Reciprocating Pump: Components, Types, Working Principle & Application

Reciprocating pump is a positive displacement type of pump which works by using a piston within a cylinder to pressurize liquid.

For a liquid to move from one point to another via pipes, it needs pressure.

Pumps come to use when this action is needed.

In this article, I’m going to share with you the component, types, working principle and application of a reciprocating pump.

I wrote an article about centrifugal pump too, if you want to check it out click the link below.

You might like this: Centrifugal Pumps: Types, Working Principle, Uses & Advantages

You can also say that a reciprocating pump is a mechanical machine that converts mechanical energy by the use of a piston or plunger.

For you to understand the working of reciprocating pump, you first must know the components of this pump.

Component of reciprocating pump.

Reciprocating pump has the following components;

Suction pipe and suction valve.
Delivery pipe and delivery valve.

Cylinder.
Piston and piston rod.
Crankshaft and connecting rod.

Air vessels.
Strainer.

Before I share with you how the reciprocating pump works, understand the functions of these components.

1. Suction pipe and suction valve.

The suction valve connects on the suction pipe. These two components work hand on hand to draw liquid in to the cylinder.

The suction valve is the component that opens to allow liquid into the cylinder while the suction pipe takes liquid from the liquid sump (liquid source).

2. Delivery pipe and delivery valve.

The delivery valve connects to the delivery pipe. They work together to discharge liquid out of the cylinder to allow another volume of liquid to occupy the space.

When the pressure is high enough within the cylinder, the delivery valve opens while the suction valve closes to allow the liquid under high pressure to leave the cylinder via the delivery pipe.

You can term delivery pipe as a ‘discharge pipe’.

3. Cylinder.

The cylinder is a tube-like structure that accommodates liquid and the piston or plunger.

In the cylinder is where the compression of liquid happens. The piston in the cylinder compresses the liquid.

The cylinder is the heart of the pump, since the pressure of the liquid develops here.

4. Piston and piston rod.

The piston rod connects to the piston. They work together to move forward and backward within the cylinder to create pressure within the liquid.

5. Crankshaft and connecting rod.

Crankshaft supplies power to the piston via the connecting rod. Crankshaft connects to a motor or engine that can supply power to the pump.

The connecting rod connects the piston and the crankshaft.

6. Strainer.

The main function of the strainer is preventing contamination from entering the suction pipe.

If by any chance the dirt enters the suction pipe, the pump will jam, thus affecting its activity.

7. Air vessels.

The air vessels in the reciprocating pump provide a uniform discharge rate of the liquid.

With these few descriptions of these components, you now know their functions in the pump. We can jump straight to the types of reciprocating pump.

Types of reciprocating pump.

Reciprocating pump has two main categories, which include;

Single acting reciprocating pump.
Double acting reciprocating pump.

1. Single acting reciprocating pump.

Single acting reciprocating pump achieves its pumping mechanism by only engaging with one side of the piston.

Every cycle the piston takes it either draws liquid in to the cylinder or discharges it.

In a single acting reciprocating pump, there is no continuous discharge of liquid since one volume of liquid is discharged at a time.

2. Double acting reciprocating pump.

Double acting reciprocating pump achieves its pumping mechanism by using two sides of the piston.

It comprises two suctions pipe and two delivery pipe.

They connect on a H structure like, while the piston is in the middle.

In this pump, forward and backward strokes, both discharges liquid from the pump.

This pump offer continuous discharge of liquid, hence discharging a higher volume of liquid than single acting reciprocating compressor.

When the piston moves on the right side of the cylinder, the left suction pipe draws liquid into the cylinder while the right suction pipe is closed by the valve.

The right suction valve is closed and the delivery valve on the right side of the piston opens to allow the pressurized liquid out of the cylinder via the delivery pipe.

When the piston moves on the left side of the cylinder, the right suction pipe draws liquid into the cylinder while the left suction pipe closes to allow the pressurized liquid to leave the cylinder through the left delivery pipe.

The initial volume of the liquid left in the cylinder after the piston moves either to the right or left of the cylinder keeps a continuous loop of liquid discharge with every stroke.

Working principle of reciprocating pump.

The general working principle of reciprocating pumps involves of expansion and compression of the liquid in the cylinder.

I will discuss how the liquid becomes pressurize after every stroke.

To understand this process, precisely, think of the bicycle pump as you read the working of its working principle.

During the upward stroke.

During the upward stroke, the volume within the cylinder increases, creating a partial vacuum.

This decreases the pressure within the cylinder, since the atmospheric pressure acting on the sump liquid is higher than the pressure in the cylinder, the suction pipe will draw liquid in and the suction valve will open to allow liquid into the cylinder.

After the liquid enters the cylinder, the suction valve closes to prevent liquid from flowing back to the source via the suction pipe.

During the downward stroke.

During the downward stroke, the volume of within the cylinder decreases, hence increasing the pressure of the liquid.

When the liquid is under high pressure, the delivery valve opens to allow the pressurized liquid out of the cylinder via the delivery pipe.

The delivery valve closes after the liquid enters the delivery pipe to prevent the back-flow of liquid into the cylinder.

The delivery pipe discharges liquid to the reservoir.

The crankshaft facilitates the movement of the piston because it connects with the motor or engine.

Failure of the motor facilitating the movement of the piston, the pump will not work too.

Application of reciprocating pump.

Reciprocating pump delivers liquid at large heights because of its excellent pumping power.
Vehicle washing centres use a reciprocating pump in their work.
It is used in equipment that depends on hydraulic energy.

Petroleum industries use a reciprocating pump in pumping their products.
Reciprocating pump is used to fill pressure in football and bicycle tires.
Pneumatic pressure system use a reciprocating pump for the pumping mechanism.

Reciprocating pump is also used in feeling boilers condensate return.

The reciprocating pump is used in any area that requires high pressure but low discharge.

The reciprocating pump can be used in any areas with the need of low discharge rate but higher pressure at a considerable height.

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