|
ASBESTOS and OTHER FIBERS by PCM:METHOD 7400,Issue 2,dated 15 August 1994-Page 12 of 15
<br /> [15] McCrone,W.,L.McCrone and J.Deily,"Polarized Light Microscopy,"Ann Arbor Science(1978).
<br /> [16] Ogden,T.L."The Reproducibility of Fiber Counts,"Health and Safety Executive Research Paper 18
<br /> (1982).
<br /> [17] Schlecht,P.C.and S.A.Schulman."Performance of Asbestos Fiber Counting Laboratories in the
<br /> NIOSH Proficiency Analytical Testing (PAT) Program;"Am.Ind.Hyg.Assoc.J.,47,259-266(1986).
<br /> [18] Chatfield,E.J.Measurement of Asbestos Fiber Concentrations in Workplace Atmospheres,Royal
<br /> Commission on Matters of Health and Safety Arising from the Use of Asbestos in Ontario,Study No.
<br /> 9, 180 Dundas Street West,22nd Floor,Toronto,Ontario,CANADA M5G 1 Z8.
<br /> [19] Walton,W.H."The Nature,Hazards,and Assessment of Occupational Exposure to Airborne Asbestos
<br /> Dust:A Review,"Ann.Occup.Hyg.,25, 115-247(1982).
<br /> [20] Cherrie,J.,A.D.Jones,and A.M.Johnston."The Influence of Fiber Density on the Assessment of
<br /> Fiber Concentration Using the membrane filter Method"Am.Ind.Hyg.Assoc.J.,47(8),465-74(1986).
<br /> [21] Baron,R A.and S.Shulman."Evaluation of the Magiscan Image Analyzer for Asbestos Fiber
<br /> Counting"Am.Ind.Hyg.Assoc.J.,(in press).
<br /> [22] Taylor,D.G., R A.Baron,S.A.Shulman and J.W.Carter."Identification and Counting of Asbestos
<br /> Fibers,"Am.Ind.Hyg.Assoc.J.45(2),84-88(1984).
<br /> [23] "Potential Health Hazards of Video Display Terminals,"NIOSH Research Report,June 1981.
<br /> [24] "Reference Methods for Measuring Airborne Man-Made Mineral Fibers(MMMF)I"WHO/EURO
<br /> Technical Committee for Monitoring an Evaluating Airborne MMMF,World Health Organization,
<br /> Copenhagen (1985).
<br /> [25] Criteria for a Recommended Standard...Occupational Exposure to Fibrous Glass,U.S.Department
<br /> of Health,Education,and Welfare,Publ.(NIOSH)77-152(1977).
<br /> METHOD WRITTEN BY:
<br /> Paul A.Baron, Ph.D.,NIOSH/DPSE.
<br /> APPENDIX A.CALIBRATION OF THE WALTON-BECKETT GRATICULE
<br /> Before ordering the Walton-Beckett graticule,the following calibration must be done to obtain a
<br /> counting area (D) 100 µm in diameter at the image plane.The diameter,do(mm),of the circular counting
<br /> area and the disc diameter must be specified when ordering the graticule.
<br /> 1. Insert any available graticule into the eyepiece and focus so that the graticule lines are sharp and
<br /> clear.
<br /> 2. Set the appropriate interpupillary distance and,if applicable,reset the binocular head adjustment so
<br /> that the magnification remains constant.
<br /> 3. Install the 40 to 45x phase objective.
<br /> 4. Place a stage micrometer on the microscope object stage and focus the microscope on the
<br /> graduated lines.
<br /> 5. Measure the magnified grid length of the graticule,Lo(µm),using the stage micrometer.
<br /> 6. Remove the graticule from the microscope and measure its actual grid length,La(mm).This can best
<br /> be accomplished by using a stage fitted with verniers.
<br /> 7. Calculate the circle diameter,do(mm),for the Walton-Beckett graticule:
<br /> dc = a x D.
<br /> L.
<br /> Example:If L.= 112 µm,La=4.5 mm,and D= 100 µm,then do=4.02 mm.
<br /> 8. Check the field diameter,D(acceptable range 100 µm±2 µm)with a stage micrometer upon receipt
<br /> of the graticule from the manufacturer.Determine field area(acceptable range 0.00754 mm2 to
<br /> 0.00817 mm2).
<br /> NIOSH Manual of Analytical Methods(NMAM),Fourth Edition
<br />
|