Why is it necessary to specify the distance of the straight pipe sections before and after the flow meter during installation?
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Why is it necessary to specify the distance of straight pipe sections before and after the flow meter during installation? Is it to ensure stable flow?
It is to ensure stable flow regime, rather than stable flow rate.
Generally, for a flow meter to measure flow accurately, it requires a stable and uniform flow field. In a pipe, to generate such a flow field, there must be sufficient straight sections of pipe to create it. Depending on the installation site and the type of flow meter, the requirements for the minimum straight pipe section vary to some extent; for detailed information, please refer to the flow meter’s installation and operation manual.
It is mainly to prevent the effects caused by turbulence. . . . . . . .
The straight pipe sections at both ends of a bent-tube flow meter can be made as long as possible, but the pressure tapping point of the flow meter is located at the bend.
The design of flow meters is based on the spatial distribution of fluid motion (flow field) for specific fluids. Pipelines of different shapes have distinct flow fields as well. It is not possible for flow meters to be designed differently for various flow fields; instead, the most representative flow fields and the corresponding pipe configurations that are easiest to implement in practice must be chosen for design purposes. If a orifice plate with elbows for inlet and outlet were designed, far more complicated specifications would have to be established regarding the shape and size of those elbows, among other things; there would also be requirements before the flow enters the elbows. It’s likely that no one would use such a flow meter.
Punching helps to stabilize the flow pattern of the fluid; only with a stable fluid can measurements be more accurate.