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Sunday, August 7, 2016

Characteristic Curve Q-H Curve

This curve is known as Q-H Curve. When the discharge valve is fully closed, head developed by the pump is maximum. At this point, discharge is zero. This head is known as Shutoff Head. As we slowly open discharge valve, flow starts and flow increasea whereas head developed by the pump decreases. We can see on graph that at point A, flow q1 corresponds to head h1. And at point B, flow q2 corresponds to head h2. We can see that q2>q1 and h1>h2.

On field, if we want to know the head developed by the pump, place a pressure gauge just above pump discharge or at discharge flange (if tapping is provided). We can then take the reading of pressure gauge and convert it to head. Remember the conversion from pressure to head and vice versa?. Sp.gr. is very important. Hence if any doubt is there, pl refer to Head section of this app.

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