Pump Design Point 1

[fej]

I am working on my first water distribution system. I have set up my network, calculated necessary demands, and sized the water tank. WaterCad 6.0 will generate a system head curve after pump design points are chosen. For a preliminary design one point will suffice. I was wondering if anyone had input on calculating the preliminary design head and flow.

Thanks

 

[BobPE]

fej:

The system or model you created of the system will determine the where the pumps you select will operate on their curves. One point will not be enough since you will have to create a system curve at the point in the system that you will be placing the pumps.

BobPE

 

[quark]

System curve is drawn based on maximum flow rate required and head requirement at that flow rate. As the head required is nearly proportional to square of velocity for subsequent points, drawing a system curve is similar to drawing a parabola. But as Bob rightly said, it is better to check for multiple requirements to actually assess the situation.

Preliminary flow is the maximum flow you require. Head will be static discharge head + frictional losses(at particular flow rate) + pressure drop across equipment(at particular flow rate).

Your pump selection should be such that the system curve meets the pump curve at the best efficiency point or just left to it.