QLD Gas Test

Question 1

Name the 9 gases relevant to underground coal mining, their chemical symbol and specific gravity.

Answer 1

Hydrogen - H₂, 0.07.
Methane - CH₄, 0.55.
Carbon Monoxide – CO, 0.97.
Nitrogen - N₂, 0.97.
Oxygen - O₂, 1.1.
Hydrogen Sulphide, H₂S, 1.19.
Carbon Dioxide - CO₂, 1.53.
Nitrogen Dioxide – N0₂, 1.6.
Sulphur Dioxide - SO₂, 2.26.

Question 2

Explain the effect on a person at the following Oxygen concentrations:
19%
12%
<10%

Answer 2

18% - Slight increase in breathing effort, some loss of night vision.
12% - Impaired respiration can cause cardiac damage, poor judgement and abnormal fatigue on exertion.
Less then 10% - Nausea, vomiting, inability to move or cry out, loss of consciousness may occur.

Question 3

State the minimum Legislated general body concentration of oxygen to which a coal mineworker can be exposed:

Answer 3

19%

Question 4

State the gas constituents of normal air and their percentage:

Answer 4

Oxygen – 20.93%.
Nitrogen – 78.11%.
Carbon Dioxide – 0.03%.
Inert Gases – 0.93%.
Water Vapor 0-3%.

Question 5

At what percentage of oxygen does the following occur:
Flammable liquids -
All flaming combustion ceases
All combustion ceases

Answer 5

a. Flammable liquids – 17%.
b. All flaming combustion ceases at – 12.5%.
c. All combustion ceases at – 2%.

Question 6

What effect does an atmosphere enriched with oxygen have on the UPPER FLAMMABLE LIMIT of flammable gases?

Answer 6

Increases / raises the upper flammable limit.

Question 7

Is Nitrogen an explosive gas?

Answer 7

NO

Question 8

Can Nitrogen support life

Answer 8

No

Question 9

A person must not be exposed to an atmosphere at the mine containing a general body concentration of carbon dioxide exceeding? - convert to PPM

Answer 9

1.25%
12500ppm

Question 10

Explain what effect occur to a person at the following concentrations of Carbon Dioxide.
2%
3%
10%

Answer 10

2% - respirations increase by 50%.
3% - Respirations increase by 100%.
10% - headache, collapse, increase in blood pressure.

Question 11

Carbon dioxide is regarded as a hot gas due to its low thermal conductivity. Explain.

Answer 11

Heat is not conducted away as rapidly as in normal air so a person standing in it will feel warmth about their lower limbs

Question 12

Carbon Dioxide, how is it produced, give 2 examples and where is it found in a coal mine?

Answer 12

Seam Gas, accumulates on the floor.
Product of complete combustion, behind seals, diesel exhaust.

Question 13

Describe the physical and chemical properties of carbon dioxide.

Answer 13

Colourless, slight pungent smell, soda water taste. Incombustible, will not support life.

Question 14

Describe the physiological effects of carbon dioxide.

Answer 14

At low concentrations – it acts as a stimulant to the respiratory and central nervous system.
At high concentrations – depresses the central nervous system producing unconsciousness and narcosis.

Question 15

State the long term exposure limit concentrations of the following gasses:
Carbon Monoxide –
Hydrogen Sulphide –
Nitrogen Dioxide -
Sulphur Dioxide –

Answer 15

Carbon Monoxide –
30ppm
Hydrogen Sulphide – 10ppm.
Nitrogen Dioxide - 3ppm.
Sulphur Dioxide – 2ppm.

Question 16

How is the human body poisoned by carbon monoxide?

Answer 16

Carbon monoxide is absorbed into the blood stream which prevents the blood from taking up and transporting oxygen to the various cells.

Question 17

In regards to carbon monoxide poisoning, what is meant by the term blood saturation?

Answer 17

Red blood cells take up carbon monoxide in preference to oxygen. Blood becomes saturated with carbon monoxide.

Question 18

Carbon monoxide poisoning is said to have a cumulative effect. What is meant by cumulative effect?

Answer 18

A person can be exposed to a number of short terms to carbon monoxide to no ill effect. Over time the body will not displace all of the carbon monoxide. The person then becomes more susceptible to the effect with each exposure.

Question 19

How is carbon monoxide produced in coal mines? Give 4 examples.

Answer 19

Product of incomplete combustion.
Diesels.
Spontaneous combustion and oxidation.
Fire.

Question 20

Is carbon monoxide an explosive gas and if so at what concentration?

Answer 20

Yes – 12.5% - 74%

Question 21

Name six signs and symptoms that would be associated with carbon monoxide poisoning.

Answer 21

Headaches.
Giddiness.
Nausea.
Heart palpitations.
Breathing Difficulties.
Weakness in limbs.

Question 22

State the chemical and physical properties of carbon monoxide.

Answer 22

COT. Soluble in water.

Question 23

What is the ignition temperature of methane?

Answer 23

650⁰ - 750⁰.

Question 25

What is the minimum concentration of oxygen, (at normal atmosphere) for a methane explosion to occur?

Answer 25

12.4%

Question 26

What is the legal limit requirements, for (methane) passing through a mine’s main fan?

Answer 26

There is no stated limit.
The ventilating air passing through the fan must be monitored by at least 1 automatic methane detector.
The detector must automatically activate a visible alarm when the concentration exceeds the set limit.

Question 27

What is the explosive range of methane is normal air and ambient temperature?

Answer 27

5 to 14%.

Question 28

What is the most easily ignited % of methane from a heated surface in a mixture of CH4 and air?

Answer 28

5 to 6%.

Question 29

Explain the term ‘Lag of Ignition’.

Answer 29

The period of time that a gas must be in contact with a heat source for an ignition to take place.

Question 30

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

Answer 30

2 seconds.

Question 31

Explain how methane is produced and where methane is found in a coal mine.

Answer 31

Produced during coalification process. Is a seam gas and mostly given off during winning of coal. With a specific gravity of 0.55, it is mostly found in higher parts of the mine.

Question 32

What effect can the presence of coal dust suspended in the atmosphere have on the Lower Explosive Limit of methane?

Answer 32

Can reduce from 5% to 0.

Question 33

What percentage of Methane is recognised as the most explosive in air?

Answer 33

9.5%

Question 34

What effects does the increase of ambient temperature have on a flammable gas and air mixture?

Answer 34

Increases the upper explosive limit and lowers the lower explosive limit.