Blue-White Sonic-Pro Hybrid Ultrasonic Flowmeters - Manual (Page 49)

The rate of fluid flow in the pipe is measured by the flowmeter many times per second.
To improve accuracy and the stability of the display, these measurements are averaged
over a configurable time and new values are presented to the display at a configurable
rate.
The averaging algorithm used is the Simple Moving Average (SMA), which is “the un-
weighted mean of the previous n data points”. Rather than selecting n, you can configure
Flow Rate Averaging to be performed over some number of seconds. All measurements
taken during that period are averaged to form each displayed flow reading. The
averaging time can be configured by selecting a value of 0.25, 0.5, 1, 2.5, 5 or 10 seconds
.
The time period at which the flowmeter display updates is configurable in Setup Mode
to 0.25, 0.5, 1, 2.5 or 5 seconds. Each time the display is updated, the SMA of the flow
measurements is computed and written to the display as described above. Setting the
display update period to be much greater than the averaging time may not make sense.
For example, averaging over one second and updating the display every five seconds will
mean that 80% of the measurements taken will never contribute to a displayed flow
value. The flowmeter does not prohibit or warn against such inconsistent settings.
The units of measure for flow rate can be configured in Setup Mode. The units in which
both volume and time are expressed can be selected from appropriate options. A custom
unit of measure for volume can be selected by specifying the size of one U.S. Gallon in
that unit.
may wish to suppress the display of very small flow values. The can configure a
Low Flow Cutoff value so that if the flowmeter would display a value smaller than this,
it displays zero instead. By symmetry, the user can configure a High Flow Cutoff value.
If the flowmeter would display a value larger than this, it displays the cutoff value
instead. Note that these values are entered in the Setup Mode as numbers and must be
given in the units of measure configured for flow rate display. If at some later time
change the units of measure, the cutoff values will upon inspection appear to have
changed, but will represent the same flow rate, just in different units of measure.
Should observe that the flowmeter’s readings are consistently in error by a
measurable amount, it is possible to correct this situation by configuring a Scaling
Offset. The Factory Default for this is 1.00. The flowmeter will accept values from 0.00
to 9.99. Every measurement taken by the flowmeter is multiplied by this number before
further processing. Flow rate and flow total will therefore be affected. The Scaling
Offset is part of a Configuration Set, so it does not apply to the flowmeter as a whole
and should be set as required in each numbered Set.
If flow measurement is restarted (by passing through the Startup State, for whatever
reason), then all prior measurements previously stored for the purpose of averaging are
discarded. A new average is computed using only new flow measurements and they begin
to arrive after the restart. The display area in which the flow rate appears is blanked
(made empty) until the first measurement is made and the first average is computed.
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7.1.1
Flow Rate
Measurement
Page 49 Sonic-Pro
Industries, Ltd. Industries, Ltd.
ProSeries
by Blue-White Ind.
TM