In general, pumps are classified into two major groups, the dynamic pump and positive displacement pump. These two big groups are divided into few more.
Dynamic pump is divided into several kinds, centrifugal pumps, axial pumps, and special-effect pumps. These pumps generate high fluid velocity by converting velocity into pressure through the changes of cross-sectional fluid flow. This type of pump has lower efficiency than positive displacement pump, but has lower cost in maintenance. Dynamic pumps can also operate at high speeds and high flow discharge.
- Centrifugal Pump
- Axial Pumps
- Special-Effect Pump
Centrifugal pump composed of an impeller with inlet channel in the middle. With this design, when the impeller rotates, fluid flows into the pump casing around the impeller as a result of centrifugal force. This casing decreases the fluid flow velocity while impeller rotation speed remains high. The fluid velocity is converted into pressure by the casing so that the fluid can reach its outlet point. Centrifugal pump has some advantages include smooth operation in pumps, uniform pressure at pump discharge, low cost, and can work at high speeds so that further applications can be connected directly with steam turbines or electric motors. The use of centrifugal pumps in the world reaches 80% because of its suitable use to cope with large amounts of fluid than positive-displacement pumps.
Axial pump is also called propeller pump. This pump produces most of the pressure and lifting force from the propeller. These pumps are widely used in drainage and irrigation systems. Single-stage vertical axial pumps are more commonly used, but sometimes two-stage axial pumps are more economical to implement. Horizontal axial pumps are used for large fluid flow discharge with small pressure and usually involve the siphon effect in the flow.
This type of pump used in industries with certain conditions. This type of pump are jet-eductor, gas lift, hydraulic ram, and electromagnetic.
Jet-eductor pump is using venturi effect of a convergent-diverging nozzle to convert pressure energy from moving fluid to motion energy to create a low pressure area, than can suck fluid on the suction side.
Gas Lift Pump is a way to lift fluid inside a column by injecting a certain gas causing the drop of hydrostatic weight from the fluid so that the reservoir can lift it to the surface.
The hydraulic ram pump is a cyclic water pump using hydropower.
And an electromagnetic pump is a pump that drives metal fluids by using electromagnetic forces.
Positive Displacement Pump
Positive displacement pumps are devided into reciprocating and rotary pumps. The positive displacement pump works by assigning a certain force to the fixed fluid volume from the inlet side to the pump outlet point. The advantages of using this type of pump is that it can produce a larger power density, and also provides fluid displacement that is fixed/stable in every turn.
- Reciprocating Pumps
- Rotary Pump
At this type of pump, a certain amount of fluid volume enters the cylinder through the inlet valve at entry step and then pumped out under positive pressure through the valve outlet in a step forward. The fluid coming out of the reciprocating pump, pulsating and can only change when the pumping speed changes. This is because the volume of the inlet side is constant. This type of pump is widely used for pumping sediment and sludge.
Metering Pump is included in the reciprocating pump type. This pump can varied the fluid pressure discharge as needed. Metering pumps typically used to pump additives inserted into a particular fluid stream.
Is a pump that drives the fluid by using the principle of rotation. The vacuum is formed by the rotation of the pump and then sucks the incoming fluid. The advantage of this type is its high efficiency because it naturally removes air from its flow pipe, and reduces the user’s need to manually remove the air.
This pump weakness is, because of its natural design, the clearence between the swivel blade and the follower blade should be as small as possible. It’s also has requirement to rotate at low and stable speed. If the pump is working at a very high speed, then the working fluid can eroded the pump blades.
Rotary pumps can be classified into several types:
- Gear pumps – a simple rotary pump where the fluid is pressed using two gears.
- Screw pumps – These pumps use two threads that meet and rotate to produce the desired fluid flow.
- Rotary Vane Pump – has the same principle as a scroll compressor, which uses a rotating cylindric rotor to produce a certain fluid pressure.
More details about the various positive displacement pumps, you can open the following article.