Types Of Centrifugal Pump Couplings

When selecting a new pump, you might be inclined to overlook the coupling. It is often included as an afterthought and can sometimes go unnoticed when looking over your purchasable options. However, the coupling is one of the least expensive components of your assembly. Just as selecting the right pump is essential for your hydraulic or plumbing process, choosing a suitable coupling is crucial since it can broadly impact the assembly’s lifespan and performance. This blog will provide you with a complete briefing of the pump coupling, its function and types, and its pros and cons. Let us dive in.

What Is a Centrifugal Pump?

Centrifugal pumps are crucial devices for hydronic and plumbing operations. They are used to transport fluids by converting the rotational kinetic energy of a motor or steam turbine into the hydrodynamic energy of the fluid flow. As a result, they are the most employed pump as compared to any other in the industry.

What Is a Pump Coupling?

A coupling serves a fundamental purpose in the functionality of a centrifugal pump. It connects the feeding pump shaft with the motor shaft to successfully transmit power to achieve transmission torque.

The couplings also ensure that the pump is aligned correctly and can withstand more wear than if it was misaligned. In addition, the flexible connections allow for easy servicing while protecting bearings.

Classification of Centrifugal Pump Couplings

Split Couplers - A split coupler is a solid metal piece connecting the pump shaft to the motor shaft. Since they are made out of steel, they do not offer any flexibility. However, they do make servicing the pump easier.

With this type of coupler, the load will be transferred directly to the pump if any vibration occurs due to motor bearing wear. For example, if the pump starts vibrating due to wear, cavitation, or simply age, the force of the load will be transferred to the motor bearing and shaft.

Flexible Couplers - Flexible couplers are used in base-mounted pumps to connect the motor of a pumping system with adjustable rubber inserts between two metal hubs. They are made of rubber material and provide flexibility while connecting the engine with the pump. In addition, it helps protect against damage due to the non-constant torque associated with HVAC motors, especially variable speed systems.

Flexible couplers allow for easy maintenance by protecting the motor bearings and pump shaft. In addition, they compensate for any misalignment during operations that are torsional, angular (inclined), parallel, or axial.

Closed Coupled or Direct Coupled HVAC Pumps - When pumps do not have any couplers, they are called close-coupled pumps. These pumps have a large single shaft extending from the motor to the pump body through an opening in the cover plate. A closed coupled pump requires a significant bearing due to no bearing assembly being available in the system to absorb the torsional load.

Pros and Cons of Centrifugal Pump Coupling

Split Couplers


  • They require less floor space
  • Pump alignment is not required
  • You can change the seal without moving the motor


  • For servicing and maintenance, the motor should be removed
  • It requires a longer pump shaft
  • If any damage occurs, it affects both motor and pump

Flexible Couplers


  • These couplers operate with little to no noise
  • No need to remove the motor to service the pumps
  • It perfectly suits a variable speed system


  • It requires large floor spaces
  • It involves alignment for effective operation

Close Coupled


  • Closed coupled pumps do not need to be aligned
  • They work perfectly in high-speed applications where the alignment tolerances are tight


  • You need to first remove the motor for seal change and maintenance.
  • If any damage occurs, it affects both the motor and pump.

In Conclusion

Couplings are a vital part of any pump. The correct coupling can make the difference between long-lasting performance and failure. However, choosing which one is difficult without knowing what kind of application your machine has, so you should consult with specialists such as Industrial Part Circuit, a trusted distributor of automation parts, industrial automation parts, industrial fasteners, and electronics. We will resolve your queries within 15 minutes of receiving a call or RFQ form.


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