Main flow and lift, in addition, shaft power, speed and required NPSH. Flow is the amount of liquid through the pump output per unit of time, generally use volumetric flow; head is the unit weight of liquid from the pump inlet to the outlet of energy increases, positive displacement pumps, energy increase mainly reflected on pressure increase, so it is usually expressed as pressure increases instead of the head. Pump efficiency is not an independent performance parameters, it can consist of performance parameters such as flow, head and shaft power calculated by formula. Conversely, a known flow, head, efficiency and can also calculate shaft power.
All performance parameters of the pump there is some interdependence between changes in relationships, you can test the pump, measured and calculated parameters, respectively, and draw curves to represent, these curves are called the characteristic curve of the pump. Each pump has a specific characteristic curve, supplied by the pump manufacturer. Usually plant characteristic curve indicates recommended performance section, known as the pump's operating range.
Actual working point of the pump from the pump curve and the pump curve intersect to determine device characteristics. Selection and use of the pump, the working point of the pump within the scope of work, to ensure that the operation of economic and security. In addition, the same pumping viscosity of different liquids, will also change its characteristic curve. Typically, pump manufacturer's characteristic curves refers to the characteristic curve for transporting clean cold water. Power pump, with the liquid viscosity, head and less efficient, shaft horsepower increased, industrial heat viscous liquids of viscosity is sometimes small, to improve transport efficiency.