material of these sections allows the air handler
components to vibrate without transmitting the motion to the attached
ducts.
• The fan compartment can be further isolated by placing it on a spring
suspension, which will mitigate the transfer of vibration through the floor.
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26. • The air handler is normally constructed around a framing system with
metal infill panels as required to suit the configuration of the components.
• In simplest form the frame may be made from metal channels or sections,
with single skin metal infill panels. The metalwork is normally galvanized
for long term protection.
• Larger air handlers will be manufactured from a square section steel
framing system with double skinned and insulated infill panels.
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28. • Such constructions reduce heat loss or heat gain from the air handler, as
well as providing acoustic attenuation.
• For strength and rigidity, steel section base rails are provided under the
unit.
• Where supply and extract air is required in equal proportions for a balanced
ventilation system, it is common for the supply and extract air handlers to
be joined together, either in a side-by-side or a stacked configuration.
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29. • Temperatures in the 68-74 ºF (19-23 ºC) range is comfortable for
working environment.
• Temperature control is important in the areas where autoclaves,
ovens, dry heat sterilization tunnels are present.
• Humidity comfort levels are in the 45-55% RH range.
• Air dryers can be used to maintain lower than normal humidity
levels.
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30. Requirements of Air :
• Air in controlled environment should have:
1. Air per cubic foot particle count of not more than 100,000 in a size
range of 0.5 micron and larger when measured with automatic
counters or 700 particles in a size range of 5.0 microns or larger
when measure by a manual microscopic method.
2. A temperature of 72ºF ± 5 or 22ºC ± 3.
3. A maximum relative humidity of 50% and a minimum of 30%.
4. A positive pressure differential of at least 0.05 inch of water with
all doors closed in relation to less clean adjacent areas.
5. At least 20 air changes per hour
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31. Clean room:
“A room in which the concentration of airborne particles is controlled
and which is constructed and used in a manner to minimize the
introduction, generation and retention of particles inside the room,
and in which the relevant parameters, e.g. temperature, humidity and
pressure are controlled as necessary” --ISO-14644-1
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32. Cleanroom Classification
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33. 33
CLASS 100
CLASS 1000
CLASS 10000 CLASS 100000

34. AIR FILTRATION SYSTEMS
 Filtration is an important aspect of environmental control in
Pharmaceutical industry.
 The main aim of filtration is to produce dust free atmosphere.
 It is required in areas like spray drying, coating, granulating, milling,
packaging etc.
 Filters are selected based on the required environment.
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35. 35
Mechanisms of air filtration
 Air filtration involves the removal of unwanted particles due
to collision of particles with the filter.
 Such removal of particles due to collisions are governed by forces
called as
1. Impingement
2. Diffusion
3. Interception

36.  Impingement
• It is also called as Inertial impaction.
• Particle inertia causes it to leave the flow streamlines and impact on
the fiber. This is called as spraining effect.
• This is not suitable for particles of size <5 microns.
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37.  Diffusion
• This is also known as Brownian Movement resulting in the
movement of particles from molecular collisions.
• Efficient method for particles of size <1 microns.
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38. Interception
• The particle/droplet collides to the one of the filter’s fibre after
coming close enough to it.
• Oil metal plates/mesh are used.
• Affects the particles above 4 microns
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39. Air filters
Air filters are made up of fibre, glass, sinter glass, charcoal, glass wool,
dry fabric, oil wetting fabric, cellulose asbestos, etc.
Arrangement:
sandwich
flat
disk
pleated
box
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Purpose:
final filter
post filter
fine filter
intermediate filter

40. Types of air filters
 Ultra low penetration and high efficiency particulate air filters
(ULPA & HEPA)
 Packed towers
 Membrane filter catridges
 Hydrophobic filters
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41. • High efficiency particulate air (HEPA),originally called high-efficiency
particulate absorber but also sometimes called high-efficiency
particulate arresting or high-efficiency particulate arrestance, is a type
of air filter.
 This type of air filter can remove 99.97% of dust, pollen, mold, bacteria
and any airborne particles with a size of 0.3 micrometres (μm)
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 Media is the filtering material.
• Eg: glass fiber, synthetic fiber, non-woven fiber
 Sealant is the adhesive material that creates a leak-proof seal
between the filter media and the frame.
 Frame is where the filter media is inserted.
• Eg: aluminium, stainless steel, plastic or wood.
 Faceguard is a screen attached to the filter to protect the filter
media during handling and installation.
 Gasket is a rubber or sponge like material used to prevent air leaks
between the filter and its housing by compressing the two together.

43. Construction:
• HEPA filter is constructed of borosilicate micro fibers in the form of
pleated sheet
• Sheet is pleated to increase the overall filtration surface area.
• The pleats are separated by serrated aluminium baffles or stitched
fabric ribbons, which direct airflow through the filter.
• This combination of pleated sheets and baffles acts as filtration
medium.
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o It is installed into an outer frame made of fire-rated particle board,
aluminium, or stainless steel
o The frame-media junctions are permanently glued or ‘‘pot-sealed’’
to ensure a leak proof.

45. HEPA filter performance is dependent upon the following
characteristics:
 Air flow
 Temperature
 Pollutant loading
 Dust holding capacity
 Filter media
 Construction of HEPA
 Operating conditions etc
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46. Testing of HEPA filters
• There are two separate tests for HEPA and ULPA filter collection
efficiencies.
• HEPA efficiency is rated using a thermal di-octyl phthalate (DOP)
test. The test dust for HEPA filters is mono-sized, 0.3 µm diameter,
DOP particles, generated by vaporization and condensation.
• A photometer measures the particle penetration of the HEPA filter
by sensing the scattering of light.
• ULPA efficiency is tested using a particle counter upstream and
downstream of the filter. An atomizer injects a solution of DOP,
alcohol, and mineral oil in hexane to generate particles ranging from
of 0.1 to 0.2 µm in diameter.
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Mono disperse particles Poly disperse particles

48. Limitations :
• HEPA filters only target airborne particles, not gasses.
• HEPA filters also tend to be more expensive than other filters.
• Filters will almost always need to be regularly replaced at least once
or twice a year, as well, means that there is an extra recurring cost in
addition to the initial price of the purifier.
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Packed towers Membrane filter
catridges
Hydrophobic
filters

50. Mechanism:
 Ionizing the gas
 Charging the dust particles
 Transporting the particles to the collecting tube
 Neutralizing the dust particles
 Removing the dust from the collecting surface
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51. • Advantages:
 Large gas volumes & high collection efficiency for small particles.
• Disadvantages:
 This is a costly method
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52. Air handling systems:
• Play a major role in the quality of pharmaceuticals
• Must be designed properly, by professionals
• Must be treated as a critical system
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53. • L. Lachman, The theory and practice of industrial pharmacy, third
edition, Varghese publishing house, pp. 902.
• https://en.wikipedia.org/wiki/Air_handler
• Bentleys textbook of pharmaceutics.
• Guidance for Sterile Drug Products Produced by Aseptic Processing.
• http://www.dustcollectorexperts.com/ >
• Handbook of heating , ventilating & air-conditioning. References
• http://www.filt-air.com/Resources/Articles/hepa/hepa_filters.aspx /
• Dop testing (2011) “basics of HEPA filtration” http://www.c-
vac.com/testing.html / >
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