A Pneumatics

8/13/2019 A Pneumatics

1/33

Meralco Foundation

PNEUMATICS


2/33

Meralco Foundation

INTRODUCTION Pneumatics is the study of air movement and air

phenomena. It is derived from the Greek term pneuma which means

breath or wind.

Pneumatic equipment is interpreted as a systemsmachine and devices operated by or relying upon an airpressure or vacuum.

Pneumatics started when the need for automation and

rationalization of operational sequences continued toincrease. Pneumatics is usually used in areas where fire or

explosion hazards exist.


3/33

Meralco Foundation

Intro.

Hydraulics defined as branch of science which treats of water or other fluid in

motion. Comes from the Greek word hydor meaning water and aulos

meaning tube or pipe. In hydraulic system water, oil or other liquid can be used. A fluid system that uses compressed air is called pneumatic system

and a fluid system that uses oil is called a hydraulic system. Fluids are substances capable of flowing, having particles which

easily move and change their relative position without a separationof mass.

Pneumatics System Hydraulic System

Force Up to 3 tons Higher forcesSpeed Erratic (fast) Smooth

Prime mover Compressor (receiver Pump (tank)

Medium Air (exhausted toatmosphere)

Oil ( return to tank)


4/33

Meralco Foundation

A Typical Pneumatic System

AIRCOMPRESSOR

DRIVINGMEANS

PRESSURECONTROL

AFTERCOOLER

AIRRECEIVER

AIRDRYER

MAINFILTER

SHUT-OFFVALVE

AIRFILTER

PRESSUREREGULATOR

AIRLUBRICATOR

AIR SERVICE UNIT

SUPPLYVALVE

DIRECTIONALCONTROL

FUNCTIONALCONTROL

CYLINDER AUTO/MANUALDRAIN

TAKE OFF PIPING SYSTEM (SLOPING)
http://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/PRESSURE%20CONTROL.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/PRESSURE%20CONTROL.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20dryer.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20dryer.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/main%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/main%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/shut-off%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/shut-off%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20regulator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20regulator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/lubricator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/lubricator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20service%20unit.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/directional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/directional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/functional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/functional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/cylinder.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/auto-manual%20drain.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/auto-manual%20drain.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/auto-manual%20drain.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/cylinder.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/functional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/directional%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20service%20unit.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/lubricator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20regulator.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/shut-off%20valve.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/main%20filter.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20dryer.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/PRESSURE%20CONTROL.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20compressor.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/air%20service%20unit.ppt


5/33

Meralco Foundation

PNEUMATIC WORKING

ELEMENTS


6/33

Meralco Foundation

a. CYLINDERS

PURPOSE: The cylinder is a common device for

producing linear movement with force.

APPLICATION: Clamping and Releasing Lifting and Lowering

Pushing and Pulling Opening and Shutting Feeding, etc.


7/33Meralco Foundation

Construction and working principle

The Single-Acting Pneumatic Cylinder Can produce work only in one direction

because the compressed air is applied to one

side only. If cylinder positive chamber (+) is supplied with compressed air apressure acts on the piston surface. If the force generated by thepressure [ F = Pressure (P) x Piston Area (A)] is greater than thecounter force of the spring, the piston moves with the piston rodto the right. This movement is termed forward of positive stroke.

If the compressed air supply is interrupted, the spring force issufficient to move the piston to the left (-) and exhaust thepositive chamber. This movement is called return or negativestroke.
http://localhost/var/www/apps/conversion/tmp/scratch_9/single-acting%20cylinder.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/single-acting%20cylinder.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/single-acting%20cylinder.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/single-acting%20cylinder.ppt


8/33


9/33



Types of cylinders Cable cylinders

A double acting cylinder, where a cable is attached to each side ofthe piston and guided over rollers.

Used in door operation, small-sized unit producing large strokelength.

Tandem cylinders The design involves two double-acting cylinders which have been

joined to form a single unit. By this arrangement and simultaneous loading of both pistons, the

force on the piston rod is almost doubled. This design is needed for such applications where a large force is

required but the cylinder diameter is restricted.

Multi-position cylinders Consist of two or several double acting cylinders

Rotary cylinder
http://localhost/var/www/apps/conversion/tmp/scratch_9/MULTIPOSITION%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/ROTARY%20CYLINDER.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/ROTARY%20CYLINDER.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/MULTIPOSITION%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/MULTIPOSITION%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/MULTIPOSITION%20VALVE.ppt



PNEUMATIC INPUT AND CONTROLELEMENT

Directional Control Valves Non-return Valves Pressure Control Valve Flow Control Valves Shut-off Valves Time Delay Valves Pneumatic amplifiers Pneumatic Counters


12/33

Meralco Foundation

RULES ON REPRESENTATIONOFDIRECTIONAL VALVES

1. Symbols are used for representing valves in circuit diagrams.These symbols specify only the function of the valve, but do notindicate the design principle which it is constructed.

2. Valve switching position are represented as square.The number of adjacent squares shows how many switchingposition the valve has.

3. The function and working principle is drawn inside the boxes(squares).Lines indicate flow paths. Arrow shows the direction of flow.

4. Shut-off positions are identified in the boxes by lines drawn atright angles.

5. Flow path junctions within a valve are represented by a dot.6. The connections (inlet and outlet ports) are shown by linesdrawn on the outside of the box representing the normal or initialpositions.


13/33

Meralco Foundation


7. The other position is obtained by shifting the squares until theflow paths correspond to the connections.The switching positions may be identified by lower case letterso,a,b,c..

8. Valve with 3 switching positions has the mid-position or neutralposition identified by lower case letter o.

9. Exhaust flow path without pipe connection (free exhaust) isrepresented by triangle directly on the symbol.

10. Exhaust flow path with pipe connection (contained exhaust) isrepresented by a triangle not directly on the symbol.

11. To ensure that the valve is properly installed, the connectionsare labelled with capital letters or numbers.

Working lines A,B,C. . . . . . .2,4,6Power connections P . . . . . . . . . .1Exhaust R,S,T. . . . . . . 3,5,7Control Lines Z,Y,X. . . . . . . 12,14, 16

a b

a bo


14/33

Meralco Foundation


12. The designation of a valve is based on thenumber of controlled connections and numberof switching positions. The first number in thedesignation specifies the number of paths, orthe controlled connections. The secondnumber specifies the switching positions ofthe valve.Example:

= 3/2 way valve

Number of switchingpositions

Number of controlled connections orNumber of paths or number of ports


15/33

Meralco Foundation

Design Characteristics ofDirectional Valves

Designs are categorized as follows: POPPET VALVES

Ball seat valve Disc seat valve

SLIDE VALVES Longitudinal slide valve

Longitudinal flat slide valve Plate slide valve (butterfly valve)
http://localhost/var/www/apps/conversion/tmp/scratch_9/POPPET%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/BALL%20SEAT%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/DISC%20SEAT%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/plate%20slide.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/plate%20slide.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/DISC%20SEAT%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/BALL%20SEAT%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/POPPET%20VALVE.ppt


16/33

Meralco Foundation

SOLENOID VALVE

These valves are used where theswitching impulse emanates from anelectrical timing device, electrical limitswitches, pressure probes or electroniccontrollers.

Is normally selected for controls involvingextremely long distances and for shortswitching time.
http://localhost/var/www/apps/conversion/tmp/scratch_9/SOLENOID%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/SOLENOID%20VALVE.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_9/SOLENOID%20VALVE.ppt


17/33

Meralco Foundation

NON RETURN VALVE

are devices which preferentially stop the flowin one direction and permit flow in theopposite direction.


18/33

Meralco Foundation

CHECK VALVE Can stop the flow completely in one direction

and the air flows in the opposite direction withas low a pressure loss as possible.

Blocking of one direction can be effected bycones, balls, plates or diaphragms.


19/33

Meralco Foundation

SHUTTLE VALVE Is also called double control valve or double

check valve. It has two inlets X and Y and one outlet A. It is also called OR valve.


20/33

Meralco Foundation

THROTTLE RELIEF VALVE

Is also known as SPEED REGULATING VALVE. Acheck valve blocks the flow of air in one direction and aircan flow only in a regulated cross-section. In theopposite, the air can flow freely through the open checkvalve.

If possible, throttle relief valve should be mounteddirectly on the cylinder.


21/33

Meralco Foundation

QUICK EXHAUST VALVE

Is used to increase the piston speed in cylinderwhen returning to its initial position.

is directly mounted on the cylinder or as near to

it as possible.


22/33

Meralco Foundation

TWO PRESSURE VALVE It has two inlets, X and Y and one outlet A. Compressed air will flow through only if signal are applied to both

inlets. May be used as interlocking control, safety control check function or

logic operations.

Position when signal is applied onboth inlets

Position when signal is applied onX inlet

Position when signal is applied on Y inlet

A

X Z


23/33


24/33

Meralco Foundation

REFLEX SENSOR

PP

A A


25/33

Meralco Foundation

APPLICATIONS


26/33

Meralco Foundation

APPLICATIONS: Allocating device ( DIRECT CONTROL OF CYLINDER)

The allocating device supplies valve blanks to a machining station. Byoperating a push button, the piston rod of a single acting cylinder is made toadvance. After releasing the actuating button the piston rod returns.


27/33

Meralco Foundation

APPLICATIONS: DISTRIBUTION CRATES(Direct Control of a Double-acting Cylinder)

The roller track is to swivel at will by means of a manual control. Afteractuating the push button the piston rod of the cylinder is to extend. Onreleasing the manual control, the initial position is to be resumed.


28/33


29/33

Meralco Foundation

SOLUTION:


30/33


31/33

Meralco Foundation

SOLUTION:


32/33

Meralco Foundation

CONTROL WITH TWO PRESSURE VALVE

PROBLEM: CUTTING DEVICE

Using a cutting device, sheets of metal are to be cut to size. Bypressing two push button switches, the cutting blade is advanced bya double acting cylinder and the sheets of metal is cut. When thepush button switch is released, the blade returned to its initialposition.


33/33

SOLUTION:

A Pneumatics

Documents

Transcript of A Pneumatics