Burkert 8136 Mode D'emploi page 24

Flow measurement with
rectangular flume
LEVEL TRANSMITTER 8136 • 4 ... 20 mA/HART - two-wire
Constructional requirements on the bypass pipe:
•
Material metal, smooth inner surface
•
In case of an extremely rough tube inner surface, use an inserted
tube (tube in tube) or a radar sensor with tube antenna
•
Flanges are welded to the tube according to the orientation of the
polarisation
•
Gap size with junctions ≤ 0.1 mm, for example, when using a ball
valve or intermediate flanges with single pipe sections
•
The antenna diameter of the sensor should correspond to the
inner diameter of the tube
•
Diameter should be constant over the complete length
4.6 Measurement setup - Flow
The short examples give you introductory information on the flow
measurement. Detailed planning information is available from flume
manufacturers and in special literature.
3 ... 4 h
max
90°
2
2
Fig. 19: Flow measurement with rectangular flume: d
sensor (see chapter "Technical data"); h
flume
1 Overflow orifice (side view)
2 Headwater
3 Tail water
4 Overfall orifice (view from bottom water)
In general, the following points must be observed:
•
Install the sensor on the headwater side
•
Installation in the centre of the flume and vertical to the liquid
surface
•
Distance to the overfall orifice
•
Distance of orifice opening above ground
•
Min. distance of the orifice opening to bottom water
•
Min. distance of the sensor to max. storage level
1
≥ 50 mm
3
3
= max. filling of the rectangular
max.
4 Mounting
90°
4
= min. distance of the
min.
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