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Coal mine Gases > Gases > Flashcards

Gases Flashcards

1
Q

Name 8 gases relevant to the coal mining industries, chemical symbol, and specific gravity

A 
Hydrogen	H2	     0.07
Methane	       CH4	     0.55
Carbon monoxide	CO	0.97
Oxygen	              O2	1.11
Hydrogen Sulphide      H2S	1.18
Carbon Dioxide	CO2	1.52
Nitrogen Dioxide	NO2	1.6
Sulphur Dioxide	SO2	2.2
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2
Q

Oxygen. Explain the effect

A

A. 16-14%- Slight increase in pulse and breathing rate, night and colour vision and judgement affected, Abnormal fatigue upon exertion
B. 14-10%- Poor judgement, abnormal fatigue upon exertion
3. 10-6%- Nausea, vomiting, inability to move or cry out, loss of consciousness may occur.

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3
Q

Minimum concentration which coal mine worker can be exposed

A

19.5%

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4
Q

Gases that constitute normal air & percentages

A 
Oxygen	20.95
Nitrogen	78.08
Carbon dioxide	.04
Argon/Inert gases	.93
Water vapour	0-3%
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5
Q

What percentage of oxygen

a) Flammable liquid cease
b) All flaming combustion ceases
c) All combustion ceases

A

17%
10-12%
2%

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6
Q

What effect does atmosphere enriched with oxygen have on Upper flammable limit.

A

Expands the flammable limits of a flammable gas.

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7
Q

Name 2 Gases released when blasting.

A

Nitric oxide & Nitrogen dioxide

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8
Q

How do you identify if nitrogen dioxide has been released in a blast?

A

Reddish brown colour in gas fume.

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9
Q

For nitrogen dioxide what is the
TWA
STEL
IDHL

A

TWA - 3ppm (0.0003%)
STEL - 5ppm
IDHL - 20ppm

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10
Q

Name 4 signs or symptoms of exposure to Nitrogen Dioxide.

A
  1. Feeling ill
  2. Coughing violently
  3. Symptoms of bronchitis and pneumonia
  4. Death
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11
Q

Carbon Dioxide. A person must not be exposed to an atmospheric concentration at a coal mine exceeding a general body concentration of carbon dioxide exceeding and convert % to ppm of above:

A

a) TWA of 1.25% - 12500 ppm

b) STEL 3.0 %- 30000 ppm

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12
Q
  1. Explain the effect of the following CO2 concentrations on a person:
A

a) 2%- 50% increase in lung ventilation
b) 4.5-5%- Anxiety, panic, irritability
c) 10%- Toxic, depresses Central Nervous System, violent panting, exhaustion, headache

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13
Q
  1. Carbon dioxide is regarded as a hot gas due to its low thermal conductivity, explain:
A

Due to its insulating properties it gives a feeling of warmth

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14
Q

Carbon dioxide:

a) How is it produced?
b) Where is it found in a coal mine?

A

Oxidation of coal and carb materials, diesel exhausts, blasting operations, fires
Diesel exhausts, fires, spon com, fire fighting inert gas. Breathing

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15
Q

Describe the physical and chemical properties of CO2

A

Colourless, slight pungent odour. Soda water taste. Non-flammable. SG of 1.52

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16
Q
  1. Describe the physiological effects of carbon dioxide at high and low concentrations:
A

Low- Stimulates the CNS. High-depresses the CNS

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17
Q

Is CO2 a flammable gas

A

Not Flammable

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18
Q
  1. State the long-term exposure limit concentrations for:
    a) Carbon Monoxide
    b) Hydrogen Sulphide
    c) Sulphur dioxide
    d) Nitrogen Dioxide
A

a) Carbon Monoxide: 30ppm
b) Hydrogen Sulphide: 10ppm
c) Sulphur dioxide: 2ppm
d) Nitrogen Dioxide: 3ppm

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19
Q

How is the body poisoned by CO Carbon monoxide

A

CO is absorbed 300 times more readily than 02 and prevents 02 from binding to the red bloods cells

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20
Q
  1. In regard to CO what is meant by the term “blood saturation”?
A

Blood becomes saturated with CO preventing the blood from taking on any more O2 or CO

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21
Q
  1. CO is said to have a cumulative effect. What is meant by cumulative effect?
A

CO can build up in a person from multiple, small exposures to CO, making the person more susceptible to it’s effect.

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22
Q

4 Examples of how CO is produced in a coal mine

A

Oxidization, heating, fire/explosion, diesel engines

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23
Q

Is CO an explosive gas? And at what concentration?

A

Yes – 12.5% to 74.2% explosive range

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24
Q

Name 6 signs or symptoms of CO poisoning

A 
Impairment of visual threshold, unsteady gait, 
becoming silent, r
osy/flushed face, 
heavy feeling in legs, 
Headache, nausea
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25
Q

State the chemical & physical properties of CO

A

Highly poisonous gas. Colourless, tasteless.
Flammable gas.
SG of 0.97.

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26
Q

What is the ignition temperature of Methane?

A

595 C

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27
Q

What is the minimum concentration of Oxygen (at norm temp) for methane explosion to occur?

A

12.2%

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28
Q

Is methane poisonous?

A

NT but will not support life

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29
Q

State physical and chemical properties of methane

A 
Colourless, 
Tasteless,
Odourless. 
Flammable gas. 
SG of 0.55
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30
Q

What is the explosive range of methane (in normal air and temp)?

A

5-15%

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31
Q

Explain “lag on ignition”?

A

The time period that a flammable gas mixture is in contact with a heat source prior to an ignition taking place. Dependent on concentration of gas and temp of heat source

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32
Q

What is the lag on ignition for methane at 5-6%?

A

2 seconds

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33
Q

Explain how methane is produced & where it is found:

A

Produced naturally during the peat to lignite transformation and found in almost all coal and some coal bearing strata.

34
Q

What % of methane is recognised as the most explosive in air?

A

9.5% of mixture

35
Q
  1. What effect does the increase in ambient temp have on a flammable gas/air mixture?
A

It is reduced when pressure and temperature rise.

36
Q

Hydrogen Sulphide

State where H2S can be found at a coal mine

A

Stagnant water, spon com in coal containing pyrites, seam gas

37
Q

What concentration of H2S causes dizziness, excitement, nausea, dryness & pain in the nose, throat chest and irritation of the mucous membranes?

A

0.02%=200 ppm. To 0.06 = 600 ppm

38
Q

Explain the physical & chemical properties of H2S

A 
Toxic. 
colourless, 
rotten egg smell. 
Sweetish taste. 
SG of 1.18
39
Q

State the physiological effects of H2S on a person

A

Toxic gas. irritates the lungs and respiratory tract and has a narcotic effect on the nervous system

40
Q

Is H2S flammable and a what percentage in air?

A

It has an auto ignition temperature of 260°C and a flammable range of 4.5% to 45%

41
Q

Sulphur Dioxide

State the chemical & physical properties of SO2

A

Toxic.

Colourless but has a pungent, sulphurous odour and almost intolerable acidic taste. SG of 2.2. NF

42
Q

State the physiological effects of SO2 has on a person:

A

Extremely poisonous, irritates eyes and respiratory passages and is intolerable to breathe at certain concentrations

43
Q

Where does SO2 occur at a coal mine?

A

Spon com in coal containing sulphur or in diesel exhaust emissions.

44
Q

Is SO2 a flammable gas?

A

It is incombustible and non-flammable

45
Q

Nitrogen Dioxide

49. State the maximum exposure limit concentration of NO2:

A

STEL is 5ppm

46
Q

How does Nitrogen dioxide occur at a coal mine

A

Component of diesel exhausts, shotfiring

47
Q

State the chemical and physical properties of NO2

A

Reddish brown colour, an acrid smell and acid taste. SG of 1.6. Although incombustible and non-flammable, it will support combustion.

48
Q

Although NO2 is not flammable, what does it support?

A

Combustion

49
Q

State the physiological effects of NO2?

A

Extremely poisonous. Coughing. Seriously irritates the lungs and respiratory passages. Symptoms of acute bronchopneumonia. Death

50
Q

Gas Sensors/Detectors

Type of gas sensors:

A 
o	Oxygen- EC									
o	Carbon monoxide- EC, IR	
o	Carbon dioxide- IR, GC							
o	Methane- Thermal, IR							
o	Nitrogen-   EC, GC								
o	Hydrogen sulphide EC							
o	Sulphur dioxide- EC				
o	Hydrogen- EC, GC								
o	Nitrogen dioxide- EC
51
Q
  1. How often does the gas detector have to be fully calibrated to NATA standard
A

Every 6 months

52
Q

How often does the gas detector have to be tested using known levels of gases.[span]:

A

Before each shift

53
Q

Electronic multi gas detectors can be cleaned using what?

A

Damp soft cloth bristle brush

54
Q

What could high [condensation] humidity do to an Oxygen sensor reading?

A

Cause sensor to fail

55
Q

Why is it not advisable to breath over sensors?

A

Moisture from exhaled breath can poison the O2 sensor

56
Q

State 2 advantages of an infrared methane sensor has over a catalytic combustion methane sensor

A
  1. Not dependant of Oxygen

2. Not cross sensitive

57
Q

What should the oxygen sensor of a handheld gas detector read.

58
Q

What is the minimum oxygen level required for correct operation of a catalytic combustion sensor?

59
Q

What is the normal measuring range for a Wheatstone Bridge or Pellistor (catalytic oxidation principle) type methanometer?

A

0% to 5% lower explosive limit

60
Q

Name 2 gases that could cause “cross Interference” on CO sensor

A
  1. H2S

2. SO2

61
Q

What does T90 refer to when using a personal gas detector?

A

The time taken to reach 90% of the test gas concentration of no more than 30secs.

62
Q

What gas detector is used to detect “Volatile Organic Compounds” VOC’s?

A

Photoionisation Dector

PID

63
Q

What does intrinsic safety mean when using a gas detector?

A

One which is intended for use in a potentially explosive atmosphere

64
Q

When should you use a pump style gas detector?

A

Remote sampling

65
Q

What are the effects of air velocities on gas detectors?

A

Displaces gases and does not give true reading

66
Q

Miscellaneous
Where could Methane be found on surface mine?
Name 3 areas :

A

1: Mining coal
2: Drill Holes
3: Blasting

67
Q

Where could Nitrogen Dioxide be found on a surface mine?

A

Blast flume,

Diesel exhaust

68
Q

Areas where Sulphur dioxide could be found?

A

When sulphur is in coal

spon com

69
Q

What are the 5 factors that must occur simultaneously for an explosion to occur?

A
  1. Oxygen
  2. Fuel
  3. Heat
  4. Suspension
  5. Confinement
70
Q

Where can carbon monoxide can be found on the surface. Name 2:

A
  1. Heatings

2. Diesel exhaust

71
Q

What 2 gases can be found in confined spaces at CHPP?

A
  1. Carbon Monoxide

2. Hydrogen Sulphide

72
Q

What gases can be found when an inversion layer occurs?

A

All seam gases

73
Q

What gases can be found when a product cylinder leaks?

A

LPG, Acetylene/

Whatever is inside the cylinder

74
Q

What risk control method is used at your mine when responding to the detection of flammable & toxic gases?

A

Follow TARP
Toxic Gases
Flammable Gases

75
Q

When coal heats gases appear at characteristic temps,

Name 6

A

The Fire Ladder

  1. Carbon dioxide CO
  2. Carbon monoxide CO2
  3. Methane CH4
  4. Hydrogen H2
  5. Ethane
  6. Hydrocarbons
76
Q

Convert 400PPM to %?

77
Q

What must occur for a person working more than the stated hours for applicable long term exposure limits

A

The TWA standard will need to be adjusted

78
Q

What is the applicable long term exposure limit concentration for various atmospheric contaminants?

A

Define long term exposure for hours in a day and hours in a week. 8h /40 h week
For a 10Hr day the TWA is adjusted by .7
For 12 hr day the TWA IS ADJUSTED BY .5

79
Q

What is the maximum general body concentration of carbon dioxide a person can be exposed if a continual personal monitoring method is used?

A

TWA- 1.25% STEL- 3%

80
Q

What should be recorded when taking gas readings in the excavations.
Name 6.

A
  1. Person name
  2. Gas type
  3. location
  4. time
  5. date
  6. Weather conditions
81
Q

Abbreviations

A 
CNS- Central Nervous System
SG- Specific Gravity
COT- Colourless, Odourless, Tasteless
EC- Electrochemical
PID- Photoionization Detector
GC- Gas Chromatograph
IR- Infrared
TWA- Time Weighted Average
STEL- Short Term Exposure Limit
LEL- Lower Explosive Limit
UEL- Upper Explosive Limit
NF- Non Flammable

Coal mine Gases (1 decks)

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