In addition to seal oil, some submersibles have an oil filled stator cavity. The oil in the stator cavity very efficiently transfers heat from the stator winding and core, and especially from the rotor, to the pump casing where convection carries it to the pumpage in which the pump is submerged. While the specifications for seal oil are fairly flexible, stator cavity oil has more constraints.

Además del aceite de sellado, algunas bombas sumergibles tienen una cavidad del estator llena de aceite. Este aceite transfiere de manera muy eficiente el calor desde el devanado y el núcleo del estator, y especialmente desde el rotor, hasta la carcasa de la bomba, donde la convección lo lleva al líquido de bombeo en el que está sumergida. Si bien las especificaciones para el aceite de sellado son bastante flexibles, el aceite de la cavidad del estator tiene más restricciones.

This presentation focusses on critical close fit tolerances and certain surface finish specifications.

When repairing centrifugal and axial flow pumps, axial thrust is a concern. An understanding of the causes and the mitigating provisions of various pump designs will help repair technicians to ensure those provisions work properly.

This video walks through the steps to adjust and set end play on a typical vertical hollow shaft pump motor.

There are many considerations for selecting a barrier fluid in general, but only a few apply to submersible pumps. When the fluid specification cannot be found or when the specified fluid is not available for the repair, there are some general guidelines to follow that are offered here.

En general, existen muchas consideraciones para seleccionar un fluido barrera, pero sólo unas pocas aplican a las bombas sumergibles. En casos en que no se pueda encontrar o no esté disponible el fluido especificado para la reparación, este artículo ofrece algunas pautas generales que se pueden seguir.

Cuando trabaje con bombas, seguramente encontrará instancias en las que se hace referencia a la curva de la bomba, junto con una serie de parámetros asociados con ella. Un parámetro clave de la curva de la bomba es el Punto de Mejor Eficiencia (BEP). Este concepto simple de un punto de operación que produce la operación más eficiente no es difícil de visualizar. Para motores eléctricos, la eficiencia varía con la carga; la mejor eficiencia está en alrededor del 75% de carga. Sin embargo, con las bombas rotodinámicas, que incluyen bombas centrífugas y de flujo axial, hay que considerar cuatro parámetros clave, uno de los cuales es la eficiencia. Estos cuatro parámetros son cabeza, caudal (también conocido como capacidad o volumen), potencia y eficiencia.

It’s common to find pump impellers with significant surface damage. The three most common causes of surface damage are erosion, corrosion and cavitation. For each of these there are characteristics which will help indicate the primary cause of the damage.

Es común encontrar impulsores de bombas con daños significativos en la superficie. Las tres causas más comunes de daño superficial son la erosión, la corrosión y la cavitación. La apariencia del daño en las superficies del impulsor refleja las características de cada uno de estos tres fenómenos.

Corrosion and/or erosion damage is inevitable for some pump applications. Pumps received for repair with significant damage may look like a candidate for the junk bin, but with proper repair techniques can often be restored to original performance – or perhaps better than original.

En algunas aplicaciones, los daños por corrosión y/o erosión de las bombas son inevitables. Las bombas enviadas para reparación que presentan daños significativos pueden parecer buenas candidatas para ser desechadas, pero a menudo con las técnicas de reparación adecuadas pueden restaurarse a sus condiciones originales o quizás a unas mejores.

End users or service centers often need to specify replacement pumps or pump motors, sometimes involving a retrofit or re-application project. A successful outcome depends on accurate assessment of application requirements and a good understanding of the parameters that govern pump performance.

Service centers are often called on to provide replacement pumps or pump motors or to advise on pump retrofit and re-application projects. A good understanding of the parameters that govern pump performance is essential to help customers with these opportunities. The information here relates to rotodynamic pumps (centrifugal and axial flow impellers) and not to positive displacement pumps.

As with most other machines commonly repaired in EASA service centers, dynamic balancing on pump impellers is an important concern. Excessive imbalance imparts forces on bearings, reducing their lives and subjecting machine mountings to vibratory energy that deteriorates foundations.

Al igual que con la mayoría de las otras máquinas reparadas comúnmente en los centros de servicio de EASA, el balanceo dinámico de los impulsores de las bombas es una cuestión importante. El desbalanceo excesivo imparte fuerzas sobre los rodamientos, reduciendo su vida útil y sometiendo los soportes de las máquinas a una energía vibratoria que deteriora las fundaciones.

While adding variable speed capability in commercial buildings is not a new idea, a new analysis confirms major energy and cost savings is available by pairing those products with a power drive system (PDS) – regardless of a pump’s load variability. A PDS combines an electric motor, adjustable speed controls and sensors that provide feedback to the equipment, allowing the equipment to slow down or speed up to meet current demand. This idea and the added flexibility a PDS can provide may be even more important as we move forward in uncertain times.

Anyone dealing with installed machinery, or even test running motors in the service center, will encounter instances where structural resonance is amplifying machine vibration. The machine may meet stringent specifications in one instance but exceed acceptable vibration levels in another. A good understanding of natural frequencies and the tests necessary to identify them will help solve these vexing situations.

It is commonly known that pump mechanical seals are temperamental devices that fail frequently. The fact is, mechanical seals are simple devices that are often misapplied, sometimes installed incorrectly, or perhaps installed on pumps that are not well suited for the application.

Para aquellos que son nuevos en el negocio de la reparación de bombas, los sellos pueden resultar intimidantes, sin embargo, es bien conocido que los sellos mecánicos de las bombas son dispositivos temperamentales que fallan con frecuencia. El hecho es que los sellos mecánicos son dispositivos simples que a menudo son utilizados de forma inadecuada, algunas veces instalados incorrectamente o tal vez montados en bombas que no son aptas para la aplicación. En la mayoría de las aplicaciones, los sellos mecánicos son lo suficientemente macizos para tolerar condiciones de operación y de manejo menos óptimas. Para aplicaciones exigentes todo debe estar bien.

The EASA Pump Reliability Seminar is a two-day program that describes in detail the factors related to pump reliability. This webinar introduces participants to those factors and how they come together to ensure a reliably operating pump.

Whether it is a simple re-application of a pump from 50 Hz to 60 Hz (or vice versa), the repurposing of an existing pump, or the application of a new pump to an existing application, determining the proper trim for an impeller can be challenging.

Centrifugal pump failures are most commonly attributed to seal failure, impeller damage and bearing failures. A good understanding of failure modes for seals, impellers and bearings is essential to providing customers with reliable pump repairs.

Vertical turbine pumps (VTP) commonly have rotors with multiple mixed-flow impellers (sometimes 12 or more) that are supported by a vertical pump motor. Such designs offer a lift adjustment for raising or lowering the pump rotor to properly position the impellers within the bowl. Depending on the type of pump, this may be critical for maximizing pump efficiency and could have a significant impact on motor load (current) and reliability.

Vertical turbine pumps depend on the vertical motor's thrust bearings to support the combined weight of the pump rotor and the motor rotor and to counteract the dynamic down-thrust that the pump impellers generate in lifting the liquid.

It happens to just about every EASA service center. A machine shows up for repair; it has leads, and there’s a motor, but the machine is a pump. Most often, it’s a close-coupled pump or a submersible pump. If your response is, “We don’t work on those here,” because you’re thinking, “We don’t know anything about repairing pumps,” you may be turning your back on some very profitable work.

Esto sucede en casi todos los centros de servicio de EASA, aparece una máquina para reparación, con cables y un motor, pero es una bomba. A menudo es una bomba sumergible o de acoplamiento cerrado. Si su respuesta es: “Aquí no reparamos estos equipos” y está pensando: “Nosotros no sabemos nada sobre reparación de bombas” puede que le esté dando la espalda a un trabajo muy rentable.

A special discounted collection of 8 webinar recordings focusing on various aspects of pump repair.

Just $40 for EASA members!

A special discounted collection of 7 webinar recordings focusing on pump design theory and how to determine is a pump is appropriate for an application.

Just $35 for EASA members!

EASA service centers looking for options for expansion, or to replace evaporating existing electric motor repair markets, have seen pump repair as a good fit. A majority of EASA service centers currently repair roto-dynamic pumps. Pumps are by far the largest category of machines driven by electric motors. If a service center is repairing electric motors, then it is almost certain that some of those motors are driving pumps, and the prospects for pump repair are its existing customers.