Dust Sampling Instrumentation And Methods

Dust SamplingInstrumentationand MethodsJay ColinetOffice of Mine Safety and Health ResearchSenior ScientistNational Institute for Occupational Safety andHealth (NIOSH)Silica Dust Control WorkshopElko, NevadaSeptember 28, 2010

Presentation Outline Current respirable dust standards and samplingrequirements Dust sampling instruments available for use inmining Sampling methods to quantify dust sources

Dust Standards for Metal/Nonmetal Mining(Federal Mine Safety and Health Act of 1977)10.0 mg/m3 total airborne dustIf silica 1%:respirable standard 10 / (% silica 2)

Gravimetric Dust Sampler Provides time-weighted-average respirable dust concentration Dorr-Oliver cyclone separates respirable and oversize dust Pump operated at 1.7 liters per minute in M/NM mines

Sampling with Gravimetric Samplers Filter is pre- and post-weighed todetermine mass gain and is used tocalculate an average dustconcentration over sampling period Filter processed using XRD analyticaltechnique for silica content (NIOSHMethod 7500) Sufficient mass must be collected tohave confidence in measurement NIOSH typically uses multiplegravimetric samplers and averagesdata

personalDataRAM (pDR) Model 1000 AN passive sampler Uses light scattering asmeasurement technology Instantaneous readingscorrelated with time and stored ininternal memory pDR concentrations impacted by:– size distribution of dust– composition of dust– water mist in air OMSHR adjusts readings withratio obtained from adjacentgravimetric samplers

pDR Field Calibration Divide average gravimetricconcentration by average pDRconcentration for same samplingperiod Multiply all individual pDR readingsby ratio Example:gravimetric average 1.4 mg/m3pDR average 1.1 mg/m3grav/pDR ratio 1.4/1.1 1.27pDR concentrations * 1.27 adjusted pDRconcentrations

pDR Provides Time Record of Dust Levels

Personal Dust Monitor(PDM) Real-time measurementof respirable dust Combines dust samplerand cap lamp into one unit Sample inlet is mountedon cap lamp Uses mass-basedmeasurement to quantifydust concentration(TEOM) Dust measurements aredisplayed on screen andstored internally for lateranalysis

Principle of Operation Exchangeable filter cartridge mounted onthe end of the tapered element collectsparticles as sample stream flows throughhollow tubeFlow Tapered element oscillates at a knownfrequency, like a tuning fork Frequency changes in direct relationto the mass collected on the filter Measurement principle does not respond toother particle characteristics such as sizedistribution or composition (heated circuitremoves moisture)Taperedelement

PDM Status Meets NIOSH sampling accuracyrequirements (NIOSH RI 9669) Equivalency to CMPDSU (gravimetricsampler) published in peer-review journal MSHA intrinsic safety approval granted foruse in underground coal mines New CFR 30, Part 74 rule enacted in 2009 Thermo Scientific began delivery ofcommercial units in July 2009 Two ongoing NIOSH research efforts(software and silica)

PDM Analytical Software Compile output from PDM samplers Provide user-selected summaries for multiple samplers (foreman,mine superintendent, etc.) or engineering evaluations Provide graphing capabilities

PDM Filter Capsule for Maintaining Sample Integrityfor Quartz Analysis Place capsule over PDM filterwhen TEOM unit removedfrom PDM Use capsule as filter removaltool and to secure dust Send to lab, remove fingertab, ash capsule Plan to conduct mine surveysto complete side-by-sidetesting with current silicaanalysis method

Sampling to Isolate a Fixed Dust Source

Sampling a Mobile Position

Using Real-time Data toQuantify Multiple DustSources Evaluate dust levels during truckhaulage cycle at an undergroundgold mine Use pDR samplers and timestudy data to quantify dustgeneration for different parts ofcycle––––loadinghauling fulldumpinghauling empty Two researchers conducting timestudies

Time-weighted-average Dust ContributionsDump location had highest dust contribution despite having theshortest duration (14% time vs. 34% dust)TramFull22%Dump34%(3.7 mins)(6.7 mins)Loading15%(4.2 mins)TramEmpty29%(11.4 mins)

Using Real-time Data to Quantify Dust Sources forMobile Workers Evaluate work tasks and associated dust levels for mobile workersthroughout their shift Merge active pDR 1500 sampling data and video (Helmet Cam) toquantify highest sources of dust generation for different tasks Develop controls and/or improved work practices to reduce mobileworkers’ dust exposure

Sampling to Isolate an Unconfined Dust SourceAWind directionDDDDA – Ambient sampling locationD – Drill sampling locations

DisclaimerThe findings and conclusions in thispresentation are those of the authors and donot necessarily represent the views of NIOSH.Mention of any company or product does notconstitute endorsement by the NationalInstitute for Occupational Safety and Health(NIOSH). In addition, citations to Web sitesexternal to NIOSH do not constitute NIOSHendorsement of the sponsoring organizationsor their programs or products. Furthermore,NIOSH is not responsible for the content ofthese Web sites. All Web addressesreferenced in this presentation wereaccessible as of the date the presentation wasoriginally delivered.

Thank you!Questions?Jay ColinetOffice of Mine Safety and Health ResearchNIOSHP.O. Box 18070Pittsburgh, PA 15236412-386-6825jcolinet@cdc.gov

(Federal Mine Safety and Health Act of 1977) 10.0 mg/m 3 total airborne dust . . (foreman, mine superintendent, etc.) or engineering evaluations . haulage cycle at an underground gold mine Use pDR samplers and time study data to quantify dust generation for different parts of