scholarly journals Systematic experimental comparison of particle filtration efficiency test methods for commercial respirators and face masks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joel C. Corbin ◽  
Greg J. Smallwood ◽  
Ian D. Leroux ◽  
Jalal Norooz Oliaee ◽  
Fengshan Liu ◽  
...  
Keyword(s):  
Standardized Test ◽  
Measurement Techniques ◽  
Test Methods ◽  
Filtration Efficiency ◽  
Experimental Comparison ◽  
Environmental Conditioning ◽  
Electric Charge Density ◽  
Face Velocity ◽  
Efficiency Test ◽  
N95 Respirators

AbstractRespirators, medical masks, and barrier face coverings all filter airborne particles using similar physical principles. However, they are tested for certification using a variety of standardized test methods, creating challenges for the comparison of differently certified products. We have performed systematic experiments to quantify and understand the differences between standardized test methods for N95 respirators (NIOSH TEB-APR-STP-0059 under US 42 CFR 84), medical face masks (ASTM F2299/F2100), and COVID-19-related barrier face coverings (ASTM F3502-21). Our experiments demonstrate the role of face velocity, particle properties (mean size, size variability, electric charge, density, and shape), measurement techniques, and environmental preconditioning. The measured filtration efficiency was most sensitive to changes in face velocity and particle charge. Relative to the NIOSH method, users of the ASTM F2299/F2100 method have commonly used non-neutralized (highly charged) aerosols as well as smaller face velocities, each of which may result in approximately 10% higher measured filtration efficiencies. In the NIOSH method, environmental conditioning at elevated humidity increased filtration efficiency in some commercial samples while decreasing it in others, indicating that measurement should be performed both with and without conditioning. More generally, our results provide an experimental basis for the comparison of respirators certified under various international methods, including FFP2, KN95, P2, Korea 1st Class, and DS2.

Demonstration of the Benefits of SAE 30 Stationary Gas Engine Oil in Full Scale Engine Tests

2021 ◽  
Author(s):  
Thijs Schasfoort ◽  
Zoe Fard ◽  
Torsten Gehrmann ◽  
Steffen Hollatz
Keyword(s):  
Positive Impact ◽  
Fuel Efficiency ◽  
Test Methods ◽  
Operating Conditions ◽  
Engine Oil ◽  
Gas Engine ◽  
Fuel Consumption Rate ◽  
Efficiency Performance ◽  
Endurance Testing ◽  
Efficiency Test

Abstract This paper evaluates the benefits of an SAE 30 monograde stationary gas engine oil (SGEO) in comparison with SAE 40 monograde SGEOs with the focus on two main areas. First, to demonstrate and quantify the positive impact of lower viscosity on the fuel consumption rate, and second to demonstrate the faster lubrication of hard to reach points in the engine during startup. The current industry recognized fuel efficiency test methods for passenger car and on-road diesel engine sectors are not suitable for evaluating the fuel efficiency performance of a gas engine oil because of the significant differences in fuel type, engine operating conditions, and oil formulations. This paper, therefore, describes comparative studies of three different gas engine oils in a modern MAN E3262 E302 gas engine that was carefully adapted and fully instrumented. The performance of each oil with respect to fuel efficiency was assessed in an extensive program comprising endurance testing, stationary tests on various load/speed points and dynamic tests running the engine fired as well as non-fired (motored). Another part of the test program explores the lubrication of hard to reach points in the engine, e.g. valve guide. The paper describes how the SAE 30 monograde oil results in faster lubrication of these parts during startup in comparison with the SAE 40 oils.

scholarly journals The protective performance of reusable cloth face masks, disposable procedure masks, KN95 masks and N95 respirators: Filtration and total inward leakage

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258191
Author(s):  
Scott Duncan ◽  
Paul Bodurtha ◽  
Syed Naqvi
Keyword(s):  
Geometric Mean ◽  
Particle Diameter ◽  
Standing Position ◽  
Filtration Efficiency ◽  
Protection Factor ◽  
Respiratory Illnesses ◽  
Particle Penetration ◽  
Preventive Health Measure ◽  
Materials Used ◽  
N95 Respirators

Face coverings are a key component of preventive health measure strategies to mitigate the spread of respiratory illnesses. In this study five groups of masks were investigated that are of particular relevance to the SARS-CoV-2 pandemic: re-usable, fabric two-layer and multi-layer masks, disposable procedure/surgical masks, KN95 and N95 filtering facepiece respirators. Experimental work focussed on the particle penetration through mask materials as a function of particle diameter, and the total inward leakage protection performance of the mask system. Geometric mean fabric protection factors varied from 1.78 to 144.5 for the fabric two-layer and KN95 materials, corresponding to overall filtration efficiencies of 43.8% and 99.3% using a flow rate of 17 L/min, equivalent to a breathing expiration rate for a person in a sedentary or standing position conversing with another individual. Geometric mean total inward leakage protection factors for the 2-layer, multi-layer and procedure masks were <2.3, while 6.2 was achieved for the KN95 masks. The highest values were measured for the N95 group at 165.7. Mask performance is dominated by face seal leakage. Despite the additional filtering layers added to cloth masks, and the higher filtration efficiency of the materials used in disposable procedure and KN95 masks, the total inward leakage protection factor was only marginally improved. N95 FFRs were the only mask group investigated that provided not only high filtration efficiency but high total inward leakage protection, and remain the best option to protect individuals from exposure to aerosol in high risk settings. The Mask Quality Factor and total inward leakage performance are very useful to determine the best options for masking. However, it is highly recommended that testing is undertaken on prospective products, or guidance is sought from impartial authorities, to confirm they meet any implied standards.

Comparison of Sand Patch Test and Multi Laser Profiler in Pavement Surface Measurement

2014 ◽  
Vol 70 (4) ◽  
Author(s):  
Haryati Yaacob ◽  
Norhidayah Abdul Hassan ◽  
Mohd Rosli Hainin ◽  
Muhammad Fudhail Rosli
Keyword(s):  
Regression Analysis ◽  
Patch Test ◽  
Measurement Techniques ◽  
Test Methods ◽  
Measurement Methods ◽  
Surface Measurement ◽  
Test Analysis ◽  
Pavement Surface ◽  
Road Pavement ◽  
Sand Patch

Pavement surface texture has been assessed with variety of test methods such as sand patch test and multi laser profiler. In recent years, road administrations face the issues of handling data acquired by totally different methods and the inconsistent correlation between different methods. Therefore, the objective of this study is to determine and compare the texture depth value of road pavement measured by different methods namely sand patch test and multi laser profiler. This paper compares the results of two measurement methods for pavement surface macro texture which referred as mean texture depth (MTD). Tests were conducted along North–South Expressway, between km 110.5 and km 107.2 (Southbound). T-test analysis shows that there is statistically significance difference on the result obtained between these methods along emergency lane. However for slow lanes,it was found that there is no significance between sand patch test and laser based measurement. Regression analysis shows that the coefficient of correlation, R obtained from emergency lane is 0.3719 and slow lane is 0.4579. These results generally conclude that there were weak correlations between the result of these two measurement techniques.

Alkali Activity of Granite Aggregates and Control in the Concrete of the Three Gorges Project

2013 ◽  
Vol 539 ◽  
pp. 249-254
Author(s):  
Zai Qin Wang ◽  
Chong Xi Liu ◽  
Zi Yun Wen ◽  
Zhen Li ◽  
Liang Xiao
Keyword(s):  
Standardized Test ◽  
Expansion Ratio ◽  
Test Methods ◽  
Observation Time ◽  
Three Gorges Project ◽  
Three Gorges ◽  
Concrete Aggregates ◽  
The Three Gorges ◽  
The Three Gorges Project ◽  
And Control

On the basis of the existing standardized test methods of concrete aggregates alkali activity, the alkali activity of the granite aggregates is studied by extending the observation time. The results showed that the alkali reaction expansion ratio of the fresh granite broke through the 0.1% criterion limit after a decade of time. The reactant microstructure characteristic is similar to the structure of the alkali-silica reaction, the thickness of reaction layer is about 2~4 µm. Controlling the total alkali content of the dam concrete and replacing cement by mixing a certain proportion of fly ash can effectively prevent the occurrence of the AAR in the Three Gorges Project.

Review of material test standardization status for the material qualification of laminated thermosetting composite structures

2020 ◽  
pp. 073168442095810
Author(s):  
Sang Yoon Park ◽  
Won Jong Choi
Keyword(s):  
Composite Materials ◽  
Material Properties ◽  
Composite Structures ◽  
Failure Modes ◽  
Laminated Composite ◽  
Test Methods ◽  
Test Method ◽  
Experimental Comparison ◽  
Laminated Composite Materials ◽  
Design Values

This paper presents a review of recent literature related to the static mechanical testing of thermoset-based carbon fiber reinforced composites and introduces a material qualification methodology to generate statistically-based allowable design values for aerospace application. Although most test methods have been found to be effective in determining the specific material properties by incorporating them into the material qualification and quality control provisions, a full validation to clarify the behavior of thermoset-based laminated composite materials is currently lacking, particularly with regard to the characterization of compressive, in-plane, interlaminar shear, and damage tolerance properties. The present study obtains information on the different types of test method that can be employed within the same material properties, and makes an in-depth experimental comparison based on the past literatures. A discussion on the scope of theoretical analysis involves a description of how the proposed test method can be adequate for obtaining more accurate material properties. This discussion is directly applicable to the assessment of material nonlinearity and the geometrical effect of specimens. Finally, the resulting failure modes and the effect of each material property are studied to aid the understanding of the load distribution and behavior of laminated composite materials.

Comparison of Standardized Test Methods for Determining the Permeability of the Surface Layer of Concrete

2015 ◽  
Vol 1122 ◽  
pp. 141-144
Author(s):  
Tereza Komárková ◽  
Monika Králíková ◽  
Dalibor Kocáb ◽  
Petr Misák ◽  
Tomáš Stavař
Keyword(s):  
Surface Layer ◽  
Water Permeability ◽  
Standardized Test ◽  
Test Methods ◽  
Standardized Assessment ◽  
Depth Of Penetration ◽  
The Individual ◽  
Durability Of Concrete

The durability of concrete can be assessed based on the quality of the surface layer of concrete, for which there are a few standardized assessment test methods. Usually, the quality of the surface layer of concrete is evaluated based on its air and water permeability. The aim of this experiment was to compare the outputs which provide some methods for determining the permeability of the surface layer of concrete (GWT, ISAT, TPT, the depth of penetration of water under pressure). The measured values using the individual methods of assessing the permeability of the surface layer of concrete very closely correspond.

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