Endress+Hauser prowirl 77, Руководство по эксплуатации

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3.2 Installation
A vortex flowmeter requires a fully developed flow profile as a prerequisite for
measuring volume accurately. The following points must therefore be noted when
mounting the Prowirl 77 in the pipeline.
Pipe inner diameter
When ordering, ensure that the nominal diameter and pipe schedule (DIN/ANSI/JIS)
are correct, since calibration of the flowmeter and therefore the achieveable accuracy
of the measuring point are dependent on these specifications.
Inlet and outlet sections
To ensure an undisturbed flow profile,
the vortex flowmeter should be mounted
upstream of any flow disturbances such
as pipe elbows, reducers or valves,
otherwise the longest possible section of
piping should be between the distur-
bance and the flowmeter. The figures on
the left show the
minimum section of
straight piping downstream of the distur-
bance as multiples of the nominal diame-
ter of the pipe in DN. If two or more flow
disturbances are located upstream, then
the longest inlet section recommended
should be used.
There must also be a straight outlet
section of sufficient length downstream
from the flowmeter to ensure that the vor-
tices are properly developed.
Flow conditioner
With limited space and large pipes, it
is not always possible to use the inlet
sections given above. In such cases the
specially developed perforated plate flow
conditioner (see page 53 ff.) can be fitted
as shown on the left. The flow conditioner
is held between two piping flanges and
centred with the flange bolts. It reduces
the length of the inlet section downstream
from flow disturbances to 10 x DN while
maintaining high accuracy measurement.
Inlet Outlet
Reducer
Expander
90° elbow or T-piece
2 x 90° elbows, 3-dimensional
2 x 90° elbows
Control valve / on-off valve
with flow conditioner
ba037
y
0
6
Fig. 3
Inlet and outlet piping
requirements
3 Mounting and Installation Prowirl 77 PROFIBUS-PA
10 Hauser