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Mine Gases Atmospheric Testing

Mine Gases Atmospheric Testing. C.4. Contributed by: Richard Black Industrial Scientific Corp. What is AIR??. Nitrogen (N 2 ) 78% Oxygen (O 2 ) 21% All other gases 1% Total 100%. Definitions. LEL: L ower E xplosive L imit - % LEL

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Mine Gases Atmospheric Testing

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  1. Mine GasesAtmospheric Testing C.4. Contributed by: Richard Black Industrial Scientific Corp.

  2. What is AIR?? Nitrogen (N2) 78% Oxygen (O2) 21% All other gases 1% Total 100%

  3. Definitions • LEL: Lower Explosive Limit - % LEL • PPM: Parts Per Million - toxic gas measurement • PEL: Permissible Exposure Limit - 8 hr/day - 40 hrs/wk - (OSHA) • TWA: Time Weighted Average - 8hr/day- (ACGIH) • STEL: Short Term Exposure Limit - 15 mins/4x shift - (w/ 1 hr break - ACGIH) • IDLH: Immediately Dangerous to Life and Health 30 mins - (NIOSH)

  4. Atmospheric Testing Where will the gases be? Lighter than air: Methane Acetylene Carbon monoxide (slightly) Heavier than air: Hydrogen sulfide Nitrogen dioxide Nitric oxide Carbon dioxide TOP MIDDLE BOTTOM

  5. Atmospheric Testing • Combustible Gas - Methane • Oxygen - Normal 21% • Low limit 19.5% • High limit 23.5% • Toxic gases - Measured in ppm - 10,000ppm=1% • Carbon monoxide • Nitrogen dioxide • Nitric oxide • Hydrogen sulfide

  6. Fire Triangle COMBUSTIBLE ATMOSPHERES detect the combustible gas (fuel) detect oxygen level (air) are intrinsically safe (not source of ignition) Approved Gas Instruments: fuel oxygen source of ignition

  7. Common Combustibles COMBUSTIBLE ATMOSPHERES Combustible LEL • Methane (natural gas) 5.0% vol • Propane 2.1% vol • Pentane (gasoline) 1.4% vol • Butane 1.9% vol • Hexane 1.2% vol • Methanol 6.0% vol • Hydrogen 4.0% vol

  8. Example of Combustion (Fire damp) Methane (CH4) 100% LEL UEL 0 5.0 15 100% Vol Too Lean to Burn Explosive Mixture Too Rich to Burn

  9. Oxygen Deficiency Risk of asphyxiation Caused by Consumption fire people oxidation decomposition Displacement humidity other gases Oxygen 19.5%

  10. Oxygen Enrichment Oxygen • Serious fire hazard • Materials burn much more rapidly • Caused by • leaking valves • leaking cylinders 23.5%

  11. Effects of Oxygen • 23.5% Maximum safe level (OSHA, MSHA) • 21.0% Oxygen content in “Air” (20.954%) • 19.5% Minimum safe level (OSHA, MSHA) • 17.0% Impairment of judgement begins • 16.0% First signs of Anoxia • 16-12% Breathing and pulse rate increase, coordination is impaired

  12. Effects of Oxygen • 14-10% Fatigue, disturbed respiration • 10-6% Nausea and vomiting, inability to move freely and loss of consciousness • <6% Convulsive movements and gasping respiration occurs; respiration stops/minutes later heart action ceases • 3-5% Life expectancy; 3 - 5 minutes

  13. TOXIC GASES TOXIC GASES

  14. Toxic Gases • Pose a threat to human life - react in the body in a poisonous fashion • Enter the body through various ways, they can be ingested, injected, inhaled or absorbed through the skin • Can react with different body systems • Often colorless and odorless

  15. Toxic Gases • Measured in parts per million (ppm) • 10,000ppm = 1.0 % by volume • Exposure risks depend on two factors • Concentration (ppm) • Time exposed

  16. Carbon Monoxide Data • CO: Colorless, odorless, tasteless, byproduct of incomplete combustion • Hazard: Flammable, LEL 12.6% – UEL 74% • Health: Very Toxic (can be absorbed 200-300 time faster than oxygen by the hemoglobin) • Exposures: PEL/TWA 50ppm (action level) STEL 400 ppm IDLH 1200 ppm • Causes: fire, blasting, gas and diesel engines • Specific Gravity = 0.967

  17. Effects of CO • 50ppm PEL/TWA, Action level (MSHA) • 400ppm Frontal headache in 2-3 hrs • 1600ppm Headache and nausea 20 mins Collapse and death in 1-2 hrs • 6400ppm Headache, dizziness in 1-2 mins, unconsciousness and death in 10-15 mins

  18. Hydrogen Sulfide Data • H2S: Colorless, Rotten egg smell • Hazard: Flammable, LEL 4.0% - UEL 46% • Health: Extremely Toxic, appears naturally from decomposition, reacts with the enzymes in the blood - inhibits cell respiration • Exposure: PEL/TWA 10ppm (action level) STEL 15ppm • Causes: Groundwater in shaft • Specific Gravity = 1.2

  19. Effects of H2S • .13ppm - Minimal perceptible odor • 10ppm - PEL,TWA, Action level (MSHA) Beginning of eye irritation • 100ppm - Coughing, eye irritation, loss of sense of smell after 2-5 minutes • 500ppm - Loss of consciousness and possible death 30 mins - 1 hr

  20. Nitrogen Dioxide Data • NO2: yellowish-brown gas with a pungent odor • Hazard: will not explode • Health: Extremely toxic • Exposures: PEL/TWA 3ppm STEL 5ppm • Causes: Blasting, diesel powered equipment • Specific Gravity = 1.6

  21. Effects of NO2 • 3ppm - PEL/TWA • 5ppm - STEL, Action level (MSHA) • 20ppm - Irritation of eyes, nose and throat ** • 50ppm - Maximum exposure for a 30 mins • 200ppm - Tightness of chest, acute bronchitis, and death in prolonged exposure ** Nitric Acid = NO2 + H2O High doses can cause pulmonary edema - drown from inside out

  22. Nitric Oxide Data • NO: Colorless gas, typically formed when air is super heated and nitric compound like dynamite explode • Hazards: will not burn, will accelerate burning • Health: extremely toxic • Exposure limit: PEL/TWA 25ppm (action level) STEL N/A • Causes: Blasting, diesel powered equipment • Specific Gravity = 1.6

  23. Effects of NO • 0-50ppm - irritation of mucus membranes • 25ppm - PEL/TWA, Action level (MSHA) • 60-150ppm - Irritation is more intense, coughing and burning of the throat is evident, symptoms will clear if victim is removed quickly to clean air. • 200-700ppm - May be fatal even after very short exposures.

  24. Sulfur Dioxide Data • SO2: Colorless gas, irritating pungent odor • Hazards: will not explode, can combine with water to form sulfuric acid (H2SO4) • Health: extremely toxic • Exposures: PEL/TWA 2ppm STEL 5ppm • Source: Hardrock mine strata • Specific Gravity = 2.2

  25. Effects of SO2 • .3-1ppm - Initially detected by taste • 2ppm - PEL/TWA • 5ppm - STEL • 20ppm - Irritation of nose, throat and eyes ** • 100ppm - Maximum exposure for 30 mins ** Sulfuric Acid (H2SO4) = SO2 + H2O

  26. Hydrogen Cyanide Data • HCN: Colorless to a pale blue gas • Hazard : will explode - LEL 5.6% - UEL 40% • Health: extremely toxic, has a distinct odor resembling bitter almonds • Exposures: PEL/TWA 10ppm STEL N/A • Sources: Leaching of precious metals, Metal mining • Specific Gravity = 0.69

  27. Effects of HCN • 10ppm Permissible Exposure Limit • 5-10ppm Headache, dizziness, unsteadiness • 50-100ppm Feeling of suffocation, nausea • 100-200ppm Death from exposure in 30 to 60 minutes

  28. Ammonia Data • NH3: colorless gas with a suffocating odor • Hazards: Difficult to burn, LEL 15% - UEL 28% • Health: extremely toxic • Exposures: PEL/TWA 25ppm STEL 35ppm

  29. Effects of NH3 • 0-25ppm - Minor irritation of the eyes and respiratory tract • 25ppm - PEL/TWA • 50-100ppm - Swelling of the eyelids, conjunctivitis, vomiting, irritation of the throat • 100-500ppm - Very dangerous concentrations, death from prolonged exposure

  30. Carbon Dioxide Data • CO2: byproduct of complete combustion, present in the atmosphere (about 400ppm), acidic taste • Hazard : Non-flammable • Health: simple asphyxiant • Exposures: PEL/TWA 5000 ppm STEL 30,000 ppm • Causes: Combustion, respiration, decomposition • Specific Gravity = 1.5

  31. Effects of CO2 • 400ppm - Approx.. ambient level • 3,000-5,000ppm - Low concentrations cause increased respiration and headaches • 8,000-12,000ppm - Headache, nausea, vomiting, and if not given air or oxygen, possible unconsciousness • >15,000ppm - High concentrations cause rapid circulatory insufficiency leading to coma and death

  32. Review Questions (Answers on the next slide) 1. What gas is the most plentiful in normal air? a. Nitrogen b. Oxygen c. Carbon dioxide d. none of the above 2. How much methane is required for an explosion to occur? a. 5% - 15% b. 15% - 20% c. 5% - 75% d. 10% - 100% 3. Which of the following gases are produced in diesel engine exhaust? a. Nitrogen dioxide b. Nitric oxide c. Carbon monoxide d. all of the above 4. Which of the following gases is heavier than air? a. Methane b. Acetylene c. Hydrogen Sulfide d. None of the above

  33. Answers to Review Questions 1. What gas is the most plentiful in normal air? a. Nitrogen 2. How much methane is required for an explosion to occur? a. 5% - 15% 3. Which of the following gases are produced in diesel engine exhaust? d. all of the above 4. Which of the following gases is heavier than air? c. Hydrogen Sulfide

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