Pump Curve 1

[rutherford703]

Dear sir,

I need help to explain the pump curve. Please see attached pump curve.
From the pump curve, my understanding is that when the discharge valve is closed there is basically no flow through the system and minimum pump torque is required to run the pump.

What does the static head mean for these curves?

Thanks in advance.

 

[Pumpsonly]

This is a Torque / Speed curve..It shown the required torque by the pump during the starting up stage from 0 RPM to full speed.

The 50% and 90% static head means the static head as a percentage of the total system head.
The total system head consist of a friction head / losses which varies roughly to the square of the flow rate and the difference in elevation or pressure between the suction tank and the discharge tank call static head.

 

[rutherford703]

Thanks Pumpsonly

 

[bimr]

The figure shows the variation during startup of the torque absorbed by mechanical friction and imparted to the fluid.

The initial torque is due to mechanical friction, so the pump starting condition corresponds to left y axis. Approximately 15% of the torque.

At about 15-20% of full speed, the torque imparted to the fluid becomes the dominant component. Thereafter, the torque depends on the system head loss curve.

For a system dominated by static headloss, no flow occurs until the speed goes above the bottom curve of no flow.

The torque follows the bottom curve corresponding to shut off conditions of no flow.

As the pump speed increases, the flow increases rapidly as does the torque as it moves upward from the bottom curve.

With a zero static lift system, the flow begins to increase with less pump speed and torque.

For a system with higher static lift, the flow will not begin until the pump speed increases enough to surpass the static head (the bottom curve).

The actual vertical height is the static head that the slurry is to overcome. Variations in the vertical height (normally measured from the liquid level on the intake side of the pump to the discharge point or the high point in the line) can have a major effect on the output of any centrifugal pump. It is, therefore, important that this vertical height be determined within reasonable accuracy (1.5 ft.).

 

[bimr]

The lines marked 0%, 50%, and 90% static head are examples of pump system curves with different proportions of static head. The curves are presented to show that no flow will occur until the pump impeller has accelerated to a speed sufficient to generate a head that will overcome the static requirement. That no flow condition is shown towards the bottom of the graph, the curve of no flow (closed valve).