CombustibleDust –An IHPerspectiveMICHAEL MURDZIA, CIH, CSP, CHMMOCTOBER 10, 2018

Goal for Presentation

u Provide practical informationregarding combustible dustidentification

u How are industrial hygienistsinvolved with combustible dustissues?

u Insight to regulatory requirementsu Options for control measures

OSHA National EmphasisProgramu Directive Number CPL-03-00-008u Issued in 2008 with modifications in

2015u Citations issued under Section

5(a)(1) of the OSH Act “GeneralDuty Clause”

u Corrective measures forcompliance reference NFPAstandards

What is Combustible Dust?

u OSHA Definition: “Combustible dust is definedas a solid material composed of distinctparticles or pieces, regardless of size, shape,or chemical composition, which presents afire or deflagration hazard when suspendedin air or some other oxidizing medium over arange of concentrations. Combustible dustsare often either organic or metal dusts thatare finely ground into very small particles,fibers, fines, chips, chunks, flakes, or a smallmixture of these.”

u Less than 420 microns (those passing througha U.S. No. 40 standard sieve)

Hazard CommunicationStandardu Physical and chemical characteristics of

the hazardous chemical (for example,vapor pressure or flash point) includingthe potential for fire, explosion, andreactivity (if known, Kst, MIE, MEC andparticle size are combustible dustcharacteristics) (1910.1200(2)(g)(ii) and(iii))

Aren’t thesesupposed to

be in theSafety Data

Sheets?

Explosiveness ofCombustible Dustu MIE

u Minimum ignition energyu Ease and likelihood of ignition of a dispersed

dust cloud

u MECu Minimum explosible concentrationu Minimum amount of dust dispersed in air

required to spread an explosion (similar to LEL)

u Kstu Relative explosion severity compared to other

dusts

Safety Data SheetExamples

u Wholegrain:https://www.agrexinc.com/assets/docs/SDS_-_Grain_SDS_2015_AGREX_INC.v1.0.pdf

u BASF Igrasof 168:https://worldaccount.basf.com/wa/NAFTA~en_US/Catalog/Additives/doc4/BASF/PRD/30546656/.pdf?asset_type=msds/pdf&language=EN&validArea=CA&urn=urn:documentum:ProductBase_EU:09007af880363a08.pdf

u Sigma Aldrich Tantalum Powder:https://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=US&language=en&productNumber=262846&brand=ALDRICH&PageToGoToURL=https%3A%2F%2Fwww.sigmaaldrich.com%2Fcatalog%2Fproduct%2Faldrich%2F262846%3Flang%3Den

Why Sample?

u Different dusts of the same chemicalmaterial can have different ignitabilityand explosibility characteristics,depending upon physical characteristicssuch as particle size, shape, and moisturecontent.

u Combustibility can also be influenced bythe processing or generation of thepowder/dust

Sample Analysis

u It can be expensiveu It can be variable

uMoisture contentu Location of fines in the dust

collection systemu Is it required by OSHA?

Standards andRegulationsuFocus on NFPA 652

uHazard identificationuRequires sampling or published

datauDust Hazard Analysis

NFPA 652 Requirements

uDetermine combustibility ofmaterials

uConduct a DHAuManage identified hazardsuEstablish safety management

systems

Dust Hazard Analysis(DHA)u A DHA shall be completed for all new

processes and facility compartmentsu For existing processes and facility

compartments, a DHA shall becompleted by September 7, 2020

u DHA to be updated and reviewedevery 5 years

u Performed by a “qualified person”u Similar to process safety management

requirements

Dust Hazard Analysis(DHA)uPrescriptive controlsuPerformance based controls

Combustible DustPentagon

History – Jahn Foundry

History – Imperial Sugar

News – Dust CollectorFires/Explosions

Dry Dust Collectors

u Fuel (in the form of a combustibledust of the right particle size and inthe right concentration)

u Suspension (usually in air)u Oxidant (usually air)u Confinement (in equipment or a

room)u Ignition source

Air Material Separators(aka Dust Collectors)u If >8 cubic feet dirty side volume,

must be located outsideu Why 8 cubic feet?u What if there is an existing process

inside a building?

Dust Collector Controls

u IsolationuBackdraft damper

uExplosion ventsuDuct orientation and velocityuChemical suppressionu Inerting

Flameless Vent

Interim Controls

u Inspection and MaintenanceuHousekeepinguCleaning frequencyuExplosion proof vacuums

Emerging Issues

uAdditive Manufacturingu3D Printing

Examples for Discussion

u>8 cubic feet dry dust collectorwith known combustible dustlocated inside a building

uNo current isolation devices orexplosion venting

uRecommendations?

Examples for Discussion

u<8 cubic feet dry dust collectorwith known combustible dust.

uDust is observed accumulatingin the collection area andresidue observed on the filtermedia.

uRecommendations?

Examples for Discussion

uNew process that generatesaluminum dust residue

uNew process that generatescombustible dust residue

u3D printing process movingfrom non-combustible powderto reactive metal powder

CSB Recommendations

uEducationuRegulationuEnforcement

Sources

u Photo slide 3: CSB, https://www.csb.gov/imperial-sugar-company-dust-explosion-and-fire/

u Photo slide 3 and last slide:https://www.masslive.com/news/index.ssf/2016/02/17th_anniversary_of_the_jahn_f.html

u Slide 11: Guidelines for Combustible Dust HazardAnalysis By the American Institute of ChemicalEngineers, Inc.

u Slide 6:file:///C:/Users/Michael%20Murdzia/AppData/Local/Packages/microsoft.windowscommunicationsapps_8wekyb3d8bbwe/LocalState/Files/S0/2114/csb_2018_factsheet_combustibledust_05[2202].pdf

Sources (continued)

u Slide 5:https://www.osha.gov/Publications/3371combustible-dust.html