Engineers Boot Camp

Properties of Water
Water exerts .434 psi per ft. of depth regardless of the size or shape of the tank or vessel.
1 psi will lift water 2.304 ft.
Water weighs 8.33 lbs per gallon (fresh)
Water freezes at 32 degrees F.
Water boils at 212 degrees F. at sea level at a barometric pressure of 14.7 mm Hg.  (It will boil at room temp under a vacuum.)

Formulas
Friction Loss:  (CQ²L)
GPM Determination:  (29.7 * d² * Square Root of Pressure)
Nozzle Reaction (smooth bore) = 1.57 * d² * NP
Nozzle Reaction (Fog) = .0505 * GPM * Square root of Pressure

Foam Calculations
Rule for Matching: (Just as you must match your socks, you must also match your nozzle GPM to your Eductor GPM)
Pump the eductor not the nozzle
Do not exceed 60 - 70 % back pressure after the eductor.
Back Pressure Determination

Rules of Thumb
Add 5 lbs of  loss for every 10 ft. of increase in elevation
Subtract 5 lbs for every 10 ft. of decreased elevation
Pump all sprinkler systems at 150 psi.  (You never know how many heads have opened up or how the system was designed.)
Add 25 psi. to your calculations for standpipes
Add 25 psi to your calculations for Master Streams
Add 25 psi. to your calculations for Ladder pipes. (Do not add an additional 25 psi for the master stream at the end of the pipe.)
Pump all fog nozzles at 100 psi.
Pump all smooth bore hand lines at 50 psi.
Pump smooth bore master streams at 80 (know mnfg limits)

Smooth Bore Discharges (Hand Lines) in GPM
1"        tip  = 210 GPM @ 50 psi.
1 1/8" tip  = 265 GPM @ 50 psi.
1 1/4" tip  = 330 GPM @ 50 psi.


Smooth Bore Discharges (Master Stream) in GPM
1 1/4" tip = 415 GPM @ 80 psi.
1 3/8" tip = 500 GPM @ 80 psi.
1 1/2" tip = 600 GPM @ 80 psi.
1 3/4" tip = 815 GPM @ 80 psi.
2"      tip = 1065 GPM @ 80 psi.