Pipe Flow Calculations Forum

Even if the system is closed and for example you have 50 m height difference, pressure on the lowest point will have at least that 50 m water pressure.

You might have that pressure due to hydrostatic pressure. What is elevation difference off the system?

Without knowing the K of valve you can't tell the flow rate even using gas discharge calculator. If you fully open valve you can use K for it from manufacturers datasheet.

You must know pipe length and position and size of branches if you have any.

Well spotted, thank you for correction!
I have just made change in calculator and theory page itself.

You can use height difference as available head in calculator, ie p1 = rho * g * h + 101325 Pa, p2 = 101325 Pa.

Roghness really depends on the level of surface treatment for new pipes and corrosion level for old ones. It can be anything up to 1 mm depending on the pipe itself.

You can look at post here: http://forum.pipeflowcalculations.com/viewtopic.php?f=3&t=10 This is similar problem as yours, but not exactly the same. Your equation is I think correct but have to clarify some abbrevations used: Vt - is volume of tank MWair what is for? rho * V * A = G = dm/dt is ma...

You can't calculate flow rate with data you provided. You have to know more. Regulator should keep outflow pressure at constant value regardless of inlet pressure and flow rate, so for any flow rate pressure should be at set point, if flow is within regulator capacity. If your question is how much g...

Calculator gives option for enter either density or temperature. If you choose to enter density, than calculator using R is calculating T prior to other calculation is done. I can't tell you about pipe roghness you should use. I think that it is the best way to be on safe side and choose values of p...