ADS Environmental Services FlowShark QR 775002 A4 - Manual (Page 29)

2-16 ADS FlowShark Manual
Sensors
The FlowShark flow monitor uses the sensors to gather raw flow
data. The ultrasonic and pressure depth sensors use independent
measurement techniques to collect information concerning the depth
of the flow. The Doppler velocity sensor gathers peak flow velocity
data.
A sewer system's hydraulics are much more stable and uniform in
the incoming pipe than in the manhole invert or outgoing pipe.
Therefore, the sensors mount to a stainless steel expandable ring or
stainless steel bands installed in the pipe upstream from the
manhole. Installing them upstream minimizes hydraulic effects and
erroneous data readings caused by foamy waters, flow waves, sewer
noise, non-laminar flow, and obstructions in the manhole.
Ultrasonic Depth Sensor
The ultrasonic depth sensor (ADS p/n 103262A-30), which mounts
at the crown of the pipe, transmits sound waves from the sensor face
to the surface of the flow. It then measures the time elapsed between
transmission and reception of the sound signal. The distance
between the sensor face and flow surface is the range. Based on the
elapsed time and the speed of sound, the monitor calculates the
depth of the flow by subtracting the range from the pipe diameter.
The monitor compensates for the speed of sound in the air using the
temperature recorded by one of two temperature sensors housed
within the ultrasonic depth sensor. The second temperature sensor
serves as a backup.