APG IRU-9400 user manual - Manual (Page 9)

Rev. B1, 3/10 IRU Series
9
Automation Products Group, Inc.
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Stand Pipe Mounting
Stand pipes are used to provide headroom
at the top of a tank when the target is
expected to come closer to the sensor
than the minimum blanking distance.
It’s very critical that the stand pipe be
installed perpendicular to the target. This
is especially important on longer range
applications. The pipe must have smooth
walls (no joints) and no burs or obstructions.
If possible, cut the end of the pipe at a 10°-
45° angle (see drawing). Use the largest
diameter pipe and shortest length possible. As a general rule, the diameter of the
pipe should be 1/2 the length. The pipe ID must remain the same through it’s
entire length.
Stilling Pipe Mounting
Stilling pipes provide access to difficult
areas and help eliminate problems with
foam. The pipe must have smooth walls (no
burs or joints). Because the sound waves
will concentrate and propagate down the
inside walls of the tube, any irregularities
on the tube walls may produce echo returns
and cause false readings. Stilling pipes are
limited to liquid targets that will not leave
heavy deposits on the tube walls. Because
the sound waves are confined inside the
pipe, it is usually necessary to greatly
reduce the sensors sensitivity and pulses
settings. A vent hole must be provided at
the top of the pipe. Be sure to keep the
vent hole inside of the blanking area.
Top of Tank
Stand Pipe
10-45
o Cut
(when possible)
Vent Hole