I.

HISTORY

 2000 BC – Egyptians invented a shadoof/shaduf to raise water. It uses a long-

suspended rod with a bucket at one end and a weight at the other.

 200 BC – Ctesibus, a Greek inventor and mathematician, was invented a water

organ, an air pump with valves on the bottom, a tank of water in between them,
and a row of pipes on top. Therefore, the principal design he used is now known
as the reciprocating pump.

II. Typical Design / Parts / Components

Reciprocating Pumps: Types
Plunger Pumps – Plunger pumps are perhaps the most common reciprocating pumps
used in industry. They are able to pump fluids at a steady flow rate regardless of the
pressure at the outlet of the pump. These are the type of pumps that uses a solid to
change the volume of the pumping cavity. Unlike piston based pumps, these pumps can
be designed to have minimal contact to the cylinder wall of the pump. Plungers are
commonly bade from a ceramic, carbon steel, or stainless steel base material. They are
then left as is, or coated depending on the application they will be used for.
Piston Pumps – Piston pumps are the same with plunger pumps except they use a
piston instead of a plunger. Piston pumps have its seal around the head of its piston
and it reciprocates with it. This will cause it to have more wearing over time than plunger
pumps which have a stationary seal where the plunger slides.

Comparison between Piston and Plunger Pump

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Reciprocating Pumps: Typical Designs

1. Single Action Pumps – These are the types of reciprocating pump that performs
suction and discharge one at a time. This pump has one suction valve where the fluid
enters and one discharge valve where the fluid exits. When the piston moves backward,
suction happens and when it moves forward, the discharge valve opens to discharge
the fluid. One common example of single action pumps are bicycle pumps.

2. Double Action Pumps – Unlike single action pumps, these pumps can perform
suction and discharge in each stroke at the same time. This kind of pump has two
suction valve and 2 discharge valves. In each stroke, the discharge valve of the

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Reciprocating Pumps: Arrangements
Reciprocating pumps comes various arrangements that can be done for specific
applications, like compensating for the pulsating effect of the pump without sacrificing
the efficiency and other advantages of the pump or just simply pumping out fluids.

1. Simplex Pump – Simplex pumps are the most basic type of reciprocating pump. It
has one piston, one discharge and suction valve. This type is used for simply pumping
out fluids.

2. Duplex Pump – Duplex pumps is like 2 simplex pumps combined together. This
design tries to compensate for the pulsating effect of the pump by letting the 2 simplex
pumps run 180 degrees from each other.

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3. Triplex Pump – Triplex pumps are like 3 simplex pumps joined together. This pump
uses 3 drive rods each at 120 degree offset around the crankshaft resulting in finer fluid
flow. This arrangement also increases the longevity of the pump because each
component has to do less work.

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Reciprocating Pumps: Parts

Piston/Plunger- These are the parts that moves reciprocally and creates a cavity inside
the cylinder where the fluid is temporarily stored until it’s pushed out through the
discharge valve. This part is also responsible for pressurizing the fluid when it exits the
cavity.
Crank and Connecting rod: Crank is a circular disk attached to the motor and used to
transfer the rotary motion of the motor to the piston. Piston, in turn, moves in a
reciprocating motion with help of a connecting rod.
Suction pipe: Liquid flows from this pipe into the cylinder. One side of the pipe is
immersed in the liquid and the other end is connected to the cylinder.
Delivery pipe: This can be understood as an outlet pipe. One end is connected to the
cylinder while the other is towards the discharge/Outlet.
Suction Valve – This part ensures that the fluid only flows in one direction, from suction
pipe to the cylinder.
Discharge Valve – This part also ensures that the fluid only flows in one direction
except the fluid flows from cylinder to the delivery pipe.

III. operation / subtypes

Operation or Working Principle of Reciprocating Pumps:

How do pumps work?

Pumps move fluid in a variety of ways:
Centrifugal Pumps use centrifugal force to push the fluid through the outlet.
Metering Pumps bellows, diaphragm, peristaltic, piston, and syringe pumps are all
metering pumps that pull the fluid through the inlet valve into a chamber, close the inlet
valve, and then push the fluid through the outlet.

Positive Displacement Pump

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 A positive displacement pump makes a fluid move by trapping a fixed amount
and forcing (displacing) that trapped volume into the discharge pipe. Some positive
displacement pumps use an expanding cavity on the suction side and a decreasing
cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side
expands and the liquid flows out of the discharge as the cavity collapses. The volume is
constant through each cycle of operation.

Positive-Displacement Pumps Bellows, double-diaphragm, flexible impeller, gear,

oscillating, piston, progressing cavity, rotary lobe, rotary vane, and peristaltic pumps
have a fixed cavity that the fluid is pushed through by rollers, gears, or impeller. As the
fluid is pushed through, it leaves a void or vacuum which pulls in more fluid.

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Single-acting Reciprocating Pump
All positive displacement pumps operate on the same basic principle. This principle
can be most easily demonstrated by considering a reciprocating positive displacement
pump consisting of a single reciprocating piston in a cylinder with a single suction port
and a single discharge port as shown below.

Operation of reciprocating motion is done by or when the power source (i.e. electric
motor or i.c engine, etc) is connected to crank, then the crank will start rotating that will
give a rotary motion and connecting rod also displaced along with crank which
translates reciprocating motion to piston in the cylinder (i.e. intermediate link between
connecting rod and piston).

The piston connected to the connecting rod will move in linear direction. If crank moves
outwards then the piston moves towards its right and create vacuum in the cylinder.

This vacuum causes suction valve to open and liquid from the source is forcibly sucked
by the suction pipe into the cylinder.

When the crank moves inwards or towards the cylinder, the piston will move towards its
left and compresses the liquid in the cylinder.

Now, the pressure makes the delivery valve to open and liquid will discharge through
delivery pipe.

When piston reaches its extreme left position whole liquid present in the cylinder is
delivered through delivery valve.

Then again the crank rotate outwards and piston moves right to create suction and the
whole process is repeated.

Generally, the above process can be observed in a single-acting reciprocating pump

where there is only one delivery stroke per one revolution of crank. But when it comes

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to double-acting reciprocating pump, there will be two delivery strokes per one
revolution of crank.
Double-acting Reciprocating Pump

In a double-acting reciprocating pump, each stroke of the piston carries out both the
functions, suction as well as delivery.
It requires two suctions pipes and two delivery pipes for double-acting pump.
When there is a suction stroke on one side of the piston, there is at the same time a
delivery stroke on the other side of the piston.
Hence, for one complete revolution of the crank, there is two delivery stroke and water
is delivered to the pipes by the pump during these two delivery strokes.

Note: It is to be noted that the reciprocating pump is a positive displacement pump

which means that the fluid can only move in one direction and can never reverse back.
So due to this, the pump is always started with outlet valve open otherwise the pressure
will keep on building and this will lead to rupturing of the pipeline or even the pump
itself. But if relief valve is fitted then this pressure will come down.

IV. TYPICAL APPLICATION

Reciprocating positive displacement pumps are highly effective, where a high
degree of accuracy and reliability under different ranges of conditions that are required.
Reciprocating pumps with very high efficiency are often available in a wide range of
hydraulic, mechanical, and material options. They are widely used across industries
such as chemical, petrochemical, refinery, pharmaceutical, cosmetic and water
treatment.

Typically, these types of pumps are used for applications such as;

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  Salt Water Disposal
 Well Services
 Descaling
 Hydraulic Fracturing
 Oil & Gas Pipelines.
Types of reciprocating pumps

Piston , Plunger or a diaphragm: All these parts have the basic functionality

of moving the liquid inside the cylinder.

The piston is a lubricated sliding shaft which moves inside the cylinder and
pushes the liquid in forward and backward motion, creating a cavity and a high
volume pressure at the outlet.

Piston pumps are widely used in applications such as :

Energy Recovery combination of high pressure piston pump and brine energy
recovery that contributes to the efficiency of the process
Steam Recovery direct acting steam pumps are mainly classified by the
number of combinations of cylinders. For example, a duplex pump has two

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steam and two liquid cylinders mounting side by side, and a simplex pump has
one steam and one liquid cylinder.

Hazardous area pumping

Manufacturers
Union
Gardner Denver
Worthington
Wilson Snyder.

In a diaphragm pump, the diaphragm is used to avoid leaking of the liquid

since it completely seals the liquid to penetrate outside, and hence they are
especially useful when the liquids are dangerous or toxic.

Diaphragm Pumps are commonly used for:

Sludge Transfer
Sludge pumps, or slurry transfer pumps as they are otherwise known, are designed
for transferring viscous fluids with high solid content. .Slurry pumps are common in
mining, construction, agricultural and industrial applications where waste fluids are
processed, and are often progressive cavity or peristaltic pumps.

Acid Pumping
Custom acid pumping systems are designed with different specifications based on the
customer's application and needs. These systems are ideal for the commercial or
chemical industries with the need of chemicals or sulphuric acid flow from one place to
another using the pumping systems.

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Chemical Fluid Transfer
In a diaphragm pump the plunger pressurizes hydraulic oil which is used to flex a
diaphragm in the pumping cylinder. Diaphragm pumps are used to pump hazardous and
toxic fluids.

Manufacturers
Wilden
Sandpiper
ARO
Roughneck
Graco.
In a plunger pump, there is a high-pressure seal which is stationary and a smooth
cylindrical plunger slides through the seal.
A type of reciprocating pump  that utilizes a solid body to change the volume of the
pumping cavity. Plunger pumps are perhaps the most common reciprocating pumps
used in industry. They are able to pump fluids at a steady flow rate regardless of the
pressure at the outlet of the pump.
Plunger Pump Components

Plungers for plunger pumps are available in many sizes and materials. Depending on
the application, plungers may be machined in-house or purchased from suppliers.
Generally, plunger pumps are made to accommodate several different diameters of
plungers to increase flow or increase pressure. The stroke length is set by the power
end of the plunger pump and is more difficult to alter. Plungers are commonly bade from

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a ceramic, carbon steel, or stainless steel base material. They are then left as is, or
coated depending on the application they will be used for. Several common types of
plunger coatings are listed below.
Ceramic: Plungers are often fully ceramic, or have a ceramic coating around a base
material. Usually alumina, the ceramic is resistant to abrasives and high mineral
content.

Tungsten Carbide: A coating is applied to a base material to help harden the surface,
reduce wear from wear. Tungsten Carbide plungers are not specifically corrosion
resistant and are recommended for uses where wear on the plunger is more of a
concern.

Rokide: Also called Chrome Oxide, a rokide plunger is often used in pumping fluids
with little lubrication, such as amine and glycol. The rokide is a hardening and protective
coating to a base material. 

Hard-Co: The plungers’ base material is coated for additional protection against wear

and corrosion. This coating consists of a nickel chrome alloy which is non-porous. It is
the standard plunger used for non-ceramic applications.

All types of reciprocating pumps are easily available in the market to meet the
diverse demands, as per different processes and applications, all mentioned
manufacturers are offering various kinds of pumps hold good reputation with respect to
quality, price, revenue (value) and market share and are preferred by many consumers.
However, a thorough check of all its features, specific to the process application, should
be ideally done to buy the most suitable reciprocating pump.

V. Advantage and disadvantages

Advantages

1. It creates high pressures from low-flow situations. A reciprocating pump draws

fluid or gas into its chamber through a small opening. It then releases that fluid or gas
when the liquid or gas is compressed by a piston. That creates a high-pressure
released from a low-flow situation.

2. Proven technology. Reciprocating pumps are one of the oldest designs still being
used. Pumps of this type have been designed to perform with up to 3,000 horsepower.

3. Durable technology. Reciprocating pumps work with highly corrosive or abrasive

materials. Because a pump can be made with everything from ceramics to carbide, this
technology is used in applications that range from air transfers to pumping cement

4. An efficient technology. A well-designed reciprocating pump often operates above

90% efficiency, even though it is one of the most affordable options of its type.

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Easy in working

Inexpensive

Compact and Easy to install

Low maintenance

Works at high speed and at low power

Priming process is not needed in this pump.

It provides high suction lift.

It is also used for air.

Disadvantages

1. It has a short half-life. Reciprocating pumps require a lot of maintenance to continue

functioning properly. Most pumps of this type require at least one full rebuild over 15
years of use, with careful maintenance occurring at all times to make it last that long.
Rebuilds are not costly, though they can be time-intensive.

2. It creates pulsations. The piston movement which moves liquids or gas creates a
pulsation within the inlet and outlet of the pump. Even if there are multiple pump
chambers incorporated into the design of the pump, these pulsations cannot be
completely eliminated. If the pulsations are severe, damage to surrounding systems
may occur.

3. It may damage itself. The movement of the pistons can be violent enough, in normal
operations, to cause the pump to damage itself over time. To counter this issue, most
reciprocating pumps require a damper of some type.

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Vi. Sample problems
Sample Problem No. 1
For a single acting reciprocating pump, piston diameter is 150mm, stroke length
is 300mm, rotational speed is 50rpm and the water is to be raised through 18m.
Determine theoretical discharge if the actual discharge is 4 liter per second. Determine
volumetric efficiency, slip and actual power required. Take the mechanical efficiency as
80 percent.
Given: Req’d:
Single acting: a. theoretical discharge, Q
D= 150mm; 0.15m b. ƞ= volumetric efficiency if Q’= 4 L/s
L= 300mm; 0.3m c. Slip
N= 50rpm d. Power required
H= 18m
Sol’n:
1. Theoretical discharge: single acting 2. Volumetric efficiency
Q= ALN ------ rps ƞ= actual discharge/theoretical
discharge
A= A=π d 2 / 4 ; A=π (0.15)2 /4 = 4 L/s / 4.425 x 10−3 mᶟ/s
= 0.0177 m2 4.425 x 10−3 mᶟ/s = 1000L/ 1 mᶟ
Q ꓔ= (0.0177)(0.3)(50)/(60) Q= 4.425 L/ mᶟ
= 4.425 x 10−3 mᶟ/s ƞ= 0.90395 ; 90.395 or 90.40

Unit analysis:
m 2 x m x rps = rev/s

3. Slip = QT- Q’/ QT 4. Power required:

= 4.425-4/4.425 x 100% Power= ρgQH
= 9.60% = (1000)(9.81)(0.004)(18)
= 706.32 W
Mechanical efficiency: 80%
0.8=power output/power input
Power required= 706.32/0.8

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 = 882.9W

Sample Prob. No. 2

A single acting reciprocating pump has a plunger diameter of 125m and stroke of
300mm. the length of suction pipe is 10m and diameter 75mm. find the acceleration
head at the beginning, middle and end of suction stroke. If the suction head is 3m,
determine the pressure head in the cylinder of the beginning of stroke when the pump
runs at 30rpm; take atmosphere head as 10.23m of water.
Given: Req’d:
D= 125mm a. acceleration head at beginning
Stroke= 300mm b. acceleration head at the middle
Ds= 75mm c. acceleration head at end
Ls=10
Sol’n:
1. Has = (LS / g) x ( A/As) RW 2 = cos wt
Ls= 10m ; W= 2πN/ 60 : 2π(30)/60 = π (3.14)
A= π(0.125 ¿ ¿2/ 4 = 0.0123m 2

As= = π(0.075¿2 / 4 = 4.42 x 10−3 m2

R= stroke/ 2 ; 300mm/2 ; 0.3/2 = 0.15
Has= (10/ 9.81) x (0.0123/= 4.42 x 10−3 ¿ (0.15)

( π ¿2= cos wt - equation 1

At beginning: wt=0 ; cos wt=1
Sub to eq. 1
Has = 4.1996m
At middle: wt= 180/2 ; cos wt=0
Has= 0
At end: wt= 360/2 ; -1
Has= -4.1996

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 2. Pressure head in the cylinder:
(at the beginning)

H= Hatm- Hsuc-Hacceleration
= 10.23-3-4.1996
= 3.0304m (abs) – atm=10.23(m)

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