Katronic Technologies FLUXUS ADM 6725, Инструкция по эксплуатации

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ADM 6725 E10
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KA T
3 - 1
Selection of the Measuring Point
3 Selection of the Measuring Point
The correct selection of the measuring point is crucial to success in achieving
reliable measurements and a high accuracy. Preconditions for obtaining good
measuring results are:
•
A pipe that can be acoustically propagated.
•
A fully developed axi-symmetrical flow profile.
3.1 Acoustic Propagation
Acoustic propagation can be assumed when pipe and medium do not attenuate
the sound so that the signals get completely absorbed. Sound attenuation
depends on:
•
the kinematic viscosity of the liquid,
•
the proportion of gas bubbles and solid particles in the liquid,
•
deposits on the inner pipewall,
•
the wall material.
When a measuring point selection is being
made, make sure that,
•
the pipe is always filled completely where
the sensors are positioned,
•
no bubbles and deposit material accumu-
late in the pipe at the measuring point.
(Also bubble-free liquids can form gas pockets where the liquid
expands, e.g. especially behind pumps and where the cross-
sectional area of the pipe extends considerably.)
3.2 Undisturbed Flow Profile
Many flow elements cause disturbances of the flow profile in the pipe, e.g. elbows,
slide valves, valves, pumps, T-sections, reducers and diffusers. Through these
disturbance sources, the flow profile is distorted to something other than an axi-
symmetrical shape.
Therefore, keep sufficient distance between
measuring point and any such disturbance
sources.
Only then can we assume that the flow profile in the pipe is fully developed.
However, FLUXUS will give you meaningful measuring results even under non-
ideal measuring conditions, i.e. with a liquid containing a certain proportion of gas
bubbles and/or solid particles, and if the recommended distances to flow
disturbance sources can not be observed to the book for practical reasons.
With careful selection of the measuring point,
you should reduce the impact of
disturbances sources.
3.3 Examples for the Selection of the Measuring
Point
Horizontal pipe