Advantages And Disadvantages Of Centrifugal Pump

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Centrifugal pump is a widely used mechanical device, mainly used for transferring liquids or increasing the pressure of liquids. It is widely used in various industries such as water supply systems, agricultural irrigation, chemical processes, fire control, heating and ventilation, etc.

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Recognizing centrifugal pumps

What is centrifugal pump?

A centrifugal pump is a common type of fluid transfer device that uses a rotating impeller (a rotating disk with multiple vanes) to convert mechanical energy into kinetic and pressure energy in a liquid. This action causes the fluid to flow and can provide a certain amount of lift or pressure. Centrifugal pumps consist of an impeller, pump casing, inlet and outlet, seals, bearings, couplings, drive unit, and pump pressure head.

Working principle of centrifugal pumps

Force is applied to the liquid by means of a rotating impeller (a spinning disk with multiple vanes mounted around its perimeter). When a motor drives the pump’s impeller to rotate, the rotational speed of the impeller causes the liquid to create a rotational motion, which creates centrifugal force. This centrifugal force pushes the liquid against the pump casing, a process that increases both the velocity and pressure of the liquid. The liquid then flows out through the outlet of the pump. While the liquid is being thrown out by the impeller, the pressure in the center of the impeller decreases, creating a low-pressure zone that allows new liquid from the pump inlet to enter and be thrown out again by the impeller, and so on, creating a continuous liquid transfer process.

Centrifugal pump applications

• Water supply system
• Agricultural irrigation
• Chemical processes
• Fire control
• Heating and ventilation
• Food and beverage industry

Relationship between process pumps and centrifugal pumps

Process pumps and centrifugal pumps are related primarily in that they are both types of pumping equipment, but they differ in their principles of operation and areas of application. Process pumps are pumps that are specifically designed for the transfer of liquids in a process and are suitable for a variety of different process applications, including chemical processing, petroleum, food and beverage production, and more. There may be a number of different types of process pumps, including centrifugal pumps, screw pumps, double diaphragm pumps, and so on, so a centrifugal pump can actually be a process pump.

Different types of centrifugal pumps

1. End-suction centrifugal pumps: Also known as single-suction centrifugal pumps, are designed so that liquid enters the pump from only one direction. These pumps are usually used in water supply and hot water systems.
2. Double suction centrifugal pumps: In contrast to end suction centrifugal pumps, double suction centrifugal pumps are designed so that liquid is introduced from two directions. This type of pump is widely used in petroleum, chemical and electric power fields.
3. Multi-stage centrifugal pumps: These pumps have multiple impeller sets, each with its own level. Each stage increases the pressure of the pump, making the multistage centrifugal pump capable of providing higher pressure. This type of pump is mainly used in high pressure washing system, boiler feed water system.
4. Self-priming centrifugal pumps: This type of pump is self priming and does not require filling of the pump body before starting. It is widely used in irrigation, utilities, sewage treatment and other fields.
5. Vertical centrifugal pumps: The motor of this pump is located on top of the pump body, the impeller is located below, and is usually completely submerged by the pumping medium. They are widely used in groundwater lifting, chemical processes and so on.
6. Submersible centrifugal pumps: These pumps are designed to operate fully submerged in the pumping medium. They are commonly used for deep well water lifting, groundwater harvesting, drainage processes, etc.

Advantages and disadvantages of centrifugal pumps

Difference between centrifugal and diaphragm pumps

What is diaphragm pump?

Diaphragm pump is a special volume pump with a wide range of applications. It uses a soft and flexible diaphragm (made of rubber, plastic or metal) to reciprocate between the two chambers of the pump, accomplishing the transfer of liquids or gases through suction and discharge action. Diaphragm pumps are also widely used in different industries.

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How to choose diaphragm Or centrifugal pumps?

1. Fluid properties: This includes the viscosity of the fluid, whether it contains solid particles, and whether it is corrosive or flammable. For example, fluids that contain a lot of solid particles or have a high viscosity may be more suitable for pneumatic pumps. Clean, low-viscosity fluids are more suitable for centrifugal pumps.
2. Flow and head requirements: Centrifugal pumps are typically used for high flow and medium head applications, whereas pneumatic pumps can provide higher pressures and are more suited to applications requiring higher heads.
3. Energy efficiency: Typically, centrifugal pumps are more energy efficient than pneumatic pumps, so if there is a high demand for energy efficiency, a centrifugal pump may be preferred.
4. Maintenance and longevity: Centrifugal pumps have a more complex structure and require regular maintenance and replacement of parts. While the structure of the air operated double diaphragm pump is simple, less maintenance needs.
5. Environment: If the working environment may have a risk of explosion, it is safer to use pneumatic pumps as they do not produce sparks. In addition, if the environment of the power supply is unstable or can not provide electricity, pneumatic pumps are also a better choice, because they can be driven by compressed air or gas.

How to use centrifugal pumps?

1. Installation: Install the centrifugal pump in the correct position, make sure it is stable and has no loose parts, and make sure that the inlet and outlet of the pump are correctly connected to the corresponding pipelines.
2. Filling with liquid: Before starting the pump, it is necessary to ensure that the pump is filled with liquid, that is, to “fill the pump”. Centrifugal pumps should not be operated without liquid, otherwise the internal structure of the pump will be damaged.
3. Start-up: Ensure that all connections are securely made and that the power is turned on. The centrifugal pump starts working, transferring liquid from one place to another.
4. Operation and monitoring: During pump operation, you need to regularly check the pump’s operating conditions, such as whether the liquid flow and pressure are normal, whether the pump has abnormal vibration or noise, and whether the motor is overheated.
5. Shutdown: When shutting down the pump, the outlet valve of the pump should be closed first, and then the power supply should be shut down.
6. Maintenance: Perform pump maintenance on a regular basis, including cleaning the inside of the pump and replacing worn parts.

How to maintain centrifugal pumps?

• Regular Cleaning
• Regular cleaning
• Regular replacement of wear parts
• Keep lubricated
• Protect against freezing and heat

summary

Centrifugal pump is a widely used equipment for transferring liquids in industry and households. It is simple in construction, easy to manufacture and maintain, smooth in operation, low in noise and vibration, and capable of delivering high head and high efficiency under the right conditions. AOBL as a specialist in fluid pumping, we offer sanitary diaphragm pumps, electric diaphragm pumps as well as pump accessories, please contact the specialized technical team for your solution.

What is a centrifugal pump?

Centrifugal pumps are classified as a dynamic pump type that use centrifugal force to turn mechanical energy into hydraulic energy. They are by far the most commonly used pumps on the market because they are reasonably priced and offer a good price/performance ratio for high flow applications. However, centrifugal pumps have a number of limitations that make them less than ideal for a range of industrial and hygienic applications. Electric diaphragm pumps solve many of these common issues.

Disadvantages of centrifugal pumps

Centrifugal pumps have several disadvantages compared to diaphragm pumps. Graco’s QUANTM pump is an electric double diaphragm pump (EODD) that addresses many of these common disadvantages of centrifugal pumps.

• Narrow optimum operating range and efficiency point
  Centrifugal pumps have a specific impeller diameter, which means they only operate at optimum efficiency at a specific flow. Any flow range below or above this best efficiency point (BEP) is quite narrow. Not only does working outside the preset range significantly reduce the pump’s efficiency, but eventually, it also leads to cavitation, vibration, impeller damage, suction and discharge recirculation, or reduced bearing and seal life forcing complete rebuilds of the whole unit. QUANTM electric diaphragm pumps are well suited to varying flow, pressure, and applications. It poses no risk for shear-sensitive liquids and can easily handle abrasives and solids.
• Impact of changes in viscosity
  Some liquids can vary in viscosity due to temperature, chemical reaction or separation (varied layers or solids). The performance of a centrifugal pump is especially impacted when pumping more viscous liquids, because of the increased resistance to flow as the impeller rotates. The volume pumped by a centrifugal pump depends on head (back pressures) viscosity and the homogeneity of the material. If these values vary dynamically in a certain application, it is difficult to keep a centrifugal pump operating close to its best efficiency and also without prematurely wearing out the pump.
• Damage caused by deadheading
  When a discharge valve is closed or a line blockage occurs, it causes the fluid to recirculate in the pump, and pressure to continue to build resulting in a build-up of motor temperatures. When a pump is run in a deadheaded condition for too long, the excess heat damages the expensive seals and reduces pump life. Without purchasing additional sensors and controllers, a centrifugal pump will continue to run until something fails. The extra cost of these additional sensors and controllers needs to be included in the total cost evaluation.
• Not self-priming
  Centrifugal pumps are not self-priming. For the pump to work properly, its casing must be filled with liquid before start-up. When the casing fills with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping. To make sure the pump remains primed and does not become gas-bound, centrifugal pumps need to be installed below the fluid level, from which the pump takes its suction. Alternatively, the pump can be primed by supplying liquid under pressure through another pump placed in the suction line. QUANTM pumps are self-priming and have excellent suction capabilities.
• Unsuitable for abrasives and solids
  Particularly in the chemical industry, selecting a centrifugal pump for pumping solids is quite a challenge, as process owners need a pump that is not only compatible with the chemicals being processed, but also capable of handling solids without choking the impeller and thus causing increased pump wear and potential blockages. The centrifugal pump types that are suited to this specific set of applications tend to have lower performance areas and be more expensive.
• Unsuitable for shear-sensitive liquids
  High-speed systems, such as the centrifugal pump, tend to shear liquids which is why this technology is not the best choice for shear-sensitive liquids.
• Unsuitable to run dry
  A centrifugal pump cannot run dry without causing damage to the system. The system needs to have resistance to dissipate rotation speed of the impeller. The QUANTM electric diaphragm pump can run dry without causing any damage to the system to avoid expensive repairs.

Common centrifugal pump applications

While centrifugal pumps are commonly used in various industries because of their efficiency with low viscosity materials and high flow rates, they may not always be the best fit for every application. Here’s a look at how centrifugal pumps are used in specific industries and QUANTM’s potential advantages:

• Food and Beverage Manufacturing
  Centrifugal pumps are commonly used to transfer beverages and other low-viscosity liquids in the food industry. But the forces generated by centrifugal pumps can sometimes damage sensitive fluids, altering quality. QUANTM pumps are able to maintain the integrity of shear-sensitive products like creams and yogurts. Additionally, their hygienic design ensures compliance with food safety standards.
• Water Treatment and Transfer
  Centrifugal pumps are often used for their ability to move large amounts of water, but they can struggle with varying pressure conditions and the presence of solids. QUANTM pumps are able to handle a wider operating range, including higher solid content fluids without the risk of clogging. Their resistance to harsh conditions makes them an ideal alternative for water treatment applications.

Centrifugal pumps vs diaphragm pumps