Sizing Pipes for Gravity Flow Systems

What is the fluid?

Fluid : water

Over head tank fluid elevation : 1202 m (1197.0 tank elevation + 5 m water height in tank)

user point El. : 1105 .00

User point is connected through steel pipe from over head tank. At user point required pressure range is from 4 to 6 bar. What should be the size of connecting pipe if velocity limited upto 2.5 m/s.

What is the required flowrate?

Well, nice learning ..

Required flow may varry in the range of 54 m3/hr to 205 m3/hr.

0.057m³/sec at 2.5m/sec gives a cross-sectional area of the pipe as 0.022m². Select a 200mm Ø pipe and there will be no problem with delivery pressure given the difference in elevations.

One might get away with 150mm Ø if one were prepared to run at higher than 2.5m/sec, depending on the overall length of the pipe.

There's oodles of pressure there.

I agree with PWSlack that 150mm should be fine but that pushes the velocity up to 3.2m/s at 205m³/hr.

Presure drop at that speed in a steel pipe is about 0.5bar per 100m of pipe, so for between 4 and 6 bar at the outlet around a kilometer of pipe would be needed to naturally lower the outlet pressure or a considerably better idea would be to use a pressure regulating valve at the end of the line just upstream of the outlet and keep your pipe lenght to a minimum.

Whats this for, as thats a huge amount of water to be moving? (Hint - School is the wrong answere :) )