Scanning High-Efficiency Air Filters for Leaks Using Particle Counting Methods

1993 ◽  
Vol 36 (5) ◽  
pp. 28-37
Author(s):  
Bruce McDonald
Keyword(s):  
Flow Rate ◽  
High Efficiency ◽  
Particle Detectors ◽  
Air Filters ◽  
Test Parameters ◽  
Counting Methods ◽  
Scan Rate ◽  
Particle Counts ◽  
Definition Of ◽  
Individual Particles

High-efficiency particulate air (HEPA) filters and ultra low penetration air (ULPA) filters such as those used in cleanrooms and clean benches are frequently scanned or probed for leaks. Increasingly, particle detectors that count individual particles are used to scan filters. The equations that govern the scanning of high-efficiency filters with particle counters have been derived. The assumptions that bound the applicability of the equations are stated. The relationships provide the means to determine the appropriate linear scan rate and to understand the effect of the test parameters on the duration and accuracy of the test. The linear scan rate is derived in terms of a leak flow rate but a method is presented to relate the leak flow to the traditional leak penetration. Further, a method is described to standardize the definition of leak penetration to eliminate the dependence of measured leak penctration on the instrument used to measure it. The linear scan rate is shown to depend on the number of particle counts used to characterize the threshold leak. The statistical impact of the count used to calculate the linear scan rate is described.

scholarly journals Use of portable partitions with high-efficiency particulate air filters in the endoscopy unit

2021 ◽  
Vol 09 (02) ◽  
pp. E278-E279
Author(s):  
Hiroyuki Fujimura ◽  
Jun Nishikawa ◽  
Takeshi Okamoto ◽  
Atsushi Goto ◽  
Koichi Hamabe ◽  
...  
Keyword(s):  
High Efficiency ◽  
Air Filters ◽  
Endoscopy Unit

Survival of Mycobacteria on Hepa Filter Material

1998 ◽  
Vol 3 (2) ◽  
pp. 65-78 ◽  
Author(s):  
Gwangpyo Ko ◽  
Harriet A. Burge ◽  
Michael Muilenberg ◽  
Stephen Rudnick ◽  
Melvin First
Keyword(s):  
High Efficiency ◽  
Ventilation System ◽  
Filter Material ◽  
Survival Curves ◽  
Mycobacterium Chelonae ◽  
Air Filters ◽  
Liquid Suspension ◽  
Static Conditions ◽  
Strain H37rv ◽  
Over Time

Mycobacterium tuberculosis (MTB) is transmitted through the air, and can be captured on ventilation air filters. People handling these filters may be exposed to infectious material. We studied the survival of strains of Mycobacterium on high efficiency particulate air (HEPA) filter material. We used a model ventilation system to evaluate survival over time of Mycobacterium chelonae and H37Ra (an avirulent stain of MTB) aerosolized and then captured on HEPA filter material. Survival curves for M. chelonae incubated at 55% and 75% RH under static conditions were not different with less than 4% survival at 24 hours. H37Ra was subjected to continuous airflow at the design airflow for the filter material following deposition on the HEPA filter material, and less than 0.1% of cells survived to 48 hours (RH not controlled). H37Ra was resistant to immobilized biocide (trimethoxysilylpropyl dimethyloctadecyl ammonium chloride) on HEPA filter material as well as the same biocide in solution. Finally, survival of H37Ra and virulent MTB strain (H37Rv) were not different following deposition onto HEPA filter material from liquid suspension and incubation under static conditions.

High-Strength High-Efficiency Particulate Air Filters for Nuclear Applications

1990 ◽  
Vol 92 (1) ◽  
pp. 11-29
Author(s):  
Volker Rüdinger ◽  
Craig I. Ricketts ◽  
Jürgen G. Wilhelm
Keyword(s):  
High Efficiency ◽  
High Strength ◽  
Air Filters ◽  
Nuclear Applications

Simulation on Linear-Motor-Driven Water Hydraulic Reciprocating Plunger Pump

2013 ◽  
Vol 842 ◽  
pp. 530-535 ◽  
Author(s):  
Zeng Meng Zhang ◽  
Yong Jun Gong ◽  
Jiao Yi Hou ◽  
Han Peng Wu
Keyword(s):  
Flow Rate ◽  
Deep Sea ◽  
High Efficiency ◽  
Control Method ◽  
Sea Water ◽  
Linear Motor ◽  
Low Flow ◽  
Flow Pulsation ◽  
Plunger Pump ◽  
Water Hydraulic

The water hydraulic reciprocating plunger pump driven by linear motor is suitable to deep sea application with high efficiency and variable control. Aiming to study the principle structure and working characteristics of the pump, two patterns of valve and piston distribution were designed. And the control method and the performance were analyzed by simulation based on the AMESim model. The results show that the pressure and flow pulsation of piston type pump are much smaller than the valve type, even though the piston type is large in scale and works at low flow rate. Compared with a valve distribution tri-linear-motor reciprocating plunger pump (VDTLMP), as the flow rate of the piston distribution double linear motor reciprocating plunger pump (PDDLMP) is decreased from 36.7 L/min to 21.2 L/min theoretically, the pressure pulsation amplitude is decreased from 46% to 2%, and the flow pulsation rate is also decreased from 0.266 to 0.007. These results contribute to the research on deep-sea water hydraulic power pack and direct drive pump with high efficiency and energy conservation.

Effect Of Equivalent Ratio (ER) On the Flow and Combustion Characteristics in A Typical Underground Coal Gasification (UCG) Cavity

2021 ◽  
Vol 86 (2) ◽  
pp. 28-38
Author(s):  
Arup Kumar Biswas ◽  
Wasu Suksuwan ◽  
Khamphe Phoungthong ◽  
Makatar Wae-hayee
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Coal Gasification ◽  
High Efficiency ◽  
Combustion Characteristics ◽  
Raw Material ◽  
Underground Coal Gasification ◽  
Equivalent Ratio ◽  
Rubble Pile

Underground Coal Gasification (UCG) is thought to be the most favourable clean coal technology option from geological-engineering-environmental viewpoint (less polluting and high efficiency) for extracting energy from coal without digging it out or burning it on the surface. UCG process requires only injecting oxidizing agent (O2 or air with steam) as raw material, into the buried coal seam, at an effective ratio which regulates the performance of gasification. This study aims to evaluate the influence of equivalent ratio (ER) on the flow and combustion characteristics in a typical half tear-drop shape of UCG cavity which is generally formed during the UCG process. A flow modeling software, Ansys FLUENT is used to construct a 3-D model and to solve problems in the cavity. The boundary conditions are- (i) a mass-flow-inlet passing oxidizer (in this case, air) into the cavity, (ii) a fuel-inlet where the coal volatiles are originated and (iii) a pressure-outlet for flowing the product Syngas out of the cavity. A steady-state simulation has been run using k-? turbulence model. The mass flow rate of air varied according to an equivalent ratio (ER) of 0.16, 0.33, 0.49 and 0.82, while the fuel flow rate was fixed. The optimal condition of ER has been identified through observing flow and combustion characteristics, which looked apparently stable at ER 0.33. In general, the flow circulation mainly takes place around the ash-rubble pile. A high temperature zone is found at the air-releasing point of the injection pipe into the ash-rubble pile. This study could practically be useful to identify one of the vital controlling factors of gasification performance (i.e., ER impact on product gas flow characteristics) which might become a cost-effective solution in advance of commencement of any physical operation.

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