Below are several important performance curves of centrifugal pumps

There is a certain relationship between the performance parameters of the water pump, such as flow rate Q head H shaft power N speed n efficiency η. The relationship between their quantitative changes is represented by a curve, which is called the performance curve of the water pump.

The mutual variation relationship and mutual constraint between the performance parameters of the water pump: Firstly, the rated speed of the water pump is taken as a prerequisite.

There are three main performance curves for water pumps: flow head curve, flow power curve, and flow efficiency curve.

A. Flow head characteristic curve

It is the basic performance curve of a centrifugal pump. Centrifugal pumps with a specific speed less than 80 have the characteristics of rising and falling (i.e., a convex center and downward bending on both sides), known as the hump performance curve. Centrifugal pumps with a specific speed between 80 and 150 have a flat performance curve. Centrifugal pumps with a specific speed above 150 have a steep drop performance curve. Generally speaking, when the flow rate is low, the head is high, and as the flow rate increases, the head gradually decreases.

B. Flow power curve

The shaft power increases with the flow rate. When the flow rate Q=0, the corresponding shaft power is not equal to zero, but is a certain value (about 60% of normal operation). This power is mainly consumed in mechanical losses. At this time, the water pump is filled with water. If it runs for a long time, it will cause the temperature inside the pump to continue to rise, and the pump casing and bearings will heat up. In severe cases, it may cause thermal deformation of the pump body, which is called "stagnant head". At this time, the head is at its maximum value. When the outlet valve gradually opens, the flow rate will gradually increase, and the shaft power will also slowly increase. Hangzhou clothing wholesale

C. Flow efficiency curve

Its curve is shaped like a hill, and when the flow rate is zero, the efficiency is also zero. As the flow rate increases, the efficiency gradually increases, but after reaching a certain value, the efficiency decreases. There is a maximum efficiency value, and near the highest efficiency point, the efficiency is relatively high. This area is called the high efficiency zone.