Flow-head characteristic curve
It is the basic performance curve of pipeline centrifugal pump. The centrifugal pump with a specific speed of less than 80 has the characteristics of rising and falling (both convex in the middle and bent on both sides), which is called the hump performance curve. Centrifugal pumps with specific speed between 80 and 150 have a flat performance curve. Centrifugal pumps with specific revolutions above 150 have a steep drop performance curve. Generally speaking, when the flow is small, the head is high, and the head gradually decreases with the increase of the flow.
Flow-power curve
Shaft power is increased with the flow, when the flow Q=0, the corresponding shaft power is not equal to zero, but a certain value (about 60% of normal operation). This power is mainly consumed by mechanical losses. At this time, the pump is full of water, if a long time of operation, will lead to the temperature in the pump will continue to rise, pump shell, bearing will heat, serious may make the pump body thermal deformation, we called "dull head", at this time the head is the maximum, when the water valve is gradually opened, the flow will gradually increase, the shaft power is also slowly increased.
Flow-efficiency curve
When the flow rate is zero, the efficiency is also equal to zero. With the increase of the flow rate, the efficiency also gradually increases, but the efficiency decreases after increasing to a certain value. The efficiency has a highest value, and the efficiency is relatively high near the highest efficiency point, which is called the high efficiency area.