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Hydrogen Sulfide Hazard Assessment

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Very brief exposures (seconds) to levels less than 100 ppm are less well understood. What is clear is that brief exposures above the TLV-TWA can be cited. – PowerPoint PPT presentation

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Title: Hydrogen Sulfide Hazard Assessment


1
Hydrogen Sulfide Hazard Assessment
  • Erik Vermulen
  • MSHA, District 9
  • Coal Safety and Health
  • 303-231-5586

2
Hydrogen Sulfide Hazard Assessment
  • Introduction
  • Occurrence in Mines, Scenarios
  • Detection
  • Range of Health Effects
  • Emergency Actions
  • Action Levels

3
Hydrogen Sulfide Hazard Assessment
  • Occurrence in Mines, Scenarios
  • Generated from reduced biomass (coal, natural
    gas, garbage), Geochemical sources in sediments,
    human metabolism
  • Released from pockets in coal, natural gas vents,
    supersaturated water
  • May be wide spread or localized constant or in
    pockets of varying concentration

4
Hydrogen Sulfide Hazard Assessment
  • Detection
  • Odor lt0.02 ppm none, 0.13 ppm perceptible,
    1.0 ppm - faint, 5 ppm - moderate, 25 ppm
    strong, 100 ppm lose odor in 2-15 minutes
  • Electro chemical sensors calibrated and within
    shelf-life
  • Detector tubes and Impregnated Paper Within
    shelf-life
  • Absorb air samples with analytical determination
  • Biological exposure methods for expired air and
    tissues

5
Hydrogen Sulfide Hazard Assessment
  • Range of Health Effects
  • (Concentration Time Effects)
  • Death due to respiratory failure with brief
    exposures to very high concentrations (seconds at
    gt1000 ppm)
  • Acute intoxication with neurological,
    respiratory, ocular and cardiac symptoms with
    potential recovery (exposures from minutes to
    hours at 250 to 1000 ppm, in animals LC-50 ranges
    from 335 to 587 ppm)
  • Sub-Acute and Chronic toxicity include cardiac
    arrhythmia, neuropathology, respiratory
    lesions/edema, blood-enzymes, ocular, cellular
    effects (exposures from 10 200 ppm for hours to
    months)
  • Lifetime exposures Carcinogenic, developmental
    - none

6
Enforcement Surveys for H2S
  • Chapter 4, Health Inspection Procedures Handbook
  • Pre-inspection Actions Select method,
    pre-calibration, UMF
  • Walk-Through to document process, duration,
    frequency, sketch
  • Select maximally exposed occupation (if refuses
    can sample BZ)
  • Follow normal 8-hour, portal to portal sampling
  • Use Vent Plan method if one is designated, record
    rationale
  • With instruments, check periodically, follow/note
    Manuf. instructions
  • Place instrument on shirt near breathing zone,
    note location
  • Recommend using a second detection method (stain
    tube, Zefluor tube, OSHA ID141) to verify, record
    sample time
  • Record miners locations, general duties,
    variance from normal
  • Fill out MSHA 2000-187 (MSHA 2000-194 if analysis
    needed)

7
Enforcement Surveys for H2S Cont.
  • Out-brief miners/operators and notify that a
    citation may be issued if later data analysis
    indicates an over-exposure
  • If instrument TLV-TWA, 8Hr, exceeds 5 PPM notify
    operator that corrective action may be required
    no citation issued but Vent Plan change.
  • Post Inspection Actions
  • Post calibrate instrument or bump test
  • Download data using manufacturers software, save
    files
  • Evaluated STEL file to see if any 15 minute
    increment gt 20PPM
  • Evaluate TLV file to see if 8 hour gt10 PPM
  • Contact District for assistance in writing the
    Citation, if applicable
  • (Note Instruments not listed by NIOSH or OSHA as
    standard method rationale important)

8
Hydrogen Sulfide Hazard Assessment
  • Range of Health Effects
  • (Receptor Susceptibility)
  • Health status and pre-existing pathology
  • asthmatics, heart patients
  • Concurrent exposures to organs (dust, CO, low 02)
  • Limited human data and uncertainty in applying
    animal data to human response
  • Small exposure range from no-effect to acute
    toxicity with uncertainty in epidemiological
    exposure levels

9
Hydrogen Sulfide Hazard Assessment
  • Emergency Actions
  • Explosive 4.3 to 46, Heavier than air
    evacuate and remove ignition sources, ventilate,
    water spray
  • Respiratory Hazard Use approved SCBA to rescue
    victims, if breathing apply 02, if not apply CPR,
    seek medical attention immediately, keep warm and
    calm, test atmosphere for toxic concentrations
  • Eye Irritant irrigate eyes with water if
    irritated

10
Hydrogen Sulfide Hazard Assessment
  • Consensus Levels
  • MSHA TLV 10 ppm, Ventilation plan actions
  • 20 ppm for 15 minutes, allowable excursion
  • OSHA 20 ppm (C), 50 ppm _at_ 10 min. peak / 1/shift
  • ACGIH 10 ppm TLV-TWA, 15 STEL (NIC 1/5 ppm)
  • NIOSH IDLH 100 ppm (Imminent Danger)
  • AIHA ERPG3 100 ppm (60 min.) (life threatening)
  • ERPG2 30 ppm (60 min.) (serious /
    irreversible)

11
Hydrogen Sulfide Hazard Assessment
  • Summary
  • Acute Risk Moderate to high respiratory
    failure, cardiac and neurological damage, ocular
    irritation
  • Small range of significant effects many will
    tolerate 50 ppm some fatalities, many injuries
    at 500 ppm
  • Odor not dependable to detect use meters,
    detectors
  • Use air supplied respirators for rescue Provide
    O2 / CPR
  • Explosive, may collect in low areas
  • Exposure concentrations may change without
    warning when low ventilation rates exist
  • Stay out Stay alive
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