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QA September 2001 Fire Topic

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1 QA September 2001 Fire Topic
Fire Stream Practices

2 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

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

4 Characteristics of Water
Molecule of two parts hydrogen and one part oxygen Solid 32 degrees (freezing point) Liquid 32 to 212 degrees (boiling point) Gas (water vapor or > 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

5 Advantages of Water as Agent
Great heat absorption capacity Readily available Inexpensive 1,700:1 vaporization expansion ratio

6 Disadvantages of Water
High surface tension Reactivity with certain materials Can freeze Low viscosity Electrically conductive Heavy

7 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.

8 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.

9 Types of Pressure Atmospheric: the pressure applied to the surface by the Earth’s atmosphere (14.7 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

10 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

11 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

12 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

13 Fire Stream Production 4 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?)

14 Fire Stream Production 4 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?)

15 Fire Stream Production 4 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.

16 Fire Stream Production 4 basic elements: (cont.)
Trained Personnel: The best supply, apparatus, and equipment will not produce effective fire streams without well trained personnel.

17 Sizes & Types of Fire Streams Fire 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.

18 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.

19 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

20 Types of Nozzles Solid Stream Nozzles Fog Stream Nozzles
Handline Nozzles Master Stream Nozzles Special Purpose Nozzles

21 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

22 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

23 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)

24 C = Coefficient specific to hose construction
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.

25 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

26 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

27 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

28 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

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