2012981-001 rev. AB
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Figure 3 Constants Tab
3.2.1 Barometric
Pressure
Barometric Pressure (PSIA) is a floating point number that represents the barometric
pressure. Enter the current barometric pressure within the corresponding field.
3.2.2 Dp
Zero
Cutoff
Dp Zero Cutoff (In H20) is a floating point value that represents the lowest expected
non-zero differential pressure reading. A reading less than this value will cause the
value, 0.0, to be used for the differential pressure for flow rate and volume calculation.
The value, shown under the Current Values tab within the Flow Measurement
application, is filtered. To test this, use the following steps.
1)
Set the Dp Zero Cutoff value to the Dp reading value. A holding register used
for the Dp ensures that this is easy to test. A Dp transducer or Totalflow test box
can be used.
2)
Select the Current Values tab.
3)
Click the Re-read button. Verify the Diff. Pressure Value is equal to or greater
than the Dp Zero Cutoff.
To view information on how to test this feature, please refer to the Test section later in
this manual.
3.2.3 Orifice
Material
The Orifice Material field enables the user to make selections based on the type of
material used for the orifice plate. The current selections are Stainless or Monel. The
selection effects the orifice expansion factor (Fa). Changing this selection will effect
flow rate by a relatively small amount. These rate changes can be viewed within the
Current Values tab.
