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


  1. DepChief

    DepChief
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    Get Tous's Rope

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    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?
     

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  2. aspartz

    aspartz
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    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
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    Get Tous's Rope

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    Well, to be fair, I did say "at the fire", so I did intend this equation to include friction loss.
     
  4. keary

    keary
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    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
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    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. ARFFormula

    ARFFormula
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    Can I use my cheet-sheet? :)
     
  7. obxprnstar

    obxprnstar
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    Goth Lover

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    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.
     
  8. DepChief

    DepChief
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    Get Tous's Rope

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

    obxemt
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    Chaplain of CT

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    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
     
  10. MEDIC1167

    MEDIC1167
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    Until the guys upstairs stop screaming "More water dangit!!!"???