Flexim PIOX S72 Series, Руководство по эксплуатации

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4 Basics – flow measurement
4.4 Undisturbed flow profile
PIOX S72*
2022-05-15, UMPIOX_S72xV1-9EN
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Observe the following notes on the selection of the measuring point:
Horizontal pipe
Select a measuring point where the transducers can be mounted laterally on the pipe, allowing the sound waves to
propagate horizontally in the pipe. Thus, solid particles on the bottom of the pipe or gas bubbles in the upper part are
prevented from influencing the propagation of the signal.
Vertical pipe
Select the measuring point at a pipe section where the fluid flows upward. The pipe has to be completely filled.
Free inlet or outlet pipe section
Select the measuring point at a pipe section where the pipe cannot run empty.
4.4 Undisturbed flow profile
Some flow elements (e.g., elbows, valves, pumps, reducers) distort the flow profile in their vicinity. The axisymmetrical
flow profile in the pipe needed for correct measurement is no longer given. A careful selection of the measuring point helps
to reduce the impact of disturbances.
It is most important that the measuring point is chosen at a sufficient distance from any disturbances. Only then it can be
assumed that the flow profile in the pipe is fully developed. The use of the disturbance correction (see section 14.2.4)
allows a measurement even at smaller distances of min. 2 D.
The recommended straight inlet and outlet pipe lengths for different types of flow disturbances are shown in the following
table.
Fig. 4.8: Recommended transducer
mounting position (laterally) Fig. 4.9: Disadvantageous transducer
mounting position (on top)
Fig. 4.10: Recommended transducer
mounting position Fig. 4.11: Disadvantageous transducer
mounting position
Fig. 4.12: Recommended transducer
mounting position Fig. 4.13: Disadvantageous transducer
mounting position