Pumping systems are responsible for a large part of the electrical expenditure in a production plant 

Within the industrial sector, regardless of the area in which we look at it, the energy consumed by pumping systems accounts for the majority of electricity costs. Occasionally, this energy is used efficiently, but in many other cases this is not the case.

It is very common for technicians to be familiar with the control and operation of pumping systems, but less common for them to be familiar with what they need to consider achieving the highest possible degree of energy efficiency.

como reparar una bomba centrifuga

Pumping systems have played an important role throughout history and especially in modern industrial processes. They are present in large thermoelectric power plants, in chemical processing companies, in food industries, in large automotive equipment….

On the other hand, they are also very present in our daily life, since, for example, they are commonly used for the supply of water, the evacuation of waste water, the operation of air-conditioning systems…

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How is the efficiency of a centrifugal pump calculated?  

Cómo se calcula el rendimiento de una bomba centrífuga
Efficiency is a ratio between the flow rate delivered, the head or pressure given by the pump, the density of the product and the energy consumed (power absorbed).
The points of maximum efficiency are usually in the central sections of what is known as the efficiency curve, i.e., both on the left (start), where the pump delivers a lot of pressure but little flow — this being the most unstable working point of the whole system — and on the right, where we are approaching the maximum allowed consumption or even over-consumption.

It is important to mention that, if a pump has no back pressure, it will always operate at the maximum possible flow rate, since this is the point on the curve where there is the least resistance.

The efficiency value can be calculated for all pumps, but it is much more common for centrifugal pumps, as they are the most widely used pumps in the world.

Engineering and design

How to calculate the efficiency in a centrifugal pump: other energy efficiency data 

Next, we will delve a little deeper into the terminology and define all the factors involved in pumping systems and centrifugal pumps to make them work efficiently.

This is the variable that determines the volume of liquid flowing in a pump per unit time under the operating conditions that have been determined. It is usually expressed in m3/h or l/h.

In this case, the total dynamic head is the algebraic sum of the total delivery loads. That is, the head losses in the pipe plus the difference in head between suction and discharge.

The power delivered by the pump to the fluid; its unit of measurement is horsepower.

Equivalent to the quotient of dividing the hydraulic power and the power absorbed, it is expressed as a percentage and is always less than unity.

Maquinaria para la producción de cosméticos México

It is the coefficient resulting from dividing the hydraulic power by the power supplied to the pump shaft, and therefore represents the percentage of power transmitted to the fluid regarding the total power supplied to the shaft.

η=P/Peb

This is the net suction head/head available, determined at the suction port of the pump, minus the liquid vapour pressure at the circulating temperature, both expressed in metres. This value depends on each system and considers the layout of the suction pipe, the height regarding the pump suction port, the temperature of the fluid to be pumped and its density.

The NPSHr is the minimum energy that a liquid must have at the pump inlet to avoid cavitation. This value is empirical and must be provided by the manufacturer.

To avoid cavitation in the pump casing, it is essential that:

NPSHd>NPSHr

These are some of the concepts that must be known and considered getting the best possible performance out of a pumping system. As manufacturers of industrial pumps, we have an extensive catalogue of models and types of pumps, which allow us to cover all the applications of the different industrial sectors we work with. We used to work for the food, pharmaceutical, cosmetics, chemicals, water treatment, etc. sectors, among others.

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If you still have any doubts about how to calculate the efficiency of a centrifugal pump or would like one of our sales engineers to contact you for a detailed quotation, just take a few seconds to fill in the form below.
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