Determining Flow With Pre-Piped Monitors; Stream Trajectory Data - Task Force Tips MASTERSTREAM Series Instructions For Safe Operation And Maintenance
Deluge nozzles with automatic pressure control
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3.3 DETERMINING FLOW WITH PRE-PIPED MONITORS
The simplest procedure to determine flow with automatic nozzles is with a flow meter. If a flow meter is unavailable, then the flow may
be estimated using pressure loss data between the nozzle and an in-line pressure gauge at the pump or considerably upstream from
the nozzle. Data is taken with a smooth bore nozzle and handheld pitot gauge. Note: Equations assume no substantial change in
elevation between in-line pressure gauge and nozzle.
Step1: Determine flow of smooth bore nozzle.
Flow water with a smooth bore nozzle and record the nozzle's size, pitot pressure and in-line pressure gauge reading. The smooth
bore nozzle's flow is calculated from the Freeman formula:
Where:
F
= 29.71 for English units (GPM, INCHES, PSI)
F
= .667 for metric units (LPM, MM, BAR) Note: 1 BAR=100 KPA
Q
flow in GPM (or LPM)
smooth
D
exit diameter in INCHES (or MM)
P
pitot pressure in PSI (or BAR)
pitot
Step 2: Find pressure loss constant.
Using the results from step 1, use the following equation to calculate the pressure loss
constant between the in-line pressure gauge and the nozzle:
Where:
C
piping pressure loss constant in GPM /PSI (or LPM /BAR)
P
in-line pressure gauge reading in PSI (or BAR)
inline
Step 3: Calculate flow with automatic nozzle.
Using the pressure loss constant from step 2 and the following equation, the
flow with an automatic nozzle can be calculated for your particular installation.
Where:
Q
automatic nozzle flow in GPM (or LPM)
auto
P
nominal nozzle operating pressure in PSI (or BAR)
auto
Mount a graph or table of the results adjacent to the in-line pressure gauge.
Deliver any desired flow by adjustment of pump pressure.
3.4 STREAM TRAJECTORY DATA
Figures 4A, 4B and 4C give the stream trajectory for the Masterstream Series nozzles at various flows.
Notes on trajectory graphs:
• Graphs show approximate effective stream trajectory at 30 degrees elevation in no wind conditions. Distance
to last water drops approximately 10% farther.
• Trajectories shown are for water. The addition of foam is expected to decrease the reach by 10%.
• Tail or head winds of 20 MPH (30 KPH) may increase or decrease the range approximately 30%.
• Stream trajectory of Masterstream 4000 based on "The Trajectories of Large Fire Fighting Jets" by A.P . Hatton
and M.J. Osborne, Reference: "The International Journal of Heat and Fluid Flow", Vol 1 No 1.
0
10
20
80
70
MASTERSTREAM 1250, 100 PSI (7 BAR, 700 KPA )
60
50
40
30
20
10
0
0
20
40
60
©Copyright Task Force Tips, Inc. 1999-2005
2
METERS
30
40
50
A
B
C
80
100
120
140
160
HORIZONTAL DISTANCE (FEET)
FIG 4A - Masterstream 1250 Stream Trajectory
2
Q
60
70
80
D
E
180
200
220
240
260
Q
= F x D
smooth
2
Q
C =
P
in-line
=
(P
auto
in-line
GPM
90
CURVE
FLOW
A
B
20
C
D
1000
E
10
LPM
FLOW
CURVE
A
1100
B
1500
0
C
1900
280
300
D
3000
E
3800
LIM-030 October 12, 2005 Rev 05
2
P
pitot
smooth
- P
pitot
- P
)C
auto
LBS
REACTION
300
150
400
200
500
260
800
400
510
KGF
REACTION
70
90
120
180
230
7
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