Nowadays, the family of centrifugal pumps plays a strong role in the country's industrial application, and among the other pumps, these are the most widely used pumps.
The positive thing about centrifugal pumps that sets them apart from others is the fluid volume flow rate, which is uniform.
This feature ensures that when the drainpipe is blocked or clogged, do not put too much pressure on the pump and do not stop the pump motor.
Pressure drop usually occurs for two reasons, one is fluid friction, and the other is the connection problem that will cause the pressure drop.
To avoid such problems, we must consider all the important points when choosing a pump and make the best choice according to the conditions and needs of the work.
In fact, the lifespan and efficiency of centrifugal pumps depend to a large extent on their precision and calculated engineering when purchasing a pump.
The operation of these pumps is such that the fluid leaves the output of the first pump and enters the second pump.
And the second impeller increases the flow rate.
What happens in a single-suction centrifugal pump is that the fluid enters from one side of the impeller, but in a dual-suction centrifugal pump, the fluid enters from both sides of the vanes.
This is what makes the high-capacity dual suction pump a more practical option.
Centrifugal Pump Suction
Considering the conditions in the suction of the pump is a key element in the performance and successful installation of the pump.
If the fluid to be pumped does not enter the impeller eye; The pump will then not be able to provide the expected amount of performance.
Therefore, a correct understanding of the conditions in the pump suction is essential.
One of the most important issues that arise in the suction of the pump is the issue of cavitation, in which many articles have been written and its effects on various pumps have been presented.
Of course, this problem is not widespread and many pumps that are currently operating have not experienced the problem, but its harmful effects are so great that it is necessary to examine it in detail.
Cavitation has a special relationship with vapor pressure.
Vapor pressure is the pressure under which a liquid will evaporate.
For example, water at 212 degrees Fahrenheit and when its pressure reaches less than 14.
7 psi, begins to evaporate.
This term is also commonly referred to as boiling.
It can also be said that water will boil at 100 degrees Fahrenheit if exposed to a vacuum pressure of 18 inches of mercury.
Everyone who works with pumps is relatively familiar with the signs and symptoms of cavitation.
This phenomenon is always accompanied by a special rattling sound and the level of vibration is also high in it.
Pitting holes have formed on the impeller and due to this phenomenon, the amount of headstock that should be provided by the pump will always be reduced.
In order to eliminate this problem, it is necessary to know in the first stage what cavitation really is and what factors cause cavitation in centrifugal pumps.
In general, the cavitation phenomenon is a two-part process that is caused by changes in the pressure of the liquid that enters the pump (impeller).
What Are the Types of Centrifugal Pumps?
Types of centrifugal pumps are classified based on the design of the impellers and the number of impellers.
A multi-stage pump has more than one impeller.
A two-stage pump has two impellers.
A two-stage pump has the same effect as a two-stage pump in series.
The output of the first pump enters the second pump.
A multi-stage pump has two or more impellers mounted on one shaft.
The discharge at the output of the second impeller is higher than the discharge at the output of the first impeller.
Increasing the number of impellers increases the final output flow.
Because liquids are almost incompressible, all impellers in the pump are designed for the same capacity.
The impellers of a multi-stage pump are the same size.
These pumps are also classified based on whether they are single suction or dual suction.
In a single suction pump, the fluid enters from one side and in a double suction pump, the impeller enters from both sides.
As the liquid enters from both sides of the impeller, a dual suction pump is used for high operating capacities.
Dual suction pumps have low NPSH.
The principle of operation of the centrifugal pump is based on the centrifugal force, in such a way that the moving part of the pump throws water droplets out of the center under rotational motion because the droplets have a high speed, and their pressure turns into pressure in contact with the shell.
In fact, their work is based on applying centrifugal force and exchanging the amount of motion in the impeller blades per unit weight of liquid.
According to the lifting height, these pumps are divided into three categories: A-Low-rise centrifugal pumps are pumps that operate up to a height of 15 meters.
These pumps are generally of the single-stage screw type with a horizontal axis, and depending on the amount of discharge, fluid may enter the impeller from one side or both sides.
B-Medium lifting centrifugal pumps are pumps that operate up to 40 meters in height.
These pumps generally have guide vanes (sprinklers) and depending on the amount of discharge, water may enter the impeller from one side or both sides.
C-Centrifugal pumps with high lifting height (high pressure) are used to lift the fluid more than 40 meters.
High-pressure pumps are generally multi-stage because a single impeller cannot easily produce such high pressure.
These pumps may be horizontal or vertical.
Lifting height is usually increased by 30 to 50 meters per level of horizontal centrifugal pumps.
Therefore, the number of layers depends on the pressure required.
Centrifugal Pumps Basics
The working basics of all the centrifugal pumps are based on the use of centrifugal force.
Any object moving in a circular or curved path is affected by centrifugal force.
The direction of the mentioned force is such that it always tends to move the object away from the axis of the center of time.
The rotating part inside the pump housing causes water to circulate with its rapid movement.
As a result of creating a relative vacuum, atmospheric pressure causes water to enter the pump body.
If there is water inside the pump and its impeller continues to move.
The impeller rotates inside the pump housing.
The water inlet or suction duct is in the center of the blade and the outlet hole is located around the body.
During operation, water is sucked out of the inlet duct and exits through the outlet duct after being affected by centrifugal force.
In a centrifugal pump, water enters a chamber through the inlet duct installed in the impeller, where it encounters the moving blades of the impeller.
The flowed water leaves the impeller with great speed and pressure and exits the pump through the duct provided for this purpose and is directed to the place of consumption.
When purchasing a centrifugal pump, the goal is to provide a pump that operates with maximum reliability and efficiency while meeting the required requirements.
In many cases, people fall into the trap of choosing a centrifugal pump, which leads to choosing a pump that is not ideal.
The main reason for improper pump selection is the lack of training on the principles of centrifugal pump hydraulics and how hydraulic design parameters can significantly affect pump life cycle costs.
But for others, choosing a centrifugal pump from the many options available can be daunting, and many factors such as required flow, differential pressure, and suction conditions must be considered against the cost of capital, and energy costs for the pump must be measured.
Finally, it should be noted that with all the recent tips, if there is a problem in choosing a pump, our experts will assist you in choosing an appropriate centrifugal pump, and the selection process will be facilitated for you.