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19 January 2023

The Classification of Pumps

We usually divide pumps into two major categories. These are Dynamic Pumps/ Kinetic Pumps, and Positive Displacement pumps.

How are Pumps Classified?

We classify pumps according to their mechanics. We also classify them according to the design of their individual working principles.

Listed Here Are 2 Key Types of Pumps

  1. Types of Dynamic Pumps/Kinetic Pumps
    Centrifugal pumps, vertical centrifugal pumps, and submersible pumps.
  2. Types of Positive Displacement Pumps
    Diaphragm pumps, gear pumps, peristaltic pumps (hose pumps), rotary lobe pumps, and piston pumps.

Types of Pumps Explained

Dynamic Pumps/Kinetic Pumps – Centrifugal Pumps

What are Centrifugal Pumps and What Do They Do?

We apply and use centrifugal pumps in many applications. The reason is they are simple to work and cost-effective to manufacture. The pressure at the inlet of the pump increases as the fluid flows through the pump. It is the difference in pressure that propels the fluid through the pumping system.

  • Centrifugal pumps use a rotating action in which they generate flow and pressure.
  • Two key parts responsible for generating power are the impeller and volute (casing).
  • The casing collects liquid discharged by the impeller. It then converts this into pressure or kinetic energy.

Types of Pumps – Centrifugal:

1. Radial Flow occurs when the impeller expels liquids at right angles to the shaft axis. Through centrifugal force, it then reaches the correct pressure. We use radial pumps in the application of low discharge and high pressure.

2. We refer to the mixed flow category when the flow direction is partly radial and partly axial, resulting in a diagonal flow. We use mixed flow pumps for medium pressure and high discharge applications. They meet pressure through partial centrifugal force, and the lift of impeller vanes.

3. We use Axial Flow type pumps for low pressure and high discharge. The flow of liquids in this centrifugal pump is parallel to the shaft axis. Pressure builds up through the propelling motion of the vanes of the impeller on the liquid.

The exact running speed of centrifugal pumps identifies the approximate ratio of the impeller eye diameter (D1) to the impeller’s outside diameter (D2). This is necessary to attain an excellent impeller design.

About Dynamic Pump Systems

We refer to fire hydrant pump systems as hydrant boosters, fire water pumps, and fire pumps. The fire hydrant is an entire system and usually not a pump. Components of a hydrant system include a centrifugal pump, control panel and motor. The motor is electric or diesel. These systems need to comply to strict regulations, and safety standards. The reason is they are of critical importance to these systems.

Fire Hydrant Pump Systems

Classification of Submersible Pumps

We often refer to submersible pumps as sewage, stormwater pumps, deep well “borehole”, and septic pumps. They work when submerged in water.

About Positive Displacement Pumps

Applications of diaphragm pumps

There are 2 main diaphragm pumps: mechanical and air-operated pumps.

What are Diaphragm Pumps & Where Do We Use Them?

We use diaphragm pumps in a wide range of industries and applications. Their versatility makes them perfect for processing a broad range of fluids. They fall under the umbrella of displacement pumps.

  • Their flow remains relatively constant during the discharge of fluids.
  • They are perfect for transferring fluids with high, low, and medium viscosities.
  • We also use them for fluid applications with plenty of solid content.
  • The design of diaphragm pumps makes them ideal for handling hard chemicals. A good example of this is hard acids.
  • They make diaphragms from a wide range of materials, resulting in a variety of diaphragms.

Air Diaphragm Pumps Explained

We use Air Diaphragm pumps for dangerous and difficult applications. We often refer to these pumps as AOD pumps or AODD pumps ( air operated double diaphragm).
Because air powers them, this makes them suitable for difficult environments.

We use Air Diaphragm pumps for transferring chemicals. We also use them for dewatering in underground mining applications.

We also apply these pumps for food manufacturing. This is necessary where the liquids have a greater resistance to flow (high viscosity).

Gear Pumps Explained

There are 2 types of gear pumps. The key difference is the placement of the gears and where they trap the fluid!

  • Gear Pumps are positive displacement rotary pumps. They assist with transferring liquids through the use of gears.
  • Gear pumps usually have over 2 internal gears. The gears create a vacuum. This causes atmospheric pressure to push fluids into the pump.
  • Gear pumps use high pressure and are small.
  • They provide a pulseless, stable flow of fluids compared to peristaltic and diaphragm pumps.
  • Other advantages of gear pumps are they are self-priming.
  • They can pump high viscosity fluids.
  • Gear pumps are easy to operate and maintain.

Peristaltic Pumps “Hose Pumps” Explained

The key benefit of peristaltic pumps is there is no cross contamination. Peristaltic pumps operate by using a pinch-and-roll type of method. This takes place along flexible tubing. The tubing pushes liquids in a backward and forward motion.

They contain the liquid inside the flexible tubing. These isolate the liquids from any moving pump and motor parts.Compression and relaxation create the difference in pressure. This is like what our bodies do when we swallow and digest food. The muscles in our oesophagus contract and relax, creating a wavelike motion. This motion helps push the content along during what we refer to as peristalsis. Hence the name of the peristaltic pump!

What are Lobe Pumps?

The #1 feature of Lobe pumps is their outstanding sanitary conditions. We also know them to be reliable and resistant to corrosion. These pumps are efficient and have CIP and SIP characteristics (clean-in-place & sterilise-in-place).

No wonder they are the number one choice for the pharmaceutical industry. They are also suitable for food & beverage applications.

What are Piston Pumps and How Do They Work?

Piston pumps are robust and simple to use. They comprise a piston, a single chamber, and 2 valves.

A piston pump functions when it drives the piston down into the chamber. It then compresses the fluids inside. Hand piston pumps use air to achieve this result.

Some piston pump actions include the transfer of chocolate, paint, and pastry products. The type of piston pump used all depends on the type of industry.

Find Out Everything About The Classification of Pumps

Get the perfect pump for your individual needs today. Our team at AxFlow Liquid Transfer is here to guide you along your pump journey. We understand that each industry has unique requirements.
Contact our AxFlow AQS Liquid Transfer specialists. Find out which one is best suited to your niche industry..
Contact us on +27 12 548 7204, or fill out our enquiry form. We are here to offer you the best and most updated information about pumps for all applications.

Do you still have questions? Give our AQS Liquid Transfer team a call on +27 12 548 7204 or fill out our enquiry form, our friendly team will get back to you with first-hand expertise on how to select a borehole pump for your needs.

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