Mace HVFlo XCi, Product Manual

Page: 206 / 255

NOTE: The above screen shot is an example of a real-time graph captured when the
stream is NOT flowing.
Interpreting real-time data
MACE XCi devices measure average stream velocity using Doppler ultrasonic technology. Anything moving
in the stream, which is acoustically reflective, may produce an echo and therefore a Doppler shift.
Acoustically reflective particles include:
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Suspended solids;
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Bubbles, eddies and waves;
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Larger particles such as, sand, leaves and pebbles.
When selected in , the user can display a real-time graph of the velocity spectrum received by the
velocity sensor. The histogram you see in real-time data is a composite spectrum of the velocities of the
stream flow as well as various other factors explained below.
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The graph is two dimensional (X-Y).
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The X-axis is the velocity (range set by user).
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The Y-axis (vertical) is the strength of the signal received by the processing electronics from each
velocity sensed in the spectrum.
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Several thousand data points are plotted to give the composite graph.
MACE XCi devices measure several thousand data points and compute an average velocity. The flow is then
calculated using the formula:
Q=V x A
where: Q= Quantity, V= Stream velocity and A= Cross-sectional area.
Users of MACE XCi devices can use the real time graph to determine the correct positioning of the velocity
sensor by assessing the shape of the curve and the signal strength. The following graph is an example of a
spectrum that was received from a full pipe irrigation flow. Under field conditions, several factors can affect
the spectrum without affecting the performance or accuracy of the velocity sensor.
Armed with an understanding of these factors and some field experience, the operator can vary the position
of the sensor and the system settings to correct site induced errors in the velocity readings.
MACE XCi User Manual - 206 -