18
4 Mounting
VEGAPULS 11 • Two-wire 4 … 20 mA
58350-EN-221027
•
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.
Alternatively, you can also take over Q/h table values provided by the
manufacturer here.
•
ISCO-Parshall-Flume
•
Q/h table (assignment of height with corresponding flow in a table)
Tip:
Detailed project planning data can be found at the channel manufac-
turers and in the technical literature.
The following examples serve as an overview for flow measurement.
3 ... 4 h
max
90°
2
3
1
h
ma
x
≥ 2 x
h
ma
x
90°
4
2
3
≥ 250 mm
(9.84
")
≥ 250 mm
(9.84"
)
Fig. 16: Flow measurement with rectangular flume: h
max.
= max. filling of the
rectangular flume
1 Overfall orifice (side view)
2 Upstream water
3 Tailwater
4 Overfall orifice (view from tailwater)
Rectangular overfall
