ADS Environmental Services FlowShark QR 775002 A4 - Manual (Page 31)

2-18 ADS FlowShark Manual
Data Scrubbing
Flow conditions and internal structures introduce many potential
obstacles to obtaining accurate flow data in sewer systems and
manholes. Some of these obstacles may include noise, turbulent or
wavy flow, a foamy flow surface, side connections, rungs, broken
pipes, or drop connections.
To minimize these effects, ADS uses a process of eliminating
erroneous data called data scrubbing. Initial data scrubbing occurs
routinely in the following way as the monitor takes readings:
 The monitor fires each sensor pair and averages the multiple
readings.
 The monitor discards the clearly erroneous readings (i.e.,
readings well outside the range of the majority of the readings).
 The monitor records the percentage of all acceptable readings
used to arrive at the average value.
Secondary scrubbing also can occur during data collection from the
monitor to the analyst's PC using the Profile software. Refer to the
Profile User's Guide (950015**) for more information.
Pressure Depth Sensor
The pressure depth sensor (ADS p/n 3704-00**-35/40) typically
mounts at the bottom of the pipe. While the ultrasonic depth sensor
can only measure depths up to slightly below full pipe capacity, the
pressure depth sensor can measure depths greater than a full pipe
that might extend up into the manhole (surcharges). The FlowShark
supports pressure sensors with ranges from 0-5 (11.5’), 0-15 (34.5’),
and 0-30 (69.0’) PSI.
The pressure depth sensor contains a differential pressure
transducer that transmits an output voltage corresponding to the
difference between the water pressure and the air pressure in the
sewer. It measures water pressure through a port on the underside of
the sensor and air pressure using an integral vent tube running to the
top of the manhole. The monitor calculates the depth of the flow by