What is a Reciprocating Pump? | An-Overview

A reciprocating pump is a special type of pump in which the reciprocating motion of the piston is used to supply water to the required area. The pump supplies pressure to the fluid at its outlet. Reciprocating pump mostly uses where the liquid’s delivery pressure is very huge.

Before 200 BC, the reciprocating pump was invented by the Greek inventor Ctesibius. Reciprocating pumps fall into the category of positive displacement machines. The swirling pump is suitable where a small discharge and high head are required. In these pumps, reciprocating motion is used to increase the compressive strength of the fluid.

A reciprocating pump is a special purpose pump. These pumps don’t utilize as centrifugal pumps. Therefore, it is only used in car washing centers that require high water pressure to wash cars. By using a rotating pump, we can achieve a much higher fluid pressure at 10 – 20 bar at the outlet, whereas in centrifugal pumps we can only get 2 – 5 bar pressure. These pumps are mainly used where you need an accurate flow rate.

In this pump, the flow controls with the help of piston speed. For low flow rates, the piston moves slowly and for high flow rates, the piston moves at high speed.

Using a reciprocating pump, we can obtain very accurate flow rates with an inaccurate state of plus-minus one (+ -1). Suppose we need a flow rate of 40 liters/min, then we can have a very accurate flow rate using reciprocating pumps, which can vary from 39 liters/minute to 41 liters/minute. It is called a dosing pump because it can give an accurate flow rate.

Components of Reciprocating Pump

1) Cylinder:

This cylinder has a piston. The cylinder stores water before delivery to the required area. It is also used to create a vacuum to absorb fluid.

2) Pistons:

The piston is inside the cylinder. This piston moves back and forth. This piston is used to create a vacuum on the fluid and to generate thrust on the liquid.

3) Piston Rod:

A rod is attached to the piston and is called a piston rod. This rod also connects to the connecting rod.

4) Connecting rod:

The connecting rod is connected to the piston rod at one end and cranked at the other end.

5) Crank:

The rotational motion of the crank provides reciprocal motion to the piston.

6) Suction valve:

When the piston is repeatedly forward and backward, the suction valve at the front of the piston is locked together with the piston. A suction valve is fitted in the suction pipe.

5) Suction pipe:

This is the pipe with the suction. Sump or reservoir water through this pump and it carries water to the pipe cylinder.

6) Delivery valves:

The delivery valve is mounted on the delivery pipe. This is a non-return valve. It opens as the liquid needs to be transported to the needed location.

7) Delivery Pipes

Delivery pipes are used to supply water from the cylinder to the point of delivery. This is a very important part of the reciprocating pump.

8) Reservoir or sump:

It is located at the bottom of the reservoir and is used to store the fluid to be pumped using a reciprocating pump.

Working of reciprocal pump:

When the piston is constantly moving in the forward and backward direction, the suction valve in the suction valve and the delivery valve opens and closes simultaneously with the piston speed.

The distance from the surface of the fluid to the center of the piston is called the suction head and the distance from the center of the piston to the outlet of the delivery pipe is called the delivery head. The connecting rod is attached to a crank‌. The crank has a radius at which it rotates. The crank is connected to the motor. It also rotates as the motor rotates. When the crank rotates from P to Q in the upper semi-circle, the piston moves backward, and when the crank moves to the lower semi-circle, i.e., from Q to P, the piston moves forward.

As there is a vacuum in the cylinder and atmospheric pressure in the suction pipe, the suction valve opens due to the pressure difference and a partial vacuum is created in the suction pipe when the suction valve is opened.

Since there is a partial vacuum in the suction pipe and atmospheric pressure acts on the liquid surface, the fluid moves from the high-pressure area to the low-pressure area and enters the suction pipe, and thus flows out of the entire cylinder.

As the cylinder completely fills with liquid, the suction valve closes. After that, the crank moves from the lowest position to the lowest position (180 = 180 to = 270). As the crank moves down the piston move forward and the pressure in the fluid inside the cylinder increases and when the pressure in the cylinder exceeds the atmospheric pressure, the delivery wave opens and the fluid at high pressure rises.

What is the difference between a reciprocating compressor and a reciprocating compressor?

The working of the reciprocating compressor and the reciprocating pump is almost the same. Both use to compress the fluids. But the main difference is that reciprocating compressor uses to compress air or gas while pump uses to pump incompressible fluids.