MFD BIT
Terms
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- Define a fire stream
- A stream of water or other extinguishing agent after it leaves a fire hose and nozzle until it reaches the desired point
- Streams are influenced by
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+Operating Pressure
+Nozzle adjustment
+Nozzle design
+condition of orifice
+velocity, gravity, wind, friction with air - Physical states of water
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+solid: -32 degrees
+liquid: -32 to 212 degrees
+gas: Above 212 degrees - Expansion capability when converted to steam
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+Cools fire by driving heat and smoke away
+Steam prudced aids in smothering and reduces oxygen
+Can cause injuries to firefighters and occupants - Ways water extinguishes
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+Cooling
+Smothering: Obsorbs heat and dilutes oxygen. coverts liquid to a gas - Surface area
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+Same principle as surface area to mass ratio
+Small droplets of water VS large solid stream of water - Why Water
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+Available and inexpensive
+Good heat obsorption
+Water to steam requires lots of heat
+Greater the water surface are the faster it obsorbs heat - Pressure Loss/Gain
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Friction loss: Total +Friction loss: pressure lost while forcing water through pipes, fittings, hose and adapters
+Elevation: Posistion of nozzle in relation to the pumping apparatus - Reason for pressure loss
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+Damage Couplings
+Kinks or bends
+Elevation
+Hose diameter/Length - Water Hammer
- Closing all nozzles and valves slowly
- Fire streams classified by size
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+Low Volume streams: Discharge less than 40gpm
+Handlines: Discharge 40-350GPM fed by 1 1/2 to 3 inch
+Master streams: Discharge more than 350 GPM fed by
2 1/2 to 3 inch supply lines - Fire Streams by characteristics
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+Pressuring device (pump)
+hose
+Agent (water)
+Nozzle - Solid Stream
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+Smooth Bore Nozzle:
Mfd Handlines; 7/8 and 1 1/8
at 50 psi
Master streams, deluge sets, and water towers at 80 psi.
1 1/4 to 2inch - Solid advantages
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+Better visibility
+Greater Reach
+Reduce nozzle pressure
+Greater penatrating power
+Less Likely to disturb thermal balance - Solid Disadvantage
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+No Pattern selection
+Less heat obsorption
+Cannot be used for foam - Fog Stream patterns
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+Straight
+Narrow fog 15-45 degrees
+Wide fog 45-80 Degreea - Fog streams
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+Composed of small water droplets
+Absorbs large amount of heat
+Nozzle settings
-Straight stream
-narrow fog
-wide fog - Factors affecting reach of fog stremas
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+Gravity
+water Velocity
+Pattern selection
+Water droplet friction with air
+wind - Fog Advantages
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+High heat obsorption due to water surface exposure
+Aid in ventilation
+Adjustable GPM Settings
+Pattern Selection - Fog Disadvantages
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+Reach and Penetration
+susceptible to wind
+May contribute to fire spread, create heat inversion and cause steam burns to FF's when used improperly without adequate ventilation