TPACC has devolved a new material-level assessment of particulate filtration efficiency for materials that could be applied for mask particulate filtration. This technique was created as a screening tool to distinguish the performance of materials that are presently being applied for mask filtration purposes.
The test method uses a altered Sioutas Particle Impactor to hold the material specimen in place during testing and has the ability to test single and multiple layers. Presently, this examination counts the up and downstream of atmosphere particles and is measured at six size ranges: 0.3, 0.5, 1, 2, 5, and 10 μm. Duration of each test is 1 minute with 3 series of testing per specimen.
The nature of this assessment is to acquire fast, efficient, and repeatable results that can be used as an initial screening for assessment of material particulate filtration efficiency.
Introductory material-level testing has revealed that in environmental conditions, particulate filtration efficiency using N95 material specimens remains the gold standard for personal protective appliance (PPA). Alongside this baseline specimen,three other specimens were tested to distinguish the material’s particulate filtration efficiency performance. These comprised a standard surgical mask, coffee filters (3 layers), and plain cotton sheeting (4 layers).
Choice of these material samples were based on the favour and convenience to the common public in response to the COVID-19 pandemic. The graph focuses on the initial data based of introductory tests used to screen the material specimens. At about 0.3 microns, the % Particulate Filtration Efficiency (%PFE) can be examined with each material specimen assessment.
]]>A test sample is mounted firmly, face-up on an angled surface. A pre-weighed sheet of blotter paper is mounted behind the sample. An amount of water is sprayed against the face of the sample. The blotter paper is then re-weighed to discover water permeation . The raise in mass of the blotter paper shows the mass of water that passed through the test sample. Lower test results show less permeation and superior water repellency of the fabric.
There are several varieties of this test, all based on the AATCC test procedure actually issued in 1945. Perhaps most eminently for the present environment, the impact permeation test is one of several used to assess Level 1-3 barrier materials for medical personal protective appliance. Anyone evolving, producing, or checking surgical gowns, isolation gowns, other protective apparel, surgical drapes, or drape accessories must understand how to select the correct test procedure.
ANSI/AAMI PB70, Liquid barrier performance and categorization of protective apparel and drapes designed for use in health care facilities, figures the requirements for protective apparel and drapes.
AATCC TM42, Test Procedure for Water Resistance: Impact Permeation is a required test for materials categorized as Level 1-3; however, it must be executed with a substitute blotter paper. The blotter paper specifications are incorporated in the AAMI PB70 standard.
The latest version of AAMI PB70 also permits WSP (Worldwide Strategic Partners) 80.3 as an alternate for AATCC TM42. WSP 80.3 has since been replaced by NWSP (Nonwovens Standard Procedure) 80.3. The blotter paper stated in these procedure is close but not exactly the same as that described in AAMI PB70. Different versions of NWSP 80.3 define different mass per unit area, while the AAMI standard registers no value for this property. Since no year is mentioned, one can presume that the most recent version of NWSP 80.3 should be used.
Although the AAMI standard shows that the procedures are equivalent, there are small dissimilarities that could influence results for some materials. All reports should show which impact permeation test was executed. A total comparison of the AATCC and NWSP procedures is incorporated below.
The blotter has been a source of puzzlement and vexation. The blotter paper conventionally used for AATCC TM42 should NOT be used for testing and categorization of barrier performance according to AAMI PB70. As mentioned above, the blotter paper described in the AAMI and NWSP standards are not quiet the similar. A complete clarification of the differences is included below.
For practical purposes, EDANA (the publisher of NWSP 80.3) prescribes Ahlstrom grade 989 blotter paper, while showing that other papers may also be appropriate. Note that not all properties stated in AAMI PB70 or NWSP 80.3 are listed on data sheets given by the blotter paper manufacturer and not all properties listed meet the specifications exactly. For instance, one data sheet shows a objective absorbent capacity of 512.0%, with a minimum of 434.0% and a maximum of 590.0%; AAMI PB70 requires an absorbent capacity of 480% ±30% (450% – 510%); NWSP 80.3 requires an absorbent capacity of ≥ 480%.
For AAMI PB70 Level 1-3, execute AATCC TM42-2017e as written, with the exception of the blotter paper. Use blotter paper meeting the specifications listed in AAMI PB70, section 5.2.1.2. For borderline results on nonwoven fabrics, it may be advantageous to use a Type II tester to lower the vibrations during testing.
As a substitute, perform NWSP 80.3.R1 (19) as written. Use blotter paper matching the specifications listed in NWSP 80.3.R1. Be assured to show the version of the procedure used as there are notable differences in the blotter paper specified in earlier versions.
Carry out AATCC TM42 or NWSP 80.3 to meet AAMI PB70 requirements; do not execute both tests.
Use the sampling plan showed in AAMI PB70 whether testing with AATCC TM42 or NWSP 80.3. This will normally require more samples than called for in the test procedures. In most cases, 15-20 samples per element is suitable. If fewer samples are examined on account of limited sample size or agreement among all parties, this should be mentioned in the test report.
While AATCC TM42 and NWSP 80.3 are designed for testing unstitched fabric, AAMI PB70 also needs testing of seams and attachment points as these are the most probable point of failure for water resistance. Test each applicable element of the protective apparel or drape independently.
Center seams widthwise so they run along the length of the sample. Center points of attachments on the sample (see Fig. 1). Check multi-layer products as they are used in the final product—incorporate all layers in the right order, outermost layer on top. Specific instructions on crucial zones for testing is added in AAMI PB70.
Execute further tests (AATCC TM127, ASTM F1671, ASTM F1670) as required, depending on intended AAMI PB70 categorization level.
Summary
* For AAMI PB70 Level 1-3, perform AATCC TM42-2017e as written, with the exception of the blotter paper. Use blotter paper matching the specifications listed in AAMI PB70, section 5.2.1.2.
* As a substitute, execute NWSP 80.3.R1 (19) as written. Use blotter paper matching the specifications listed in NWSP 80.3.R1.
* In most cases, 15-20 samples per element is appropriate.
* Test each applicable element(base material, seam, attachment, etc.) of the protective apparel or drape independently.
* Execute further tests (AATCC TM127, ASTM F1671, ASTM F1670) as required, depending on intended AAMI PB70 categorization level.
]]>Many virus varieties can be examined; familiar instances include influenza and corona virus strains. The authentic performance of the treated textile is determined by viral titer measurements using a plaque assay or TCID50 method (Median Tissue Culture Infectious Dose) comparable to a most feasible number serial dilution measurement.
The ISO 18184
Common Antimicrobial Additives
Standard mechanisms for antiviral activity need additives that can chemically or dynamically alter some aspects of the virus. Drug strategies depend on distinctly specific binding to the virus (known as receptor-ligand binding) where the receptor is on the virus, and the ligand is the drug used to bind to the receptor obstructing its motive movement.
For treated products, a more traditional approach is to chemically attack a more common feature of the virus. For coronavirus, which has a fatty (lipid) cover, antiviral products will stick to the membrane and interrupt it by making it lose its typical structure and, therefore, its ability to infect. Basic classes of antimicrobials for that activity used in textiles are quaternary ammonium combination , essential oils, and quaternary-silane molecules (quat-silane), which are comparable to surfactants or detergents but are coupled with added chemical functions to allow for their sustainable use.
Another way of antiviral activity uses a contrasting chemical approach that oxidizes the material on exposed facets of the virus; once oxidized, these viral elements can no longer function biologically and are inactive. Typical classes of antiviral and antimicrobial combinations that use this strategy are chemicals like hypochlorite or bleach. These tend to be of less use due to a absence of sustainability , but are still used as an productive cleaning mechanism.
Many buyers will request durability testing as an element of the ISO 18184 method to determine a product’s antimicrobial performance against viruses when disclosed to environmental conditions. Utilizing both Durability and Antimicrobial testing through Situ Biosciences’ product test laboratory can assist product development and performance testing while minimizing the time and costs associated with developing and distributing standard products. One circumspection is that durability assessments need to be well managed for the effects of residual cleaning products and, therefore, must be well designed for the aimed purpose of the treated product.
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