What is a pump
A pump can be considered as a mechanical device, which can be used to increase the pressure of a fluid and by that they can move the fluids or slurries by mechanical action. Pumps are classified according to the way they used to move the fluids they are direct lift, gravity and displacement pumps. Pumps will create low pressure at the suction end, so the fluids can be sucked and high pressure is created at the discharge end, so that fluid can be raised to the required height.
What are the factors that involves in pump selection
Before choosing a pump we must know certain factors they are, the pressure against which the pump must operate, the desired flow rate, suction lift, and the characteristics of the fluid. The total head, suction lift, and the flow rate are depended upon the piping system and pump’s characteristics.
What are the types of pumps
Positive displacement pumps
Positive displacement pumps can move a fixed volume of liquid per unit of time. These pumps are larger than the equal capacity dynamic pumps. Positive displacement pumps are used in the hydraulic system. One important factor of hydraulic power is the high power density. Positive displacement pump is capable to move a good quantity of liquid with each revolution
Positive displacement pumps are divided into two types based on how they move the fluid.
Rotary type positive displacement
Rotary positive displacement pumps move the fluid by a rotating mechanism which creates the vacuum and that captures and draws in the liquid. Rotary pumps are capable to move the air from the lines. It has a drawback that if it is operated at high speeds, the fluids will cause erosion, and it will cause the development of large clearance through which liquid can pass.
Reciprocating type positive displacement
These types of pumps move the fluid by using one or more oscillating pistons, plungers or membranes. The motion of the liquid is in a single direction with the help of valves. These pumps can be powered manually, or by air or steam, these pumps are mostly used for pumping high viscous fluids. Reciprocating pumps were widely used for pumping water from wells.
What are the types of positive displacement pumps
Piston pump, vane pump, regenerative pump, rotary gear pump, rotary lube pump, and peristaltic pump
What are the applications of positive displacement pumps
- They are used in chemical processing and liquid delivery
- Marine and biotechnology
- It is used in food, dairy, and beverage processing
Dynamic pumps operate by creating a high liquid velocity and it will convert the velocity of the liquid to pressure in a diffusing flow passage. These pumps have lower efficiency than the positive type pumps. These pumps are able to operate at high speeds and high fluid flow rate and the major advantage is that it has lower maintenance. Dynamic pumps can be considered as a type of velocity pumps in which the velocity of the fluid flow is increased to obtain the kinetic energy. The kinetic energy is converted into pressure. Dynamic pumps add energy to increase the fluid velocity and the velocity reduction in the pump can increase the pressure
Types of dynamic pumps
Centrifugal pump converts the energy of prime mover into velocity or kinetic energy and then into the pressure energy of fluid that is being pumped. The impeller will convert the driver’s energy into kinetic energy and the diffuser will convert the kinetic energy into pressure. when the impeller rotates liquid is discharged by a centrifugal force into a casing surrounding the impeller, the casing will decrease the velocity of the fluid which leaves the impeller at high velocity and then the velocity is converted into pressure.
The advantages of centrifugal pumps are they can provide smooth flow through the pump and uniform pressure in the discharge pipe. Their operating speed will allow connecting the steam turbines and electric motors directly.
Axial flow pump
Axial flow pump is also known as a propeller pump, these pumps are very large capacity type and they are used for supply of cooling water for steam ship condensers. The axial flow pump offers very little resistance to flow when idling so scoops are employed. While the operation considerable end trust occurs and a tilting pad thrust bearing is employed. These pumps develop most of their power by propelling or lifting action of the vanes on the liquid. These pumps are used in wet-pit drainage, low- pressure irrigation. Horizontal axial flow pumps can be used to pump large volumes.
The operation of the mixed flow pump is the combination of radial and axial flow pumps, the fluid will experience a radical acceleration and lift then it exits the impeller from the axial direction. Because of this, the mixed flow pump operates at a higher pressure than the axial flow pump and also can deliver higher discharge than the radial flow pumps.