A Numerical and Experimental Investigation of Crystalline Silica Exposure Control During Tuck-Pointing

Details

• Personal Author:
  Bennett J ; Echt, Alan S. ; Heitbrink, William A. ; Bennett J ; Echt, Alan S. ; Heitbrink, William A.
• Description:
  Tuck-pointing occurs on a scaffold, which limits the size and power of the LEV system. Thus, the goal of this study was to reduce the flowrate necessary for exposure control. Control addresses flow induced by the rotating grinding wheel, flow induced by the mortar particle stream, and particle momentum. Computational fluid dynamic (CFD) simulation of the grinder, supported by some experimental measurements, showed the relative importance of these factors through varying parameters and tracking particles. A simulation with the grinding wheel in a gap between the bricks, but with no particles, induced an airflow of 7.14 cfm out of the shroud exhaust, 6.5% less than the experimental measurement. With no gap the induced airflow was -0.461 cfm (0.461 into the exhaust take-off). However, when a stream of 10 microm particles was launched from the grinding wheel edge, the simulations with and without the gap had nearly identical induced flow rates, 10.8 and 10.9 cfm. Experiments and simulations indicated that between 80 and 100 cfm was required for good control of silica exposure, making induced flows relatively unimportant. In the simulations angle of particle launch affected whether a particle was captured. Stopping the particle stream through collision greatly reduced the required flow rate. This is difficult in practice because the gaps between the shroud and the brick and between bricks create escape paths. [Description provided by NIOSH]
• Subjects:
  Dust Occupational Health Particulate Matter Respiratory Tract Diseases Safety Silicon Dioxide
• Keywords:
  Dust-particles Dusts Masons Particulate-dust Particulates Respirable-dust Respiratory-system-disorders Silica-dusts Workers
• Publisher:
  American Industrial Hygiene Association
• Document Type:
  Text
• Genre:
  Abstract or Summary ; Abstract or Summary
• Place as Subject:
  California ; Iowa ; Ohio ; OSHA Region 5 ; OSHA Region 7 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH) ; National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology ; DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health ; Workplace Safety & Health
• Location:
  North America ; North America
• NIOSHTIC Number:
  nn:20022566
• Citation:
  American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :100
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7) ; Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2002
• NORA Priority Area:
  Work Environment And Workforce ; Research Tools and Approaches: Exposure Assessment Methods ; Research Tools and Approaches: Control Technology & Personal Protective Equipment ; Work Environment And Workforce ; Research Tools and Approaches: Exposure Assessment Methods ; Research Tools and Approaches: Control Technology & Personal Protective Equipment
• Peer Reviewed:
  False
• Source Full Name:
  American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f0383d160a9dc29e5132b602b6e6f456f0973136088de498eb5cf078238b00ba62061d2d81ef25e75446adf45da3f24ebe5e764cca22da467feaf341654bcc45
• Download URL:
  https://stacks.cdc.gov/view/cdc/199303/cdc_199303_DS1.pdf
• File Type:
  [PDF - 490.39 KB ]