Image of a male hand holding a stainless steel closed rotor.

In this post we will present the main types and materials used in rotors, fundamental parts of pumps and motor pumps.

(Eduardo Secco – FAMAC Training)

If you know about the components of a (motorcycle)pump, you know that the rotor, also called propeller or impeller, is the main component of the centrifugal pump, as it is responsible for providing energy to the liquid that will be pumped.

The principle of operation of a centrifugal rotor is that when it rotates, driven by an external driving source, it creates a depression (vacuum) in the central region of the rotor/impeller, causing the aspiration of the liquid, which starts to rotate and is directed to the the periphery by the action of centrifugal force, acquiring pressure and velocity.

The indication of this or that type of rotor has to do with the application, especially depending on the liquid to be pumped. So what do you think about seeing here what are the main types and materials used in rotors? Follow with us then.

The most common types of rotors are as follows:

  • closed, for use in clean water, without solids or objects, indicated to obtain more pressure and better performance;

  • semi-open, used in pumps with high flow, for clean, turbid or solid water;

  • peripheral, for use in clean water, indicated to obtain more pressure;

  • vortex, for use in water with the passage of solids such as fibrous materials;

  • single channel, for use in sewage, suitable for pumps with moderate flow and pressure;

  • helicoidal, for use in liquids with the presence of solid and fibrous materials, indicated for pumps with moderate flow and pressure; It is

  • double suction, for use in clean or turbid water without the presence of solids, indicated for pumps with large flows and pressures.

In addition to the rotor type, determining the material it is composed of is also important. There are applications that support all types of material, but there are more specific ones in which the rotor (or rotors, in the case of a multistage) needs to be built in a specific type of material or else the motor pump will not work properly.

For example, when the liquid to be pumped is clean water, an impeller of any material can be used, whether cast iron, aluminum, bronze, stainless steel or polymer.

For turbid water without solids, polymer is not recommended and in case of passage of solids, aluminum is not recommended either.

In the case of hot water, iron, bronze and stainless steel can be used.

As for sea water, no cast iron, choose either bronze or stainless steel!

In pool and whirlpool pumps, the impellers must always be made of polymer. This is because, in addition to the chemical aggression caused by chlorine, reducing the useful life of the rotor, as a result of this aggression, the pool water will become yellowish, due to the rust that will appear on the rotor made of inappropriate material.

For pumps that will be used in firefighting systems, the option will always have to be for materials that do not suffer from high temperatures and that is why polymer impellers are discarded as an option.

In applications in the food, chemical or pharmaceutical industry, it is better to opt for stainless steel. Some cases in the chemical industry allow opting for polymer rotors, but it will depend on the chemical product to be pumped, as well as its temperature and concentration.

Among the materials presented for the rotors, the one that shows the best resistance to pumped liquids is stainless steel. This is due to the composition of the material itself, which allows it to be used in liquids with very high temperatures, more abrasive liquids such as sea water, in addition to providing greater resistance to certain chemical products.

It was with this in mind that FAMAC developed the lines FGX e FMX of single and multistage motor pumps, respectively. They have cast iron housing and stainless steel rotors, which increase the useful life of the pump, avoiding unnecessary oxidation and wear.

And don't forget: when you need one help to identify the best product to meet your needs, feel free to contact us. Our network of resellers will be able to help you!

For today we stop here, but here on the blog and on social networks @famacmotobombas we are always sharing news and applications of FAMAC motor pumps. Be sure to follow!

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