Measurement Setup - Flow - Siemens SITRANS L Operating Instructions Manual

Foam generation
Through the action of filling, stirring and other processes in the vessel, foams which
considerably damp the emitted signals may form on the medium surface.
If foams lead to measurement errors, you should use transmitters with guided radar.
4.4

Measurement setup - Flow

Mounting
In general, the following must be observed while mounting the device:
•
•
•
•
•
Flume
Predefined curves:
A flow measurement with these standard curves is very easy to set up, as no
dimensional information of the flume is required.
•
•
•
Channel with dimensions according to 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.
•
•
•
•
•
•
Flow formula:
1
The value given takes into account the block distance. At smaller distances, the measuring accuracy is reduced, see ""Technical
data".
SITRANS LR120, HART
Operating Instructions, 10/2023, A5E49829026
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
Distance to the max. height of the orifice or flume for optimum accuracy:
> 250 mm (9.843 in)
Requirements from approvals for flow measurement, e.g. MCERTS
Palmer-Bowlus flume (Q = k x h
Venturi, trapezoidal weir, rectangular flume (Q = k x h
V-Notch, triangular overfall (Q = k x h
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)
1
1.86
)
2.5
)
Installing/mounting
4.4 Measurement setup - Flow
1.5
)
15