Thanks Martin,
For your information, the problem is with Irrigation main line design not Potable water + fire network.
Can you tell me one thing, where exactly I need to change the hydraulic parameters to improve velocity. if you see my attached model you can have a better idea about low velocities.
one more thing, if we reduce the pipe size by improving the flow velocity, head loss due to friction is going to increase and ultimately the pump head is also going to increase.
How to reduce the head loss due to friction in pipes by changing the diameters?
Thanks
Gangadhar