What’s the best size for an “attack line?” What factors are the highest priority on your department? • Maximum flow • Maximum mobility • Speed-How fast and how much • Ease of deployment and pickup • Personnel available • Water supply available 11/2” ? 1” ? 13/4” ? 2” ? 21/2” ?
Pump Pressure for 125 GPM 1” 452 psi 150 feet 156 psi 1½” 150 feet 1¾” 136 psi 150 feet 105 psi 2½” 150 feet (100 psi nozzle pressure)
Larger Attack Hose Lines Equal... • Higher initial attack flow capability • Less friction loss • Longer hose lay capability • Using more of pumps capacity Higher Flows Equal... • Quicker fire knockdown • Personnel spend less time in “combat” • More lives saved • More property saved
Fire Ground Hydraulics? 175? Pump Pressure? 120? P.S.I.? Loss per 100 ft.? Hose Diameter? Elevation Loss? Device Loss? GPM? 200? 150? Nozzle pressure?
The Preconnect... The Preconnect is always the first line off The first two lines down fight most of our fires Can they handle most anything our department is “normally” going to fight?
The Pre-Con 150 Play 150’ of 1¾” @ 150 psi = 150 GPM Works “most” of the time It’s the easiest and most often practiced Simplifies pump operation (only one pressure works) But... is it the right choice, THIS time??
How will we handle 90% of our fires? I got it, Chief!! 90% of our fires result in 10% of our losses however, 10% of our fires result in 90% of our losses!
Will we count it as a great “save”...... or a futile training exercise?
ISO Ratings • Insurance Service Offices • Grading of fire department’s capabilitiesand equipment • For determining fire insurance premiums • Notan application rate formula
NFPA Water Supply Formulas • For pre-planning water supply • To determine total quantity of water needed • For a single structure • Or a group of buildings • Type of construction • Occupancy rating • Exposures • Refer to NFPA 1231 Suburban & Rural Water Supplies
Iowa State University Formula L = Length W = Width H = Height GPM = L x W x H 100 • Fire knockdown in 60seconds or less • Normally for enclosed areas • Can be used in pre-planning water requirements for a building or room
National Fire Academy Formula for Quick Size-up... GPM = L x W 3 • Fire knockdown in 30 seconds or less • Multiply GPM by number of floors involved • Can be adjusted for actual % of involvement • Choose appropriate size & number of attack lines based on GPM required & other situational factors L = Length W = Width
Iowa State University Formula Developed in the 1950’s Fire load mostly organic materials Ventilation tactics utilized less often Attack often from outside due to lack of breathing apparatus, protective clothing, & other safety equipment National Fire Academy Formula Current information Fire load contains more synthetics Synthetics produce more BTU’s per pound & increase smoke & noxious gas output Ventilation and interior attack tactics utilized Increased water flow required due to increased heat output Formulas & Fire Loading of Structures...