QA September 2001Fire Topic

Fire Stream Practices

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Fire Extinguishment Theory

Temperature Reduction: usually by applying water Fuel Removal:

– stop fuel from being added– remove fuel from path of fire

Oxygen Exclusion or Dilution– introduce inert gas: carbon dioxide, nitrogen– separate or smother: steam, foam

Inhibiting Chemical Reaction– Dry chemicals, halons, etc. interrupt flame production.– most effective on liquid and gas fuels

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Compatibility

Determine the extinguishing method or extinguishing agent compatible with the material involved.

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Characteristics of Water

Molecule of two parts hydrogen and one part oxygen Solid (ice) @< 32 degrees (freezing point) Liquid (water) @ 32 to 212 degrees (boiling point) Gas (water vapor or steam) @ > 212 degrees Practically incompressible Weight: approximately 62.5 lb/ft3 Absorbs large amounts of heat by 2 laws of physics:

– Law of specific heat: heat-absorbing capacity of a substance (water is given a value of 1.00)

– Latent Heat of Vaporization: heat absorbed during vaporization

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Advantages of Water as Agent

Great heat absorption capacity

Readily available

Inexpensive 1,700:1

vaporization expansion ratio

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Disadvantages of Water

High surface tension Reactivity with

certain materials Can freeze Low viscosity Electrically

conductive Heavy

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6 Principles of Pressure

Fluid pressure is perpendicular to any surface.

Fluid pressure at a point in a fluid at rest is the same intensity in all directions.

Pressure applied to a confined liquid from without is transmitted equally in all directions.

The pressure of a liquid in an open vessel is proportional to its depth.

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6 Principles of Pressure (cont.)

The pressure of a liquid in an open vessel is relative to its density

The shape of a vessel is irrelevant to the pressure of the liquid.

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Types of Pressure

Atmospheric: the pressure applied to the surface by the Earth’s atmosphere (14.7 psi @ sea level)

Head: height of a water supply above discharge Static: pressure in a water system before water

flows from a hydrant Normal Operating: pressure in water distribution

system during normal consumption demands Residual: pressure remaining after overcoming

gravity and friction loss when forcing water through pipe, fittings, fire hose, and appliances

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Types of Pressure (cont)

Flow / Velocity: forward force pressure at a discharge opening while flowing water

Elevation Loss and Gain: – nozzle above pump = pressure loss– nozzle below pump = pressure gain– 0.434 psi per foot

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Principles of Friction Loss

Friction Loss: portion of total pressure lost while forcing water through pipe, fittings, fire hose, etc.– varies with length of hose– varies with velocity (if flow doubles, FL quadruples)– varies with hose diameter– FL same, regardless of pressure

Critical Velocity: turbulent agitation created when velocity limits are exceeded

Water Hammer: damaging energy surge created when water is suddenly stopped

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Fire Stream: a stream of water or water-based extinguishing agent from the time it leaves the nozzle until it reaches the desired point. The condition and effectiveness of the stream is

influenced by:– design, adjustment, and condition of the nozzle– operating pressure– velocity– gravity– wind– friction with the air

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Fire Stream Production4 basic elements:

Water Supply– Static Supply: lakes, rivers, swimming pools,

portable tanks, etc. (Where are the drafting locations in your run districts?)

– Apparatus Water Tanks (What is the capacity of your booster tank?)

– Pressurized Distribution System (Do you know the hydrant capacity color-coding system?)

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Fire Stream Production4 basic elements: (cont.)

Fire Department Pumper: receives water supply and increases pressure to required level for an effective production of fire streams (What is the rated capacity of your engine?)

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Fire Stream Production4 basic elements: (cont.)

Fire Equipment– Hose (What sizes and lengths are on your

engine?)– Nozzles: forms and shapes the stream– Appliances: wyes, siameses, manifolds, double

couplings, water thieves, etc. – Hardware: spanner wrenches, hose straps, hose

bridges, etc.

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Fire Stream Production4 basic elements: (cont.)

Trained Personnel: The best supply, apparatus, and equipment will not produce effective fire streams without well trained personnel.

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Sizes & Types of Fire StreamsFire Streams are identified by size and type.

Size: stream volume in gallons per minute (GPM)– Handline: 40 GPM to 350 GPM– Master Stream: >350 GPM

Type: stream shape or pattern– Solid: Produced by a smoothbore, fixed-orifice

nozzle (long range/ high volume). The stream must maintain continuity, must shoot 9/10ths through a 15” circle and 3/4ths through a 10” circle, must attain height in moderate wind.

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Types of Fire Streams (cont.)

– Solid (cont.): The flow rate and the reach depend upon the velocity (discharge pressure) and the diameter of the nozzle orifice. At equal pressure, doubling the nozzle size will quadruple the GPM. The maximum horizontal reach is achieved at 32 degrees. The optimum vertical reach is at 70 to 75 degrees.

– Fog Stream: varied pattern stream, composed of water droplets/ from wide (45-80 degrees), to narrow (15-45 degrees), to straight.

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Types of Fire Streams (cont.)

– Broken Streams produced by special stream nozzles (water

curtains, rotary distributor, spoon billed, etc.) or by directing two solid streams together

do not have a specific pattern composed of large drops usually not adjustable for fires in attics, basements, partitions, etc. increased water damage should be expected

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Types of Nozzles

Solid Stream Nozzles Fog Stream Nozzles Handline Nozzles Master Stream Nozzles Special Purpose Nozzles

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Foam Fire Streams

Foam concentrate is added to a water fire stream using a proportioning device, which creates a foam solution

Air is added to the solution, which creates the finished foam

Effective on flammable liquids, hazardous materials spills, confined space fires, bulk class A fires

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Foam Fire Stream Production

1. Choose appropriate foam concentrate

2. Use hydraulically compatible eductor and nozzle

3. Set eductor to proper concentration percentage

4. Attach eductor, attack hose, and nozzle to pump

5. Assemble sufficient foam concentrate at eductor

6. Place eductor suction hose in concentrate

7. Increase water pressure to eductor specifications

8. Apply finished foam

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PP = NP + FL + EL

PP: Pump Pressure NP: Nozzle Pressure

– know the manufacturer’s specifications FL: Friction Loss

– determined by field tests or by calculations– includes hose and appliances

EL: Elevation Loss– approximately 0.5 psi/ft (vertically)

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2

FL = CQ L + A

C = Coefficient specific to hose construction Q = Quantity of water in hundreds of gpm L = Length of hose in hundreds of feet A = Appliances: siameses, wyes, master

stream devices, etc.

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Strategic Objectives( in order of importance)

Rescue: direct streams to protect victims and rescuers

Exposure Protection: nearby combustibles– Interior: areas of the fire building not involved– Exterior: adjacent buildings

Confinement: coordinate streams and ventilation to attack and contain the fire

Extinguish: apply sufficient streams to seat of fire to reduce heat and heat production

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Types of Attack

Offensive: direct interior attack– greatest risk to firefighters– IC must weigh fire and building conditions, life

hazards, and building construction type– must be coordinated with ventilation efforts– attack crews must understand the principles of

fire spread– streams must be of adequate size and appropriate

type to achieve the tactical objectives

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Types of Attack (cont.)

Defensive: goal is to contain fire to building involved (“written off”)– used when available fire flow is insufficient or,– structure is obviously lost, regardless of flow, or– repeated interior attacks have failed, or – structural stability is compromised, or– interior crews’ safety is questionable– Direct streams to protect last-minute rescue and

interior attack crews’ egress

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Types of Attack (cont.)

Defensive (cont.):– concentrate on

protecting exposures– remove apparatus,

crews, appliances, and hose lines from collapse zone

– attack fire from outside with monitors and elevated master streams