35. Collection Efficiency of Air Purifying Respirators Containing Electrostatic Filter Media Loaded with Contaminants Generated from an Asphalt Melting Kettle

1999 ◽  
Author(s):  
D. Larson
Keyword(s):  
Collection Efficiency ◽  
Filter Media ◽  
Electrostatic Filter

Collection Efficiency of Various Filter Media in Diesel Exhaust

2001 ◽  
Author(s):  
M.S. Nikitidis ◽  
T. Manikas ◽  
D. Zarvalis ◽  
N. Divinis ◽  
C. Altiparmakis ◽  
...  
Keyword(s):  
Diesel Exhaust ◽  
Collection Efficiency ◽  
Filter Media

Filter Media Design for High Purity Air Applications

1986 ◽  
Vol 29 (4) ◽  
pp. 27-31
Author(s):  
James Schaefer ◽  
Marty Barris ◽  
Benjamin Liu
Keyword(s):  
High Performance ◽  
Collection Efficiency ◽  
Particle Diameter ◽  
Particle Sizes ◽  
Filter Media ◽  
Media Design ◽  
Theoretical Predictions ◽  
Media Performance ◽  
Rating Criteria ◽  
Filtration Model

The design of high performance filter media for HEPA and ULPA applications is examined comparing theoretical predictions with experimental data. The analysis employs a hybrid filtration model. Pressure drop and particle collection efficiency in the region of minimum efficiency where particle diffusion is decreasing and particle interception is increasing as the particle size increases are examined as functions of particle diameter, velocity, and media geometry including fiber diameter, solidity, and thickness. Several grades of filter media are characterized and tested for particle sizes in the region of the point of minimum efficiency at typical media rating and application velocities. Filter media performance comparisons are made that show how the point of minimum efficiency can be altered by velocity and media geometry changes. This information is used for a discussion of HEPA and ULPA media performance rating criteria with respect to test and application conditions. Based upon the results of this study, filter media design, analysis, evaluation and application tools are presented for optimizing high performance filter media for HEPA applications, with suggested future trends based upon projected needs for improving the performance of HEPA media.

scholarly journals Development of Filter Media by Electrospinning for Air Filtration of Nanoparticles from PET Bottles

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 293
Author(s):  
Daniela P. F. Bonfim ◽  
Fabiana G. S. Cruz ◽  
Vádila G. Guerra ◽  
Mônica L. Aguiar
Keyword(s):  
Collection Efficiency ◽  
Fine Particulate Matter ◽  
Electrospinning Process ◽  
Air Filtration ◽  
Filter Media ◽  
Gas Filtration ◽  
Pressure Drops ◽  
Support Materials ◽  
Pet Bottles ◽  
Needle Diameter

Air pollution and solid pollution are considered global problems, and endanger human health mainly due to the emission of fine particulate matter released into the atmosphere and improper disposal of post-consumer plastic bottles. Therefore, it is urgent to develop filter media to effectively protect the public. The properties of plastics make them potential candidates for nanofiber mat formers due to their attractive structural and mechanical characteristics. This work aims to produce and evaluate novel PET electrospun fibers dispensed with the use of support materials to be used as filter media to remove nanoparticles from the air. The electrospinning process was carried out by changing the concentration of the polymer solution, the needle diameter, and the electrospinning processing time at two rotation speeds. The average diameters of the micro- and nanofibers of the filter media produced ranged from 3.25 μm to 0.65 μm and it was possible to conclude that, as the size of the fibers decreased, the mechanical strength increased from 3.2 to 4.5 MPa. In filtration tests, a collection efficiency of up to 99% with low-pressure drops (19.4 Pa) was obtained for nanoparticles, demonstrating high quality factor filter media, which could be applicable in gas filtration.

To What Extent are Inelastically Scattered Electrons Useful in the Stem?

1973 ◽  
Vol 31 ◽  
pp. 286-287 ◽  
Author(s):  
H. Rose
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Correlation ◽  
Quantum Noise ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Cloud ◽  
Scanning Time ◽  
Transmission Electron ◽  
Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

High energy resolution spectrometer for the dedicated STEM

1984 ◽  
Vol 42 ◽  
pp. 558-559 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Collection Efficiency ◽  
Core Loss ◽  
Beam Current ◽  
High Energy ◽  
High Energy Resolution ◽  
Acquisition Time ◽  
Good Definition ◽  
Loss Analysis ◽  
Definition Of ◽  
Acceleration Voltage

Use of the STEM to obtain precise electronic information has been hampered by the lack of energy loss analysis capable of a resolution and accuracy comparable to the 0.3eV energy width of the Field Emission Source. Recent work by Park, et. al. and earlier by Crewe, et. al. have promised magnetic sector devices that are capable of about 0.75eV resolution at collection angles (about 15mR) which are great enough to allow efficient use of the STEM probe current. These devices are also capable of 0.3eV resolution at smaller collection angles (4-5mR). The problem that arises, however, lies in the fact that, even with the collection efficiency approaching 1.0, several minutes of collection time are necessary for a good definition of a typical core loss or electronic transition. This is a result of the relatively small total beam current (1-10nA) that is available in the dedicated STEM. During this acquisition time, the STEM acceleration voltage may fluctuate by as much as 0.5-1.0V.

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