Elkhart Brass Cobra 7250 EXM Monitor - Manual (Page 36)

36
MONITOR AND NOZZLE HYDRAULIC DATA
Interpreting Flow Data
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.
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.
ΔP
S
= H
F
+ ΔP
V
ΔP
S
= Total Static Pressure Drop
H
F
= Friction Loss
ΔP
V
= Velocity Pressure Loss