5 Selection of the Measuring Point
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UMFLUXUS_G8V4-6-1EN, 2018-10-10
Both demands cannot be observed always at the same time. In these cases, the measuring point has to be selected in
such way that the influence of noise is min. and the measuring point is as far from the disturbances of the flow profile as
possible.
example:
fluid: natural gas
pipe material: stainless steel
length of pipe segment 1: 20 D
length of pipe segment 2: 5 D
number of sound paths: 2
• area with developed flow profile:
disturbance source: 90°-elbow
recommended area for the measuring point: l
≥
20 D (complete pipe segment 2) (see Tab. 5.2)
• area with low influence of noise:
reflection point: flange
recommended area for the measuring point: l
≥
3 D and outside of l = (7.5 ± 2) D on pipe segment 1 (see Tab. 5.2)
Fig. 5.3: Area for the measuring point with low influence of noise and not fully developed flow profile
In the example, there is no area where both demands are met at the same time. The measuring point has to be selected
as far as possible from the elbow, at a point where the influence of noise can be neglected: 3...(7.5 - 2) D on the right side
of pipe segment 1. In the example, a distance of 16 D from the elbow was selected.
5 D
20 D
(7.5 - 2) D
3 D
16 D
