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11 Applications and functions
VEGAMET 861 • 4 … 20 mA/HART
58866-EN-200401
be output via a corresponding number of pulses on the relay/current
output (flow rate pulse). A sampling pulse can also be configured.
Every flume generates a different level of backwater depending on its
type and version. The specifications of the following flumes are avail
-
able in the instrument:
Predefined curves
A flow measurement with these standard curves is very easy to set
up, as no dimensional information of the flume is required.
•
Palmer-Bowlus flume (Q = k x h
1.86
)
•
Venturi, trapezoidal weir, rectangular flume (Q = k x h
1.5
)
•
V-Notch, triangular overfall (Q = k x h
2.5
)
Dimensions (ISO standard)
When selecting these curves, the dimensions of the flume must be
known and entered via the assistant. As a result, the accuracy of the
flow measurement is higher than with the specified curves.
•
Rectangular flume (ISO 4359)
•
Trapezoidal flume (ISO 4359)
•
U-shaped flume (ISO 4359)
•
Triangular overfall thin-walled (ISO 1438)
•
Rectangular flume thin-walled (ISO 1438)
•
Rectangular weir broad crown (ISO 3846)
Flow formula
If the flow formula of your flume is known, you should select this op
-
tion, as the accuracy of the flow measurement is highest here.
•
Flow formula: Q = k x h
exp
Manufacturer definition
If you use a Parshall flume from the manufacturer ISCO, this option
must be selected. This gives you a high accuracy of flow measure
-
ment with easy configuration.
•
ISCO Parshall flume
Flume
