The performance parameters of the self-balancing multistage pump are such as a certain relationship between the flow rate Q head H axis power N speed n efficiency η. The relationship between the magnitude changes between them is represented by a curve, which is called the performance curve of the pump. The mutual relationship between the performance parameters of the self-balancing multistage pump and the mutual constraints: First, the rated speed of the self-balancing multistage pump is precondition.
A, flow-lift characteristic curve
It is the basic performance curve of a self-balancing multistage pump. Centrifugal pumps with a specific speed less than 80 have the characteristics of ascending and descending (both middle and convex) and the hump performance curve. A self-balancing multistage pump with a specific speed between 80 and 150 has a flat performance curve. The self-balancing multistage pump with a specific number of revolutions above 150 has a steep drop performance curve. Generally speaking, when the flow rate is small, the lift is high, and as the flow rate increases, the lift gradually decreases.
B, flow-power curve
The shaft power is increased 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 by mechanical losses. At this time, the self-balancing multi-stage pump is full of water. If it is operated for a long time, the temperature inside the pump will rise continuously. The pump casing and the bearing will heat up. In severe cases, the pump body may be thermally deformed. "At this time, the lift is the maximum value. When the outlet valve is gradually opened, the flow rate will gradually increase and the shaft power will increase slowly.
C, flow-efficiency curve
Its curve is like a hill shape. When the flow rate is zero, the efficiency is also equal to zero. As the flow rate increases, the efficiency gradually increases. However, after increasing to a certain value, the efficiency decreases, and the efficiency has the highest value. Near the point, the efficiency is relatively high. This area is called the high efficiency area.
