Can a pipe with multiple bends be modelled as a single pipe with Pipe Flow Expert?

Yes. A single pipe of a given pipe material, with a constant diameter, which changes direction via multiple bends at various points along the pipe can be modelled as a single pipe within Pipe Flow Expert.

In this case the pipe is drawn as a single straight line where the total length is specified together with the change in elevation between the start and end of the pipe (any change in elevation, up or down, that occurs in the middle of the pipe can be ignored since these cancel out in terms of energy losses that need to be overcome when flow occurs). Any and all fittings (bends) within that section of piping must then be included as a group on the single pipe. This arrangement will give the same hydraulic calculation result as that which would be obtained by splitting the pipe at each bend and starting a new pipe on the drawing at that point (and adding individual bend fittings on to each new pipe).

The following conditions must be met in order to achieve equivalence between a single pipe with multiple bends and the same length of pipe split into several different pipes each with a single fitting / bend:

  1. The total length of piping must be the same, i.e if the system with multiple pipes has three pipes of 3 metres, 5 meters and 6 meters, the equivalent single pipe must have its length set to the sum of these lengths (14 metres).
  2. All of the fittings that are present in the piping when drawn with multiple pipes must be included and added to the equivalent single pipe (so that the single pipe model contains all of the fittings within that section of piping).

This will make the single pipe system equivalent to the multi-pipe system, and the calculated pressure drop and flow rate will be the same for each model (since they are equivalent models).

Please refer to Example System "Common_03_Fittings_Bends.pfe", supplied with Pipe Flow Expert, for an illustration of this.

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