abs air tech presentation for hepa filters

HEPA FILTERS

Air Cleaning Systems

www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


What is a 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 micrometers (μm)


Types of HEPA FILTERS

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


Construction

• HEPA filter is constructed of borosilicate microfibers 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


Construction

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


HEPA FILTER


Filtration Mechanisms

• 1. Inertial Impaction :

particle inertia causes it to leave the flow streamlines and impact on the fiber.



• 2. Diffusion:

The particles traverse the flow stream, they collide with the fiber and are collected.



• 3.Interception :

These mid-sized particles follow the flow stream as it bends through the fiber spaces. Particles are intercepted or captured when they touch a fiber.


HEPA in Laminar Air Flow Systems• Laminar air flow systems are used for cleaning

air in aseptic rooms.

• In laminar air flow systems, clean air is obtained through HEPA filters

• This air flows at a speed of 100 ft/min & sweeps dust particles making entire room free of particulate matter


Classification of Clean Rooms• Six classes have been established to designate

clean room cleanliness .Class 1 Class 10 Class 100 Class 1,000 Class 10,000 Class 100,000


Types of Laminar Air Flow Systems

• Laminar air flow systems are of 3 types

1. Downward flow systems 2. Horizontal flow systems 3. Wall to floor flow systems

Downward Flow Systems • This system consists of false floor

& ceiling

• The air is filtered through pre-filters ,electrostatic filters and HEPA filters in sequence

• These 3 filters are placed in false ceiling

• From the false floor, a small portion of filtered air is recalculated in to false ceiling through a recirculation duct.


Horizontal Flow Systems• The air is filtered through

prefilters ,HEPA filters which are placed in lateral walls.

• Air is recirculated through punched plate wall or recirculation duct.

• Achievement of complete sterile conditions is not possible because the airflow is not focussed on working area



Wall to Floor Flow Systems

• The filtered air enters from lateral wall with an inclined flow towards the floor.

• In this system working area is offered with high aseptic conditions.

• This system is more expensive


Conditions That Will 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 (in. wg) internal or differential across filter media


Corrosive : 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

Shock pressures

Conditions That Will Damage HEPA Filters


Shipment, Storage , Handling • The HEPA filter is extremely fragile and should

be shipped, stored, and handled in the same manner as delicate instrumentation. Personnel responsible for receiving and handling HEPA filters should receive training in proper handling technique. All incoming HEPA filters should be visually inspected for apparent


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abs air tech presentation for hepa filters

Environment

clean air

cleaning air

downward flow systems

horizontal flow systems

air flows

flow streamlines

type of air filter

doe c laminar flow