VI. M
ONITOR
& S
TREAM
S
HAPER
1. 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.
ǻ
P
S
= H
F
+
ǻ
P
V
ǻ
P
S
= Total Static Pressure Drop
H
F
= Friction Loss
ǻ
P
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.
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