pressure loss
pressure loss
(OP)
I am designing a test loop that will have water flow (~30 gal/min) through a 4 cm pipe with an orifice of about .75 cm. I cannot find any information about approximate pressure drop accross an orifice with such a small diameter ratio. Does anyone have a back of the envelope equation I could approximate this loss (+- 10 psi)? Thanks





RE: pressure loss
try:
((V2^2-V1^2)^0.5 = (alpha)(2 X g X Htap)^0.5
Permanent Pressure Loss (PPL) = (1- d^2/D^2)
V2 is velocity through orifice in m/s
V1 is velocity down pipe m/s
alpha is the discharge coefficient normally about 0.61 (better values in fluids books)
g is gravitational acceleration 9.8 m/s^2
Htap is the head difference immediately across the orifice in metres of fluid
d is orifice diameter.
D is downstream pipe diameter (infinite for open end so PPL=1 in open end case. Units consistent with d.
So the head loss caused by an orifice in a pipeline is
PPL X Htap
As d/D approaches 1 the results become less accurate.
Cheers
Steve
RE: pressure loss
M777182
RE: pressure loss
American Society of Mechanical Engineers (ASME). 2001. Measurement of fluid flow using small bore precision orifice meters. ASME MFC-14M-2001.
You may also try this:
http://www.lmnoeng.com/Flow/SmallOrificeLiq.htm
RE: pressure loss
Follow this link:
http://www.mcnallyinstitute.com/13-html/13-07.htm
RE: pressure loss
RE: pressure loss
Also, I expect a large delta p. Will thickness of orifice be adequate to take the force created by the pressure drop?