ADS Environmental Services FlowShark HV QR 775005 A2 - Manual (Page 9)

ADS FlowShark HV O&M Manual 9
System Overview
The portable, battery-powered FlowShark HV determines peak flow velocity through
pulse Doppler measurement. A piezoelectric crystal on the sensor transmits
ultrasonic bursts (signals) of a known frequency in rapid succession into the flow for
reflection off existing particles. The FlowShark HV evaluates the echos returned
within a defined time to determine the distances from the sensor to the particles based
on the reflected signals. Analyzing and evaluating the displaced frequencies from the
signals and compensating for the temperature of the flow provides a consistent peak
velocity measurement.
FlowShark HV components – control unit (left) and sensor (right)
Measuring velocity using the Doppler principal requires the presence of scattered
particles, such as air or solid particles, in the flow. To ensure detection, a scattered
particle must be larger than 0.02 inches (0.5 mm) in diameter and occur within flow
containing solids greater than 100 parts per million per volume unit.
v =
∆f
∆f = f
E
- f
S
Where,
∆f = Doppler frequency
f
S
= frequency emitted by sensor
f
E
= frequency displaced by velocity of particles in the flow
C = speed of sound in the flow