Hazards Of Vertically Mounting Centrifugal Pumps

13 May.,2024

 

Hazards Of Vertically Mounting Centrifugal Pumps

Mounting centrifugal pumps in a vertical configuration certainly has its benefits. It can provide a much smaller footprint, and it makes sense for inline pumping applications. But before running a centrifugal pump vertically, it is important to review the environment that the seal will see.

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Fluids with high amounts of dissolved gases or entrained air can cause serious problems for vertically mounted centrifugal pumps. Air bubbles in the fluid tend to rise and could accumulate in pump's stuffing box area depending on pump design and process conditions, creating a potential for. This will prevent fluid properly lubricating the mechanical seal, running it dry.

Mechanical seals need a small amount of fluid between the seal faces to operate properly. The fluid vaporizes creating a barrier between the faces and reduces friction between the faces. The fluid is also needed to help dissipate heat created by the seal faces. Without it, mechanical seals can experience thermal shock, coking, heat checking, and blistering of the seal face. That doesn't mean mounting in this configuration is impossible.

Venting / Flush Plan

To ensure the mechanical seal does not run dry, consideration should be taken for air that is potentially in the stuffing box. During selection of a pump it is important to speak with an engineer, who knows pumps and mechanical seals, for a recommendation on the proper venting and flush plan for your application.

A venting procedure at start-up  could be as simple as opening a valve on a line coming of the stuffing box area to give a low pressure area for it to go.   

Another option is a permanent line that allows for movement of any accumulated air and process fluid in this area. A common flush plan for this application is API Plan 13. This flush plan recirculates product from the seal chamber back to the pump suction. This creates a pressure differential that promotes circulation and  the evacuation of air through the process fluid.

Here's a good illustration of how the plan works:

In vertical mounting applications, it is important to provide an environment for that seal that will provide a long life and reduce downtime. If you’re unsure, be sure to contact an engineer who understands the complications that can come with this configuration.

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Pump FAQs

Rotodynamic pumps are used in most all municipal, process, power, oil and gas markets and many more. The markets and applications are too many to list, but a few are provided for perspective.

Water, Wastewater and Irrigation

Modern living depends heavily on water supply, wastewater removal, and irrigation, which all require pumps which are among the oldest machines ever used. These needs constitute a large market for pumps and are the heart of civilization.

The water that we take from the faucet gets to us by the action of pumps, which move the water through pipelines from the reservoir to our homes. Water may also come from deep wells which require vertical deep-well pumps to bring it to the surface.

Water from the sink and tub is collected and treated before disposal. Pumps are needed to move the water to the treatment plant, as shown here, and during the treatment process.

Water is also vital to the irrigation of farm products, shrubs and lawns. Pumps supply the water and pressure needed for sprinkler systems as shown or trenches to carry the water to rows of farm products.

Oil & Gas, and Process Industry

Manufacturers of liquid products that we use every day are a second major market for pumps. Making chemical products, for example, requires pumps for processing. Petroleum products, including gasoline, are derived from crude oil which must be processed at high temperatures and pressures with the aid of pumps.  Operating temperature for such pumps can be over 800°F.

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Electric Power Industry

Electricity which we use to light our homes and drive electric motors is produced in large electric power generating plants. Electricity is generated by large turbines using steam from high pressure boilers. Many pumps are needed in this process and make up a third large market for pumps. These powerful high pressure pumps are used to feed water at high pressure to steam boilers (Image 1).

Other pumps in power plants are necessary to remove the condensed steam from the bottom of massive steam condensers and send it to heaters which increase the water temperature. Heater drain pumps then move the water to the boiler feed pump.

Cold water is needed to cool the spent steam and turn it back to water. These pumps circulate water from the cooling tower through the condenser and back to the cooling tower where it is cooled as it splashes down through the tower.

Exhaust gas from the furnace in electric generating stations is scrubbed by water from pumps in order to remove solid particles.

Mining and Metals Industry

Mining and the refining of metals is a fourth major market of pumps. To facilitate deep pit mining, pumps are needed to remove ground water.

After steel is produced in large ingots, it is heated and rolled into many different shapes.

High pressure water from pumps removes scale, which appears on the outside surface of the steel sheets and rods.

Other Industries

Commercial construction of buildings is a fifth key market for pumps. Buildings require pumps for applications such as fire protection. These fire pumps are engine driven in case of an electrical power failure (Image 2).

Heating and air conditioning in buildings requires pumps to circulate hot water for heating or chilled water for air conditioning (Image 3).

There are many addition pump markets and applications that are too many to list, but one can get the idea of how common pumps are in our daily life, even though we may not be thinking about them on a regular basis.

For more information on pump applications, and training on rotodynamic pump fundamentals refer to HI’s web based Rotodyanmic Pumps eLearning course at pumps.org.

July 2019

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