HEPA Filters

Gordon Farquharson

July 2017

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Images courtesy of CamfilFarr

Air Filters at work

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How filters work

Sieving Effect

Straining

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Filter Efficiency curve

MPPS, typically at 0.2 micron particle size

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Some important filter considerations

• The correct pre-filters protect systems& prolong life of final filters

• HEPA filters are the GMP filters.They are required in cleanroom & safety ventilationapplications.

• Designs and installation must allow for convenient & safe filter testing

• Make sure you know what filters are installed in the system

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Filter Test Methods

MPPS = 0.2 m

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Some Test Equipment

Thermo-Pneumatic Aerosol Generator

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Some Test Equipment

Laskin Nozzle Cold Generator

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Some Test Equipment

Aerosol Photometer

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CEN TC 195 - Air Filtration

EN 1822-3

Testing Planar Filter Medium to determine the MPPS -- Most Penetrating Particle size. The processes of Interception, Diffusion & Straining give the following classic curve. Performance is velocity dependent.

HEPA & ULPA Filters

v1

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HEPA & ULPA FiltersEN 1822 - Factory Test

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EN 1822-1 Filter Classifications

To avoid problems with In-situ test, always specify a face

scanned filter from the supplier !

Local efficiency = 5x 0verall

Overall Effic/Pen Local Effic/Pen

H10 85 / 15% na / na

H11 95 / 5 na / na

H12 99.5 / 0.5 na / na

H13 99.95 / 0.05 99.75 / 0.25%

H14 99.995 / 0.005 99.975 / 0.025

U15 99.9995 / 0.0005 99.9975 / 0.0025

U16 99.99995 / 0.00005 99.99975 / 0.00025

U17 99.999995 / 0.000005 99.9999 / 0.0001

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Local & Overall EfficiencyH 14 example

Overall penetration

< 0.005 % @ MPPS

Local pen

< 0.025 %

Local pen

< 0.025 %

Local pen

< 0.025 %

@ MPPS

Local & Overall

Pen % must pass

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Leak test In-situ

Overall penetration

< 0.001 or 0.003 % @ MPPS

Local pen

< 0.01 %

Local pen

< 0.01 %

Local pen

< 0.01 %

PAO test

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Choosing the Right HEPA Filter

http://www.phss.co.uk/Refers to filter grades in accordance with EN 1822 ULPA , & HEPA

EU GMP Grade

ClassAt Rest

14644-1 209E

0.5 m

ClassIn Operation14644-1 209E

0.5 m

Air flow regimeand final filterconfiguration

Final Filterspecification to

EN 1822

In situ test leak testmethod

Testacceptancecriteria =stated %

U15 0.001 %A

ISO 5100M3.5

ISO 5100M3.5

UDAFTerminal HEPAfilter H14

Face scan withaerosol &photometer 0.01 %

BISO 5100M3.5

ISO 7

10,000M5.5

N-UDAFTerminal HEPAfilter

H14Face scan withaerosol &photometer

0.01 %

CISO 710,000M5.5

ISO 8100,000M6.5

N-UDAFTerminal HEPAfilter

H14Face scan withaerosol &photometer

0.01 %

DISO 8100,000M6.5

Not definedN-UDAFIn plant final filter

H13 Volumetric overallpenetration.

0.01 %

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The Installed HEPA Filter

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Typical Aseptic Facility Design (From ISPE HVAC GPG)

Outside air treatment AHU

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HEPA Filter Systems for Potent, Toxic, Biohazard applications

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BIBO (Bag-In, Bag-Out Housing

Cover Panel

Access door for BT damper

Scan section

Hepa Section

Pre filter section

Air intake

levelling feet

Fully Self contained system with fan, integrated dampers & automatic scan section optional

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Filter Leak Test Procedure!

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Filter Leak Test Procedure!

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Duct mounted double exhaust housingSafety ventilation systems - typical contemporary BSL-3 exhaust system

• High Total Cost of Ownership

• Large

• Each system must be specifically oriented

• Costly to test

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High Efficiency Particulate Air(HEPA) Filter

Typical BSL-3 HEPA Filter Exhaust System

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Filter leak testing – manual scanning a ducted filter

• Potential Risk to Certifier

• Requires lab shutdown and system decontamination

• Slow process

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Control Unit

Field system leak testing – automated scanning

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Conclusions

Be aware of the Different Standards

Understand the configuration

Specify filters correctly (including leak testing)

Install carefully

Test In-situ

Plan re-testing

Keep records

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Thank you for your time.Questions?

Gordon Farquharson

gordon.farquharson@pharmout.net

www.pharmout.net

Executive Consultant