See here are the shapes which are made on the suction head of compressor, enter image description here

What are these, and why are they on the suction head pipe?

  • 1
    $\begingroup$ I've never seen this before, but my first thought is guide vanes. faqs.org/patents/imgfull/20110241334_04 What brand of compressor is this? $\endgroup$
    – morristtu
    Commented Feb 25, 2016 at 3:43
  • $\begingroup$ @morristtu guide vanes, absolutely not. it has separate big guide vanes attach in the middle of the compressor. $\endgroup$ Commented Feb 25, 2016 at 5:14
  • $\begingroup$ I believe that the compressor is rotary. (Large inlet port means high discharge). Correct me if I am wrong. $\endgroup$
    – Fennekin
    Commented Feb 25, 2016 at 12:48

3 Answers 3


Notice that the "shapes" are in a right angled bend where the flow changes directions.

Sometimes vanes are placed in right angled bends to reduce shock losses by reducing the turbulence of the flow as it goes through the bend.

The "shapes" the picture appear to be on the outside of the bend, in which case they have been placed there to reinforce the bend to make it stronger.


I suspect that the crescent shaped sections penetrate all the way through the pipe and are turning vanes to help direct the flow around the sharp corner.

In pipe of this size it is much easier to fabricate a mitered corner than a radiused bend and the vanes are intended to make the change in flow direction less abrupt.

In this case holes have been cut in the pipe, the vanes (probably cut from sections of pipe) pushed through and then welded on from the outside.

In this case they are pretty crude and all have the same tight radius so I'm not entirely convinced that they are doing much good.


You can see that the elbow is immediately upstream of the diameter reducer, which means it's immediately upstream of the pump. That's a problem, because the elbow should be a large-radius curve, and at least 5 diameters away from the pump. The reason the elbow should be away from the pump is the same reason that the pipe is oversized and reduced at the pump inlet: to eliminate unbalanced flow at the pump inlet.

Since the elbow is sharp and adjacent to the pump, of course it has inline flow conditioning. As shown, there's not even room to insert a simpler straight flow-conditioning section (which would be cheaper)

Inline flow conditioning inserts don't always show up on outside of the pipe, but since we know that they must be there (in a properly designed system), our immediate observation is that those odd shapes correspond to internal flow conditioning vanes. figure source


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