loss of pressure head
loss of pressure head
(OP)
the problem is that if diesel oil is passed through a pipeline equiped with different control curves and valves the flow rate is lower compared to a similar pipeline with the same number of curves and control valves.I calculated the pressure loss of the two pipelines and discovered that the pressure loss on the pipeline minus that due to the control valves where the same.
I would like to know if this difference in flow rate can only be due to the control valves.
I would like to know if this difference in flow rate can only be due to the control valves.





RE: loss of pressure head
Same inside diameter, elevations, roughness, density of diesel, fittings, viscosity of diesel, inlet pressure, outlet pressure, inlet temperature, outlet temperature?
Check the valve Cv vs Position at the valve's %Open, then you'll know what the pressure drop across the valves should be.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: loss of pressure head
RE: loss of pressure head
To give you some ideas, I just searched for valve Cv and found a discussion of Cv and the metric equivalent Kv, and these tables here,
http://www.crispinvalve.com/kflosite/cvvalues.htm
http
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: loss of pressure head
thanks
VALVES P1 P2 P1-P2 FLOW RATE CV
FV64 6 1,5 4,5 51,8m3/h 25,5
FV65 6 4,3 1,7 51,8m3/h 41,6
RE: loss of pressure head
Cv = gpm/(psi * SG)^0.5
The only way do it without changing the valve %open and the corresponding Cv, is to change one of the two inlet pressures, so that the downstream pressures are equal. BUT, If you do that, you will probably also be changing the flowrate in the upstream pipeline segments. I think you probably don't want to do that, but here goes,
Solving the equation to have P2 for both valves = 1.5 requires that valve FV65 have an upstream pressure, P1 = 2.64
Solving the equation to have P2 for both valves = 4.5 requires that valve FV64 have an upstream pressure, P1 = 5.76
I think it is some other slight dissimilarity that is causing the different pressure drops, perhaps the interior valve trims are different, but I really can't say with the info you've provided.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: loss of pressure head
RE: loss of pressure head
That will give you an idea on what Cv the valve will have at various %Opens, then tie that back to actuator travel.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: loss of pressure head