Mine Gases Questions and Answers Basic Principles Specific Gravity

Mine Gases

Everything you wanted to know
about gases but were afraid to ask!
   MSHA Training Module 2202: Mine Gases
Mine Gas Charts linked below
Coal Mine Gas Chart  
M/NM Mine Gas Chart  


Methane Carbon Monoxide Oxides of Nitrogen
Hydrogen Oxygen Nitrogen
Diffusion of Gases Carbon Dioxide Sulfur Dioxide
Hydrogen Sulfide Mine Damps Miscellaneous

Conversion Tip:  Percent and PPM
Move the decimal point 4 places right or left.
Examples:
2% equals 20,000 PPM
1500 PPM equals 0.15%


Methane
Q:What is the specific gravity of methane?
A:0.5545.
Q:What is the chemical symbol of Methane?
A:CH4.
Q:Where is Methane most likely to be found in a mine?
A:Near the roof, as it is lighter than air.
Q:What is a flammable mixture of methane and air which can either burn or explode when ignited called?
A:Firedamp
Q:What is the ignition temperature of methane?
A:1100 - 1380 F.
Q:What instruments are most often used in detecting methane?
A:The flame safety lamp and methane detectors.
Q:What is the least percentage of methane that can be detected with a flame safety lamp?
A:About one percent (1%).
Q:What effect does the presence of methane have upon the explosibility of coal dust?
A:The coal dust is more easily ignited and the force of the explosion is greater.
Q:What effect does coal dust in the air have upon the explosibility of methane?
A:The lower explosive limit is decreased.
Q:What dangerous gas is most likely to be encountered above a pillar fall?
A:Methane.
Q:What effect does the presence of methane have upon the explosibility of coal dust?
A:The coal dust is more easily ignited and the force of the explosion is greater.
Q:What effect does coal dust in the air have upon the explosibility of methane?
A:The lower explosive limit is decreased.
Q:What dangerous gas is most likely to be encountered above a pillar fall?
A:Methane.
Q:Why will methane accumulate in an inadequately ventilated place?
A:It is lighter than air and will rise and stratify if not properly diffused.
Q:What is the principle combustible gas usually found in coal mines?
A:Methane.
Q:Is methane (CH4) poisonous?
A:No.
Q:What is the color of methane?
A:Methane is colorless.
Q:Which is the heaviest, one cubic foot of methane or one cubic foot of air?
A:One cubic foot of air.
Q:What gas is found near the roof and cavities on falls?
A:Methane (CH4).
Q:What gas is odorless, tasteless, non-toxic, colorless and explosive in the concentration of 5%-15%?
A:Methane
Q:What is the source of methane in coal mines?
A:It is liberated from coal and adjoining strata.
Q:Where is methane usually found in mines?
A:Along the roof, to the rises, in the vicinity of working faces, in dead ends and above falls.
Q:Is methane an explosive by itself?
A:No.  Oxygen is required to support combustion.
Q:Why can there be no explosion when the percentage of methane is greater than fifteen percent (15%)?
A:Because the amount of Oxygen present is insufficient for rapid combustion to occur.
Q:How can methane gas be detected in a coal mine?
A:Chemical analysis, flame safety lamp and methane detectors.
Q:What is the explosive range of methane?
A:Five to fifteen percent.
Q:What is the percentage of methane required for maximum explosive violence?
A:Ten percent (10%).


Carbon Monoxide
Q:What percent of Carbon Monoxide can cause death in less than one hour?
A:0.4 percent or more.
Q:What is the ignition temperature of Carbon Monoxide?
A:1100 F.
Q:Why are small quantities of Carbon Monoxide injurious?
A:Because it is not easily eliminated and it accumulates in the blood.
Q:What is the chemical symbol of Carbon Monoxide?
A:CO.
Q:What is the specific gravity of Carbon Monoxide?
A:0.967.
Q:What is Carbon Monoxide (CO)?
A:It is a colorless, odorless, tasteless, combustible, and poisonous gas.
Q:How can Carbon Monoxide be detected?
A:By Carbon Monoxide detectors, and by chemical analysis.
Q:Workers should not be employed for a period of 8 hours where the Carbon Monoxide content exceeds what?
A:50 PPM (0.005%).
Q:What percentage of Carbon Monoxide might produce symptoms of poisoning if breathed indefinitely?
A:0.01% (100 ppm).
Q:What is the source of Carbon Monoxide?
A:It is the product of incomplete combustion (combustion with an insufficiency of Oxygen).
Q:When is Carbon Monoxide most likely to be found in mines?
A:When there is a mine fire or after an explosion.
Q:What does the presence of CO in a sealed mine area indicate?
A:A fire.
Q:What percentage of blood saturation by Carbon Monoxide (CO) will cause death?
A:70% - 80%.
Q:The explosive range of Carbon Monoxide is what?
A:12.5% - 74%.
Q:What percentage of Carbon Monoxide will produce slight symptoms in several hours?
A:200 PPM (.02%).
Q:What percentage of Carbon Monoxide will produce discomfort in two or three hours?
A:400 PPM (.04%).
Q:What percentage of Carbon Monoxide will produce a tendency to stagger in one and one-half (1) hours?
A:1200 PPM (0.12%).
Q:What percentage of Carbon Monoxide will produce symptoms of unconsciousness in thirty (30) minutes?
A:2000-2500 PPM (0.20% - 0.25%).
Q:How much greater affinity does hemoglobin have for Carbon Monoxide than for Oxygen?
A:About three hundred (300) times.
Q:What is the principal poisonous gas produced by explosions?
A:Carbon Monoxide.
Q:What effect does Carbon Monoxide have on life?
A:It is extremely poisonous.
Q:How does Carbon Monoxide cause injury to life?
A:By combining with the hemoglobin of the blood and excluding Oxygen.


Oxides of Nitrogen
Q:How are Oxides of Nitrogen formed?
A:From the use of explosives in mines.
Q:How do Oxides of Nitrogen cause death?
A:Causes fluid to accumulate in lungs resulting in asphyxia.
Q:How are results from analysis of Oxides of Nitrogen reported?
A:In terms of Nitrogen dioxide.
Q:What is the chemical symbol of Nitrogen Dioxide?
A:NO2.
Q:List the threshold limit value for Oxides of Nitrogen.
A:5 ppm (0.0005%).
Q:What is the specific gravity of Nitrogen Dioxide?
A:1.589.
Q:What is the specific gravity of Nitric Oxide?
A:1.036.


Hydrogen
Q:What is the specific gravity of Hydrogen?
A:It is the lightest of all gases with a specific gravity of 0.0695
Q:What is the chemical symbol of Hydrogen?
A:H2.
Q:What are the sources of Hydrogen in a mine?
A:Charging batteries, mine fires, and explosions.
Q:Hydrogen is always present after what type of explosion?
A:Coal dust explosions.
Q:Is Hydrogen explosive?
A:Yes.
Q:Name the gas which is generated from a storage battery.
A:Hydrogen (H2).
Q:What is the explosive range of Hydrogen?
A:4.0% - 74.2% with as little as 5% Oxygen present.
Q:How is Hydrogen detected?
A:By chemical analysis.
Q:Is Hydrogen flammable?
A:Yes.
Q:Is Hydrogen water soluble?
A:No.
Q:What concentration produces the most violent explosion?
A:Very violent explosions are possible when air contains more than 7 to 8 percent Hydrogen.
Q:Can Hydrogen affect the explosive range of other gases?
A:Yes, the presence of small quantities of Hydrogen greatly increases the explosive range of other gases.


Miscellaneous
Q:Write down the chemical symbols of Methane and Hydrogen Sulfide.
A:CH4 and H2S
Q:Name the non-explosive gases found in coal mines.
A:Carbon Dioxide (CO2) and Nitrogen (N2)
Q:Name the explosive gases found in bituminous coal mines in Pennsylvania.
A:Methane (CH4), Carbon Monoxide (CO), and Hydrogen Sulfide (H2S).
Q:What is TLV?
A:Threshold limit value.
Q:Convert 0.01 percent of Carbon Monoxide to ppm.
A:100 ppm.
Q:What is noxious gas?
A:Any gas in the air which is harmful to life when inhaled.
Q:What is the percentage of Oxygen below which no explosion of a Methane air-mixture can occur?
A:12%.
Q:What effect does an atmosphere with a reduced Oxygen content have upon the explosibility of methane?
A:A greater percentage of methane is necessary to start an explosion in an atmosphere which contains less than the normal percentage of Oxygen.



Oxygen
Q:What is the specific gravity of Oxygen?
A:1.105.
Q:What is the chemical symbol of Oxygen?
A:O2.
Q:What percentage of the earth's atmosphere is Oxygen?
A:20.94% Oxygen.
Q:A sealed area of a coal mine after a period of time will be found to have the absence of what?
A:Oxygen.
Q:Can there be a mine fire or an explosion without the presence of Oxygen?
A:No.
Q:Is Oxygen flammable or explosive?
A:No, Oxygen alone will not burn or explode, it merely supports combustion.  However, Oxygen enriched atmospheres, along with the presence of the ignition of a flammable material will produce extremely rapid burning and in some cases flash, which perpetuates the myth that Oxygen is flammable and explosive.
Q:Mine air should not contain less than what percentage of Oxygen?
A:19.5%.
Q:How does the body receive Oxygen?
A:Through breathing, the Oxygen is taken up by the hemoglobin of the blood and carried to all parts of the body.
Q:What supports the chemical reaction that produces fires and explosions?
A:Oxygen.
Q:What percent Oxygen can a person most easily work in?
A:20.9%.
Q:What percent Oxygen will a person breathe faster and deeper while at work?
A:17%.
Q:A flame safety lamp will go out when the Oxygen percentage is below what?
A:16%.
Q:What element in the air is essential for life?
A:Oxygen.
Q:How does the body receive Oxygen?
A:By breathing, Oxygen is absorbed by the blood and carried to the cells of the body.
Q:When is the Oxygen (O2) level in air considered to be dangerous?
A:When the Oxygen (O2) level falls below 16%.


Nitrogen
Q:What is the specific gravity of Nitrogen?
A:0.967.
Q:What percent of the earth's atmosphere is Nitrogen?
A:78.09% Nitrogen.
Q:What is the chemical symbol of Nitrogen?
A:N2.
Q:What is the threshold limit value of Nitrogen?
A:81%.
Q:What is Nitrogen?
A:It is a tasteless, odorless and colorless gas which will neither support life nor combustion.
Q:Is Nitrogen combustible?
A:No.
Q:What effect does Nitrogen have towards propagating an explosion?
A:None.
Q:What effect does Nitrogen have upon life?
A:It has no effect, except when it depletes Oxygen to the extent that there is a deficiency of Oxygen.
Q:Does Nitrogen have an ignition temperature?
A:No, Nitrogen will not explode.


Diffusion of Gases
Q:Once two or more gases mix uniformly will they separate or come apart?
A:No.
Q:Define the term diffusion of gases.
A:Diffusion is a phenomenon by which gases mix by natural forces.
Q:What is the law of diffusion?
A:The rate of diffusion varies inversely as the square root of specific gravity.
Q:What is stratification?
A:When gases do not diffuse completely, layers of gas stratify horizontally.
Q:What type of atmosphere is easy for the detection of a gas a diffused one or a stratified one?
A:A stratified one.


Carbon Dioxide
Q:Is Carbon Dioxide combustible?
A:No.
Q:What is the specific gravity of Carbon Dioxide?
A:1.529.
Q:What is the chemical symbol of Carbon Dioxide?
A:CO2.
Q:Where might concentrated accumulations of Carbon Dioxide ordinarily be found?
A:Near the floor, in inadequately ventilated places.
Q:What effect does Carbon Dioxide have upon life?
A:Respiration is increased as concentration of Carbon Dioxide increases.
Q:How is Carbon Dioxide detected?
A:Usually by chemical analysis.
Q:What is Carbon Dioxide (CO2)?
A:Carbon Dioxide is a colorless and odorless gas formed by the chemical combination of Carbon and Oxygen.
Q:How is Carbon Dioxide formed in a mine?
A:By combustion, by breathing of miners and animals, by decay of vegetable and animal matter, by the oxidation of coal and by chemical action of acid water on carbonates.
Q:What is a product of complete combustion?
A:Carbon Dioxide.
Q:Where might concentrated accumulations of Carbon Dioxide ordinarily be found?
A:Near the floor, in inadequately ventilated places.
Q:What effect does Carbon Dioxide have upon life?
A:Respiration is increased as concentration of Carbon Dioxide increases.
Q:How is Carbon Dioxide detected?
A:Usually by chemical analysis.  However, in poorly ventilated areas of a mine, increased CO2 levels will be present when low Oxygen is detected.
Q:How is Carbon Dioxide formed in a mine?
A:By combustion, by breathing of miners and animals, by decay of vegetable and animal matter, by the oxidation of coal and by chemical action of acid water on carbonates.
Q:What is a product of complete combustion?
A:Carbon Dioxide.


Sulfur Dioxide
Q:How is Sulfur Dioxide formed in a mine?
A:By burning coal containing pyrites.
Q:What is the specific gravity of Sulfur Dioxide?
A:2.263.
Q:What is the chemical symbol of Sulfur Dioxide?
A:SO2.
Q:What is the particular danger of Sulfur Dioxide?
A:It is extremely poisonous even in small amounts.
Q:How is Sulfur Dioxide detected?
A:By the sense of smell and its effect on the air passages.
Q:What is the first effect on a person exposed to Sulfur Dioxide?
A:It is extremely irritating and suffocating and is intolerable to breathe.
Q:Is Sulfur Dioxide combustible?
A:No, it is incombustible.
Q:Is Sulfur Dioxide soluble in water?
A:Yes.


Hydrogen Sulfide
Q:What is the specific gravity of Hydrogen Sulfide?
A:1.191.
Q:What is the chemical symbol of Hydrogen Sulfide?
A:H2S.
Q:What are the properties of Hydrogen Sulfide?
A:Poisonous and colorless with an odor like rotten eggs.
Q:What mine gas can be detected by its odor?
A:Hydrogen Sulfide.
Q:What is the origin of Hydrogen Sulfide?
A:It is liberated by burning explosives containing Sulfur such as black powder or dynamite.
Q:How can Hydrogen Sulfide be detected other than by sense of smell?
A:By the Hydrogen Sulfide detector or by paper dipped in acetate of lead, which will turn black immediately on exposure to Hydrogen Sulfide.
Q:What distinctive odor does Hydrogen Sulfide gas smell like?
A:Smells like rotten eggs.
Q:What is the explosive range of Hydrogen Sulfide?
A:4.3% - 45%.
Q:Is Hydrogen Sulfide poisonous?
A:Yes, it is extremely poisonous even in small amounts.
Q:Have there been any mine deaths attributed to Hydrogen Sulfide poisoning?
A:Most definitely, yes.  Two of most famous accidents involving H2S poisoning were at the Barnett Complex Mine in 1971 and the Sullivan Mine (Canada) in 2006.  The Barnett mine was an ore mine.  Sullivan was a lead/zinc mine.
Q:What is the immediate effect of Hydrogen Sulfide on a person?
A:It is extremely irritating to the eyes.
Q:What is the threshold limit value of Hydrogen Sulfide?
A:10 PPM (0.0001%).
Q:Among Methane, Carbon Monoxide, and Hydrogen Sulfide, which one has the lowest ignition temperature?
A:Hydrogen Sulfide (700F).


Mine Damps
Q:What is meant by the term "blackdamp"?
A:An atmosphere deficient in Oxygen.
Q:What is the effect of blackdamp on flame safety lamp?
A:The flame of a safety lamp is dimmed or extinguished depending on concentration of gases present.
Q:What is the most simple and safe test for the presence of blackdamp?
A:A flame safety lamp.
Q:Stinkdamp refers to which gas?
A:Hydrogen Sulfide.
Q:Whitedamp refers to which gas?
A:Carbon Monoxide.
Q:How much methane is present in a Firedamp atmosphere?
A:30% - 70%.
Q:What is Afterdamp?
A:Afterdamp is a mixture of Carbon Conoxide, Carbon Dioxide, Methane, Oxygen, Nitrogen and Hydrogen.