air handling systems


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presentation regarding air filters and dust collectors


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A seminar on Air Filtration Systems:

By Bhavana. S M. Pharmacy 1 st year Priyadarshini college of pharmaceutical sciences Chowdaryguda, Ghatkesar mandal, R. R. District 1 A seminar on Air Filtration Systems

Contents :

Introduction Types of air filtration Mechanisms of air filtration Checking of filters Types of air filters in pharmaceutical industries Dust control Types of dust collecting systems References 2 Contents

Introduction :

Filtration is an important aspect of air conditioning in pharmaceutical industry. The main aim of filtration is to produce a dust free atmosphere where in the products can be handled in clean conditions or for the development of sterile environment for carrying out various aseptic processes. Areas like spray drying, fluid bed drying, coating, granulating, milling and packaging, nuisance dust collecting require air filtration. air filtration systems should be constructed in open spaces to ensure high flow rates along with large enough openings of filters compared to the particles to be filtered. 3 Introduction

Requirements of Air :

Air in controlled environment should have: A 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. A temperature of 72 F ± 5 or 22 C ± 3. A maximum relative humidity of 50% and a minimum of 30%. a positive pressure differential of at least 0.05 inch of water with all doors closed in relation to less clean adjacent areas. At least 20 air changes per hour. 4 Requirements of Air

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 5 C lean room

Cleanroom design specifications :

6 Cleanroom design specifications

Facilities: Cleanroom Classification:

Facilities: Cleanroom Classification

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Class 10,000 cleanroom Class 100 cleanroom Facilities: Cleanroom Classification

Facilities: General Cleanroom Design:

Facilities: General Cleanroom Design HEPA/ULPA filters on ceiling Exhaust vents on floor Drains in aseptic processing areas are inappropriate Airlocks and interlocking doors to control air balance Seamless and rounded floor to wall junctions Readily accessible corners Floors, walls, and ceilings constructed of smooth hard surfaces that can be easily cleaned Limited equipment, fixtures and personnel Layout of equipment to optimize comfort and movement of operators

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Sneezing produces 100’s of thousands of aerosol droplets that can then attach to dust particles. In the absence of any filtration system these particles which may contain bacterial spores, or viruses may be present in the air for weeks.

Types of Air Filtration:

Removal of unwanted particles is due to collision of the particles with the filter. Such removal of particles due to collisions are governed by forces called as Impingement Diffusion and Interception These forces are not applicable for very small particles. For those particles van der Waals forces acts. 11 Types of Air Filtration

Types of Air Filtration:

Impingement This type of filtration is also called as inertial impaction which refers to the capture of particles due to the in ability of the particle to deviate from change in the flow path due to inertia. This is efficient at high velocities and not suitable for very small particles (of size less than 5 microns). 12 Types of Air Filtration

Types of Air Filtration:

Diffusion This is also called as Brownian motion resulting in the movement of particles from molecular collisions. Efficient method even for particles of size less than 1 microns in low velocities. 13 Types of Air Filtration

Types of Air Filtration:

Interception most commonly affects particles above .4 microns. The particle sticks to one of the filter's fibers after coming close enough to it. It is as if the fiber reaches out and catches the particle. 14 Types of Air Filtration

Air filter efficiency :

Minimum – if impingement is at low velocity diffusion is at high velocities Maximum – if impingement is at high velocity diffusion is at low velocities 15 Air filter efficiency

Mechanisms of air filtration :

Generally three methods are employed. They are 1)Based on use of oil metal plates/ mesh (direct interception by filters). 2)By the use of fibrous/ granular material such as cotton wool, slag wool or glass wool (dry method). 3)Separation of solid particles by electrostatic precipitation. 16 Mechanisms of air filtration

Electrostatic method:

Highly efficient but costly method 17 Electrostatic method Electric field of high potential Incoming air Dust particles are ionized and removed. 98% efficiency Series of wires of potential 12 KV and Series of collector plates at 7 KV.

Checking of air filters :

Working of General air filters can be checked photo metrically by passing filtered and unfiltered air simultaneously through standard areas of a chemical filter paper. Relative discoloration indicates the efficiency. Bacteria proof filters can be checked by using a standard infected air and testing by slit sampler after filtration. 18 Checking of air filters

Types of air filters:

The type of filters required for different applications depends upon the quality of the ambient air and the return air and also on the air change rates. various filtration levels are recommended for protection in pharmaceutical industry (table 1). 19 Types of air filters

Types of air filters (cont.…):

Level of protection Recommended filtration Level 1 Primary filters only (ex- EN 779 G4 filters) Level 2 Protected areas operating on 100% outside air: primary + secondary filters. (ex- EN 779 G4 + F8 or F9 filters) Level 3 Production facility operating on recirculated + ambient air, where potential for cross contamination exists: primary + secondary+ tertiary filters. (ex- EN779 G4+ F8+ EN 1822 H13 filters) 20 Types of air filters (cont.…) Table 1: recommended filtration levels

Types of air filters:

Various types of air filters being used in the pharmaceutical industry are Ultra low penetration and high efficiency particle air filters (HEPA and ULPA). Packed towers. Membrane filter cartridges. Hydrophobic filters. 21 Types of air filters


Highly efficient and low resistance filters remove greater than 99.97% of air borne particles having a diameter in excess of 0-30 µm. Its use is in HVAC systems, other air handling systems, aseptic processing areas, clean benches, hazardous materials, hoods and barrio isolation systems. 22 HEPA and ULPA


Types Application Performance A industrial, noncritical 99.97 % @ 0.3 µm B nuclear containment 99.97 % @ 0.3 µm (certified by DOE) C laminar flow 99.99 % @ 0.3 µm D ultra-low penetration air ULPA 99.9995 % @ 0.12 µm E stopping toxic, nuclear, chemical and biological threats 99.999 % efficiency Types of HEPA FILTERS

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 aluminum baffles or stitched fabric ribbons, which direct airflow through the filter. This combination of pleated sheets and baffles acts as filtration medium. 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 C onstruction



HEPA filter performance:

HEPA filter performance is dependent primarily upon the four following characteristics: Air Flow Temperature Pollutant loading Dust holding capacity Filter media Construction of HEPA Operating conditions etc. 26 HEPA filter performance

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. Alternative aerosols can also be used as specified or required for given applications. 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. 27 T esting of HEPA filters

Dop test:

28 D op test Mono disperse particles Poly disperse particles

Conditions that damage HEPA filters:

Moisture: 95-100% relative humidity Hot air: greater than 275 °F Fire: direct fire or high concentrations of particulate matter produced by fire High pressure: 8 in. of water, gauge internal or differential across filter media Corrosive mist: dilute moist or moderately dry concentrations of acids and caustics Any acid and some caustics will attack uncoated aluminum separators Hydrofluoric acid will attack the media Nitric acid will attack wooden boxes making highly flammable nitrocellulose Shock pressures C onditions that damage HEPA filters

Applications :

HEPA filters are critical in the prevention of the spread of airborne bacterial and viral organisms and, therefore, infection. Typically, medical-use HEPA filtration systems also incorporate high-energy ultra-violet light units to kill off the live bacteria and viruses trapped by the filter media. Some of the best-rated HEPA units have an efficiency rating of 99.995%, which assures a very high level of protection against airborne disease transmission. 30 Applications

Applications :

Pharmaceutical Bio and gene technology Chemical industry Nuclear air ventilation Hospital operating rooms Emergency burn centers Medical industry Food industry Automotive industry Surface engineering Precision engineering Nano materials Space industry Controlled and ultraclean environments for critical technologies 31 Applications

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, meaning that there is an extra recurring cost in addition to the initial price of the purifier. 32 L imitations

Packed towers:

33 P acked 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.

Membrane filter cartridges :

34 M embrane filter cartridges These are compact, easily handled and can be manufactured as fully disposable form. These are available as either pre filter (particulate and liquid aerosol) or sterilizing filter(bacterial contaminants).

Hydrophobic filters :

35 H ydrophobic filters These are generally used as vent filters. They protect the contents of the containers against contamination by addition or with drawl of the stored liquids in the air which enters or leaves them.

Dust collectors :

Contamination is a severe problem found frequently during various operations in the pharmaceutical industry. Identification and removal of general cross contamination show an impact on the plant layout, design and construction of production areas. They are permanent in all pharmaceutical industries but sometimes they need to be re assayed due to some specifications. Ex- development of increasingly sensitive methods for testing of penicillin along with the hypersensitivity of the drug to some people resulted in the complete relocation of the production plant away from other production to avoid possible cross contamination. 36 Dust collectors

Objectives of dust collectors :

Protection of the operator. Protection of the production equipment from dust. Protection of the pharmaceutical product from the effects of dust. Protection of quality of environment in a premises. Recovery of the expensive materials. 37 Objectives of dust collectors

Choice of a dust collector :

Dust collectors vary widely in design, operation, effectiveness, space requirements, construction, and capital, operating, and maintenance costs. Each type has advantages and disadvantages. However, the selection of a dust collector should be based on the following general factors: Dust concentration and particle size Degree of dust collection required Characteristics of airstream Characteristics of dust Methods of disposal 38 Choice of a dust collector

Main features of dust collectors :

DCCs are mainly used for pre-cleaning Most commonly used for all type of medium from coarse to fine Except < 5micron dia. Particles Low cost & maintenance All kind of sizes Collection efficiency of 10 to 100microns with Multi clones. 39 Main features of dust collectors

Types of Dust Collectors:

Types of Dust Collectors


Electrostatic precipitators (ESP ) Mechanism: Ionizing the gas Charging the dust particles Transporting the particles to the collecting surface neutralizing the dust particles removing the dust from the collecting surface 41 Types

Electrostatic Precipitators :

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 needed PROBLEMS : Not suited where exhaust gas is flammable or explosive Lose of efficiency between cleaning cycles if not maintained properly 42 Electrostatic Precipitators

Electrostatic Precipitators :

43 Electrostatic Precipitators

Dust Collector Types:

Fabric Collectors Collection mechanism : I ) impaction Ii ) interception Iii) diffusion Design features : I ) type of fabric Ii ) fabric configuration Iii) intermittent or continuous service Iv) type of reconditioning V) housing configuration 44 Dust Collector Types

Fabric collectors ( Contd.):

Amount of filter area depends on: Release characteristics of dust Porosity of dust cake Concentration of dust in carrier gas stream Type of fabric and surface finish if any Type of reconditioning Reconditioning interval Air flow pattern within the collector Temperature and humidity within the gas stream 45 Fabric collectors ( Contd.)

Fabric Collectors ( Contd.):

Advantages: Can handle varying exhaust gas flow rates & particle loading Problems : Bag failure Abrasion Chemical degradation of fabric Exceeding temperature limit of fabric 46 Fabric Collectors ( Contd.)

Dust Collector Types:

Wet Collectors Collection mechanism : Contact particles with water or another liquid Collect the droplets Types : chamber or spray tower packed towers wet centrifugal collectors wet dynamic precipitator orifice type Venturi type 47 Dust Collector Types

Wet Collectors ( contd.):

ADVANTAGES: Can handle high-temperature and moisture-laden gases Dust which represent explosion or fire hazards in the dry form can be wetted and collected PROBLEMS : Use of water may introduce corrosive conditions. Freeze protection needed if the collectors are used outdoors in cold climates. Plugging of nozzles due to chemical imbalances in scrubbing liquids 48 Wet Collectors ( contd.)

Wet Collectors ( contd.):

49 Wet Collectors ( contd.)

Dust Collector Types:

Dry centrifugal collectors Collection efficiency is influenced by size , shape and weight of the particles size and design of the collector inlet velocity concentration of dust Types : gravity separators inertial separators cyclone collectors high efficiency centrifugals 50 Dust Collector Types

Dry centrifugal collectors :

51 Dry centrifugal collectors Cyclone separator Gravity settlers

Dry centrifugal collectors :

52 Dry centrifugal collectors Inertial seperator High efficiency centrifugal seperator

Dust Collector Types:

V) GASEOUS CONTAMINANT COLLECTORS TYPES : Absorbers Adsorbers Thermal oxidizers Direct combustors Catalytic oxidizers VI) UNIT COLLECTORS : Small fabric collectors having capacities in the range 200 - 2000cfm 53 Dust Collector Types


Many industrial processes like Milling Grinding Abrasive blasting Welding , etc. uses dust collectors to improve quality of air inside the plant Applications


L. Lachman(20o7), The theory and practice of industrial pharmacy, third edition, Varghese publishing house, pp. 902. Bentleys textbook of pharmaceutics. Guidance for Sterile Drug Products Produced by Aseptic Processing. Dust collectors (2011) “learning guide for dust collectors” [Internet] available at URL: < > [accessed on 3 rd April, 2012] Handbook of heating , ventilating & air-conditioning. References


Filt air(2007) “HEPA filters” [Internet] available at URL: < / > [accessed on 3 rd April, 2012] Dop testing (2011) “basics of HEPA filtration” [Internet] available at URL: < / > [accessed on 3 rd April, 2012] 56 References

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