K factors for Hydraulic Manifold Block
K factors for Hydraulic Manifold Block
(OP)
Hi all,
Does anyone have any suggestions or know of published data on K factors for a machined hydraulic manifold block. What I am most interested in is a typical 90 degree bend (eg R/d = 0) created from boring into the block from different sides of block.
Also, does standard 'equivalent length' theory hold if the bends are only 2 or 3 diamters apatr?
Dave
Does anyone have any suggestions or know of published data on K factors for a machined hydraulic manifold block. What I am most interested in is a typical 90 degree bend (eg R/d = 0) created from boring into the block from different sides of block.
Also, does standard 'equivalent length' theory hold if the bends are only 2 or 3 diamters apatr?
Dave





RE: K factors for Hydraulic Manifold Block
Using a series of standard Ks for any custom machined valve wouldn't be very accurate. It would be much better to test the valve and determine the exact K factors from the closed position all the way to full open.
Possibly you may find some simularity to Ks for an angle globe valve, but I doubt it.
Theoretically you can add Le without regard for distance between fittings, but there is bound to be some unquantified effects. Those Le values could not be developed for every piping configuration. Although though you can get 12 significant figures from a hydraulic analysis spreadsheet, don't count on getting real accuracies within more than 2 significant figures. Be conservative and allow yourself from +/- 10% up to 20%, depending on the configuration.
http://virtualpipeline.spaces.msn.com
RE: K factors for Hydraulic Manifold Block
Your description suggests you can use the K factor for a 90 Deg miter (one cut).
There is a proximity interaction that is normally ignored in process piping. There are some correction factor tables and charts published for bend-bend interactions in Internal Flow Systems Design and Performance Prediction by D. S. Miller.
RE: K factors for Hydraulic Manifold Block
Unfortunately I don't have access to this particular book, but you are correct a 90 deg mitre is the closest description I have seen. The only reference to a loss factor k for this I can find is 1.1 from BS Massey.
RE: K factors for Hydraulic Manifold Block
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RE: K factors for Hydraulic Manifold Block
Yes the diameters are around 20mm - 30mm. Thanks for the input.
Dave
RE: K factors for Hydraulic Manifold Block
The Cameron Hydraulic Data handbook gives the following resistance coefficient K values for 90 deg mitre bends versus pipe size : -
Nominal Pipe Size K Value
1/2" 1.62
3/4" 1.50
1" 1.38
1 1/2" 1.26
Hope this helps.