Hydraulic Formulas
Formulas
Volume = L x W x H
Gallonage = Volume x 7.481
Volume of a circle = Pi X R2 x H
Quantity = Flow/100
Acre Foot = 300 x 150 x 1 x 7.481
Flow = 30 x D2 x square route of ‘P’
Friction Loss = 2Q2 (For 2 ½’’ hose)
Engine Pressure = FL + AP + NP + /-EL + Residual
1 Gallon of water weighs = 8.34#
1 Cubic Foot of water weighs = 62.5# (7.481 gallons)
1 Foot deep water = psi (round to .5psi)
Nozzle Pressure
Fog=100 psi
SS Hand Held =50 psi
MS=80 psi
Hand Held SS GPM Rates
1 ” = 200 GPM
1 1/8” = 250 GPM
1 1/4” = 300 GPM
FL in Devices
Master stream devices = 20 psi
Wyes/Siamese=15 psi
StandPipes=25 psi
EL MS up to 50’
4’’=80 psi
6’’=35 psi
Add 5 psi for each additional floor above 50’
L= Length
W= Width
H= Height
EP=Engine Pressure
FL=Friction Loss
EL=Elevation
NP=Nozzle Pressure
Q=Quantity
SS=Straight Stream
MS=Master Stream
F=Flow
D=Diameter
P=Pressure
AP=Appliances
Hose Conversion Factors
1’’= x 86
1 ½’’= x 13
1 ¾’’= x 6
2’’= x 3
2 ½’’= x No conversion factor
3’’= x .4
4’’= x .09
5’’= x .03
Sprinkler Discharges
.5 x P +15
Always Pump Sprinkler System at 150 psi
Rule of Eights for Smooth Bore Master Streams
TAKE THE TIP SIZE (1 1/4”), AND DROP OFF THE 1 AND CONVERT THE
FRACTION TO EIGHTHS (1/4 = 2/8), NEXT, DROP THE DENOMINATOR (8),
THEN ADD 2 TO THE NUMERATOR (2 + 2 = 4), MULTIPLY THE SUM BY
100 TO GET FLOW IN GPM
1 ¼” or 1 2/8” = 400 GPM
1 3/8” = 500 GPM
1 ½” or 1 4/8” = 600 GPM
1 5/8” = 700 GPM
1 ¾” or 1 6/8” = 800 GPM
1 7/8” = 900 GPM
2” or 1 8/8” = 1000 GPM
DROP TEN METHOD
THE DROP TEN METHOD IS USED FOR DETERMINING FL IN 2 1/2” HOSE
WHEN YOU KNOW THE FLOW OR GPM.
EXAMPLE: USING 600 GPM
GPM = 600 DIVIDED BY 100 = 60
DROP 10
- 10
FRICTION LOSS = 50 PSI
PER 100” OF 2 1/2” HOSE
Solid stream exact
GPM = 29.7 x d2 x √NP
Solid Master streamRule of 8s
[tip size > 1 x/8] (X+2)x 100 = gpm
e.g. 1 ½ 4/8 x=4 (4+2)= 6 = times
100gpm = 600gpm
Solid streamHandline
1” 200 1 1/8 250 1 ¼ 300
Friction Loss
• Old
• (2 x Q2) + Q = FL/100’ (2.5”)
• (1½”=10)(1¾”=6)(2”=3)(3”=.4)
• (3½”=.18)(4”=.1)(5”=.03)
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IFSTA
C x Q2 x L = FL/100’
(1½”=24)(1¾”=15.5)(2”=8)
(2½”=2) (3”=.8)(3½”=.34)
(4”=.2)(5”=.08)
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Fire ground
[(GPM x HS)/10] – 10 FL/100’
(1”=8)(1½”=4)(1¾”=3)
(2”=2)
(2½”=1)
Master stream big hose
[Q x (Q-1)] / N = FL /100 ft.
N= 1 (3”), 4 (4”), 12 (5”)
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Nozzle reaction
•
solid
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•
Fog
•
NR=1.57 x d2 x NP
NR = 0.0505 x Q x
√NP
Appliance FL
• Appliance >350gom
• 10 hand line
• 20 stand pipe
• 25 master (deck gun 0-60)
• 50 ladder pipe (45-90)
• 0 single inlet Portable
Monitor
• 25 multiple inlet Portable
Monitor
Nozzle Pressures
Solid stream handline = 50psi
Solid stream master stream = 80 psi
Conventional fog streams = 100psi
Pumping Sprinklers
100 if nothing showing
150 if water flowing
Manufacturer’s Table low pressure
75psi fog
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GPM
95
125
150
175
200
FL/100’
10psi
20psi
30psi
40psi
50psi
Water
 8.33 lbs. /gallon
 62.5 lbs./ cubic foot
 7.49 gallons / cubic foot
 231 cubic inches / gallon
 1728 cubic inches / cubic foot
 .434 psi / ft. elevation
o 0.5psi / ft. fireground
o 5 psi / story in multistory
Volume formulas
 Rectangle container volume = L x
HxW
 Cylinder Volume Π R2 H
 Cylinder Volume = 0.7854 x D2 x
L
Available water
Static – residual x 100 = %
Static
0-10% 3 like lines, 11-15% 2 like lines,
16-25% 1 like line, >25 some water
or
Static – residual = X
First digit of Static (FDS) x1 > X 3 like
lines
FDS x2 > X 2 like lines
FDS x3 > X 1 like line
FDS x4 > X some water