Gases Flashcards
Name 8 mine Gases
Hydrogen H2 .07 Methane CH4 .55 Carbon Monoxide CO .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
What percent of oxygen
Flammable liquid ceases
All flammable combustion ceases
All combustion ceases
Flammable liquid ceases 17%
All flammable combustion ceases 10-12%
All combustion ceases 2%
What effect does atmosphere enriched with oxygen have on Upper flammable limit.
Expands the flammable limits of flammable gas
2 x Gases released when blasting.
Carbon monoxide
Nitrogen dioxide
How do you identify if nitrogen dioxide has been released in a blast?
Reddish brown colour in gas fume
For nitrogen dioxide what is the:
TWA
STEL
IDHL
TWA- 3ppm (0.0003%)
STEL- 5ppm
IDHL- 20ppm
Name 4 signs or symptoms of exposure to Nitrogen Dioxide.
- Feeling ill
- Coughing violently
- Symptoms of bronchitis and pneumonia
- Death
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: TWA-%~ppm
STEL-%~ppm
a) TWA of 1.25% - 12500 ppm
b) STEL 3.0 %- 30000 ppm
Explain the effect of the following CO2 Carbon Dioxide concentrations on a person:
2%
4.5%~5%
10%
a) 2%- increase in lung ventilation
b) 4.5-5%- Anxiety, panic, irritability
c) 10%- Toxic, depresses CNS, violent panting, exhaustion, headache
Carbon dioxide is regarded as a hot gas due to its low thermal conductivity, explain:
Due to its insulating properties it gives a feeling of warmth
Carbon dioxide:
a) How is it produced?
b) Where is it found in a coal mine?
a) How is it produced? Oxidation of coal and carb materials, diesel exhausts, blasting operations, fires
b) Where is it found in a coal mine? Diesel exhausts, fires, spon com, fire fighting inert gas. Breathing
. Describe the physical and chemical properties of CO2
Colourless, slight pungent odour. Soda water taste. Non-flammable. SG of 1.52
Describe the physiological effects of carbon dioxide at high and low concentrations:
Low Stimulates the CNS/ 50% increase in lung ventilation
High-depresses the CNS / Respiratory failure
. Is CO2 a flammable gas
Non flammable
State the long-term exposure limit concentrations for:
a) Carbon Monoxide:
b) Hydrogen Sulphide:
c) Sulphur dioxide:
d) Nitrogen Dioxide:
a) Carbon Monoxide: 30ppm
b) Hydrogen Sulphide: 10ppm
c) Sulphur dioxide: 2ppm
d) Nitrogen Dioxide: 3ppm
How is the body poisoned by Carbon Monoxide
CO is absorbed 300 times more readily than oxygen and prevents O2 from binding to the red blood cells
In regards to CO what is meant by the term blood saturation
Blood becomes saturated with CO preventing the blood from taking on any more O2 or CO
CO is said to have a cumulative effect What is meant by cumulative effect
CO can build up in a person from multiple small exposures to CO making the person more susceptible to it’s effect
Examples of how CO is produced in a coal mine
Oxidation /heating /fire /explosion /Diesel engines
Is CO an explosive gas and and at what concentration
Yes 12.5%-74.2% explosive range
Name 6 signs and symptoms of CO poisoning
Impairment of visual threshold /unsteady gait /becoming silent /rosy flushed face /heavy feeling in legs /headache /nausea
State the chemical and physical properties of carbon monoxide
Highly poisonous gas /colourless /tasteless /flammable gas /Density.97
What is the ignition temperature of Methane
537 c
What is the minimum concentration of oxygen at normal temperature for methane explosion to occur
12.2%
Is methane a poisonous gas
Non toxic but will not support life
State physical and chemical properties of methane
Colourless /odourless /tasteless /flammable gas/ .55 density
What is the explosive range of methane in normal air and temperature
5%~15%
Explain Lag Ignition
The time period a flammable gas mixture is in contact with a heat source prior to an ignition taking place/Dependent on concentration of gas and temperature of heat source
What is the most easily ignited % of methane from a heated surface in a mixture of CH4 and air
5%~6%
What is the lag ignition for methane at 5%~6%
2 seconds
Explain how methane is produced and where it is found
Produced naturally through the peat to lignite transformation and found in almost all coal and some coal bearing stratas
What effect can the presence of coal dust suspended in the atmosphere have on the LEL of methane
Can lower the LEL from 5% to 0%
What % of methane is recognised as the most explosive in air
9.5% of mixture
What effect does the increase in ambient temperature have on a flammable gas/air mixture
Makes it more easily ignited
State where hydrogen sulphide H2s can be found at a coal mine
Stagnant water/Spon com/ Seam gas
What concentration of H2s causes dizziness,excitement,nausea,dryness and pain in the nose/ throat/chest and irritation of the mucous membranes ?
250-600 ppm
Explain the physical and chemical properties of H2s
Toxic/colourless/rotten egg smell/sweetish taste/SG of 1.18
State the physiological effects of H2s on a person
Irritates the lungs and respiratory tract/has a narcotic effect on the central nervous system
Is H2s flammable and at what percentage in air
Flammable gas at 4.3% to 45%
State the Chemical and physical properties of Sulphur Dioxide So2
Toxic/Colourless/Sulphurous odour/Acidic taste. Density 2.2 Non flammable
State the physiological effects of SO2 has on a person
Poisonous gas irritating the respiratory passages
Where does SO2 occur at a coal mine
Spon Com in coal containing Sulphur or in diesel exhaust fumes
Is SO2 a flammable gas
It is incombustible and non flammable
State the chemical and physical properties of Nitrogen Dioxide NO2
Reddish Brown colour/Acrid taste/Density 1.6
State the maximum exposure limit of NO2
STEL
STEL 5 ppm
How does Nitrogen Dioxide occur at a coal mine
Shot firing/ Diesel exhaust
Although NO2 is non flammable,what does it support
Combustion
State the physiological effects of NO2
Irritates the respiratory passages/coughing
Types of Gas sensors
Gas Chromatograph GC Electrochemical EC Infrared IR Tube Catylitic Combustion CC Hydrogen GC EC Methane GC IR CC Carbon monoxide GC EC IR Tube Oxygen GC EC Hydrogen Sulphide GC EC Tube Carbon Dioxide GC EC IR Tube Nitrogen Dioxide GC EC Tube Sulphur Dioxide GC EC Tube Nitrogen GC
How often does the gas detector need to be calibrated to NATA standard
Every 6 months
How often does the gas detector have to be tested using known levels of gases
Prior to each use
Electronic multi gas detectors can be cleaned using what
Damp soft cloth/ soft bristle brush
What could high condensation/ humidity do to an oxygen sensor
Cause the sensor to fail
Why is it not advisable to breathe over sensors
Moisture from breath can poison O2 sensor
State 2 advantages of infrared methane sensor has over a catalytical combustion methane sensor
Not dependant of oxygen
Not cross sensitive
What should the oxygen sensor of a hand held gas detector read
20.9% oxygen
What is the minimum oxygen level required for correct operation of a catalytic combustion sensor
10%
What is the normal measuring range for a Wheatstone bridge or pallistor ( catalytic oxidation principle ) type of methanometer
0%~5% LEL Lower Explosive Limit
Name 2 gases that could cause cross interference on a Carbon Monoxide CO sensor
Hydrogen Sulphide H2s
Sulphur Dioxide SO2
What does T90 refer to when using a personal gas detector
The time taken to reach 90% of the test gas concentration of no more than 30 seconds
What gas detector is used to detect Volatile Organic Compounds
Photionization Detector PID
What does intrinsic safety mean when using a gas detector
One which is intended for use in a potentially explosive atmosphere.The detector is incapable of releasing enough thermal/electrical energy to ignite a flammable / combustible mixture of air
When should you use a pump style gas detector
Remote sampling
What are the effects of air velocities on gas detectors
Displaces gases and does not give a true reading.Can damage the detector
Oxygen % explain the effects
16%~14%
14%~10%
10%~6%
16%~14% - Slight increase in pulse and breathing/ night and colour vision affected
14%~10% - Poor judgment/abnormal fatigue
10%~6% - Nausea/vomiting
Minimum concentration of oxygen which coal mine workers can be exposed
19.5%
Gases that constitute normal air and percentages
Oxygen 20.94% Nitrogen 78.11% Carbon Dioxide.04% Argon/Inert gases .93% Water vapour 0-3%
Where could Methane be found on a surface mine
Mining coal
Drill holes
Coal bearing strata
Where could Nitrogen Dioxide be found on a surface mine
Diesel exhaust
Blast fume
Area’s where Sulphur Dioxide could be found
When Sulphur is in coal/ Spon com
What are 5 factors that must occur simultaneously for an explosion to occur
Oxygen Fuel Heat Suspension Confinement
Where can Carbon Monoxide be found on a surface mine: Name 2
Heatings
Diesel exhaust
What 2 gases can be found in confined spaces at the CHPP
Carbon Monoxide
Hydrogen Sulphide
What gases can be found when an inversion layer occurs
All seam gases
What gases can be found when a product cylinder leaks
LPG/Acetylene/Whatever is inside the cylinder
What risk control method is used at your mine when responding to the detection of flammable and toxic gases
Follow the TARP
When coal heats gases appear at characteristic temperatures:Name 6
Carbon Dioxide Carbon Monoxide Methane Hydrogen Ethane Ethylene/ Hydrocarbons
Convert 400 ppm to %
.04%
What must occur for a person working more than the stated hours for applicable long term exposure limits
The TWA standard will need to be adjusted
What is the applicable long term exposure limit concentration for various atmospheric contaminants
Define long term exposure for hours in a day and hours in a week. 8hr day/40 hr week
What is the maximum general body concentration of Carbon Dioxide a person can be exposed if a continual personal monitoring method is used
TWA -1.25%
STEL - 3%
What should be recorded when taking gas readings in the excavations:Name 6
Person’s name Gas type Location Time Date Weather Conditions
