MAGICAL USE OF PNEUMA IN INDUSRIAL AUTOMATION Maharshi Trivedi
5 th semester MH 074, Faculty Of Technology, Dharmsinh Desai
University, Nadiad
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Content Fluid Power System Brief History of PNEUMATICS Use and
Advantages of PNEUMATICS System Basic Parts of any PNEUMATIC
Circuits Air Generation and Distribution Air service Unit Filter
Air Presser regulator Lubricator Flow Control Valve D.C. Valve
Actuators Energy Conversion Cycle Some PNEUMATIC Circuits
Slide 3
Fluid Power System Fluid power systems are used in most of the
modern machineries in order to achieve the success in POWER
TRANSMISSION, because sometimes the mechanical drives are bulky and
complicated. Fluid power system is the properly pressurized flow of
air or liquid which is used to actuate the mechanical means which
is further used to achieve the work. Thus, the fluid power energy
is broadly classified as, 1) Fluid power energy with air medium 2)
Fluid power energy with liquid medium So, Compressed air as the
working medium = PNEUMATICS Liquid as the working medium =
HYDRAULICS
Slide 4
Brief History of PNEUMATICS The first man whom, we know with
certainly to have engaged himself with pneumatics i.e. the use of
compressed air as the working medium was the Greek KTESIBIOS, he
built a compressed air impulse catapult(Shown in the fig is
mechanical catapult). The term PNEUMA is described as the ambient
Greek and meant breath or heavy wind and also the soul in
philosophy. PNEUMATICS is derived from the word PNEUMA. The use of
it is preferred when the need of automation and rationality of
optional sequences continued to increase.
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Use and Advantages of PNEUMATICS System USE: For pneumatic
tools for automation of m/c tools (ex. CNC LATHE). In mining
industries and refineries and also in aviation field. In automation
of food processing and in chemical material handling. In plastic
manufacturing industries. For building up the specific atmosphere
condition in textile industries. In spray painting. ADVANTAGES:
There will be no spark hazards in an explosive atmosphere, as it is
having the air as the working medium and the temperature
conductance of air is less then the liquid. Air is readily
available and compressed air can be stored in a tank for instant
use and a small compressor can be used to fill the air for
intermittent use.
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Basic Parts of any PNEUMATIC Circuits Air Compressor Service
Unit: F-R-L: Filter Pressure Regulator Lubricator Air distributor
or Junction box Valves Cylinders
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Air generation and distribution The main function of the air
generation and distribution system is to supply the clean, dry air
at the required pressure. Compressors are the air generation
units.(Classification of compressors are shown in the fig.)
Compressors compress the air and supply it to the distribution
system in the factory and also it air service unit(FRL unit)
prepares the air and delivers to the control unit. (Compressors are
not much discussed in this ppt, the diff. types are used as per the
requirement)
Slide 8
Air Service Unit (FRL Unit) The air service unit is a
combination of: 1.Compressed air filter(With water separator)
2.Compressed air regulator 3.Compressed air lubricator The main
function of the service unit is to provide the pneumatic system
with a well cleaned, lubricated and regulated compressed air. The
three units Filter-Regulator- Lubricator together are termed as FRL
Unit or Service Unit.
Slide 9
Cont. They are commonly fitted to each and every pneumatic work
station. After it is determined whether fog-or-mist-type
lubrication is best suited for the application, lubricators are
selected according to piping size. Air Filter: Air filters are used
in a pneumatic system to perform the following main functions: To
prevent entrance of solid contaminants to the system. To condense
and remove the water vapour that is present in the air passing
through it, in short it makes the air dry and clean. To arrest any
submicron particles that may pose a problem in the system
components.
Slide 10
Construction of Air Filter The main component of the filter is
the filter cartridge, is made of bronze or brass. This helps to
provide a random zig-zag passage for the air to flow which in turn,
will arrest the solid particles. The water vapour gets condensed
inside the filter and collects at the bottom of the filter bowl. At
the bottom of the filter bowl there is an on-off drain valve which
could be manually opened to drain off the accumulated water and
other solid particles.(Construction is shown in fig.)
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Oil free Filter Element If absolutely oil and moisture free air
is required, coalescent type(To form whole as a unit means removal
of oil and moisture) of filter may be used. The filter medium is
made of metal- wools which is kept compressed inside a stainless
steel shell and the outer shell is made of some porous material,
e.g. ceramic or borosilicate which can absorb the finer oil-
molecules. The filtration medium is housed on a seat made of
stainless steel.
Slide 12
Air Pressure Regulator The main function of pressure regulator
valve is to regulate the in coming pressure to the system so that
desired air pressure is capable of flowing at a steady condition.
The pressure regulation is achieved by opening the poppet valve.
This is done by adjustable screw. It will move the diaphragm. The
pressure of the flowing air will be directly proportional to the
compression of the spring underneath the diaphragm.
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Lubricator In most of the system the air is first filtered,
then regulated to the specific pressure and made pass through the
lubricator in order to form mist of oil and air to providing
lubrication of the mating components of the valve. Lubricator unit
follow the principle of venturimeter. According to the law, as soon
as compressed air flows into the throttled zone of the pipe, a
pressure differential sets in. Due to this, the oil is pushed up to
the pipe when air is fed to the oil reservoir through the
pipe.
Slide 14
Diagram of construction of Lubricator with symbol
Slide 15
Flow Control Valves Flow control valves are used in circuits to
control the flow rate of the compressed air from one part of the
circuit to another. They regulate the amount of the compressed air
passing through a valve by means of a metering orifice. Examples
are throttle valve and one-way flow control valve.
Slide 16
Throttle Valve(Restriction or needle valve) Throttle valve is
used to control the speed of pneumatic cylinders in both direction
of motion. So if the symbol is not mentioned on the valve by
manufacturer, then also it can be connected in both the direction
due to its geometry. It consists of an orifice whose cross- section
can be controlled by an externally adjustable needle.
Slide 17
One way Flow Control Valve (Throttle relief Valve or Throttle
check Valve) A one way flow control valve is used to control the
flow of pneumatic cylinders in one direction of motion only. The
valve is a parallel arrangement of a throttle valve and a check
valve. The check valve blocks the flow of air in one direction
forcing the air to flow through the controlled cross-section. In
opposite direction the air flows freely through the opened check
valve. (Figure for this valve is shown in the next slide.)
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Why it is one way Flow Control Valve???
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Direction Control Valves
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D.C. Valves Direction control valves are used to direct the
flow of the pressurize fluid in the desired directions. The main
functions of these valves are to: Start Stop Regulate the direction
of air flow They can be actuated to assume different positions by
various actuating mediums. This results in corresponding connection
or disruption of flow between various port openings. The openings
are termed ways or ports. The ways are designated by letters:
P=Compressor line port R=Exhaust port | A and B=Working ports to
cylinders or motors
Slide 22
Slide 23
Symbolic representation of D.C. Valves To represent valves in
circuit diagram, symbols are used. Each position in the symbol is
denoted by squares. Two positions are represented by two adjacent
squares.
Slide 24
How to Understand the Symbols in the circuits??? A valve
position is represented by a square. Number of squares is equals to
the no. of distinct positions that the valve can take up. Inside a
square, the lines indicate the flow and the arrows, the direction
of flow. Cut-offs of air flow are shown by short traverse lines
inside the square. Connections to inlet and outlet ports are drawn
only to a connecting position, i.e. neutral or initial
position.
Slide 25
Types of D.C. Valves Poppet valves (or seat valves) In a poppet
valve, a simple valve seat is used in conjunction with a movable
disc or ball to open or close internal air passages. A poppet valve
quickly opens up a relatively large orifice in a short travel to
permit the full flow of air. Slide valves (or spool valves) In a
slide valve, a spool moves axially within the valve body to control
the direction of flow. A slide vane is especially used as a final
control element to handle the power signal to an actuating device
because it is easy to shift the spool to perform the required
switching function.
Slide 26
Working diagram of poppet and slide valve Poppet valves (or
seat valves) Slide valves (or spool valves)
Slide 27
2/2 and 3/2 Way D.C. Valve(Normally Closed)
Slide 28
Check Valves A check valve permits the air flow in one
direction but stops it completely in the opposite direction. It
basically consists of a valve body, movable ball or plate, it is
biased by a spring force. As soon as the pressure applied by the
compressed air becomes greater then the spring force, it allows the
air to flow.
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Actuators Actuators are used for mechanical work which is
developed by the power of compressed air: It is further classified
as: Linear actuators Single acting cylinders Double acting
cylinders Rotary actuators
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Energy Conversion Cycle
Slide 31
Actual Valve Body 3/2 D.C. Valve (FESTO company)D.C.
Valve(Actuation by push button )
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Some Pneumatics Circuits
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Working Circuit Video (Triggering D/A Cylinder with Limit
Switch)
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PNEUMATIC Circuit in MATLAB!!!
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My Experiment of Hydraulic circuits with MATLAB!!!