Bacterial Filtration Fabric Testing With Controlled Aerosol Particle Size
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Solution Overview
Problem
Existing methods for testing bacterial filtration efficiency of fabrics, particularly woven fabrics, face challenges in maintaining the mean particle size of droplets within the required range and result in unreliable evaluations due to variations in test results and difficulty in achieving the specified particle size.
Innovation Solution
A method involving the use of a specific concentration of NaCl in peptone water (30g/L to 150g/L) and controlling the temperature of the cascade impactor (-15°C to 15°C) to generate aerosols with a mean particle size of 2.7 to 3.3 µm, ensuring reliable bacterial filtration efficiency testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standard method according to EN 14683 is applied for testing bacterial filtration efficacy, then the testing procedure can be performed, but the mean particle size of droplets containing bacteria cannot be maintained within the required range (2.7-3.3 μm), resulting in unreliable evaluation
Solution Approach 1:
The patent modifies the peptone water composition by adding specific concentrations of NaCl (0.9%, 1.8%, or 2.7%) to change the physical-chemical parameters of the bacterial aerosol generation system. This parameter change enables precise control of droplet mean particle size within the required 2.7-3.3 μm range, directly resolving the contradiction between reliable evaluation and particle size control.
2Productivity
If tests are performed according to EN 14683 on woven fabrics, then the testing can be completed, but the results vary between tests and the mean particle size falls outside the required range
Solution Approach 1:
By modifying the peptone water with specific NaCl concentrations, the patent ensures consistent droplet generation parameters across multiple tests. This leads to reproducible mean particle sizes within 2.7-3.3 μm and consistent bacterial filtration efficiency measurements, resolving the contradiction between testing productivity and measurement precision.
3Ease of operation
If the mean particle size of droplets is not maintained within the required range, then the testing can proceed, but the bacterial filtration efficiency evaluation becomes unreliable
Solution Approach 1:
The patent changes the peptone water composition parameters by adding NaCl at specific concentrations, which simplifies the operation of maintaining required particle size while ensuring reliable BFE evaluation. The modified solution naturally produces droplets within 2.7-3.3 μm range, making the testing both easy to execute and reliable.
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
This approach allows for reproducible and reliable determination of bacterial filtration efficiency by maintaining the mean particle size within the required range, enhancing the accuracy of fabric testing.
Implementation Method 1
A method involving the use of a specific concentration of NaCl in peptone water (30g/L to 150g/L) and controlling the temperature of the cascade impactor (-15°C to 15°C) to generate aerosols with a mean particle size of 2.7 to 3.3 µm
Implementation Method 2
flowing said solution through a cascade impactor to provide a plurality of bacteria colonies in a plurality of plates present in a plurality of stages of said cascade impactor
Implementation Method 3
flowing said solution through a cascade impactor to provide a plurality of bacteria colonies in a plurality of plates present in a plurality of stages of said cascade impactor
Data Source
AI summary
The present invention relates to method of testing the bacterial filtering efficiency of a fabric, the method including the steps of preparing a solution including bacteria, peptone water and NaCl, feeding said solution including bacteria to a nebulizer, generating an aerosol of said bacterial solution and flowing said solution through a cascade impactor to provide a plurality of bacteria colonies in a plurality of plates present in a plurality of stages of said cascade impactor, characterized in that the concentration of NaCl in the peptone water used to prepare said bacterial solution is in the range of 30g/L to 150g/L and in that the temperature of said cascade impactor is in the range of -15°C to 15°C.