Simulation and evaluation of respirator faceseal leaks using computational fluid dynamics and infrared imaging

Details

• Personal Author:
  Lei Z ; Roberge R ; Yang J ; Zhuang Z
• Description:
  This paper presents a computational fluid dynamics (CFD) simulation approach for the prediction of leakage between an N95 filtering facepiece respirator (FFR) and a headform and an infrared camera (IRC) method for validating the CFD approach. The CFD method was used to calculate leak location(s) and 'filter-to-faceseal leakage' (FTFL) ratio for 10 headforms and 6 FFRs.The computational geometry and leak gaps were determined from analysis of the contact simulation results between each headform-N95 FFR combination. The volumetric mesh was formed using a mesh generation method developed by the authors. The breathing cycle was described as a time-dependent profile of the air velocity through the nostril. Breathing air passes through both the FFR filter medium and the leak gaps. These leak gaps are the areas failing to achieve a seal around the circumference of the FFR. The CFD approach was validated by comparing facial temperatures and leak sites from IRC measurements with eight human subjects. Most leaks appear at the regions of the nose (40%) and right (26%) and left cheek (26%) sites. The results also showed that, with N95 FFR (no exhalation valves) use, there was an increase in the skin temperature at the region near the lip, which may be related to thermal discomfort. The breathing velocity and the viscous resistance coefficient of the FFR filter medium directly impacted the FTFL ratio, while the freestream flow did not show any impact on the FTFL ratio. The proposed CFD approach is a promising alternative method to study FFR leakage if limitations can be overcome. [Description provided by NIOSH]
• Subjects:
  Filtration Occupational Health Personal Protective Equipment Protective Clothing Respiratory Protective Devices Respiratory System Safety
• Keywords:
  Air-purifying-respirators Analytical-processes Anthropometry Author Keywords: Computational Fluid Dynamics Breathing-zone Dynamic-structural-analysis Equipment-reliability Face-masks Filter-materials Filters Fluid-mechanics Fluids Headgear Infrared Image Leak Leak-detectors Personal-protective-equipment Photographic-equipment Respirator Respirator Fit Respirators Respiratory-equipment Simulation-methods Testing-equipment Volumetric-analysis

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• ISSN:
  0003-4878
• Document Type:
  Text
• Funding:
  Contract
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; OSHA Region 6 ; Pennsylvania ; Texas
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  NPPTL - National Personal Protective Technology Laboratory
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  493-506
• Volume:
  57
• Issue:
  4
• NIOSHTIC Number:
  nn:20042519
• Citation:
  Ann Occup Hyg 2013 May; 57(4):493-506
• Contact Point Address:
  James Yang, Department of Mechanical Engineering, Human-Centric Design Research Laboratory, Texas Tech University, Lubbock, TX 79409, USA
• Email:
  james.yang@ttu.edu
• Federal Fiscal Year:
  2013
• NORA Priority Area:
  Healthcare and Social Assistance
• Peer Reviewed:
  True
• Source Full Name:
  Annals of Occupational Hygiene
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:36262357a75226c4c531ef832ec15cdcbfbf375f76de7f1e1b40687b631c8b9e274148aae61bded8e9947477cbf729e63229f6fe9f93af05c5938d454f9c4472
• Download URL:
  https://stacks.cdc.gov/view/cdc/194716/cdc_194716_DS1.pdf
• File Type:
  [PDF - 3.07 MB ]