Minimum distance of the pressure measurement point from the pipe elbow
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Generally, it should be selected in a straight pipe section, away from vortices and dead zones. I need to select a location in front of the elbow on pipe 90. What is the minimum distance required from the elbow? Are there any relevant specifications? I couldn’t find it. The installation manual for automated instruments states that if it is located behind a elbow, the distance should be 3D (the original wording is: Generally, the distance from the pressure sampling point to the interface behind the 90-degree elbow should be no less than 3D)
Under normal circumstances, it is sufficient to place the pressure measurement point 3D in front of the elbow. The influence range of a single elbow on the flow bundle within the pipe extends from 12D in front of the elbow to 22D behind it. However, engineering surveys usually don’t require such precision; if there are no special requirements, it’s sufficient to use the first 5D and the last 3D of the source component, without any other fittings.