Mallareddy college of Pharmacy

AIR HANDLING SYSTEMS

guided by: Presented By Dr. Satyabrata Bhanja Aslesha.E

M.Pharmacy 1st yr

AIR HANDLING SYSTEMS

CONTENTS

HVAC systems Air handling units Air filteration systems Dust collectors Humidity and temperature control

HVAC systems

Heating Ventilation and Air Conditioning systems are the integral part of environmental control system design.

Basic components of HVAC:1. Air Handling Unit2. Air distribution

Dust network Insulator Dampers/valves Return lower & grills.

3. Air filters

Air Handling Unit AHU is a device used to condition 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, humidity & temperature control loops. 

Air Handling Unit

Temperature and humidity control

Temperatures in the 68-74 F (19-23 C) range is comfortable for working environment.

Temperature control is important in the areas where autoclaves, ovens, dry heat strerilization 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.

AIR FILTERATION SYSTEMS

CONTENTS

Introduction Types of filteration Mechanisms of filteration Types of air filters

Introduction

Filteration is an important aspect of environmental control in Pharmaceutical industry.

The main aim of filteration 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.

Mechanisms of air filteration

Air filteration 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

a) Impingementb) Diffusionc) Interception

Mechanisms of air filteration

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.

Mechanisms of air filteration

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.

Mechanisms of air filteration

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.

Air filter efficiency

Air filter efficiency is

Maximum – impingement in low velocity diffusion at high velocities

Minimum – impingement in high velocity diffusion at low velocities

Air filters

Air filters are made up of fibre glass, sinter glass, charcoal, glass wool, dry fabric, oil wetting fabric.

Arrangement: sandwichflatdiskpleatedbox

Purpose: final filterpost filterfine filterintermediate filter

Types of air filters

1. Ultra low penetration and high efficiency particulate air filters (ULPA & HEPA)

2. Packed towers3. Membrane filter catridges4. Hydrophobic filters

HEPA FILTER

HEPA is an acronym for “High Efficiency Particulate Air”

This type of air filter can remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 micrometres (μm)

HEPA FILTER 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: aluminum, 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.

HEPA FILTER

Construction: HEPA filter is constructed of borosilicate

microfibres in the form of pleated sheet Sheet is pleated to increase the overall

filtration surface area. The pleats are separated by serrated

aluminum baffles or stitched fabric ribbons, which direct airflow through the filter

This combination of pleated sheets and baffles acts as filtration medium.

HEPA FILTER

It is installed into an outer frame made of fire-rated particle board, aluminum, or stainless steel

The frame-media junctions are permanently glued or ‘‘pot-sealed’’ to ensure a leak proof

HEPA FILTER

HEPA filter performance is dependent upon th following characteristics:

Air flow Temperature Pollutant loading Dust holding capacity Filter media Contruction of HEPA Operating conditions etc.

Testing of HEPA filters There are 2 separate tests for HEPA and ULPA filter

collection efficies. HEPA efficeincy is rated using a thermal di octyl

phthalate (DOP) test. The test dust for HEPA filters is mono-sized, DOP particles, generated by vapourization and condensation. Photometer measures particle penetration by sensing the scattered light.

ULPA efficiency is tested using a particle counter upstream & downstream of filter. Automizer injects DOP,alcohol & mineral oil in hexane to generate particles.

Mono disperse particles

Poly disperse particles

Types of air filters

2.Packed towers

Packed towers are custom designed to provide removal efficiencies in the range of 95% to 99% for acid and toxic gases with a low pressure drop

Types of air filters

3. Membrane filter catridgesoThese are compact, easily handled and can be manufactured as fully disposal form.oThese are available as either pre filter (particulate and liquid aerosal) or sterilizing filter (bacterial contaminents).

Types of air filters

4. Hydrophobic filters These are generally used as vent filters. They protect the contents of the containers

against contamination in the air which enters or leaves them.

Dust collectors

Dust collectors are used for equipment maintanance.

Air pollution is controlled.

Main features Low cost & maintainance Most commonly used for all type of medium

from coarse to fine except <5 microns particles.

Collection efficiency of 10 to 100 microns with multiclones.

Dust collectors

Types of dust collectors

1) Dry mechanical collectors2) Wet collectors & scrubbers3) Fabric collectors4) ESP

Types of dust collectors

1.Electrostatic precipitators(ESP)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

ESP

TYPESi. Cottrell or single stage – combines

ionization and collection in a single stageii. Penny or Two stage – ionization and

collection in different stages

Advantages: Large gas volumes & high collection

efficiency for small particles.Disadvantages: This is a costly method

ESP

Dust collectors

2.Fabric collectors

Collection mechanism: Impaction Interception Diffusion

Advantages: can handle varying exhaust gas flow rates

& particle loading

Fabric collectors

The amount of filter area depends on:

Release characteristics of dust Porosity of dust cake Conc. Of dust in carrier gas stream Type of fabric & surface Airflow patternn within the collector Temperature & humidity within the gas

stream

Fabric collectors

Dust collectors

3. Wet collectorsCollection mechanism: Collect the droplets Contact particles with water or another

liquid

Advantages: Can handle high temperature & moisture Dust which represent explosion or fire

hazards in the dry form can be wetted and collected

Wet collectors

Types: Spray dryer Packed towers Wet centrifugal collectors Wet dynamic precipitator Venturi type Orifice type

Dust collectors

4. Dry centrifugal collectors

Collection efficiency is influenced by size, shape, weight of the particles Conc. Of dust & inlet velocityTypes Gravity seperators Inertial seperators Cyclone collectors High efficiency centrifugals

Cyclone filter

Inspecting the air handling plant

1. Verification of design documentation, including description of installation and functions specification of the requirements

2. Operating procedures

3. Maintenance instructions

4. Maintenance records

5. Training logs

6. Environmental records

7. Walking around the plant

Conclusion

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

References

L.Lachman, The theory and practice of industrial pharmacy

Bentleys textbook of pharmaceutics Dust collectors – learning guide for

dust collectors [Internet] Handbook of heating, ventilation &

air-conditioning.