Siemens SITRANS L - Measurement Setup - Flow

Installing/mounting
4.4Measurement setup - Flow
Foam generation
Through the action of filling, stirring and other processes in the vessel, compact
foam can form on the medium surface, damping the emitted signals considerably.
If foams lead to measurement errors, you should use transmitters with guided radar.
4.4 Measurement setup - Flow
In general, the following must be observed while mounting the device:
• Mounting the transmitter on the upstream or inlet side
• Installation in the centre of the flume and vertical to the liquid surface
• Distance to the overfall orifice or Venturi flume
• Min. distance to the max. height of damming for optimum accuracy: 250mm
(9.843in)
1
Detailed project planning data can be found at the channel manufacturers and in the
technical literature.
The following examples serve as an overview for flow measurement.
Rectangular overfall
1
Overfall orifice (side view)
2
Upstream water
3
Tailwater
4
Overfall orifice (view from tailwater)
Figure4.9 Flow measurement with rectangular flume: h
max.
= max. filling of the rectangular
flume
1
At smaller distances the measuring accuracy is reduced, see "Technical data".
SITRANS LR120
Operating Instructions, 08/2020, A5E49829026
17