Pressure and Velocity Reduction in Water Pipes

The pressure in the pipe is not relevant in this case.

To obtain average velocity, divide the flowrate by the cross-sectional area of the pipe. 2.2m/s sounds about right, and would be acceptable, being below 3m/s.

For such pipe , a 150 gal/min gives a High speed , about 7 m/s

lenght pipe will affect flow.

The original poster has 150lpm, not 150gpm.

My fault , sorry.

yes your 1.5 inch pipe will give 150LPM flow rate basing it on pipe nomograph @ fairly rough pipe material @ 1.2m/s velocity

regarding water velocity in 1.5" pipe at 150L/min.

to calculate velocity, V = 1273.2 x L/s / d*

V = 1273.2 x 2.5l/s / 38.1*mm = 2.19m/s

To determine pressure drop in Kpa per meter, assume D'Arcy friction factor of 0.017

loss of head = 0.017 x 1 x 2.19* / 2 x 9.97 x 1000 = 0.109m

pressure drop = 0.19 x 1000 x 9.79 = 1.06Kpa per meter.

hope this helped

To calculate the flow through a pipe, you need not just the size and pressure at a single point, but the pressure at two points and the type and material of the pipe. A 1.5 inch sch 80 pipe has a diferent inside diameter than a sch 40 PVC pipe. Other posters have shown that is is possible to see the flow you are asking for, but that does not guarantee that that flow is present.

A good online pipe flow calculator I use a lot is http://www.pipeflowcalculations.com/

The pressure is not a factor for flow rate, but the difference in pressure is the cause, and may be your piping system have a 100 kg/cm² in static condition, and there is no flow rate.

From piping hydraulics handbook, for 1 1/2 inch steel pipe schedule 40 used for water at 60^o F:

● For flow rate 3 gallons/min: the velocity is 0.473 ft/sec & pressure drop is 0.043 lb/in² per 100 ft.

● For flow rate 4 gallons/min: the velocity is 0.630 ft/sec & pressure drop is 0.071 lb/in² per 100 ft.

● For flow rate 5 gallons/min: the velocity is 0.788 ft/sec & pressure drop is 0.104 lb/in² per 100 ft.