5-9
Rerange
The Range Values command sets the 4 and 20 mA points (lower and
upper range values). Setting the range values to the limits of expected
readings maximizes flowmeter performance; the flowmeter is most
accurate when operated within the expected pressure ranges for your
application. In practice, you may reset the flowmeter range values as
often as necessary to reflect changing process conditions.
NOTE
Regardless of the range points, the ProPlate will measure and report all
readings within the digital limits of the sensor. For example, if the 4
and 20 mA points are set to 0 and 10 in H
2
0, and the flowmeter detects
a pressure of 25 in H
2
0, it digitally outputs the 25 in H
2
0 reading and a
250% percent of span reading. However, there may be up to ±5.0%
error
associated with output outside of the range points.
You may use one of three methods to rerange the flowmeter. Each
method is unique; examine all three closely before deciding which
method to use.
The calculation used to rerange the ProPlate output is as follows:
New DP Range
For instance, if the ProPlate is currently setup as follows:
ProPlate Information
Model: ProPlate
Serial#: 222222.2
Max Flow @ 20 mA: 15 GPM
Max DP @ 20 mA: 30 in H
2
O
And then you want to rerange 20 mA to 20 gpm, the
calculation is as follows:
New DP Range
The ProPlate can now be reranged to the following new settings:
4 mA = 0 in H
2
O
20 mA = 53.3 in H
2
0
QHZ4PD[
ROG4P D[
()
2OG'35DQJH
()
=
LQ+
2 LQ+
2
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