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 Unit

2. 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) Impingement

b) Diffusion

c) Interception

Mechanisms of air filteration

Impingement

It is also called as Inertial impaction.

Particle inertia causes it to leave the flowstreamlines and impact on the fiber. This iscalled as spraining effect.

This is not suitable for particles of size <5microns.

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: sandwich

flat

disk

pleated

box

Purpose: final filter

post filter

fine filter

intermediate filter

Types of air filters

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

2. Packed towers

3. Membrane filter catridges

4. 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 borosilicatemicrofibres in the form of pleated sheet

Sheet is pleated to increase the overallfiltration surface area.

The pleats are separated by serratedaluminum 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 thfollowing 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 octylphthalate (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. Automizerinjects 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 catridges

oThese 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 collectors

2) Wet collectors & scrubbers

3) Fabric collectors

4) 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

TYPES

i. Cottrell or single stage – combines ionization and collection in a single stage

ii. 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 collectors

Collection 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 velocity

Types

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.