Mine Gases
Atmospheric Testing
Contributed by: Richard Black
Industrial Scientific Corp.
C.4.
What is AIR??
 Nitrogen
(N2) 78%
 Oxygen (O2) 21%
 All other gases
1%
 Total
100%
Definitions
LEL:
Lower Explosive Limit - % LEL
PPM: Parts Per Million - toxic gas measurement
PEL:
Permissible Exposure Limit -
8 hr/day - 40 hrs/wk - (OSHA)
TWA: Time Weighted Average - 8hr/day- (ACGIH)
STEL: Short Term Exposure Limit 15 mins/4x shift - (w/ 1 hr break - ACGIH)
IDLH: Immediately Dangerous to Life and Health
30 mins - (NIOSH)
Atmospheric Testing
Where will the gases be?
Lighter than air:
Methane
Acetylene
Carbon monoxide (slightly)
Heavier than air:
Hydrogen sulfide
Nitrogen dioxide
Nitric oxide
Carbon dioxide
TOP
MIDDLE
BOTTOM
Atmospheric Testing
 Combustible
Gas - Methane
 Oxygen - Normal 21%
Low
limit 19.5%
High limit 23.5%
 Toxic
gases - Measured in ppm - 10,000ppm=1%
Carbon
monoxide
Nitrogen dioxide
Nitric oxide
Hydrogen sulfide
COMBUSTIBLE ATMOSPHERES
Fire Triangle
Approved Gas Instruments:
detect the combustible gas (fuel)
detect oxygen level (air)
are intrinsically safe
(not source of ignition)
fuel
oxygen
source of ignition
COMBUSTIBLE ATMOSPHERES
Common Combustibles
Combustible
 Methane (natural gas)
 Propane
 Pentane (gasoline)
 Butane
 Hexane
 Methanol
 Hydrogen
LEL
5.0% vol
2.1% vol
1.4% vol
1.9% vol
1.2% vol
6.0% vol
4.0% vol
Example of Combustion
100% LEL
UEL
(Fire damp)
Methane
(CH4)
0
Too Lean
to Burn
5.0
15
Explosive
Mixture
100% Vol
Too Rich
to Burn
Oxygen Deficiency

Risk of asphyxiation
Caused by
 Consumption
fire
 people
 oxidation
 decomposition
 Displacement
 humidity
 other
gases
19.5%
Oxygen
Oxygen Enrichment
 Serious
fire hazard
 Materials burn much more rapidly
 Caused by
leaking
valves
leaking cylinders
Oxygen
23.5%
Effects of Oxygen
 23.5%
Maximum safe level (OSHA, MSHA)
 21.0%
Oxygen content in “Air” (20.954%)
 19.5%
Minimum safe level (OSHA, MSHA)
 17.0%
Impairment of judgement begins
 16.0%
First signs of Anoxia
 16-12%
Breathing and pulse rate increase,
coordination is impaired
Effects of Oxygen
 14-10%
Fatigue, disturbed respiration
 10-6%
Nausea and vomiting, inability to move
freely and loss of consciousness
 <6%
Convulsive movements and gasping
respiration occurs; respiration
stops/minutes later heart action ceases
 3-5%
Life expectancy; 3 - 5 minutes
TOXIC GASES
TOXIC
GASES
Toxic Gases
 Pose
a threat to human life - react in the body in a
poisonous fashion
 Enter
the body through various ways, they can be
ingested, injected, inhaled or absorbed through the
skin
 Can
react with different body systems
 Often
colorless and odorless
Toxic Gases
 Measured
in parts per million (ppm)
10,000ppm
 Exposure
= 1.0 % by volume
risks depend on two factors
Concentration
Time
exposed
(ppm)
Carbon Monoxide Data
CO: Colorless, odorless, tasteless, byproduct of
incomplete combustion
 Hazard: Flammable, LEL 12.6% – UEL 74%
 Health: Very Toxic (can be absorbed 200-300
time faster than oxygen by the hemoglobin)
 Exposures: PEL/TWA 50ppm (action level)
STEL
400 ppm
IDLH
1200 ppm
 Causes: fire, blasting, gas and diesel engines
 Specific Gravity = 0.967

Effects of CO

50ppm
PEL/TWA, Action level (MSHA)

400ppm Frontal headache in 2-3 hrs

1600ppm Headache and nausea 20 mins
Collapse and death in 1-2 hrs

6400ppm Headache, dizziness in 1-2
mins, unconsciousness and
death in 10-15 mins
Hydrogen Sulfide Data
 H2S:
Colorless, Rotten egg smell
 Hazard: Flammable, LEL 4.0% - UEL 46%
 Health: Extremely Toxic, appears naturally from
decomposition, reacts with the enzymes in the
blood - inhibits cell respiration
 Exposure: PEL/TWA 10ppm (action level)
STEL
15ppm
 Causes: Groundwater in shaft
 Specific Gravity = 1.2
Effects of H2S
 .13ppm
- Minimal perceptible odor
 10ppm
- PEL,TWA, Action level (MSHA)
Beginning of eye irritation
 100ppm - Coughing, eye irritation,
loss of sense of smell after
2-5 minutes
 500ppm
- Loss of consciousness and
possible death 30 mins - 1 hr
Nitrogen Dioxide Data
 NO2:
yellowish-brown gas with a pungent odor
 Hazard:
 Health:
will not explode
Extremely toxic
 Exposures: PEL/TWA 3ppm
STEL
5ppm
 Causes: Blasting, diesel powered equipment
 Specific Gravity = 1.6
Effects of NO2
 3ppm
- PEL/TWA
 5ppm
- STEL, Action level (MSHA)
 20ppm
- Irritation of eyes, nose and throat **
 50ppm
- Maximum exposure for a 30 mins
 200ppm
- Tightness of chest, acute bronchitis,
and death in prolonged exposure
** Nitric Acid = NO2 + H2O
High doses can cause pulmonary edema drown from inside out
Nitric Oxide Data
NO: Colorless gas, typically formed when air
is super heated and nitric compound like
dynamite explode
 Hazards: will not burn, will accelerate burning
 Health: extremely toxic
– Exposure limit: PEL/TWA 25ppm (action level)
STEL
N/A
 Causes: Blasting, diesel powered equipment
 Specific Gravity = 1.6

Effects of NO

0-50ppm
 25ppm

-
irritation of mucus membranes
-
PEL/TWA, Action level (MSHA)
60-150ppm -
Irritation is more intense,
coughing and burning of the
throat is evident, symptoms
will clear if victim is removed
quickly to clean air.

200-700ppm - May be fatal even after very
short exposures.
Sulfur Dioxide Data
 SO2:
Colorless gas, irritating pungent odor
 Hazards: will not explode, can combine with
water to form sulfuric acid (H2SO4)
 Health: extremely toxic
 Exposures: PEL/TWA 2ppm
STEL
5ppm
 Source: Hardrock mine strata
 Specific Gravity = 2.2
Effects of SO2
 .3-1ppm
- Initially detected by taste
 2ppm
-
PEL/TWA
 5ppm
-
STEL
 20ppm
-
 100ppm
Irritation of nose, throat and eyes **
- Maximum exposure for 30 mins
** Sulfuric Acid (H2SO4) = SO2 + H2O
Hydrogen Cyanide Data
HCN: Colorless to a pale blue gas
 Hazard : will explode - LEL 5.6% - UEL 40%
 Health: extremely toxic, has a distinct odor
resembling bitter almonds
 Exposures: PEL/TWA 10ppm
STEL
N/A
 Sources: Leaching of precious metals,
Metal mining


Specific Gravity = 0.69
Effects of HCN
 10ppm
Permissible Exposure Limit
 5-10ppm
Headache, dizziness,
unsteadiness
 50-100ppm
Feeling of suffocation, nausea
 100-200ppm
Death from exposure in 30 to
60 minutes
Ammonia Data
 NH3:
colorless gas with a suffocating odor
 Hazards: Difficult to burn, LEL 15% - UEL 28%
 Health: extremely toxic
 Exposures: PEL/TWA 25ppm
STEL35ppm
Effects of NH3
 0-25ppm
-
Minor irritation of the eyes
and respiratory tract

25ppm -
PEL/TWA

50-100ppm -
Swelling of the eyelids,
conjunctivitis, vomiting,
irritation of the throat

100-500ppm - Very dangerous concentrations,
death from prolonged exposure
Carbon Dioxide Data
CO2: byproduct of complete combustion, present
in the atmosphere (about 400ppm), acidic taste
 Hazard : Non-flammable
 Health: simple asphyxiant
 Exposures:
PEL/TWA 5000 ppm
STEL
30,000 ppm
 Causes: Combustion, respiration, decomposition

 Specific
Gravity = 1.5
Effects of CO2

400ppm -
Approx.. ambient level

3,000-5,000ppm -
Low concentrations cause
increased respiration and
headaches

8,000-12,000ppm -
Headache, nausea, vomiting,
and if not given air or oxygen,
possible unconsciousness

>15,000ppm -
High concentrations cause
rapid circulatory insufficiency
leading to coma and death
Review Questions (Answers on the next slide)
1. What gas is the most plentiful in normal air?
a. Nitrogen
b. Oxygen
c. Carbon dioxide
d. none of the above
2. How much methane is required for an explosion to occur?
a. 5% - 15%
b. 15% - 20%
c. 5% - 75%
d. 10% - 100%
3. Which of the following gases are produced in diesel engine exhaust?
a. Nitrogen dioxide
b. Nitric oxide
c. Carbon monoxide
d. all of the above
4. Which of the following gases is heavier than air?
a. Methane
b. Acetylene
c. Hydrogen Sulfide
d. None of the above
Answers to Review Questions
1. What gas is the most plentiful in normal air?
a. Nitrogen
2. How much methane is required for an explosion to occur?
a. 5% - 15%
3. Which of the following gases are produced in diesel engine exhaust?
d. all of the above
4. Which of the following gases is heavier than air?
c. Hydrogen Sulfide