Mine Gases section 1 Flashcards
name 8 gases relevant to coal mining
hydrogenH2.07 methaneCH4 .55 carbonmonoxideCO .97 oxygen O2 1.11 hydrogen sulphideH2S 1.18 carbondioxideCO21.52 nitrogendioxideNO21.6 sulphurdioxideSO22.2
explain the effects on a person of oxygen concentrations @ 16 - 14%, 14 - 10% and 10 - 6%
slight nausea, increase in pulse/breathing rate, nigh/colour vision & judgement affected, abnormal fatigue on exertion : PJ, AFOE : nausea&vomiting, inability to move or cry out, loss of conciousness may occur
what is the minimum concentration of oxygen a cmw can be exposed to?
19.5%
what are the gas constituents of normal air and their percentages?
nitrogen 78.08% oxygen 20.95% argon/inert .93% water vapour/carbon dioxide .04%
at what percentages of oxygen do a)flammable liquids cease burning b)all flaming combustion stops c) all combustion ceases
a) 17% b) 10 -12% c) 2%
what effect does an oxygen enriched atmosphere have on the UPPER FLAMMABLE Limit of FG?
expands the flammable limits of a FG
what 2 gases are released when blasting with explosives?
Nitrogen dioxide N02 Carbon monoxide CO
how can you identify if Nitrogen Dioxide has been released during a blast?
a reddish brown colour in the gas fume
what is the TWA, Short Term Exposure Limit STEL & Immediate Danger to Health or Life IDHL for Nitrogen dioxide NO2
TWA 3ppm (0.0003 %)
STEL 5ppm
IDHL 20ppm
Name 4 signs or symptoms of exposure to NO2
feeling ill, coughing violently, symptoms of bronchitis/pneumonia, cessation of life
a cmw must not be exposed to an atmosphere at the mine containing a general body concentration 0f CO2 exceeding?
TWA - 1.25% = 12,500 ppm
STEL - 3% = 30,000 ppm
explain what effects occur to a person at the following concentrations of CO2?
2% - 5% increased in lung ventilation
4.5 - 5% - anxiety, panic, irritability
10% - toxic, depresses CNS (Central Nervous
System) violent panting, exhaustion,
headache
carbon dioxide CO2 is described as a “hot gas” due to its low thermal conductivity, explain
due to its insulating properties it gives a feeling of warmth
carbon dioxide CO2 a) how is it produced and b) where is it found on a mine site?
a) oxidisation of coal & carbon based materials, exhaust fumes from combustion engines, blasting operations and fires
b) diesel exhaust, blast fume, spon com, inert firefighting gases
describe the physical and chemical properties of CO2
CO2 - specific gravity SG 1.2 non flammable NF colourless, slight pungent odour, soda water taste
describe the physiological effects of carbon dioxide CO2 at low and high concentrations
low - stimulates central nervous system CNS
high - depresses CNS
is carbon dioxide CO2 a flammable gas? if so, at what concentration?
it is an inert gas, non-flammable NF
state the long term exposure limits for carbon monoxide CO, hydrogen sulphide H2S, nitrogen dioxide NO2, sulphur dioxide SO2
CO - 30ppm, H2S - 10ppm, NO2 - 3ppm, SO2 - 2 ppm
how is the human body poisoned by carbon monoxide CO?
CO is absorbed 300x more readily by the body than oxygen O2 and prevents O2 from binding to the red blood cell
in regards to carbon monoxide poisoning, what is meant by the term blood saturation?
blood becomes soaked with CO that prevents the blood from taking on anymore O2 or CO
carbon monoxide poisoning is said to have a cumulative effect. what is meant by cumulative effect?
multiple small exposures to CO can build up in a person making them more susceptible to its effect
how is carbon monoxide CO produced in coal mines? give 4 examples
oxidisation of coal, fires, heating, explosions and diesel engine exhaust
is carbon monoxide CO an explosive gas? if so, at what concentration?
yes, it is explosive
explosive range is 12.5 % - 74 %
name 6 signs and symptoms that would be associated with carbon monoxide CO poisoning
1) impairment of visual threshold 2) nausea/headache 3) rosy/flushed face 4) becoming silent 5) unsteady gait 6) heavy feeling in legs
state the chemical and physical properties of carbon monoxide
CO - SG 0.97 flammable, highly poisonous
COT - Colourless/Odourless/Tasteless
what is the ignition temperature of methane CH4?
595’C Australian Standard
what is the minimum concentration of oxygen O ( at normal atmosphere ) for a methane CH4 explosion to occur?
12.2 %
is methane CH4 poisonous?
non-toxic, will not support life
state the chemical and physical properties of methane CH4
CH4 - SG 0.55
Flammable, COT
what is the explosive range of methane CH4 in normal air and ambient temperature?
5 % - 15 %
what is the most easily ignited % of methane CH4 from a heated surface in a mixture of air & CH4?
5 % - 6 %
explain the term “Lag of Ignition”
time period that a flammable gas mixture is in contact with a heat source prior to an ignition taking place. it is dependant on gas concentration and temperature of heat source
what is the Lag of Ignition for methane CH4 at 5% - 6%?
2 seconds
explain how methane CH4 is produced and found on a mine site?
a) produced naturally during peat to lignite transformation
b) found in almost al coal seams & some coal bearing strata
what effect can the presence of coal dust suspended in the atmosphere have on the LEL of methane CH4?
can lower the LEL from 5% to 0%
what percentage of methane CH4 is recognised as the most explosive in air?
9.5%
what effects does the increase of ambient temperature have on a flammable gas/air mixture?
increases the upper explosive limit UEL and lowers the lower explosive limit LEL
state where hydrogen sulphide H2S could be found on the mine?
stagnant water, seam gas, spon com in coal containing pyrites
what is the concentration of hydrogen sulphide H2S that causes dizziness, excitement, nausea, dryness & pain in nose/throat/chest, coughing and irritation of mucus membranes?
250 - 600 ppm
explain the chemical and physical properties of hydrogen sulphide H2S?
H2S SG 1.18
Flammable, colourless, rotten egg smell, sweetish taste
state the physiological effects hydrogen sulphide H2S has on a person
toxic, irritates eyes,throat and respiratory tract, narcotic effect on the central nervous system CNS
is hydrogen sulphide H2S a flammable gas? if so, at what percentage in air?
4.3% - 45% flammable limit
auto ignition temp of 260’C
state the chemical and physical properties of sulphur dioxide
SO2 - SG 2.2 N-F
colourless, suffocating pungent odour, almost intolerable acidic taste
state the physiological effects sulphur dioxide SO2 has on a person
extremely poisonous, irritates lungs and respiratory passage, intolerable to breathe at certain concentrations
where does sulphur dioxide occur on the mine site?
spon com in coal containing sulphur, diesel exhaust emissions, burning rubber
is sulphur dioxide SO2 a flammable gas? if so, at what percentage?
no, it is incombustible and non-flammable
state the chemical and physical properties of nitrogen dioxide
NO2 - SG 1.6 N-F (will support combustion)
reddish brown colour
acrid smell, acid taste
state the maximum exposure limit for nitrogen dioxide NO2
short term exposure limit STEL 5 ppm
how does nitrogen dioxide occur at the mine?
shotfiring
component of diesel exhaust
although nitrogen dioxide is N-F what does it support?
combustion
state the physiological effects nitrogen dioxide NO2 has on the body
extremely poisonous
coughing
seriously irritates lungs, eyes, respiratory tract
symptoms of acute bronchopneumonia
cessation of life
