plchacker
Member
Does anyone know the formula for calculating the maximun flow through an orifice? The fluid in this case is water. I have the dia and K factor. (0.8630", and 0.62)
I even have test data. We pumped 5 gal of H2O in 21 seconds, with a DP of 1" H2O. We ran this test three times and counted 21 seconds each time.
The formulas I have depend on knowing the max flow for the orifice. After searching the internet, I have found lots of software people willing to spit an answer out for a price. I have found a few equations:
Q=AVK, where Q is the flow rate in ft^3/sec; A is the area in ft^2 of the orifice; V is the velocity in ft/sec and K is the K factor of the orifice.
___
V = V2gh where g is 32.2 ft/sec and h is the head across the orifice. (I think in this case PSI?)
______
That gives me Q = A * K * V64.4*h
If I substitute my data, I get the following:
h= 1"H2O or .0361 psi
Q = .004 * .62 * 42.2
Q = .0105 ft^3/sec = .784 gal/sec
Test data is 5 gal/21 sec or .238 gal/sec
Does anyone see a mistake? Do you have a better equation? If the equations are right and my math is right, then I must have made a mistake in measurement, most likely in DP. I may set back up using a DP cell rather than gauges.
Thanks in advance. This is not an emergency situation, Just a lab experiment that I want to get right before presenting it to my students.
I even have test data. We pumped 5 gal of H2O in 21 seconds, with a DP of 1" H2O. We ran this test three times and counted 21 seconds each time.
The formulas I have depend on knowing the max flow for the orifice. After searching the internet, I have found lots of software people willing to spit an answer out for a price. I have found a few equations:
Q=AVK, where Q is the flow rate in ft^3/sec; A is the area in ft^2 of the orifice; V is the velocity in ft/sec and K is the K factor of the orifice.
___
V = V2gh where g is 32.2 ft/sec and h is the head across the orifice. (I think in this case PSI?)
______
That gives me Q = A * K * V64.4*h
If I substitute my data, I get the following:
h= 1"H2O or .0361 psi
Q = .004 * .62 * 42.2
Q = .0105 ft^3/sec = .784 gal/sec
Test data is 5 gal/21 sec or .238 gal/sec
Does anyone see a mistake? Do you have a better equation? If the equations are right and my math is right, then I must have made a mistake in measurement, most likely in DP. I may set back up using a DP cell rather than gauges.
Thanks in advance. This is not an emergency situation, Just a lab experiment that I want to get right before presenting it to my students.