ADS Environmental Services IETG FlowHawk QR 775012 A4 - Manual (Page 63)

3-4 IETG FlowHawk Manual
Investigating Site Characteristics
Before beginning installation activities, conduct a thorough
investigation of hydraulic and site conditions.
Flow Hydraulics
The hydraulics of a site directly affect the monitor's ability to
accurately measure flow depth and velocity. The following
characteristics indicate when a site exhibits hydraulic conditions
favorable for effective flow monitoring activities:
 Smooth Flow with Central Peak Velocities The
potential site should exhibit minimal ripples or waves. Choppy
or foamy flow will adversely affect sensor accuracy. Bulging
pipe joints, upstream curves, or upstream merging of pipes can
contribute to choppy surfaces and off-center peak flow
velocities.
 Absence of Significant Silt Buildup at Pipe Bottom
Silt present at an otherwise favorable site must be accounted
for to obtain accurate flow measurements. The mounting ring
or band might require rotation to position (up to 15 degrees)
the Peak Combo Sensor up the side of the pipe and out of the
silt. (Refer to Installing the Ring in the Pipe on page 3-25.)
 No Evidence of Surcharging Debris present on ladder
rungs or joints in the manhole may indicate that the site
experiences surcharging. If this occurs on a regular basis,
consider finding an alternate location for monitoring the flow.
 Relatively Quiet Pipe A monitoring point in a pipe
experiencing loud noises, such as active drop connections, can
adversely affect the accuracy of air ultrasonic depth
measurements.