Flowrate behind orifice
Flowrate behind orifice
(OP)
Hello all!
I have 8-bar pressurized clean water system with 50 mm ID pipework and a hydrant. On this hydrant I want to install orifice plate and connect 50 mm hose. However I am limited by a maximum flowrate behind orifice which can't be higher than 5 m/s.
The equation everyone is familiar with uses Cd*srqt(2*g*H) where typical Cd is probably about 0.62.
From these using continuity equation A=Q/V I could obtain orifice diameter.
Could you please tell me whether this approach is suitable? As a pressure (head) difference would you use 8 bar - 1 bar (atmospheric)= 7 so 70 m? Is there any way to estimate whether Cd will be closer to 0.6 or 0.7?
Thank you in advance.
Jed
I have 8-bar pressurized clean water system with 50 mm ID pipework and a hydrant. On this hydrant I want to install orifice plate and connect 50 mm hose. However I am limited by a maximum flowrate behind orifice which can't be higher than 5 m/s.
The equation everyone is familiar with uses Cd*srqt(2*g*H) where typical Cd is probably about 0.62.
From these using continuity equation A=Q/V I could obtain orifice diameter.
Could you please tell me whether this approach is suitable? As a pressure (head) difference would you use 8 bar - 1 bar (atmospheric)= 7 so 70 m? Is there any way to estimate whether Cd will be closer to 0.6 or 0.7?
Thank you in advance.
Jed





RE: Flowrate behind orifice
http://www.tlv.com/global/TI/calculator/water-flow...
Also do you mean velcoity of 5m/sec? If so what is pipe size so you can work out flowrate.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Flowrate behind orifice
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Flowrate behind orifice
I meant volumetric flowrate of 5 m3/s is the maximum I can't exceed behind the orifice (actually at the end of the hose).
To be completely sure I got it right:
1. From vol. flowrate I can obtain velocity and then using Bernoulli and Darcy-Weisbach for losses in the hose I can obtain total head that will be needed to discharge 5 m3/s at the end of the hose. My total head here would consist of velocity head and frictional head loss
2. Knowing that upstream to orifice I have 8 bars of pressure I don't need to use Darcy to calculate losses here.
3. My pressure drop is 8 bars minus the value I got from point 1.
Did I get it right or made mistakes?
RE: Flowrate behind orifice
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Flowrate behind orifice
RE: Flowrate behind orifice
A jet velocity of 2,500m/sec would be some fire hose alright...
Or maybe it's something like this... https://www.youtube.com/watch?v=pn-CVQh62Eo
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.