pump performance curves.

[hienvd]

Dear All,
in pump performance curves (attached file), I do not know how min flow was establised or caculated? and second, in some handbook of pump, I see the shape of brake horsepower line is the same as efficiency line. but in this pump, It's the straight line leaning from left to right.
someone gives me a hand?

[josefreitas]

1. If you examine the graph you have:
process load characteristic (a straith line) that gives the operating point for the pump at diferents speeds( for example:
Q=420 Nm3/h, Head=75m, Efficiency=80% Speed=603 rpm Power=4x25=60kW

2. Minflow - is done by the left straight line Qmin=130 nm3/h at speed=603 rpm and at minimum speed=457 rpm is 97 Nm3/h.

[hienvd]

thank for reply. but according to curve, you can see that 603mm and 407mm are the impeller diameters. not speed of pump

[ECH1]

Trying to clarify the previous answer, you have the minimum impeller diameter in 457 mm, and maximum impeller diameter in 603 mm.
You can see the Minflow line as a straight line (this is so because the relationship between impeller diameter and flow is linear) it starts at
~ 90 m3/h and finish at ~ 130 m3/h.
The power line is not so clear, but you can multiply flow x DP and divide by efficiency using consistent units.
I hope this help you.

[bmshah]

If you examine the graph you have:
At 603 impeller dia the min flow is 130m^3/hr
At 530 impeller dia the min flow is 110m^3/hr
At 521impeller dia the min flow is 107m^3/hr
At 457 impeller dia the min flow is 95m^3/hr
Hope to have clarified you.