Elkhart Brass Scorpion 8394-04 - Manual (Page 23)

20
VIII. M
ONITOR
& N
OZZLE
H
YDRAULIC
D
ATA
The following graphs offer the pressure losses for the monitor (and other devices) in terms of
Total Static Pressure Drop. This Total Static Pressure Drop can be found by measuring the
difference between the static inlet pressure and the static outlet pressure. The static pressure
at either of these points can be found using a simple pressure gauge. An illustration of this
method can be seen below.
In mathematical terms, the Total Static Pressure Drop is the change in Velocity Pressure plus
Friction Loss. The change in Velocity Pressure results from the change in velocity of water
caused by the change in the cross section of a waterway. Friction Loss results from the drag
and sidewall interference of the water through a device. A simple equation can be seen
below.
ΔP
S
= H
F
+ ΔP
V
ΔP
S
= Total Static Pressure Drop
H
F
= Friction Loss
ΔP
V
= Velocity Pressure Loss
In the firefighting industry, the terms Total Static Pressure Drop and Friction Loss tend to be
used interchangeably. However, these are significantly different measurements. This
misconception could ultimately lead to lower than anticipated performance from equipment.
When designing a system and determining performance, Total Static Pressure Drop is
the value that should always be used. The Friction Loss curve is also supplied in order to
make a comparison with competitor products that may only supply Friction Loss curves. If
there are any further questions regarding this matter, please contact Elkhart Brass.