MINE GASES

Normal Air is made up of:

Nitrogen 78%

Oxygen 21%

Trace Gases 1%

Specific Gravity:

• The weight of a gas compared to an equal volume of normal air

at the same temperature and pressure.

• Normal air has a specific gravity of 1

• This determines where in mine atmospheres, or within a

confined space, we will find concentrations of particular gases

Examples:

Carbon Dioxide 1.529 floor to
mid drift

Hydrogen 0.0695 against
back or roof

Oxygen 1.105 evenly
distributed

Hydrogen Sulfide 1.2 floor to
mid drift

Carbon Monoxide 0.967 evenly
distributed
Sulfur Dioxide 2.264 floor

Gases can and do pool

Gases tend to flow as fluids in

quantity

These effects can displace

Oxygen.

Ventilation:

Heavier gases are harder to ventilate

than lighter gases.

WHY?

What are we ventilating with?

Normal Air specific gravity of

1.0

THE EXPOLSIVES!

Methane 5-15
%

Carbon Monoxide 12.5-75
%

Hydrogen 4-74 %

Hydrogen Sulfide 4.3-45
%

Hazards of ventilating

concentrations of any of these are:

IGNITION SOURCES!

MOVING IRRESPIRABLE GAS!

THE LAW!

In a mine or within a confined space,

what is the minimum percentage of

Oxygen necessary?

19.5%

Anything less means VENTILATE!

Most digital Oxygen detectors are set

to alarm at 19.5%

THE QUIZ!

Which gas has the greatest specific

gravity?

A. Sulfur Dioxide

B. Carbon Dioxide

C. Oxygen

D. Nitrogen Dioxide

A. Sulfur Dioxide

The explosive range of Hydrogen is?

A. 5 - 15 %

B. 12.5 - 75 %

C. 4 - 45 %

D. 4 - 74 %

D. 4 - 74 %

Which gas has an acidic taste in high
concentrations?

Carbon
Dioxide

Which of the following gases are

explosive?

A. Methane

B. Oxygen

C. Carbon Dioxide

D. Nitrogen

E. Carbon Monoxide

F. Hydrogen Sulfide

G. Hydrogen

Methane, Carbon Monoxide, Hydrogen

Sulfide & Hydrogen

What gases and what percent of each

make up normal air?

Nitrogen 78 %

Oxygen 21 %

Trace gases 1 %

If you are ever concerned regarding the air

quality

in any area of the mine or on the surface…

MAKE SURE

Your life and the person who finds you

depends on YOU

If there are no gas detection instruments

immediately available,

DO NOT ENTER!

VENTILATE