What are the three characteristic curves of centrifugal pumps and what are their functions?

Category: Water pump knowledge

2024-06-07

Pressure head, flow, power and efficiency are the main performance parameters of centrifugal pumps, the relationship between these parameters can be measured by experiments, centrifugal pump production departments will be the basic performance parameters of its products expressed by the curve, these curves are called the characteristic curve of centrifugal pumps, for the use of departments to select pumps and operation reference.

Use of characteristic curve of 1. centrifugal pump

The three characteristic curves of centrifugal pumps are very important indicators in the design and use of centrifugal pumps. They can tell us a lot of useful information, including:

1. Best working condition: The best working range of the centrifugal pump can be determined by the H-Q curve to ensure its normal and stable operation.

2. Optimized design: The speed of the centrifugal pump can be controlled through the N-Q curve to maximize its efficiency and reduce energy consumption.

3. Performance evaluation: The performance and energy consumption of centrifugal pumps under different working conditions can be measured through the η-Q curve, which provides a basis for optimal design.

In short, the three characteristic curves of centrifugal pumps can help engineers have a more comprehensive and in-depth understanding of the performance and working status of centrifugal pumps, and achieve the goals of optimizing design, reducing energy consumption, and improving efficiency.

Three characteristic curves of 2. centrifugal pump

Centrifugal pump is currently the most widely used type of pump, its working principle is to rely on centrifugal force to make the liquid flow. In the design and use of centrifugal pumps, there are three characteristic curves are very critical, they are:

1. H-Q curve: H represents head and Q represents flow. It refers to the change curve of centrifugal pump head under different flow. The curve can reflect the performance of the centrifugal pump in different working conditions, through which the best working range of the centrifugal pump can be determined.

2. N-Q curve: N represents the speed, Q represents the flow. It refers to the change curve of centrifugal pump speed under different flow. This curve can help engineers optimize the working state of the centrifugal pump so that it can maintain stable performance under different flow rates.

3. η-Q curve: η represents efficiency and Q represents flow. It refers to the change curve of centrifugal pump efficiency under different flow rates. The curve can help engineers to evaluate the performance and energy consumption of centrifugal pump, and provide the basis for optimizing the design.

Three. Influence of physical properties of liquids

The characteristic curve provided by the pump production department is obtained by using clear water as an experiment. When the nature of the liquid transported is different from that of water, the influence of viscosity and density on the characteristic curve should be considered.

1. Effect of solute:

If the liquid being delivered is an aqueous solution, the change in concentration necessarily affects the viscosity and density of the liquid. The higher the concentration, the greater the difference with water. The influence of concentration on the characteristic curve of centrifugal pump is also reflected in viscosity and density. If the conveying liquid contains solid substances such as suspended solids, the pump characteristic curve is not only affected by the concentration, but also by the type of solid substances and the particle size distribution.

2. Effect of viscosity:

The greater the viscosity of the liquid being transported, the more energy is lost in the pump body. As a result, the pressure head and flow rate of the pump should be reduced, the efficiency should be reduced, and the shaft power should be increased, so the characteristic curve should be changed.

3. Effect of density:

The pressure head of a centrifugal pump is independent of density, which can be explained conceptually. Liquid at a certain speed, the centrifugal force is proportional to the density of the liquid. However, the pressure head obtained by the centrifugal force of the liquid is equivalent to the pressure formed by the centrifugal force divided by the cross-sectional area of the impeller outlet, and then divided by the product of the liquid density and the acceleration of gravity. In this way, the influence of density on the indenter is eliminated. However, the shaft power of the pump varies with the density of the liquid. Therefore, when the density of the delivered liquid is different from that of water, the N-Q curve provided by the pump cannot be used, but should be recalculated according to (2-4a) and (2-5).

Previous: Effective NPSHA (NPSHA) and Required NPSHB (NPSHB) for centrifugal pumps

Next: Factors Affecting Several Important Characteristic Curves of Centrifugal Pump

Contact Us

Free Hotline:+86 18142662779

Fixed telephone:+86 19313001794      

Mobile:+86 18142662779(WeChat/WhatsAPP)

E-mail:info@sanchangpump.net