Lesson 9 - Control of Fluid Flow 1 SAQ
This lesson allows you to test yourself on the material covered in the Control of Fluid Flow 1 lesson and determine the level to which you have met the learning outcomes.
Suggested Response - Q6
*/**A centrifugal pump is used to bottom fill a tank with water (pump curve below). The base of the tank is 1.5 m above the pump outlet, and the tank has a working (full) level 10 m above its base. What would be the flow rate at the start, mid-point and end of tank filling? A zero-suction head on the pump may be assumed throughout filling, and any pressure loss in the discharge line from the pump to the tank may be ignored.
Response:
This pumping situation is comparatively straightforward, in that there are no complex calculations to do, but rather it tests your understanding of a pump curve. Let us sketch out the process. An example is shown below.
With zero-suction head, and by ignoring any pressure drop on the discharge line from the pump to the tank, we know that any total head produced by the pump will be used to sustain a head of water in the tank.
At the start of filling, the head on the pump will only be 1.5 m of water. From the pump curve, at that total head, the pump will have a capacity of 975 hL/h.
At the mid-point of filling, the head in the tank will be 5 m (above its base), which accounting for the 1.5 m elevation of the tank will be equivalent to 6.5 m of total head, which corresponds to a capacity of 920 hL/h.
Likewise, at tank full, a total head of 11.5 m will yield a capacity of 825 hL/h.