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Fires, Firefighting, and Explosions

Fires

Firefighting Equipment

Firefighting

Indirect Firefighting

Explosions

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Fires

The Fire Triangle

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Classification of Fire

A (ash) Carbon-paper,wood,coal

B (boil) Liquids-gasoline,diesel fuel

C (current) Electrical- cables, motors

D (ding) Metals- magnesium, titanium

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Firefighting Equipment

Hand Held Extinguishers Rockdust Water Foam Inert Gases

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Hand held Extinguishers

Monammonium phosphate Rated for ABC fires, interrupts the basic chemistry of fire. Not recommended for D fires. (Red body & pressure gauge)

CO2

Rated for BC fires, will only extinguish surface area, heated core may reignite. (Red body & horn, no gauge)

Halon Rated for BC fires, used mainly in electronics, dangerous because Halon displaces

oxygen. (Red body and gauge)

Pressurized Water Rated for A fires only, usually a baking soda charge. (Stainless steel body)

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Using hand held extinguishers

Remember: Select the right type Used mostly for small fires Will usually discharge in less than one minute Training is a must Stay low to avoid fumes Never block escape route

When extinguishing a fire “PASS”

P Pull the pin A Aim low S Squeeze the handle S Sweep from side to side

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Water

Water is highly effective on Class A fires, by cooling down the fire and surrounding atmosphere.

At most mines, water is usually in plentiful supply. Can be used to cool down the firefighting team to prevent

heat exposure.

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Disadvantages

Water should not be used to control a B or C fire. Inadequate pressure or too high pressure The volume of water can be restricted to the length of water

lines and hoses(frictional loss- 1/2 lbs. for every ten feet of 1 1/2 inch hose).

The fire nozzle can clog to non-filtered materials in the lines.

Hydrogen can be produced by applying water to super hot fires.

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Nozzles– Many mines use fixed nozzles that limit

the amount of water to be used– Volume not pressure will put out the fire– Nozzles in the mine today may not handle

the high water pressure and may blow out Hoselines

– Any hoseline under 2 inch diameter will have frictional loss

– Hoselines must a bursting pressure at least 4 times the mine’s outlet pressure

– Multiple walled hoses should only be used– Proper deployment and storage of

hoseline will determine if firefighting efforts are successful

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Foam

Protein– Animal protein from entrails or blood (Class A & B fires)– Burn back protection, not film forming, adheres well to roof

Fluoroprotein– Animal protein with fluorinated surfactants (Class A & B fires)– Burn back protection, film forming

Aqueous Film Forming Foam (AFFF)– Synthetic (Class A & B fires)– Burn back protection, film forming

Alcohol Type Concentrates (ATC)– Used mainly in alcohol based liquids (Class A & B fires)– Burn back protection, film forming

High Expansion Foam– Special detergent concentrate, expands 1000 times its own volume (Class A

fires)– No burn back protection, not film forming

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Training All persons directly involved should have hands on

training. Support personal should participate in monthly mine

rescue training and MERD exercises. Mine rescue team members shall have at least 4 hours

training monthly or 8 hours bimonthly(Pa State Trained Teams train at least 6 hours monthly).

State Trained teams participate in simulated exercises at Niosh(Lake Lynn facility and Bruceton.

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Before Going Underground

Before sending teams underground make sure that: A. The main fan is running B. A guard is monitoring the operation of the fan C. Tests are being made at main returns for any mine gases

All persons should be aware if the fire is spreading or a possible explosion can occur.

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Do not make any sudden changes in mine ventilation

Determine location of battery or diesel operated equipment

Determine location of storage areas for explosives, oil and grease, diesel fuel, bottled gas

Cut off electric power to affected area, to prevent arcing starting additional fires and safety to mine

rescue teams.

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Locating Fires & Assessing Conditions

Information given by mine officials and workers where smoke, fumes or heat was last seen

The amount of afterdamp gases could determine what is burning and how much is burning

Laboratory analysis could determine if the fire is still burning

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Information received from the rescue teams during exploration

Gas readings near the fire area to determine if the atmosphere is potentially explosive

Check on ventilation controls for damage

Roof must continually be evaluated since heat will weaken the strata

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Direct Firefighting

High volume of water is recommended Use of wide angle fog for team safety and

steady steam for direct contact with fire Hazards include: electrocution, toxic and

asphyxiating gases, explosive gases, heat, smoke and steam

Firefighting teams have to be very close to the fire area

Teams should approach fire from intake side to ensure safety

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Use of a transverse brattice

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Indirect Firefighting

Mine hazards include: high temperatures, bad roof, or explosive gases

Necessary to fight the fire from a distance by sealing the area or by filling the fire area with foam or water

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Six factors to consider sealing the fire area:

1. Volatility of the coal seam- High vol coal burns faster and much more difficult to fight directly

2. Amount of methane liberated by the coal seam 3. Location of the fire and the area involved 4. Presence of head coal and the composition of roof strata 5. Availability of materials and transportation 6. Building sites for the seals

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Sealing the Area

Purpose: to lower oxygen level so fire may burn out in addition to foaming or flooding the area

Seal area should have good roof Even roof and rib Temporary seals should used before permanent seal are

built Air sampling tubes install for gas and temperature readings Make sure no abrupt ventilation change over fire area All persons should leave mine in case explosive gases

build up in seal area Possible to use boreholes from surface to pump water

and/or nitrogen to fire area

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Explosions

As in fire, explosions need fuel, oxygen and heat Methane and/or coal dust are the most likely source of fuel(

2% methane and the right amount of coal dust can create an explosion)

Coal dust explosions travel at a speed exceeding 3000 ft. per second

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Ignition sources include: electric arc, open flame, misuse ox explosives, sparks from continuous cutting heads

Once an explosion occurs, there is a chance of more explosions due to the ventilation systems being damaged

Before going under ground, make sure that the fan is running and guarded

Tests are made at the fan for dangerous gases