Mace HVFlo XCi, Product Manual

Page: 210 / 255

This real-time graph displays velocities captured by a sensor at a wastewater pump site. Pumped flows
typically exhibit graphs with a broader base than gravity flows.
A general rule of thumb, if a spectrum has low signal strength but gives a consistent velocity reading, then the
measurements should be accurate. However, if the spectrum has low signal strength and gives inconsistent
velocity readings or none at all, the site may be unsuitable for flow measurement with Doppler ultrasonic flow
sensors.
Very distorted signals such as that described in the diagram on the previous page may result from
interference to the velocity sensor by the build-up of debris or siltation.
In sites where there is an expectation of sedimentation, the velocity sensor should be mounted in a raised
position. In a full-pipe application, it is recommended that the sensor be mounted (or inserted) on the side of
the pipe to avoid sedimentation.
Similarly, in partially full pipes, the sensor may be offset from the invert of the pipe. In these instances, the
depth reading will need to be offset accordingly.
Covering the sensors with algae and other materials that are saturated generally does not affect the accuracy
of velocity readings. This is because saturated materials exhibit the same speed of sound as water.
MACE XCi devices include several signal processing features specifically designed to overcome anomalous
data produced by such phenomena as: aquatic life (fish, weeds, small invertebrates); surface waves
(produced by turbulence and wind); and background noise.
NOTE: It should always be remembered when examining real-time graphical data,
that settings within the unit itself can have a marked effect on the data displayed. The
configuration of the instrument should always be checked thoroughly before viewing
real-time data.
MACE XCi User Manual - 210 -