Length of the straight sections before and after the orifice plate
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In the length of the straight sections before and after the orifice plate, what does xxxD refer to? Is D the diameter of the pipe or the diameter of the orifice? Is the pipe diameter the outer diameter or the inner diameter? Or nominal diameter?
The straight pipe sections before and after the orifice plate refer to the diameter of the process pipeline, usually denoted by the nominal diameter.
D refers to the inner diameter of the tube, while d refers to the orifice diameter of the orifice plate.
Here, D is the pipe diameter, and by pipe diameter it is of course the inner diameter that is meant.
In the specification regarding the length of the straight sections before and after the orifice plate, the value xxxD refers to the outer diameter of the pipe, not its nominal diameter; generally, the straight sections before the orifice plate should be 20D in length, while those behind it should be 7D in length
The length of the straight pipe sections before and after the orifice plate is XD, where D refers to the nominal diameter of the pipe.
The nominal diameter DN – for example, for a pipeline with DN200, the outer diameter is 219 and the wall thickness is 6. In my opinion, the wall thickness can be chosen; it is the value of 219 that determines it as DN200
After looking at the answers, I’m even more confused – what is the correct one?
It’s the diameter – I just don’t know whether it’s the outer diameter, the inner diameter, or the nominal diameter
GB/T 2624-2006 \"Measurement of fluid flow rate in fully filled pipes using differential pressure devices installed in circular cross-section pipes\" provides detailed specifications.