Mine GasesAtmospheric Testing

C.4.

Contributed by: Richard Black

Industrial Scientific Corp.

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)

TOP

MIDDLE

BOTTOM

Where will the gases be?Where will the gases be?

Lighter than air:Lighter than air:

MethaneMethane

AcetyleneAcetylene

Carbon monoxide (slightly)Carbon monoxide (slightly)

Heavier than air:Heavier than air:

Hydrogen sulfideHydrogen sulfide

Nitrogen dioxideNitrogen dioxide

Nitric oxideNitric oxide

Carbon dioxideCarbon dioxide

Atmospheric Testing

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

Fire TriangleApproved Gas Instruments:

fuel oxygen

source of ignition

detect the combustible gas (fuel)

detect oxygen level (air)

are intrinsically safe (not source of ignition)

COMBUSTIBLE ATMOSPHERES

Combustible LELMethane (natural gas) 5.0% volPropane 2.1% vol Pentane (gasoline) 1.4% volButane 1.9% volHexane 1.2% volMethanol 6.0% volHydrogen 4.0% vol

Common Combustibles

COMBUSTIBLE ATMOSPHERES

100% LEL UEL

0 5.0 15 100% Vol

Example of Combustion

(Fire damp)

Methane (CH4)

Too Lean to Burn

Explosive Mixture

Too Rich to Burn

Oxygen Deficiency

Risk of asphyxiation

Caused byConsumption

firepeopleoxidationdecomposition

Displacementhumidityother gases

Oxygen19.5%

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

TOXICGASES

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 = 1.0 % by volume

Exposure risks depend on two factors

Concentration (ppm)

Time exposed

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

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 shaftCauses: Groundwater in shaft Specific Gravity = 1.2Specific Gravity = 1.2

Hydrogen Sulfide Data

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: will not explode

Health: Extremely toxic Exposures: PEL/TWA 3ppm

STEL 5ppm

Causes: Blasting, diesel powered equipmentCauses: Blasting, diesel powered equipment Specific Gravity = 1.6Specific 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

High doses can cause pulmonary edema - drown from inside out

** Nitric Acid = NO2 + H2O

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 equipmentCauses: Blasting, diesel powered equipment Specific Gravity = 1.6Specific Gravity = 1.6

Effects of NO 0-50ppm - irritation of mucus membranes

25ppm - 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 - Irritation of nose, throat and eyes

**

100ppm - 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. Nitrogenb. Oxygenc. Carbon dioxided. 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 dioxideb. Nitric oxidec. Carbon monoxided. all of the above

4. Which of the following gases is heavier than air?a. Methaneb. Acetylenec. Hydrogen Sulfided. None of the above

Answers to Review Questions1. 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