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MARINE AUTOMATION 2
PNEUMATICS
• A PNEUMATIC SYSTEM is a system that uses
compressed air to transmit and control energy.
• PNEUMATIC SYSTEM are used extensively in various
industries.
• Most PNEUMATIC SYSTEM rely on a constant
supply of compressed air to make them work.
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Why do we use Pneumatics?
• Pneumatic control systems are used in a variety of
industries; one of which being in manufacturing
facilities to power factory automation; with this
comes low initial and ongoing maintenance costs.
These control systems are more cost effective in
mechanical movements therefore, when compared
to electric systems, pneumatic wins every time due
to its simple design, simplicity and compressed air
mechanism.
Uses of Compressed Air
Onboardship
• Starting Air - use to start auxiliary engine and main
diesel engine
• Service Air - use for general purpose. Eg. Cleaning,
deck equipments
• Control Air - The control air is a filtered branch of
the service air which is made free of any moisture
and oil carry-over. This controlled air is used for
pneumatic controllers and is important for the
operation of machinery onboard ships.
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Compressed Air System
Components
• A compressed air system is much more than just an
air compressor. A basic compressed air system is
made up of the following components:
• Air Intake Filter
• Air Compressor
• Aftercooler
• Air Receivers / Air tank / Air reservoir
• Air Dryer
Air Filter
• Air Intake Filter is a device composed of fibrous
materials designed to trap atmospheric airborne
particles such as dust, pollen, mold, etc. before
they can reach the compressor.
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Air Compressors
• is a machine used to convert power (usually from
an electric motor, a diesel engine or a gasoline
engine) into kinetic energy by compressing and
pressurizing air.
• A marine air compressor decreases the air volume
and increases its energetic potential to provide
additional power for other tasks onboard. A ship air
compressor's purpose is to maintain the overall
function of a ship.
Air Compressors
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Aftercooler or Intercooler
• an intercooler cools the air leaving the first stage
outlet before the second stage inlet, an aftercooler
cools the air leaving the final stage that goes out
from the compression unit.
Air Reciever / Air Reservoir
• Provide compressed air storage capacity to meet
peak demand events and help control system
pressure by controlling the rate of pressure change
in the system. These tanks are provided with
pressure relief valves.
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Air Dryer
• removes condensation from compressed air in
order to prevent damage to the system.
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Compressed Air System
Components
Air Dryer
Intake Filter
Aftercooler
Air compressor
AiI reservoir
Uses
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Types of Air Compressor
• Reciprocating Air Compressor
• Rotary Screw Compressor
• Rotary Vane Compressor
• Centrifugal Compressor
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Reciprocating Air Compressor
• The reciprocating air compressor, also known as
piston air compressor, is the most commonly used.
This is a positive displacement compressor; this
means that the compression is done through
decreasing the volume of the container that the air
is in.
• There are two main types of reciprocating air
compressors: the single stage and the two stage.
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Reciprocating Air Compressor
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Rotary Screw Compressor
• Just like the reciprocating air compressor, the rotary
screw compressor is a positive displacement
compressor.
• The rotary screw compressors make use of two
screws spinning in opposite directions. A vacuum is
created because of this motion, causing air to get
stuck between the screws. During their rotations,
the screws both compress the air between them
and move it towards the output area, where it’s
ready to be bottled and used.
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Rotary Screw Compressor
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Rotary Vane Compressor
• The rotary vane compressor works in a similar
fashion to the rotary screw compressor, essentially
using vanes – wide and rotating blades – instead of
screws.
• The air first comes through an input valve and gets
stuck between the vanes. The middle point of the
vanes is off-center and the blade lengths are
uneven, so as the air moves with the blades, it has
less space and gets pressurized. In this compressed
state, the air goes through the output and is ready
for use.
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Rotary Vane Compressor
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Centrifugal Compressor
• Unlike the reciprocating air, rotary vane, and rotary
screw compressors, the centrifugal compressor
doesn’t use positive displacement to compress the
air. Instead, it implements dynamic displacement,
which increases the speed of the air and then
restricts its motion to build pressure.
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Pneumatic Control System
• Pneumatic control is an automated system that
uses compressed air or other gases to drive a wide
variety of mechanical devices.
• Pneumatic control systems are designed as
pneumatic circuits. These circuits are formed with
various components like pneumatic valves,
cylinders, and directional control valves.
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Advantages of Pneumatic Control
Systems
• Cost-effectiveness: Pneumatic systems generally
have lower initial costs and maintenance
requirements compared to other systems.
• Safety: Compressed air is non-flammable, reducing
the risk of fire hazards.
• Reliability: Pneumatic systems are less prone to
contamination and can withstand harsh operating
conditions.
• Simplicity: Pneumatic components are relatively
simple to design, install, and maintain
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Pneumatic Control System
• A pneumatic circuit has two primary functions:
• 1. one valve to control other valves
• 2. For controlling the release and injections of
compressed air inside a cylinder
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Types Of Pneumatic Control
Systems
• 1. Single Pressure System
• 2. Dual Pressure System
• 3. Modulated Pressure System
• 4. Pulse Controlled System
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Single Pressure System
• This is the simplest option and uses a single valve
to control pressure in the system. It is best suited
for applications that require a consistent pressure
level.
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Dual Pressure System
• This system uses two valves to control pressure
levels and is often used in applications that require
accurate speed control, or where there is a need for
two separate pressure zones in the system.
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Modulated Pressure System
• This type of system uses multiple valves to create a
stepped pressure increase which can be used for
precise flow control over a wide range of pressures,
making it ideal for applications such as fuel
injection systems
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Pulse Controlled System
• This system utilizes quick pulses of compressed air
to actuate various devices, making it useful in
applications such as robotic assembly lines where
accuracy and fast response times are required.
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Basic Components of Pneumatic
Control System
• Pneumatic Actuators/Cylinders
• Pneumatic Valves
• Pneumatic Tubing
• Pneumatic Fittings
• Pneumatic Air filters/dryers
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Pneumatic Actuators/Cylinder
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Pneumatic Cylinders/Actuators
• Pneumatic actuators are devices that convert the
energy of compressed air into a mechanical motion
that regulates one or more final control elements.
They are used as a form of automation control to
reduce mandatory human interaction with a
system’s internal mechanisms, which is particularly
beneficial for automatic modulation and
emergency shutdowns.
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Two main types of pneumatic
actuators
• Linear actuators: These actuators produce linear
motion and are often used in applications such as
pushing, pulling, or lifting loads
• Rotary actuators: These actuators generate
rotational motion and are commonly used for tasks
such as turning, mixing, or tightening.
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Linear Actuators
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Linear Actuator
• Pneumatic actuators are often considered to be the
most cost-effective and simplest of all actuators.
Pneumatic linear actuators function using
compressed air to create movement, either by
extending and retracting a piston or, more rarely,
using a carriage that runs on a driveway or a
cylindrical tube. The retraction of the piston is
either done with a spring or by supplying fluid from
the other end.
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Rotary Actuators
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Pneumatic Valves
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Pneumatic Valves
• these devices are an integral part of controlling
airflow. Without pneumatic valves, a pneumatic
control system would not run efficiently.
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Types of Pneumatic Valves
• Directional Control Valves
• Flow Control Valves
• Pressure Control Valves
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Directional Control Valves
• These valves direct the flow of compressed air to
different parts of the system and are commonly
classified by their port and position configurations
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Flow Control Valves
• These valves regulate the flow rate of compressed
air in the system, allowing for precise control over
the speed of actuators.
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Pressure Control Valves
• These valves maintain the desired pressure levels
within the system by regulating the pressure of the
compressed air.
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Pneumatic Tubing
• tubing functions as a hose that transmits
pressurized air to other devices, such as actuators,
tools, and valves.
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Pneumatic Fittings
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Symbols
A symbol should have the following characteristics
Function
Shut-off position of the valve
Number of ports (connections)
Number of switching positions
General operating principle
Methods of actuation and return
Direction of flow
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Standard Pneumatic Symbols
The valve switching
position is shown by a
square.
The number of squares
corresponds to the number
of switching position.
Lines indicate the flow
paths, arrows indicate the
direction of flow.
Closed ports are shown by
two lines drawn at right
angles to one another.
The connecting lines for
supply and exhaust air are
drawn outside the square.
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Designations of Connections
To ensure that valves are installed, the connections
are labeled with capital letters or numbers.
• Working lines A,B,C or 2,4,6
• Power connections P or 1
• Exhaust R,S,T or 3,5,7
• Control lines Y,X,Z or 12,14,16
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