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DepChief
01-02-2005, 07:59
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?

aspartz
01-02-2005, 13:04
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

DepChief
01-02-2005, 15:24
Well, to be fair, I did say "at the fire", so I did intend this equation to include friction loss.

keary
01-02-2005, 15:56
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

aspartz
01-02-2005, 23:12
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

ARFFormula
01-03-2005, 19:47
Can I use my cheet-sheet? :)

obxprnstar
01-04-2005, 22:25
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.

DepChief
01-05-2005, 09:30
Originally posted by obxprnstar
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.


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

obxemt
01-06-2005, 10:18
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

MEDIC1167
01-27-2005, 00:25
Until the guys upstairs stop screaming "More water dangit!!!"???