Reciprocating Pump | Working Principle Of Reciprocating Pump.

What is Reciprocating Pumps and It’s Working Principles of Reciprocating Pump

Reciprocating Pumps and Types of Reciprocating Pump

In this article, you will learn about the Reciprocating pump and its working principle. and how it is different from the centrifugal pump.

It is a device which converts the mechanical energy into hydraulic energy by sucking the liquid into a cylinder. In this pump, a piston is reciprocating, which use thrust on the liquid and increase its hydraulic energy.

This pump is also known a  called a positive displacement pump. Because it discharges a definite quantity of liquid.

It is often used in where a small quantity of liquid is to handled and where a delivery pressure is quite large.

1. Construction Parts of Reciprocating Pump

The following are the main parts of the reciprocating pump.

  1. Cylinder
  2. Suction Pipe
  3. Delivery Pipe
  4. Suction valve
  5. Delivery valve
  6. Air vessels


A cylinder, in which piston is moving to and fro. The moment of the piston obtains by a connecting rod, which connects the piston and crank.

Suction Pipe:

In which the source of water connects the cylinder together. The suction pipe allows the water to flow in the cylinder.

Delivery Pipe: 

After the process, the source of water leaves the cylinder and discharge through the delivery pipe.

Suction valve: 

In this valve, the flow of water enters from the suction pipe into the cylinder.

Delivery valve: 

In this valve, the flow of water discharge from the cylinder into the delivery pipe.

Air vessels: 

It is a closed chamber made up cast iron. Having to two ends one ends is open at its base through which the water flows into the vessel cylinder. The air vessels fitted to the suction pipe and delivery pipe of the reciprocating pump to get a uniform discharge.

Air vessels filled To Reciprocating Pump

Functions of Air Vessels 
  • The air vessels use to get the continuous flow of water at a uniform rate.
  • To reduce the amount of work in overcoming the frictional resistance in the suction pipe and delivery pipe.
  • To run the pump at high speed with separation.

2. Type of Reciprocating Pump

Following are the types of reciprocating pumps according to the source of work and mechanism.

  1. According to the source of work
    1. Simple hand-operated reciprocating pump
    2. Power-operated deep well reciprocating pump
  2. According to the Mechanism
    1. Single-acting reciprocating pump
    2. Double-acting reciprocating pump
    3. Triple-acting reciprocating pump
  3. According to the Air vessels
    1. Pump with air vessels
    2. Pump without air vessels

3. Working Principle of Reciprocating Pump

There are two types of working principle in the reciprocating pump

  1. Single acting reciprocating pump and
  2. A double acting reciprocating pump.

3.1 Single Acting Reciprocating Pump

In this pump, A cylinder, in which a piston moves forward and backwards. The piston is reciprocating by means of connecting rod. The connecting rod connects the piston and the rotating crank. the crank is rotating by means of an electric motor.Single Acting Reciprocating Pump

The suction and delivery pipes with suction and delivery valve are arranged to the cylinder.

  • The suction valve allows the water to the cylinder and
  • The delivery valve leaves the water from the cylinder.

As the crank rotates, during the first stroke of the piston (called suction stroke), the water enters into the cylinder. In suction stroke, the crank is rotating from A to C (from 0° to 180°) the piston is moving towards the right side of the cylinder. Due to this, the vacuum creates in the cylinder. This vacuum causes the suction valve to open and the water enters the cylinder.

In the next stroke called delivery stroke, the water leaves the cylinder. In the delivery stroke, the crank is rotating from C to A (from 180° to 360°) the piston is moving to the left side of the cylinder.

Due to this, the pressure of the liquid increases inside the cylinder. This pressure causes the suction valve to close and delivery valve to open.

Then the water is forced into the delivery pipe and raised to a required height.

3.2 Double Acting Reciprocating Pump

In case of a double acting reciprocating pump, the water is acting on both sides of the piston as shown in the figure.

Thus two suction pipes and two delivery pipes are required for a double acting pump.Double Acting Reciprocating Pump

When there is a suction stroke on one side of the piston, at the same time there is a delivery stroke on the other side of the piston.

Hence for one complete revolution of the crank, there is two delivery stroke and the water is delivered to the pipes by the pump during these two delivery strokes.

4. Difference Between Centrifugal Pump and Reciprocating Pump

Centrifugal Pump is simple in construction, less weight, less wear and tear, less maintenance cost, low efficiency and can run at higher speed. Reciprocating Pump is complicated in construction, more weight, more wear and tear, high maintenance costs, high efficiency and cannot run at higher speed.

Centrifugal pumps are suitable for large discharge with small heads, it requires less floor space and it can handle dirty water Reciprocating pumps are suitable for less discharge with high heads, it requires more floor space and it cannot handle dirty water.

Centrifugal pump needs priming, it cannot require air vessels and operations is quite. Reciprocating pumps no need of prime, it requires air vessels and complicated in operation.


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