Wednesday, October 4

A Guide to Multistage Pumps

In recent years, multistage centrifugal pumps have become one of the most popular types of pumps. Their ability to provide engineers with a wide range of flow and head, as well as their high energy economy, make them an excellent choice for a variety of applications. Could they be a good fit for you?

About Multistage Centrifugal Pumps

Two or more impellers are used in multistage centrifugal pumps. Depending on the configuration, the rotors might be mounted on the same or distinct shafts. The rotors can also be connected in series if significant outflow pressures are necessary. However, when great capacity is required, they are frequently connected in parallel.

Multistage centrifugal pumps are used to create high pressure on the shaft in the same housing, saving money over a single impeller pump. The channels within the pump housing function as part of the pump structure, directing an impeller discharge to suck the other.

Water enters the pump and travels from left to right through a set of rotors. Water travels from the spiral of one rotor around the spiral of the next rotor, creating suction for the next rotor. Pumps of this sort are usually single-stage pumps. A multi-stage centrifugal pump performs significantly better.

Axial pressure forces can be balanced in some multi-stage centrifugal pumps by balancing blades positioned at the back of the impellers. The remaining forces are absorbed by the angular ball bearing on the drive side and the heavy-duty ball bearing on the drive side.

Two outer bearings are included with multi-stage centrifugal pumps, as well as a seal pressure-balancing line that releases pressure from the seal section on the discharge side to the suction side. Even when the pump is operating at high pressures, this unique design allows for more cost-effective sealing arrangements.

Horizontal Multistage Centrifugal Pumps

A segmented casing with modular interstage components is used in this type of pump. The spinning assembly is held in place by bearing housings, resulting in a better balanced system that can withstand high pressures.

In comparison to vertical multistage pumps, they can handle higher flow rates (with the exception of vertical turbine pumps).

Multistage pumps with a horizontal layout work best in applications like these:

  • Reverse Osmosis
  • Cogeneration
  • Pressure Boosting
  • Boiler Feed
  • Shower
  • Spray
  • High Pressure Cleaning
  • Snow making
  • Condensate
  • Mine dewatering

However, this style of pump requires a lot of upkeep. Working on these pumps and ensuring that they are properly reassembled requires a high level of skill. They can also be rather expensive up front, depending on the level of specification required and the construction materials used.

Vertical Multistage Centrifugal Pumps

Vertical multistage centrifugal pumps have a vertical shaft with multiple stages stacked on top of each other. Note that vertical turbines are technically multistage pumps, they aren’t the pumps we’re talking about here.

Because the clearances in these pumps are minimal, they are best used in clean water applications:

  • High pressure shower systems
  • Boiler feedwater
  • Desuperheater feed

Vertical multistage pumps are ideal for places where space is at a premium. Its capacity to generate high pressure output with a single pump body and motor is also advantageous.

It’s vital to bear in mind, though, that this type of pump can’t handle debris or large solids, and it’s also susceptible to deadheading.

Multistage pumps offer numerous advantages, ranging from energy savings to the capacity to operate in a variety of flow/head circumstances. If you think it would be a good fit for your project, talk to a certified engineer first. They’ll make certain that the proper pump is chosen for your needs.