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Looking for energy efficiency: Industrial plants with many pipes
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Maintaining pressure: Flow losses of industrial valves

The movement of fluid in hydraulic systems creates resistance caused by the friction of the fluid at the pipe wall, by deflections and, last but not least, by the valves fitted. Find out what factors are decisive for the efficiency of a system.
The movement of fluid in hydraulic systems creates resistance caused by the friction of the fluid at the pipe wall, by deflections and, last but not least, by the valves fitted. Find out what factors are decisive for the efficiency of a system.

Pumps need a lot of energy without consuming it.

According to a survey conducted by the Fraunhofer Institute for the EU Commission, 12.6 % of the entire energy consumed in the EU is used for driving pumps, with pumps in industry making up the lion's share. Modern variable speed high-efficiency motors and flow-optimised pump hydraulic systems offer enormous saving potentials. However, pumps that transport liquids in industrial plants always just form one part of larger overall systems. Such systems also especially comprise pipes and valves. The question is: Is this somewhere opportunities for increasing efficiency may be found – so pumps can be dimensioned smaller or run at a lower rotational speed? To provide a direct answer: Yes, it is. By reducing flow losses.
Strictly speaking, it is incorrect to assume that pumps use a lot of energy – the pumps themselves consume only a relatively small share. Quite the opposite: It is the pump's task to put energy into a system, in the form of the fluid's kinetic energy. In actual fact, the energy is only consumed in the system. Assuming that a pump has got an efficiency of up to 90 %, the actual energy consumed by the pump itself is only 10 % – the remaining energy is transferred to the system, where it is consumed. See the illustration.
Schematic: Pressure loss in a piping system

The schematic clearly illustrates that the differential pressure built up by the pump – the energy pumped into the system – slowly decreases while passing through the pipes and fitted valves.


Where are the true energy guzzlers hiding?

When a fluid flows through a pipe, pressure losses are inevitable. First of all, they are caused by friction between the fluid and the pipe wall: The rougher the inside of the pipe, the higher the friction and, with that, the pressure loss. The material (e.g. metal, plastic or clay) as well as possible deposits and oxidation in the pipe play a role. Secondly, friction effects also develop within the fluid due to the fluid viscosity (internal friction). The internal friction effect increases with the flow velocity of the fluid. Plant designers can significantly influence the losses from flow velocity by using larger pipes. Note: The flow velocity is squared in the pressure loss calculation.
The main cause of flow and pressure losses, however, are vortices and flow separation. Simply put: Wherever fluid is hindered from continuing its even flow, energy is lost. A piping system is not made up of a single, straight pipe. Usually, such a piping system comprises several pipe bends (elbows), branches, reductions/increases in cross-section, measuring instruments, strainers and, naturally, valves (from Open/Closed valves to control valves). Each one of these components causes some pressure loss and therefore energy loss. 
These pressure losses are indicated by the loss coefficient ζ – zeta. This is a dimensionless unit for the pressure loss of a component (e.g. valve). The larger the zeta value of a valve, the higher the pressure loss. To help with the selection, valve manufacturers also provide the Kvs value, also known as flow coefficient, of the fully open valve. The flow coefficient is the flow rate of water at 20 degrees Celsius that causes a differential pressure of one bar in the valve.
When adding up all pressure losses in the different piping system elements, a system curve of the piping can be drawn. The system curve forms the basis for calculating the required head of the pump as a function of the flow rate. You can imagine that in very large systems with several hundreds of valves, many deflections and long pipes, large amounts of energy will be lost.

What role do valves play in the pressure loss of a piping system?

As the wall area within a valve is very small compared to the overall piping system, wall friction losses in a valve can generally be ignored. The lion's share of pressure loss (the resistance coefficient zeta ζ) is caused by vortex formations, flow separation and secondary flows. The flow resistance of valves primarily depends on how much the fluid is deflected when passing through the valve, whether the cross-section is reduced and whether vortices form at the edges.
Valves are categorised according to their design features into the basic types of globe, gate, butterfly, ball or plug and diaphragm valves, and according to the functions they perform, i.e. shut-off valves, safety valves, control valves and check valves or strainers. A look at the internal design of the different types quickly shows that their flow passages vary significantly.
Schematic of the functionality of a gate valve, type KSB ECOLINE GT 40

This simple gate valve of type KSB ECOLINE GT 40 demonstrates that the fluid flow is hardly disturbed at all in fully open valve position. The fluid can almost pass through freely.


Schematic of the functionality of a shut-off valve, type KSB BOA-Compact

This BOA-Compact shut-off valve with slanted-seat design and vertical bonnet has also got a hydraulically optimised port. However, a minor pressure loss may be caused by the reductions in cross-section and by vortices. The obturator being designed in the special shape of a throttling plug makes this valve an excellent match for throttling and control tasks.


Schematic of the functionality of a bellows-type globe valve, type KSB BOA-H

This bellows-type globe valve of the type KSB BOA-H clearly illustrates what path the fluid has to take through the valve. The flow is deflected at several points. This flow deviation results in a certain flow resistance but also provides the valve with a good design for throttling and control tasks.


Table with zeta values at the example of some KSB valves

The table shows the zeta values of different KSB valves of different nominal sizes (for BOA-W the values refer to the previous type series; the current values are better). The difference in resistance of the type series is due to their individual design types. Generally speaking, the simple connection between a low zeta value and a high energy efficiency mainly applies to shut-off valves. For throttling or control valves, integrating additional resistances is desirable or essential.

KSB offers the right valve solution for every application.

As a full-range supplier for the valves sector we offer a broad range of different designs. Alongside globe valves, gate valves, butterfly valves, ball valves, diaphragm valves and control valves, KSB's valve product range also includes actuators, positioners and strainers. No matter how different our products are in design, they all benefit from our 150 years of experience and our mission to always develop the best solution for our customers. 
Especially in times of strongly increasing energy costs, efficiency is gaining more and more in significance – in complex industrial applications even more so than in building services. Pressure losses are less relevant in building services as the flow velocity is relatively low at 0.7 m/s. In industry, flow rates can reach up to 4 m/s, which explains the trend towards considering the entire system's energy consumption in this field.
Our engineers develop products with a focus on several points: Maximum operating reliability and longevity naturally take centre stage. At the same time, the valves are hydraulically optimised to the maximum extent possible. Our BOAX or ISORIA butterfly valves, for example, are fitted with particularly thin discs to keep resistance to a minimum. Being economically efficient is the third criterion our products have to meet. Not everything that is technically possible makes sense from a commercial point of view. This is where an optimum has to be found without compromising on quality.
Product development at KSB: The previous BOA-W compared to the current BOA-Compact and BOA-SuperCompact

A clear development towards a higher efficiency: On the left, you can see a no-longer-current soft-seated valve of the type BOA-W (previous type series), in the middle a BOA-Compact and on the right the especially efficient and compact valve of the type BOA-SuperCompact.


KSB generally places a high value on offering products of the highest possible efficiency – no matter if they are giant motors for driving heavy-duty pumps or small butterfly valves. Our aim is to always use resources as sparingly as possible and leave the smallest possible CO₂ footprint.

Suitable products

BOA-Compact

BOA-Compact
Documentos

Válvula de globo conforme a DIN/EN con bridas, distancia entre caras compacta EN 558/14, asiento inclinado y parte superior recta, cuerpo monobloc, obturador de regulación revestido de EPDM, cierre de paso con asiento elástico y asiento posterior, indicador de posición, dispositivo de bloqueo, ajuste de carrera, tapa aislante con anticondensación, sin mantenimiento, totalmente aislable.

Detalles

BOA-H

BOA-H
Documentos

Válvula de globo conforme a DIN/EN, con bridas, fuelle, parte superior recta, obturador de cierre o regulación, indicador de posición de serie con sistema de codificación por colores, obturador reemplazable, fuelle protegido con la válvula totalmente abierta, superficie de contacto asiento/ obturador de acero al cromo o acero al cromo níquel resistente al desgaste y a la corrosión.

Detalles

ISORIA 10/16

ISORIA 10/16
Documentos

Válvula de mariposa de eje centrado con extremo del eje cuadrado conforme a ISO 5211, con anillo de elastómero, palanca manual o engranaje reductor manual, actuador neumático, eléctrico o hidráulico; cuerpo anular (T1), cuerpo con orejetas de desmontaje (T2), cuerpo tipo lug (T4) o cuerpo en forma de perfil en U con cara plana (T5). Los tipos de cuerpo T2 y T4 permiten el desmontaje aguas abajo y el uso como válvula de final de línea con una contrabrida. Conexiones según EN, ASME, JIS.

Detalles

SISTO-20

SISTO-20
Documentos

Válvula de membrana conforme a DIN/EN con bridas, conexión de manguito roscado o conexión de manguito soldado, con alma en paso recto, cierre en el paso y hacia el exterior a través de una membrana con apoyo y confinada, carcasa con recubrimiento o revestimiento, indicador de posición con protección integrada del husillo, los componentes funcionales sin contacto con el fluido de operación no requieren mantenimiento.

Detalles

NORI 40 ZXLF/ZXSF

NORI 40 ZXLF/ZXSF
Documentos

Válvula ON/OFF conforme a DIN/EN con bridas, extremos butt weld o socket weld, con empaquetadura de prensaestopas, parte superior recta, obturador de cierre o de regulación, vástago no giratorio y superficie de contacto asiento/ obturador de acero al cromo o acero al cromo níquel resistente al desgaste y la corrosión.

Detalles

SERIE 2000

SERIE 2000
Documentos

Válvula de retención de doble clapeta tipo wafer, cuerpo monobloc de fundición con grafito laminar, fundición nodular, acero o acero inoxidable, cierre del eje de metal-elastómero o de metal-metal, sin mantenimiento, conexiones según EN, ASME o JIS.

Detalles

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Asesoramiento en Eficiencia Energética

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Optimice gracias a FluidFuture® la eficiencia energética de su instalación en cuatro pasos. El enfoque sistemático de KSB le garantiza el máximo ahorro de energía.
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SES Servicio de Eficiencia del Sistema

SES – Servicio de Eficiencia del Sistema

Las bombas que no hayan sido adaptadas adecuadamente a la instalación consumen demasiada energía. Esto puede cambiar con el SES Servicio de Eficiencia del Sistema de KSB.
  • Análisis de eficiencia energética
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Reparación de Válvulas

Reparación de Válvulas

A medida, personalizado, integral: KSB le ofrece un servicio profesional para válvulas de todas las marcas, independientemente del tipo, del tamaño y del fabricante.
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