What is Reciprocating Pump: types, Parts, Working, Advantages, and Disadvantages

What is reciprocating pump? its a one of the most common type of pump used for all types of applications including domestic water pump. 

A reciprocating pump is one that move water due to the reciprocating (forward and backward action) motion of its piston. 

Piston moves back and pump suck in water from its source and as piston move forward the pump pushes the water out with great force and pressure.

Types of Reciprocating Pump

Follow are the three fields in which the reciprocating are classified

1. According to the contact between water and plunger

2. According to the number of cylinders

3. According to the air vessel

According to the contact between water and plunger

Single acting pump

A single acting pump is one which has one suction valve, delivery valve and one suction and delivery pipe. It suck up the fluid only in one direction and in single stroke called  suction stroke and deliver it in a single stroke called delivery stroke

Single acting reciprocating pump

Double acting pump

A double acting pump is one which has two suction valves, delivery valves and two suction and delivery pipes. If we suppose that piston is in the center of the cylinder then one suction and delivery pipe is on one side and one delivery and suction pipe is on other side of the piston.

double acting reciprocating pump

According to the number of cylinders

1. Single cylinder pump

Single cylinder pump is one in which their is only cylinder connected to a single shaft. It could be a single acting or double acting pump.

2. Double cylinder pump

Double cylinder pump is one which have two cylinder attached to a single shaft. Separate suction and delivery valve is provided to each cylinder. Crank of the pump is set at an angle of 180 

3. Triple cylinder pump

When the pump has three cylinders attached to a single shaft then the pump is called triple cylinder pump. Crank is set at an angle of 120

According to the air vessel

1. With air vessel

Some reciprocating pump are provided with a separate air vessel attached to the suction and delivery valve. Its main function is to accumulate excess quantity of water by compressing the air in the vessel

2. With out Air vessel

Some pump lack the air vessel because of the nature of their work. for example the reciprocating boiler feed pumps does not have air vessel because they may introduce air into the deairated water

Parts of reciprocating pump 

Parts of reciprocating pump with their details are as follow

Crank

Crank is a circular disk attached to the motor and used to transfer the rotation motion of the motor to the piston

Connecting rod

Connecting rod is the long solid rod. It provide connection between crank and the piston. It also convert the rotation motion of crank into the linear motion of the piston.

Piston  

Piston is the solid cylinder like part of the pump which moves linearly in the hollow cylinder of the pump. It motion is main reason behind suction and deliverance of the liquid

Components of reciprocating pump

Cylinder

It is a hollow cylinder in which piston moves. Suction and deliverance take place with in it. Suction and delivery pipe and valves are attached to its one end piston come and go back from other end.

Suction pipe

Pipe which take liquid from the source and provide it to the cylinder of the pump  is called suction pump

Suction valve

It is one way valve place between suction pipe and cylinder of the pump. It is open when suction take place and close when delivery of the water is taking place

Delivery pipe

Pipe which take water from the cylinder of the pump and provide it to the tank is called delivery  pipe.

Delivery valve

It is one away vale and placed at the point of attachment of delivery pipe with cylinder. It is open when delivery of water is taking place and closed when suction of water in taking place

Strainer

It is a filter like parts provided at the end of suction pipe. Its main function is to stop is solid particles from entering into the pipe

Air vessel

Installed at the suction and delivery pipe and its main function is to give a steady flow by reducing the frictional head 

Working of Reciprocating Pump

Now we will discuss the working of two basic types of reciprocating 

• single acting reciprocating pump 
• double acting reciprocating pump

Working of Single acting reciprocating pump

Suction

Let us suppose that the pump piston is at the inner dead centre and the crank start to rotate in the clock wise direction. As the crank start to rotate piston start to move toward the outer dead centre. 

As the piston moves back vacuum is created and force the suction valve to open and suck up the water from the sump into the cylinder of the pump

Delivery

Now after the suction process is complete, piston of the pump is at the outer dead centre. As crank continuous to rotate the piston of the pump is now force to move toward the inner dead centre and in doing so piston force the water and creates the pressure inside the pump and as the pressure reached a specific value delivery valve is open and water is transfer to the tank.

Working of Double acting reciprocating pump

Piston moving in right direction

let us suppose that the piston is initially at the centre of the cylinder and crank start to rotate on clock wise direction so the piston will move toward the right side and thus vacuum is created at left side of the piston and pressure is created at the right side of the piston. 

Vacuum at left side force the water to move into the cylinder from the sump and pressure at the right force the water to move up from the delivery pipe in to the tank

Piston moving in left direction

As the crank continuou to rotate, piston after reaching at one end now moves is left direction and so pressure is created at the left side of the piston and vacuum is created on the right side of the pump. Vacuum cause the water to move up in the pump and pressure cause the water in pump to move into the tank.

Advantages and Disadvantages of Centrifugal Pump

Following are the advantages and disadvantages of reciprocating pump

Advantages of reciprocating pump

• High efficiency

• No priming needed

• Can deliver water at high pressure

• Can work in wide pressure range

• Continuous rate of discharge

Disadvantages of reciprocating pump

• More parts mean high initial cost

• High maintenance cost

• No uniform torque

• Low discharging capacity

• Pulsating flow

• Difficult to pump viscous fluid

• High wear in parts