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Quiz

Discussion in 'Firefighter/EMS Talk' started by DepChief, Jan 2, 2005.

  1. DepChief

    DepChief Get Tous's Rope

    4,908
    0
    Nov 27, 2004
    Outer Banks, NC
    You lay 250 feet of 2 1/2 hose from your engine to a dry standpipe on ground level of an apartment building. On the fifth floor you run another 100 feet of 2 1/2 from the standpipe connection, up 2 more flights of stairs to a gated wye. From the wye, you run 150 feet of 1 1/2 hose to a fog nozzle at the fire. To get 100 lbs. pressure at the nozzle, what will your pump pressure be?
     
  2. aspartz

    aspartz

    3,281
    133
    Oct 19, 2000
    Sandstone, MN 55072
    Flow rate?

    I'll take the easy answer -- static, flow rate = 0
    NP = 100
    lift = 7 floors = 70 feet = c. 35 psi.

    Pump pressure = 135 psi. :)

    Now if you plan on opening those nozzles and friction becomes an issue and the math gets more complicated...

    ARS
     


  3. DepChief

    DepChief Get Tous's Rope

    4,908
    0
    Nov 27, 2004
    Outer Banks, NC
    Well, to be fair, I did say "at the fire", so I did intend this equation to include friction loss.
     
  4. keary

    keary

    16
    0
    Mar 2, 2002
    Western Hills
    I figure about 225psi PDP. I did not include any FL for the standpipe nor did I figure any FL for the gated wye.

    Keary
     
  5. aspartz

    aspartz

    3,281
    133
    Oct 19, 2000
    Sandstone, MN 55072
    Assuming 2 handlines from the wye, 125 gpm each:

    All flow loss is from Akrons data sheets -- my slide rule is at the hall:

    250' 2.5" hose, 250 GPM total: 13 psi/100' -- 32 psi
    50' elevation -- 1 psi/2' -- 25 psi
    standpipe friction loss is negligible -- 0 psi
    100' 2.5" hose, 250 GPM total: 13 psi/100' -- 13 psi
    20' elevation - 1 psi/2' -- 10 psi
    Wye -- some say 0 psi if less than 350 gpm, I was taught 5 psi
    150' 1/5" hose, 125 GPM: 38 psi/100' -- 57 psi

    32
    25
    0
    13
    10
    5
    57
    ---
    147 psi lost

    EP = 100 + 147 = 247.

    If you use 1.75 handlines the loss drops 21 psi.
    If you use only one handline on 1.5" hose the loss drops 35.

    ARS
     
  6. obxprnstar

    obxprnstar Goth Lover

    1,009
    0
    Jan 8, 2003
    Zombie Patrol
    I shotgun guessed 190, but I have the fire/rescue field guide in my turnouts, and it is opened to the friction loss cheat sheet. @ my old FD, I printed that thing up along with friction loss formulas and taped it to the inside of the engineer compartment door.
     
  7. DepChief

    DepChief Get Tous's Rope

    4,908
    0
    Nov 27, 2004
    Outer Banks, NC

    Your old fire Dept made your engineer sit in an compartment?
    Yeah, I think I remember that dept.
     
  8. obxemt

    obxemt Chaplain of CT

    DC, sometimes you just have to get down to basics first:

    "Throttle up upon cavitation. Trying to suck more water through flat 5-inch LDH is extremely effective for water delivery."
    -- Avon F.D. SOP Manual
     
  9. MEDIC1167

    MEDIC1167 Millennium Member

    61
    0
    Apr 30, 1999
    Northern CT
    Until the guys upstairs stop screaming "More water dangit!!!"???