ADS Environmental Services FlowShark QR 775003 A2 - Manual (Page 54)

2-12 ADS FlowShark IS Manual
Sensors
The FlowShark IS flow monitor uses various sensors to gather raw
flow data. The IS 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.
IS Ultrasonic Depth Sensor
The IS ultrasonic depth sensor (ADS p/n 106186A-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
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.