Reciprocating Pumps
From: https://housing.com/news/what-is-a-reciprocating-pump/
Reciprocating pump: Parts, advantages and disadvantages
When a precise amount of fluid is required for delivery, reciprocating pumps are
used.
A reciprocating pump converts mechanical energy into hydraulic energy. It does
it by sucking liquid inside a stationary cylinder using thrust, a piston or a
plunger. Reciprocating pumps are also called positive displacement pumps or
piston pumps because of the use of a piston or plunger during pumping.
The delivery pressure of this pump is usually quite significant, and a small
quantity of liquid is handled. If maintained and handled with care, reciprocating
pumps last for a few decades. However, they can be lost to wear and tear if
subjected to carelessness.
Source: Pinterest
Table of Contents
Reciprocating pump: Parts
The parts of the reciprocating pump include:
- Cylinder
The piston inside the cylinder moves to and fro, and the piston obtains
moment through the help of a connecting rod, connecting the piston and
crank.
- Piston and piston rod
To start the suction, the piston inside the cylinder moves back, while for
liquid discharge, the piston is moved to the forward section. The function
of the piston rod is to move the piston in a linear direction, either
forward or backwards.
- Suction pipe
The reciprocating pump’s suction pipe collects water from the water sump.
It then sends the water to the cylinder with the help of a suction valve.
Therefore, the suction pipe is responsible for allowing water to flow inside
the cylinder.
-
Suction valve
The suction valve is referred to as the non-return valve, found on the
suction pipe inlet. The water flows by entering the suction pipe into the
cylinder but cannot send it back. Hence, the flow in this valve is
unidirectional. The valve only opens when there is the suction of fluid and
closes when it discharges towards the outside.
- Water sump
As the name suggests, the water sump is the water source for the cylinder or
pump. The water gets transported towards the delivery pipes through the use
of pistons from this very water sump.
- Strainer
The strainer is located at the end of the suction pipe and plays a very
important role in separating the solids from the water or liquid. It also
acts as a mesh used to separate dirt, dust particles, or other obstructions
from the water released. Without the presence of the filter, all kinds of
dirt or dust may enter the water in the cylinder, further resulting in it
jamming the area and stopping the smooth working of the pump.
Source: Pinterest
known about the self priming pump
- Air vessels
The air vessel refers to a closed chamber constructed out of cast iron and
has two ends. One of the ends stays open at the base of the cylinder through
which the liquid is flown into the vessel cylinder. To get a uniform
discharge, air vessels are fitted in the pump’s suction pipe and delivery
pipe. The air vessels also work to reduce the amount of effort that is put
in to overcome the frictional resistance in the delivery or suction pipe.
Another function of the air vessels is to make sure that the pump runs at
high speed along with separation.
- Crank and connecting rod
The crank is connected to a power source, such as the engine or motor, for
rotation to take place. It is shaped into a circular disc. On the other
hand, the connecting rod is placed as a medium between the crank and the
piston used to convert rotary motion into linear motion.
Delivery pipe
The task of the delivery pipe is to move water from the desired location to
another. This pipe transfers water from the cylinder itself. It also
connects the pump cylinder to the discharge outlet.
Delivery valve
Similar to the suction valve, this valve is also known as a non-return
valve. It is used for the discharge of water from the cylinder to the
delivery pipe. When suction is in practice, the delivery valve is closed due
to suction. When a discharge is in action, the suction valve remains closed,
and the delivery valve is opened to transfer water.
Types of reciprocating pump
- 1)Single-acting reciprocating pump
In this type of reciprocating pump, there is a cylinder, inside which there
is a piston designed to move forward or backwards. This piston reciprocates
with the help of rods connecting the piston and the rotating crank. In turn,
this crank rotates with an electric motor’s help. On the rotation of this
crank, the first stroke by the piston is made, referred to as the suction
stroke, and then the water is entered into the cylinder.
When the suction stroke starts, the crank rotates from an angle of 0° to
180°, which is A to C, and the piston then starts moving towards the right
side of the cylinder. As a result of this process, the vacuum gets created,
causing the valve to then open, therefore, allowing the water to enter the
cylinder.
After this happens, the next stroke is delivered, known as the delivery
stroke, during which the cylinder releases the water. During this stroke,
the crank rotates back from C to A, which is a degree of 180 degrees to 360
degrees, and the piston then starts moving towards the left side of the
cylinder.
As a result, inside the cylinder, the pressure of the liquid keeps
increasing. This pressure then results in the suction walls closing and the
delivery valve, on the other hand, opening. As a result, the water is then
pushed into the delivery pipe, raising it to the needed level.
Source: Pinterest
- 2) Double-acting reciprocating pump
In this kind of reciprocating pump, the requirements are two delivery pipes
and two suction pipes. Unlike the single-acting reciprocating pump, the suction
stroke and delivery stroke happen simultaneously but only at different sides of
the piston.
Therefore, to complete one reciprocation of the crank, two delivery strokes
are needed, after which the water is transferred to the pipe using the pump.
See also: Types of building materials
Other types of lesser-known reciprocating pumps are:
- Pump with air vessel
- Pump without air vessel.
- Single cylinder
- Double cylinder
- Triple cylinder pump.
How reciprocating pumps work
When the crank is connected to the power source and a motor, it starts
rotating, putting the connecting rod and crank into movement. Following
this, the piston, which is attached to the connecting rod, will start moving
in a linear direction. The piston moves to the right when the crack moves
outwards, creating a vacuum inside the cylinder, further leading the suction
valve to open. As a result of this process, the water from the source gets
sucked into the cylinder with the help of the suction pipe.
On the other hand, the piston moves to the left when the crank starts moving
inwards of the cylinder, putting pressure on the liquid or water in the
cylinder. This results in the generation of pressure, which further causes
the delivery valve to open and allows the liquid to flow through the
delivery pipe.
When the piston finally reaches the extreme left position, all the water in
the cylinder is then pushed through the help of the delivery valve. The
crank then spins outwards, resulting in the piston moving to the right to
create suction. This process keeps on repeating for the working of the
reciprocating pump.
How is the reciprocating pump different from the centrifugal pump?
- A reciprocating pump is a positive displacement type pump built on the
principle of movement of the piston in either forward or backward directions. On
the other hand, a centrifugal pump uses the impeller’s kinetic energy to supply
liquid from one destination to another.
- The centrifugal pump is comparatively easier to construct, has less weight,
provides more durability, has less maintenance cost, and can run at a higher
speed. However, the centrifugal pump also has low efficiency. The reciprocating
pump, on the contrary, has more complications in its construction, has more
weight, requires a lot more maintenance to ensure no wear and tear, has high
maintenance costs, and cannot run at a higher speed.
- While reciprocating pumps are considered to be suitable for fewer
charges with higher heads, centrifugal pumps are suitable for opposites,
that is, large discharges with the help of small heads. It is also notable
that reciprocating pumps cannot handle dirty water and require more floor
space than centrifugal pumps.
- Reciprocating pumps require air vessels to function and are also
complicated to operate in comparison to centrifugal pumps, which only need
priming and do not require air vessels. Operating the centrifugal pumps are
also comparatively easier than the reciprocating pumps.
Reciprocating pump: Where is it used?
- Reciprocating pumps can be used in oil drilling operations and are the
primary choice for light oil pumping.
- They have also been said to be helpful for pneumatic pressure pumps and
are also used to feed small boilers.
- One can also find reciprocating pumps in high-pressure pumps that are
used for the rivers’ osmosis system, hydro testing of tank vessels, and
various others.
- These pumps are also used to clean several elements, including sewer
line cleaning, vehicle cleaning, wastewater treatment system, and more.
Advantages and disadvantages of reciprocating pumps
- These machines can deliver the desired flow rate with high preciseness
while maintaining a continuous discharge rate.
- Reciprocating pumps also deliver fluids at high pressures, and no
priming is required for these kinds of pumps.
- The efficiency of a reciprocating pump is at least 10% to 20% greater
than that of a centrifugal pump.
- The capital cost of these pumps is extremely high. Other than that, the
flow rate of these pumps is also low.
- Reciprocating pumps cannot pump viscous liquids, and the maintenance
charges of these pumps are extremely high due to the large number of parts
associated with them.
FAQs
What is meant by reciprocating action?
Reciprocating action is referred to as simply the act of reciprocating. It
means to do something that is a response to a specific action as
corresponding or equivalent to the previous action.
What is a reciprocating pump used for?
Reciprocating pumps are used when a precise amount of fluid is required for
delivery. The pumps are also used when the delivery pressure is supposed to
be higher than what can be acquired through other types.
Which one of the centrifugal and reciprocating
actions is better?
Both of them have their advantages, with centrifugal being the cheaper
option and reciprocating being the option with more complications. However,
it depends on the kind of area that they will be working in to define which
one is better.