ePTFE HEPA Filter Media for Aseptic Pharmaceutical Filtration

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Solution Overview

Problem

Current HEPA air filtration media in aseptic pharmaceutical cleanrooms are fragile and prone to damage, leading to leaks and reduced functionality due to handling issues, pressure, and regular high-concentration aerosol testing, which shortens the filter life and increases maintenance costs.

Innovation Solution

A dual-layer bi-component ePTFE HEPA filtration media with a laminated ePTFE membrane, using ultra-low concentrations of PAO aerosol for testing, and a discrete particle counter for accurate leakage detection, reducing fouling and extending filter life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If regular high-concentration aerosol testing is performed to ensure filter effectiveness, then filtration reliability is improved, but filter media damage and leakage increase

Engineering Contradiction:

Improvefiltration effectivenessVSAvoidmedia integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the concentration parameter of the aerosol challenge from high (traditional levels) to ultra-low concentrations. This parameter change allows effective testing of filter integrity while minimizing damage to the fragile ePTFE media, thereby maintaining reliability without compromising strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs disposable pre-filters that can be easily replaced. These pre-filters protect the main ePTFE filter media during handling and installation, reducing damage and extending the life of the primary filtration media

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If standard microglass HEPA filters are used in aseptic environments, then filtration performance is achieved, but handling damage and leaks occur

Engineering Contradiction:

Improvefiltration performanceVSAvoidhandling durability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent uses ePTFE (expanded polytetrafluoroethylene) composite material instead of traditional microglass media. ePTFE combines the required filtration performance with superior mechanical durability and resistance to handling damage, eliminating leaks while maintaining aseptic filtration effectiveness

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The ePTFE media is presented as a flexible, resilient thin film structure that can withstand handling, pressure differentials, and installation procedures without cracking or breaking, unlike rigid microglass media

Inventive Principle:

Principle #30Flexible shells and thin films

3Measurement precision

If high concentration PAO aerosol is used for filter challenge testing, then leakage detection sensitivity is improved, but filter life is reduced

Engineering Contradiction:

Improveleakage detection sensitivityVSAvoidfilter life

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The patent changes the concentration parameter of the challenge aerosol from high to ultra-low levels. Advanced detection equipment measures leakage with high precision at these low concentrations, maintaining measurement sensitivity while dramatically reducing the cumulative exposure damage to the filter media and extending filter life

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical/chemical challenge methods with ultra-low concentration aerosol and advanced optical/detector-based measurement systems. This substitution enables precise leakage detection without the damaging effects of high-concentration aerosol exposure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a durable HEPA filtration media with extended life and reduced energy costs, maintaining efficiency and integrity without additional pre-filter requirements, while allowing for regular and accurate leakage testing at ultra-low aerosol concentrations.

Implementation Method 1

a HEPA filter having a bi-component scrim wherein an ePTFE membrane is laminated between a top and a bottom bi-component layer

Methodology Applied

Scientific EffectPhysical barrier filtration: Filter (physical)

Implementation Method 2

a discrete particle counter for accurate leakage detection

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentEP2637772B1Eptfe filter for aseptic pharmaceutical use and method of using

Publication Date: 2017.06.28 AAF MCQUAY INC D B A AAF INT

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AI summary

A HEPA filter which utilizes spun bond scrim material and ePTFE membrane for use in an aseptic pharmaceutical filtration air handling system for installation and testing is provided. The installation and testing configuration includes the ePTFE filter with a low or ultra-low concentration of challenging aerosol in the upstream side of the filter along with a scanning device for determining the upstream concentration, all completed in situ within a pharmaceutical air handling system. At the downstream side of the ePTFE filter is positioned another scanner which may be a discrete particle scanner for calculating the penetration percentage of the aerosol through the filtering media of ultra-low concentrations. The system and configuration allows for exposure to ePTFE filtration media for certification by low or ultra-low concentrations of oil based challenging compounds.