Industrial Air Controls

Industrial Pneumatic Fundamentals

Pneumatic Fundamentals

Ejercicios de ¿Qué Pasa Si? y de Diagnóstico y Solución de ProblemasIn

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Objectives• Define States of Matter (with emphasis

on liquids & gases and their effects on pneumatic equipment)

• Define Fundamental Pneumatic Terms and concepts and constituents of air

• Define Gas Laws• Define Force• Review Air Preparation

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Physical vs. Chemical State Change

• Physical State Change

• Chemical State Change

Physical Change Of Water Into Ice

Chemical Change Of Water Into Hydrogen Peroxide

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Physical States of Matter

(See notes for definitions of each state)

Gas, Liquid, Solid, Plasma, and Bose-Einsten Condensate (BEC)

Cool or compress Cool

Heat or reduce pressure

Total disorder; much empty space; particles have complete freedom of motion; particles far apart.

Disorder; particles or clusters of particles are free to move relative to each other; particles close together.

Ordered arrangement; particles are essentially in fixed positions; particles close together.

Gas LiquidCrystalline

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Water – Changes of State

Heat added (each division corresponds to 4kJ)

Ice Ice and liquid water (melting)

Liquid water

Ice and liquid and vapor (vaporization)

Water vapor

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Relative Humidity andDew Point

• What does this have to do with a pneumatic system?

100= 100% Relative Humidity (Dew Point)

= 50% Relative

40 500-10-20 20 30

Temperature (degrees C)

ir)Amount of Water in Air at 100% Relative Humidity

Across a Range of Temperatures

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Pressure Fundamentals

• Pressure – the force exerted by a fluid at rest per unit area on which the force acts.

• Units – pound-force per square inch or psi (European unit is the bar; 1 bar = 14.5-psi).

• Differential pressure – difference in pressure between two regions

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Pneumatic Terms

• Standard Temperature Pressure (STP)

• Normal air• Free air • Standard Cubic Feet per Minute

(SCFM) • Relative Humidity • Dew Point

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Pneumatic Terms• Desiccant

• Adsorption

• Absorption

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Advantages / Disadvantages of Pneumatics

Advantages:– The working fluid (air) is abundant, readily available,

inexpensive, cleaner, and safer to use than oil-based hydraulic fluids, and is less environmentally hazardous.

– Return lines are unnecessary.

– Due to the compressibility of air, pneumatic equipment is less likely to be damaged by overpressure conditions.

• Disadvantages

– Energy density is lower than hydraulics. Higher pressures are used in hydraulics, therefore the energy to move loads is available.

– Pneumatic systems require bleeding pressure off to release a load, whereas in hydraulics a slight movement of the load releases the pressure.

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Constituents of (Free) Air• 78.084% Nitrogen (inert, and as a result, slows

combustion of Oxygen)– 20.946% Oxygen (readily supports combustion)– 0.934% Argon– 0.038% Carbon Dioxide– 1% water Vapor– 0.002% other (Neon, Helium, Methane, Krypton,

Hydrogen, Nitrous Oxide, Xenon, Ozone, Nitrogen Dioxide, Iodine, and trace amounts of Carbon Monoxide and Ammonia)

Total = 100.004 (due to rounding and does not include water vapor, which is contained in the air, not part of it)

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Characteristics of Gases vs. Liquids

Gases expand to fill all of the available space, liquids do not.

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The Gas Laws• Bernoulli’s Principle• Boyle’s Law

• Charles’ Law (principle)

• General Gas Laws

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• Assuming one of the three variables to be held at a constant value, we can look at the relationship between the other two for each case:– Constant temperature

– Constant pressure

– Constant volume

Gas Law Concepts

constant

VT = constant

PV= constant

For any given mass of air, the variable properties are pressure, volume and temperature.

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Bernoulli’s Principle

PSI PSI PSI

In the small section pipe, velocity is maximum. More energy is in the form of motion, so pressure is lower.

“in a system with a constant flow rate, energy is transformed from one form to the other each time the pipe cross-section size changes”

Velocity decreases in the larger pipe. The kinetic energy loss is made up by an increase in pressure.

Ignoring friction losses, the pressure again becomes the same as at “A” when the flow velocity becomes the same as at “A.”

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Boyle’s Law• “if the temperature of a confined body of gas

is maintained constant, the absolute pressure is inversely proportional to the volume.”

V1P1 V2

P2 V3P3

P1 X V1 = P2 X V2 = P3 X V3 = constant where P = pressure and V= volume

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Constant Temperature

0 2 4 6 8 160

Volume V

Pressure Pbar absolute

P1·V1 = P2·V2 = constant

10 12 14

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0 2 4 6 8 160

10 12 14

Volume V

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0 2 4 6 8 160

10 12 14

Volume V

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0 2 4 6 8 160

10 12 14

Volume V

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Charles’ Law• If heated by 1 K degree at constant

pressure, air expands by 1/273 of its volume.• This is shown by Charles’ Law where:

1eTemperatur

VolumeeTemperatur

Volume

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Constant Pressure

0 0.25 0.5 0.75 1 2-60

Volume

TemperatureCelsius

1.25 1.5 1.75

V1 V2T1(K) T2(K) = c=

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Constant Pressure

0 0.25 0.5 0.75 1 2-60

Volume

TemperatureCelsius

1.25 1.5 1.75

100 366.25K

V1 V2T1(K) T2(K) = c=

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Constant Pressure

0 0.25 0.5 0.75 1 2-60

Volume

TemperatureCelsius

1.25 1.5 1.75

219.75K

V1 V2T1(K) T2(K) = c=

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Constant Pressure

0 0.25 0.5 0.75 1 2-60

Volume

TemperatureCelsius

1.25 1.5 1.75

100 366.25K

219.75K

V1 V2T1(K) T2(K)

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The Combined Gas LawThe combined or general gas law is where pressure, volume and temperature may all vary between states of a given mass of gas but their relationship results in a constant value.

= constantP1 .V1

P2 .V2

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CompressibilityReview of Boyle’s LawFor a fixed mass of ideal gas at fixed temperature, the product of pressure and volume is a constant.

• VP = k• V1P1 = V2P2

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Compressibility – Charles Law

• V/T = k• V1T2 = V2T1

Review of Charles’ LawAt constant pressure, the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature (in Kelvin) increases or decreases.

-65°C 250°C

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Compressibility

• pV = nRT (or for most conditions) V1T2 = V2T1

• P1V1T2 = P2V2T1 or P1V1/T1 = P2V2/T2

Review of General or Ideal Gas LawsThe state of an amount of gas is determined by its pressure, volume, and temperature according to the equation:

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Compressibility

Conclusion – gases are easily compressible, liquids are not.

– Gases – compressible roughly 1700 to 1– As gas pressure increases, temperature

increases and volume decreases.– Liquids – roughly 1 to 1 (considered non-

compressible)

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Pressure ScalesPressure in pneumatic systems is measured in one of three scales: absolute (psia), gauge (psig), and vacuum ("Hg).

Gauge Pressure

Vacuum-negative gauge Pressure

Absolute Pressure

Atmospheric Pressure

Absolute Zero

Absolute Pressure

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Measuring Atmospheric Pressure

• Average sea level pressure = 101.325-kPa (kilopascals)1-kPa = 1-millibar

• US reports atmospheric pressure in inches (hundredths of inches) of Mercury (& in mbar)

• 101.32-mbar is reported as 132

Atmospheric pressure facts:29.92”

Sea Level Atmospheric

Pressure

Barometer

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Atmospheric Pressure

Atmospheric pressure values are displayed on weather maps.

101.5 mb

101.2 mb

100.8 mb

100.0 mb

996.0 mb

• Lines (called isobars) show contours of pressure in millibars.

• Lines help predict wind direction and force.

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Pressure at Various AltitudesAltitude above sea

level in FeetBarometer Reading in Inches of Mercury

Approx. Atmospheric Pressure in pounds

per square inch (PSI)0 29.92 14.7

1000 28.8 14.22000 27.7 13.63000 26.7 13.14000 25.7 12.65000 24.7 12.16000 23.8 11.77000 22.9 11.28000 22.1 10.89000 21.2 10.4

10000 20.4 10.0

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″Hg / PSI ConversionsExample : ″Hg to PSI• 10 ″Hg x 0.491 = 4.91-psia• 29.92 ″Hg x 0.491 = 14.69-psia

Example: PSI to ″Hg • 14.7-psia / 0.491 = 29.93 ″Hg • 10-psia / 0.491 = 20.36 ″Hg

Remember:• PSIA = PSIG + 14.7• PSIG = PSIA – 14.7

PSIGVacuum

25”29.92”

Sea Level Atmospheric

Pressure531

Mercury Column Height

X 0.491 = P.S.I.

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Comparing ″Hg Vacuum to ″Hg Absolute

″Hg absolute measures atmospheric pressure (determined by how high a column of mercury the pressure will cause)

″Hg vacuum measures pressure below atmospheric pressure

0510152025

30(29.92)

252015105

In. Hg. Abs.

Pressure

In. Hg. Vacuum

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Pressure Scales• Either of two

pressure scales are used to measure pressure — an absolute scale or a gage scale. Abs

le29.7

le24.7

14.711.07.353.67

0 07.514.922.429.92 0

PSIA In. Hg. Abs.

Press.

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Pressure Ranges

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Gage Operation(Plunger Gage)

Pointer

Fluid In

Plunger

Bias Spring

Plunger Gage

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Gage Operation(Bourdon Tube)

Fluid in

Linkage

Needle Pointer

Bourdon Tube

10001500

Absolute Pressure + 14.7 P.S.I.Gage

Reading=

Bourdon tube

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Gage Reading Basics• Reading accuracy – gages may

be read to one-half of the smallest increment.

• Make sure equipment is depressurized before opening system or performing maintenance..

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Vacuum Gage

Vacuum in Hg.

Absolute Pressure = 30 - Vacuum

Reading

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Pneumatic Transmission of Energy

• Pneumatics energy is used to perform work.• Energy is stored in the form of compressed air and the

energy is released when the air is allowed to expand.• A device is needed (an air compressor) to supply

compressed air at a desired pressure.• A cylinder is one type of device that can be used to

convert the stored energy into work.

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Force TransmissionThrough a Solid

Movable Piston

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Force TransmissionThrough a Liquid

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Force TransmissionThrough a Gas

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Measuring Fluid Performance

• Pascal’s Law simply stated says: “Pressure applied on a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas, and at right angles to the surface.”

Pressure exerted by fluid equal in all directions

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Force Transmission Through a Fluid – Pascal’s Law

Pascal’s Law (principle)

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Force TransmissionThrough a Fluid

1000 lbs.

Object of resistance

100 psi.10

100 psi.

1500 lbs.

Piston area 10 sq. in.

Piston area 15 sq. in.

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Definition of Pressure

• Definition of pressure:If F is the magnitude of the normal force on a piston and A is the surface area of a piston, then the fluid pressure, P, is the ratio of the force to area.

AreaForceessure Pr

Pressure in PSI (pounds per square inch) if Force in in pounds (lbs) and area is in square inches.

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Primary/Secondary Air Treatment

• Secondary air treatment – conditioning of air at or near the point of usage.

• Conditioning equipment:– Filters– Lubricators– Regulators

Primary air treatment – conditioning of air before, during, and after compression; but before distribution.

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Compressed Air System

Compressor

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Regulator

Drawing Symbol

Diaphragm

Spring

Adjusting Screw

Valve SeatDamping spring

Valve disc

Vent hole

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Air Filter

An in-line air filter collects and retains contaminants.

Drawing Symbol

Air InAir Out

Filter bowl

Baffle plate

Filter

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Lubricators

Inlet Outlet

ValveDrip Duct

Check Valve

Drip Chamber Duct

Oil passage

Drawing Symbol

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Venturi Principle• The pressure difference Δp (pressure gradient)

between the pressure in front of the air nozzle and the pressure at the smallest section of the nozzle is used to draw liquid (oil) from a container and to mix it with the air.

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Drawing Symbol

Filter Regulator and Gauge

Lubricator

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Types of Compressors

Piston Compressor

Diaphragm Compressor

Types of Compressors

Reciprocating piston Compressors

Rotary piston Compressors

Flow Compressors

Radial flow Compressor

Axial flow Compressor

Sliding vane rotary Compressor

Two axle Compressor

Lobe type Compressors

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ReciprocatingPiston Compressor

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Diaphragm Compressor

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Sliding Vane Rotary Compressor

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Screw Compressor

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Lobe Compressor

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Axial-Flow Compressor

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Radial Flow Compressor

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Summary

• Review Objectives• Question and Answer Session

Pneumatic Controls and Devices

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Objectives

• Define types of pneumatic valves and symbols

• Define types of logic valves and symbols

• Define pneumatic actuators and symbols

• Define piston force• Define pneumatic motors and symbols

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Pneumatic Valves• The basic function of valves is to switch air

flow• The range of pneumatic valves is vast • To help select a valve they are placed in a

variety of categories: – style– type– design principle– type of operator– function– size– application

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• Style reflects the look of a valve range as well as the underlying design principle

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• Type refers to the valves installation arrangement for example sub-base, manifold, in line, and valve island

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• Design refers to the principle of operation around which the valve has been designed, for example, spool valve, poppet valve and switch or plate valves.

Design

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Valve Operators

TwistPushButton

ShroudedButton

MushroomButton

KeyOperated

Switch

KeyReleased

SolenoidPilot

Roller

Air Pilot

Plunger

EmergencyStop

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General manual

Push button

Pull button

Push/pull button

Treadle

Manual

Rotary knob

Operator Symbols - Manual

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Mechanical

Plunger

Spring normally as a return

Roller

Uni-direction or one way trip

Pressure

Pilot pressure

Differential pressure

Detent in 3 positions

Operator Symbols - Mechanical

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Solenoid direct

Solenoid pilot

Solenoid pilotwith manual overrideand integral pilot supply

Solenoid pilotwith manual override and external pilot supply

Electrical

When no integral or external pilot supply is shown it is assumed to be integral

Operator Symbols - Electrical

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Valve Function• Function is the

switching complexity of a valve

• This function is shown by two figures 2/2, 3/2, 4/2, 5/2, 3/3, 4/3 & 5/3

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Valve functions 5/3• Three position valves have a normal central position

that is set by springs or with a manual control such as a lever

• The flow pattern in the centre position varies with the type. Three types will be considered

• 1, All ports sealed• 2, Outlets to exhaust, supply sealed• 3, Supply to both outlets, exhausts sealed

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123514

2 Position, 5 Port ValveControl Input to Valve Input 14

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123514

2 Position, 5 Port ValveControl Input to Valve Input 12

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Valve Size• Size refers to a valve’s port thread.

• The port size progression M5, R1/8 , R1/4, R3/8 , R1/2, R3/4, R1.

M5R1/8 R1/4

R3/8 R1/2

R3/4R1

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Application• Application is a category for valves described

by their function or task • Examples of specialist valves are quick

exhaust valve, soft start valve and monitored dump valve

• Examples of standard valves are power valves, logic valves, signal processing valves and fail safe valves

• A standard valve could be in any category depending on the function it has been selected for in a system

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Other Valve Designs

• Shut off Valves• Limit Switches• Selector Switches• Pressure Switches• Flow Regulators/Control• Quick Exhaust• AND / OR Valves

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Shutoff Valves

Drawing Symbol

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212 10

Limit Switch Valves

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12 3 4

Selector Switch Valves

12 3 4

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Pressure Switch (pneumatic)• Relay to boost weak signals• Relay for a pneumatic time

delay• When the signal at port 12

reaches about 50% of the supply pressure at port 1, the pressure switch operates to give a strong output signal at 2

• For time delays at any pressure only the linear part of the curve will be used giving smooth adjustment

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Off Actuated

Pressure Switches

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• This example uses a built in single acting cylinder to operate a standard changeover microswitch

• The operating pressure needs to overcome the combined force of the cylinder and microswitch springs

• Adjustable pressure switches are also available allow adjustment to the operating pressure

Adjustable

Pressure Switch - Electrical

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Flow Regulator

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Flow Regulation for Speed

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Quick Exhaust Valve

Symbol

Circuit example

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Air Logic

• In the age of microchips and personal computers, air logic can still provide an effective, efficient, and inexpensive means of control for certain pneumatic machines.

• Air logic controls can perform any function normally handled by relays, pressure or vacuum switches, time delays, limit switches, and counters. The circuitry is similar, but compressed air is the control medium instead of electrical current.

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Logic “OR” Shuttle Valve

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Logic “AND” Shuttle Valve

Popular oldsymbol

ISOsymbol

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SYMBOL

Timing Chamber

OR gate – 1 or 2 passes to timing

2 enables 1 to pass to 3 or

output

When timing done will block input air from output if not

present already

Two Hand Anti-tie Down

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Timers

ONINPUT

ONOUTPUT

TIMEDELAY

INPUT OUTPUT

Positive Timer Symbol

Positive Timer Example

Negative Timer Symbol

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One Shot Timer

Logic symbol ANSI symbol

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• Pneumatic actuators include linear cylinders and rotary actuators.

• They are devices providing power and motion to automated systems, machines and processes.

• A pneumatic cylinder is a simple, low cost, easy to install device that is ideal for producing powerful linear movement.

• Speed can be adjusted over a wide range.• A cylinder can be stalled without damage.

Actuators

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• Adverse conditions can be easily tolerated such as high humidity, dry and dusty environments and cleaning down with a hose.

• The bore of a cylinder determines the maximum force that it can exert.

• The stroke of a cylinder determines the maximum linear movement that it can produce.

• The maximum working pressure depends on the cylinder design. Thrust is controllable through a pressure regulator.

Actuators

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Basic Construction

Cylinder BarrelBase Cap Bearing Cap

Piston Rod Packing ring

Bushing

Construction of a pneumatic cylinder with end position cushioning

SealsPiston

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• Pneumatic actuators are made in a wide variety of sizes, styles and types including the following

• Single acting with and without spring return• Double acting

– Non cushioned and fixed cushioned– Adjustable cushioned– Magnetic

• Rodless• Rotary• Clamping• Bellows

Some Fundamental Designs

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Piston Force

Cylinder Piston

Piston RodCylinder Piston

Piston Rod

)(Pr)()( 2 psiessureinArealbsForce

inDiameterinArea

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Example of Cylinder Force

A cylinder with a 4 inch diameter and 1.5 inch cylinder rod diameter with air pressure of 80 psi (pounds per square inch).

Area = 12.6 sq in.Area of rod end = 1.8 sq in.

Force = 80 X (12.6 – 1.8) = 864 lbs on retract of cylinder.

Force = 80 X 12.6 = 1008 lbs on extend of cylinder.

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•An air take up is used to keep a chain conveyor from becoming slack due to load changes. This is a common application to production chains a mile long in automobile plants.•If a take-up cylinder has a 12 inch diameter and 3 inch cylinder rod diameter and the chain pull has been determined to be 2225 pounds then what should the air pressure be set to. •The pull is at the rod end.•Use Pressure = Force ÷ Area

Force Of A Take-up Air Cylinder

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Cylinder Force TableCYLINDER FORCE TABLE (Pounds)

Bore (in)

Piston Area (in)

PRESSURE (PSI)

10 20 30 40 50 60 80 90 100

0.75 0.44 4.4 8.8 12 17.6 22 26.4 35.2 39.6 44

1 0.79 7.9 15.8 23.7 31.6 17.4 47.4 63.2 71.1 79

1.5 1.77 17.7 35.4 53.7 71 88 106 141 159 177

2 3.14 31.4 62.8 94.2 126 157 188 251 283 314

2.5 4.91 49.1 98.2 147.3 196 245 295 393 442 491

3.25 8.3 83 166 249 332 415 498 664 747 830

4 12.57 125.7 251.4 377.1 503 628 754 1,005 1,131 1,257

5 19.63 196.3 392.6 588.9 785 982 1,178 1,571 1,767 1,963

6 28.27 282.7 565.4 848.1 1,131 1,414 1,696 2,262 2,545 2,827

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Cylinder Rod Force Deduction Chart

Rod (in)

Rod Area (in)

PRESSURE (PSI)

10 20 30 40 50 60 80 90 100

0.25 0.049 0.49 0.98 1.47 1.96 2.45 2.94 3.92 4.41 4.9

0.5 0.196 1.96 3.92 5.88 7.84 9.8 11.76 15.68 17.64 19.6

0.625 0.307 3.07 6.14 9.27 12.28 15.35 18.42 24.56 27.63 30.7

0.75 0.441 4.41 8.82 13.23 17.64 22.05 26.46 26.46 39.69 44.1

1 0.785 7.85 15.7 23.55 31.4 39.25 47.1 62.8 70.65 78.5

1.375 1.485 14.85 29.7 44.55 59.4 74.25 89.7 118.8 133.65 148.5

3 7.068 70.68 141.36 212.04 282.72 353.4 424.08 565.44 636.12 706.8

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Cylinder Speed

• Finally calculate the flow rate CFM (cubic feet per minute) needed to move the load

siteatessureAbsoluteessureAbsolutecylinderatessurerationCompressio

__PrPr__Pr_

• Volume is V = A x S• Compression Ratio

8.22___

filltoTime

rationCompressioVolumeCFM

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Actuators• Cylinders symbols can be any length.• The piston and rod can be shown in the

retracted, extended or any intermediate position

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Single Acting

• Normally in

• Normally out

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Double Acting

PistonPiston Rod

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Double Ended

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Cylinder MountingFoot Mounted Thread Mounted

Front Flange Rear Flange

Swivel Flange Front

Swivel Flange Center

Swivel Flange Rear

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Air Motors Advantages

• Advantages– Do not require electric power– Smaller than electric motors– Do not need reducers– Simple regulation using flow controls– Torque varied by regulating pressure– Do not need relays or motor controllers– Do not generate much heat

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Air Motor Disadvantages

• Disadvantages– Cost can exceed an electric motor– Cost of operating can be greater– Speed control not as accurate– Plant air variations cause speed and

torque fluctuations

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Piston Air Motors

Motor Single Direction Symbol

Motor Bi-directional

Symbol

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Vane MotorsMotor Single

Direction Symbol

Motor Bi-directional

Symbol

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Vacuum generator

Vacuum cups

Vacuum switch pneumatic 1

Vacuum Equipment

Vacuum filter

Vacuum silencer

Vacuum gauge

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Vacuum Cup

Orifice that generates vacuum or suction via the venturi principle

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Summary

Pneumatic Symbols and Drawings

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Objectives

• Define Industry Standards used for Industrial Electrical Drawings.

• Define Pneumatic Diagrams or Drawings and how they are structured.

• Define Pneumatic Symbols and logic applied to pneumatic drawings.

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Standards• STANDARDS ARE IMPORTANT FOR THE

FOLLOWING REASONS.– · Components must be interchangeable and

must perform to known standards. This includes actuators, valves and pipe fittings.

– · Symbols must be interpreted the same way by any competent person so that they can follow a circuit diagram and install them correctly.

– · Drawings layouts and drawing symbols must be interpreted the same way by any competent person and this involves both circuit and layout drawings.

– · There are many other standards concerning things such as health and safety, hydraulic fluids and filters.

– There are various organizations devoted to producing standards in the field of fluid power.

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Shapes• Shapes and lines that are used to

construct symbols and circuits:

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Basic Symbols (shapes)Circles

energy conversion units

measuring instrument

mechanical link

roller

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Basic Symbols (shapes)

Square at 45o

conditioning apparatusconnections to corners

Squarecontrol componentconnections perpendicular to sides

Rectangle cylinders and valves

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Basic Symbols (shapes)

certain control methods

Rectangles

cushion

piston

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Basic Symbolsrotary actuator, motor or pump with limited angle of rotation

Semi-circle

mechanical connectionpiston rod, lever, shaft

Double line

Capsule pressurised reservoir air receiver, auxiliary gas bottle

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Basic Symbols

Line Working line, pilot supply, return, electrical

Chain Enclosure of two or more functions in one unit

Dashed Pilot control, bleed, filter

Line Electrical line

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Functional Elements

Long sloping indicatesadjustability

Spring

Triangle Direction and nature of fluid,open pneumatic or filled hydraulic

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Functional Elements

Straight or sloping path and flow direction, or motion

Arrows

Restriction

Tee Closed path or port

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Functional Elements

90o angleSeating

rotary motionCurved arrows

clockwise from right hand end

Shaft rotation

anti-clockwise from right hand end

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Functional Elements

Indication or controlsize to suit

Temperature

Operator Opposed solenoid windings

Prime mover M MElectric motor

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Flowlines

not connectedCrossing

Junction Single

Hose usually connectingparts with relative movement

Flexibleline

Junction Four way junction

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Connections

ContinuousAir bleed

Air exhaust No means of connection

Temporary by probe

With means of connection

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Connections

Both to exhaustCoupling quick release

Coupling quick release self sealing

Source sealed

Coupling quick release self sealing

Both sealed

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Connections

Rotary connection one line

Rotary connection two lines

Rotary connection three lines

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Function components

Silencer

Pressure to electric switch preset

Pressure to electric switch adjustable

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Function components

Uni-directional flow regulator

Rotating joint

Pressure indicator

Pressure drop indicator

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Air receiver

Isolating valve

Air inlet filter

MCompressor and electric motor

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Combination unitsFRL with shut off valve

and pressure gauge

Lubro-control unit

Filter and lubricator

FRL Combined unit

Filter regulator with gauge

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Filters

Filter with manual drain

Filter with automatic drain

Filter with automatic drain and pressure drop indicator

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Pressure regulators• A pressure regulator symbol represents a normal state with the spring holding the regulator

valve open to connect the supply to the outlet.

Adjustable Regulator with pressure gauge simplified

Adjustable Regulator simplified

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Pressure relief valves• A pressure relief valve symbol represents a

normal state with the spring holding the valve closed.

Adjustable relief valve simplified

Preset relief valve simplified

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Pressure regulators

Pre-set relieving

Adjustable relieving

Adjustable relieving with pressure gauge

Pre-set relieving with pressure gauge

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Valve symbol structure • The function of a valve is given by a pair of

numerals separated by a stroke, e.g. 3/2..• The first numeral indicates the number of main

ports. These are inlets, outlets and exhausts but excludes signal ports and external pilot feeds.

• The second numeral indicates the number of states the valve can achieve.

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Valve symbol structure• A 3/2 valve therefore has 3 ports

(normally these are inlet, outlet and exhaust) and 2 states (the normal state and the operated state)

• The boxes are two pictures of the same valve

normaloperated

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• Valve switching positions are illustrated with squares on a schematic.

• The number of squares is used to illustrate the quantity of switching positions.

• Lines within the boxes will indicate flow paths with arrows showing the flow direction.

• Shut off positions are illustrated by lines drawn at right angles to the flow path.

• Junctions within the valve are connected by a dot.• Inlet and outlet ports to the valve are shown by

lines drawn to the outside of the box that represents the normal or initial position of the valve

Basic Valve Symbology

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Valve symbol structure• A valve symbol shows the pictures for

each of the valve states joined end to end

normaloperated

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Valve symbol structure• A valve symbol shows the pictures for

each of the valve states joined end to end

normaloperated

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Valve symbol structure• The port connections are shown to only one of

the diagrams to indicate the prevailing state

normal

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Valve symbol structure• The operator for a particular state is

illustrated against that state

Operated state produced bypushing a button

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Normal state produced bya spring

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Normal state produced bya spring

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Valve symbol structure• The valve symbol can be visualised as

moving to align one state or another with the port connections

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Valve symbol structure• A 5/2 valve symbol is constructed in a

similar way. A picture of the valve flow paths for each of the two states is shown by the two boxes. The 5 ports are normally an inlet, 2 outlets and 2 exhausts

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Valve symbol structure• The full symbol is then made by joining the two

boxes and adding operators. The connections are shown against only the prevailing state

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Valve symbol structure• The boxes can be joined at either end but the operator

must be drawn against the state that it produces. The boxes can also be flipped

• A variety of symbol patterns are possible

normallyclosed

normallyopen

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Valve functions 5/3• Three position valves have a normal

central position that is set by springs or with a manual control such as a lever

• The flow pattern in the centre position varies with the type. Three types will be considered

• 1, All ports sealed• 2, Outlets to exhaust, supply sealed• 3, Supply to both outlets, exhausts sealed

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Valves 5/3All valves types shown in the normal position

Type 1. All ports sealed

Type 2. Outlets to exhaust

Type 3. Supply to outlets

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Valves 5/3All valves types shown in the first operated position

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Valves 5/3All valves types shown in the second operated position

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Operators

General manual

Push button

Pull button

Push/pull button

Treadle

Manual

Rotary knob

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OperatorsMechanical

Plunger

Spring normally as a return

Roller

Uni-direction or one way trip

Pressure

Pilot pressure

Differential pressure

Detent in 3 positions

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Operators

Solenoid direct

Solenoid pilot

Solenoid pilotwith manual overrideand integral pilot supply

Solenoid pilotwith manual override and external pilot supply

Electrical

When no integral or external pilot supply is shown it is assumed to be integral

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Port markings

AlphabeticalDesignations

NumericalDesignations

Working Lines

A, B, C …….. O (excludes L)

2, 4, 6 . . . .

Leakage Fluid L ………………………… 9

Supply Air P ………………………… 1Exhaust R, S, T ………………..W 3, 5, 7 ……Pilot Lines Z, Y, X ………………….. 12, 14, 16, 18…

The valve connections can be labelled with capital letters or numbers as follows:

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Port Markings

212 10

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Port Markings

212 10

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Actuators• Cylinders symbols can

be any length.• The piston and rod can

be shown in the retracted, extended or any intermediate position

“l”

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Rotary actuatorsSemi rotary double acting

Rotary motor single direction of rotation

Rotary motor bi-directional

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Simplified cylinder symbolsSingle acting load returns

Single acting spring returns

Double acting non cushioned

Double acting adjustable cushions

Double acting through rod

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Sample Pneumatic DrawingITEM DESCRIPTION QTY. I.D. SPECIFICATION

12345678

DWG. NO. Drawn:

CheckedScale

Installation

Air Cylinder

Flow Control

A11 REX C23-76002/5 DC Valve

Safety Shut OffShut Off Valve

SilencerRegulator and Gauge

Filter

1213211

V1FV1,2

S1,2R1F1

SV1,2,3

NG-7124/3/8NG-7128/3/8NGS-7126/3/8NG-7129/3/8

S-407/3/8R-88/3/8F-88/3/8

Cyl. A1

FV1 FV2

SV1 SV2

Track Switch

AD003 T. Smith Jones None

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Summary

Example Pneumatic Circuit

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Objective• To demonstrate and explain the

reading of pneumatic drawings by way of example.

R GR G R G

PV1BINITIAL CAMS CLOSED

PV1AINITIAL CAMS OPEN

PV2BSECONDARY CAMS CLOSED

PV2ASECONDARY CAMS OPEN

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

CAM C CAM A

CAM B CAM A

BH3 BH1 BH5AIR CLOSEBH4

CONSTANT AIR

CLOSE OPEN

AIR APPLIED TO OPEN INPUT

START OF DIE OPEN SEQENCE – LV1 , LV3 AND LV5 ARE CLOSED – LV31, LV2, LV4, LV6 ARE OPEN

SHUTTLE BALL BLOCKS CLOSE

INPUT LINES

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

RV1, RV2 and RV44 SHIFT WITH L1 AND

L3 CLOSED

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

PV1 SHIFTS WITH L1 AND L3

CLOSED AND RV1 SHIFTED

‘A’ and ‘B’ CYLINDERS BEGIN EXTENDING

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

LV1 AND LV3 OPEN WHEN A AND B CYLINDERS BEGIN MOVEMENT

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

LV31 CLOSES OPEN WHEN AS B CYLINDER

CONTINUES MOVEMENT

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

PV2 SHIFTS WITH L31 CLOSED

‘C’ CYLINDER EXTENDS

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

LV2, LV4, LV6 CLOSE WHEN ALL THREE CYLINDERS ARE EXTENDED AND LV5 OPENS

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

RV3 AND PV3 SHIFTS WITH L2, L4 AND L6

CLOSED

LIFTER CYLINDERS EXTEND

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPENEND OF DIE OPEN SEQENCE – OPEN AIR INPUT OFF – LV 2, LV4, LV6, LV31 ARE CLOSED AND LV1, LV3 AND LV5 ARE OPEN

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPENSTART OF CLOSE DIE SEQENCE – AIR INPUT TO CLOSE PORT

AIR IS APPLIED TO CLOSE INPUT –

SHUTTLE BALL SHIFTS TO BLOCK AIR FROM

OPEN LINES

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

RV1, RV2 AND RV4 ARE OPERATED

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

PV1 AND PV3 ARE OPERATED

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

LV5 CLOSES WHEN ‘C’ CYLINDER RETRACTED

RV3 AND PV1 OPERATE

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPEN

‘A’ AND ‘B’ CYLINDERS RETRACT

ALL CYLINDERS RETRACTED: LV 1 AND LV3 ARE CLOSED; LV2, LV4,

LV6 AND LV31 ARE OPEN

R GR G R G

CAM A CYLINDER

CAM B CYLINDER

CAM C CYLINDER

LIFTER CYLINDERS

PV3BLIFTERS DOWN

PV3ALIFTERS UP

PV1PV2

RV3RV2

LV1LV31LV2

LV5CAM C CAM A

CAM B CAM A

CONSTANT AIR

CLOSE OPENEND OF CLOSE DIE SEQENCE AIR REMOVE FROM CLOSE INPUT– RETURN TO START OF OPEN SEQUENCE

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Summary

Industrial Air Controls

Business

Industrial-Controls S0712 M

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