TECHNICAL DOCUMENTATION6

6.1/02

PRINCIPLES OF PNEUMATICS

• Density of air, measured to20°C to the atmospheric pressure:

1.275kgm3

Pressure: The ratio between a force and the surface on which it acts.

Atmospheric pressure: Equivalent to the pressure exerted on a surface at sea level at 20°C and with65% humidity: 10.33 m H2O; 760 mm Hg; 1.013 x 105 Pa.

Absolute pressure: The pressure above the absolute zero value - pressure 0 = absolute vacuum.Gauge pressure: The pressure referring to ambient atmospheric pressure: it is normally indicated

by the pressure gauges used in pneumatic circuits.

P= ––––––– = PaS (m2)

F (N)

Pressure readon gauge (6 bar)

Gau

ge p

ress

ure

(6 b

ar)

Absolute vacuum

Atmospheric pressure

Abs

olut

e pr

essu

re(7

bar

)

Gauge pressure = (absolute P) - (atmospheric P.)

Upstream pressure: Pressure of the compressed air at the pneumatic component inletDownstream pressure: Pressure of the compressed air at the pneumatic component outlet!P pressure drop: Difference between upstream and downstream pressureFLOW RATE: The volume of air passing through a given section in a unit of time. In pneumatics,

the volume unit of measurement is Nl (Normal litre). In practice it representsthe volumetric capacity of the air referring to ambient atmospheric pressure.E.g. in a conduit of a given section, there is a mass flow of 1 litre of air (1 dm3)at 7 bar absolute pressure. This value expressed as volume of air correspondsto 7 litres of air (7 dm3) at the ambient atmospheric pressure (1 bar).

=1 dm3

7 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

1 dm3

1 barabsolute

Mass flow

Volumetric flow rate(referring to absolute pressure)

• With the same pressure, the flow rate is directly proportional to the port cross section.• With the same cross section, the pressure is directly proportional to the flow rate.• Without a !P (difference between upstream and downstream pressure), there can be no flow rate.

Pascal’s law: A confined fluid transmits externally applied pressure uniformly in all directions.

6.1/03

6

CALCULATING THE FLOW RATE OF A VALVE USING FLOW COEFFICIENT KV

Coefficient kV gives approximate values when used for compressed air.The flow rate QN at a normal volume through a valve is:

Subsonic flow: P2 > Supersonic flow: P2 <

whereQN = flow rate at a normal volume [Nl/min]QN* = critical flow rate at a normal volume [Nl/min]

kV = hydraulic coefficient in

P1 = absolute upstream pressure [bar]P2 = absolute downstream pressure [bar]!P = difference in pressure P1 – P2 [bar]t = input air temperature [°C]

P1

2P1

2

QN = 28,6 · kv · P2 · !P!"""#""293273 + t Q*N = 14,3 · kv · P1 ·#""293

273 + t

The flow rate QN at a normal volume through a valve is:

Subsonic flow: P2 > b · P1 Supersonic flow: P2 < b · P1

whereQN = flow rate at a normal volume [Nl/min]QN* = critical flow rate at a normal volume [Nl/min]C = conductance in [Nl/min · bar]P1 = absolute upstream pressure [bar]P2 = absolute downstream pressure [bar]r = upstream pressure : downstream pressure ratio P2 /P1b = critical pressure ratio b = P2* /P1t = input air temperature [°C]

The flow rate QN at a normal volume through a valve is:

Subsonic flow: P2 > 0,528 · P1 Supersonic flow: P2 < 0,528 · P1

whereQN = flow rate at a normal volume [Nl/min]QN* = critical flow rate at a normal volume [Nl/min]CV = coefficient of flow [US · GPM / p.s.i.]P1 = absolute upstream pressure [bar]P2 = absolute downstream pressure [bar]t = input air temperature [°C]

lmin

kgdm3 · bar( )1/2

CALCULATING THE FLOW RATE OF A VALVE USING FLOW COEFFICIENTS C and b

QN* = C · P1 ·#""293273 + t

QN = C · P1 · 1 – ·#"""r – b1 – b( )2 #""293

273 + t

CALCULATING THE FLOW RATE OF A VALVE USING FLOW COEFFICIENTS CV

QN = 400 · CV · P2!P ·#""273273 + t#"" QN* = 200 · CV · P1 ·#""273

273 + t

6.1/04

The nominal flow rate QNm of a valve, i.e. the flow at normal volume passing through a valve with P1 = 6[bar] (P1 =7 [bar] absolute) and !P = 1 [bar], can be obtained from the previous formula as follows:

QNn = 66 · kv

QNn = 943,8 · CV

QNn = 7 · C ·

Equalising the first two formulae gives: kv = 14,3 · CV ·

• REACTIONS BETWEEN QNn - CV - kv - KV - S - de2

CALCULATING THE NOMINAL FLOW RATE

1 –!""""0,857 – b1 – b( )2

Cv Se de2

QNn kv Kv

0.055

18

0.785

1.273

943.

8

0.00

1

1.25

9

0.79

4

66

0.0151

16.66

0.060

0.01

9

52.4

514.3

0.070

lmin

kgdm3 · bar( )1/2

m3

hkg

dm3 · bar( )1/2

QNn = flow rate in [Nl/min] with p1 = 6 [bar] (P1=7 [bar] absolute) and !P = 1 [bar]

kv hydraulic coefficient in

KV hydraulic coefficient in

CV coefficient of flow [US · GPM / p.s.i.]

Se equivalent cross section [mm2]

de2 = S · — through diameter2 in [mm2] obtained from the equivalent cross section4

"

6.1/05

6

CONVERSION TABLESTABLE 1 – CONVERSION BETWEEN SYSTEMS OF MEASUREMENT

TABLE 2 – TEMPERATURE CONVERSION TABLE 3 – MULTIPLES AND SUB-MULTIPLES

TABLE 4 – PRESSURE UNIT CONVERSION FACTORS

Length

TimeArea

Volume

SpeedAccelerationMass

Force

TorqueDensitySpecific weightWork, energy

HeatPower

Pressure

Mass flowVolume flowDynamic viscosity

Kinematic viscosity

Technical system andCGS system Multiply by International system Multiply by British system

m

sm2

m3

m·s–1

m·s–2

kg·s2·m–1

kg o kpkg

kg·mkg·s2·m–1

kg·m–1

kg·m

Calkg·m·s–1

CVkg·m–2

kg·cm–2

kg·cm–2

kg·s·m–1

m3·s–1

Nl/min–1

kg·s·m–2

Po (poise-system CGS)m2·s–2

St (stokes-system CGS)

1

11

1

11

9,81

9,810,9819,819,819,819,81

41869,817359,81

9,81·100,9819,81

10,0000167

9,810,11

10–4

mms

m2

m2

m3

m3

m·s–1

m·s–2

kgkgN

da N = 10 NN·m

kg·m–3

N·m–3

JKWh=3,6·106J

JWWPaPa

bar = 105Pakg·s–1

m3·s–1

Nm3 · S–1

Pa·sPa·s

m2·s–2

m2·s–2

0,02540,3048

10,000645

0,092916,39·10–4

0,028320,30480,30480,453614,5944,4483

1,35616,02

157,161,356

1055,11,3558745,7

6,8948·10

0,45360,02832

0,0004726,896

0,0929

in (inch)ft (foot)

sin2

ft2in2

ft2ft·s–1

ft·s–2

lb (pound)slug = lb ƒ ·s2·ft–1

lb ƒ (pound)

lb ƒ ·ftlb·ft–3

lb ƒ ·ft–3

lb ƒ ·ft

BTUlb ƒ ·ft·s–1

HPp.s.i.=lb ƒ ·in–2

lb·s–2

ft·s–1

SCFMlb ƒ ·s·in–2

ft2·s–1

Nameteragigamegakiloettodecadecicentimillimicronanopico

SymbolTGMkhdadcm!np

Value1012

109

106

103

102

1010–1

10–2

10–3

10–6

10–9

10–12

Technical system andCGS system Divide by International system Divide by British system

°F = [1,8 · °C] + 32°C = [°F - 32] · 0,55°K = °C + 273

°C = degrees Celsius

°K = degrees Kelvin

°F = degrees Fahrenheit

Source unitsPakPaMPabarmbarkp/cm2

cm H2Omm H2Omm Hgp.s.i.

To obtain the pressure for the following units, multiply the number given for the source units by the coefficient shown.

Pa1

103

106

105

10098.066,598,06659,80665133,3226.894,76

kPa10–3

1103

102

0,198,0665

98,0665·10–3

9,80665·10–3

133,322·10–3

6,89476

MPa10–5

10–3

110–1

10–4

98,0665·10–3

98,0665·10–6

9,80665·10–6

133,322·10–3

6,89476·10–3

bar10–5

10–2

101

10–3

0,9896650,98665·10–3

98,0665·10–6

1,33322·10–3

68,9476·10–3

mbar10–2

10104

103

1980,6650,98665

98,0665·10–3

1,3332268,9476

kp/cm2

10,1972·10–6

10,1972·10–3

10,19721,01972

1,01972·10–3

110–3

10–4

1,35951·10–3

70,307·10–3

cm H2O10,1972·10–3

10,197210,1972·103

1,01972·103

1,019721000

10,1

1,3595170,307

mm H2O101,972·10–3

101,972101,972·103

10,1972·103

10,197210.000

101

13,5951703,07

mm Hg7,50062·10–3

7,500627,50062·103

750,0620,750062735,559

0,73555973,5559·10–3

151,7149

p.s.i.0,145038·10–3

0,1450380,145038·103

14,503814,5038·10–3

14,223314,2233·10–3

14,2233·10–3

19,3368·10–3

1

6.1/06

Grams of water vapour per cubic metre (g / m3) of air at ambient atmospheric pressure 1.013 bar (0 bar gauge pressure), saturated and compressed at the given pressures and temperatures.

TABLE 7 – VOLUME FLOW UNIT CONVERSION FACTORS

TABLE 5 – AIR CONSTANTS

TABLE 6 – CONTENT OF WATER VAPOUR IN SATURATED COMPRESSED AIR

EntityDynamic viscosityKinematic viscosityDensitySpecific heat at constant pressureSpeed of soundGas constant

Symbol

!"#

CpaR

Value17,89·10–6

14,61·10–6

1,2251,004340,29287,1

Pa sm2s–1

kg m–3

KJ kg–1 K–1

m s–1

J kg–1 K–1

Pressure - bar

Temperature °C05101520253035404550

0 4,82 6,88 9,4112,717,423,630,53949,663,581

0,4 3,45 4,93 6,74 9,0812,516,921,827,935,545,4558

0,63 2,97 4,24 5,80 7,8310,714,618,82430,639,249,9

1 2,42 3,46 4,73 6,39 8,7511,915,319,624,931,940,7

1,6 1,87 2,68 3,66 4,94 6,77 9,1811,915,219,324,731,5

2,5 1,39 1,99 2,72 3,67 5,02 6,82 8,8111,314,318,323,4

4 0,97 1,39 1,90 2,56 3,51 4,77 6,16 7,871012,816,4

6,3 0,67 0,95 1,30 1,76 2,41 3,27 4,22 5,40 6,87 8,7911,2

80,540,771,061,431,952,653,434,385,577,139,10

100,440,630,871,171,602,172,813,594,555,847,45

12,50,360,520,700,951,301,772,292,923,724,766,07

160,290,410,560,761,041,401,812,322,953,774,82

200,230,330,450,610,841,141,471,882,393,063,90

Source units

m3/sl/scm3/sm3/hm3/minl/hl/minft3/minUK gallon/minUS gallon/min

m3/s

110–3

10–6

0,277778·10–3

16,667·10–3

0,27778·10–6

16,667·10–6

0,47195·10–3

75,768·10–6

63,090·10–6

l/s

103

110–3

0,2777816,667

0,27778·10–3

16,667·10–3

0,4719575,768–3

63,090·10–3

cm3/s

106

103

10,277778·103

16,667·103

0,2777816,667–6

0,47195·103

75,76863,090

m3/h

36003,6

3600·10–6

160

10–3

60·10–3

1,69900,272760,22712

m3/min

6060·10–3

60·10–6

16,667·10–3

116,667·10–6

10–3

28,317·10–3

4,5461·10–3

3,7854·10–3

l/h

3,6·103

3,6·103

3,6103

6·104

160–3

1,6990·103

272,76227,12

l/min

60·103

6060·10–3

16,667103

16,667·10–3

128,3174,54613,7854

ft3/min(scfm)

2,1188·103

2,11882,1188·10–3

0,5885635,313

0,58856·10–3

35,313·10–3

10,160540,13368

gallone/min UK

13,198·103

13,19813,198·10–3

3,6661219,97

3,6661·10–3

219,97·10–3

6,22881

0,83266

gallone/min USA

15,850·103

15,85015,850·10–3

4,4028264,17–3

4,4028·10–3

264,17·10–3

7,48041,2009

1

To obtain volume flow for the following units, multiply the number given for the source units by the coefficient shown.

6.1/07

6

Maximum recommended flow rate in Nl/min for pneumatic circuit piping. Flow rate values are calculated as follows:• pipes Ø 2 to Ø 12 with a pressure drop equal to 0.3% of operating pressure per metre of pipe.• pipes Ø 15 to Ø 40 with a pressure drop equal to 0.15% of the operating pressure per metre of pipe.

TABLE 8 - RECOMMENDED FLOW RATE

Inside diameter in mm - Nominal diameter in gas inches

Pressurebar2468

10

Ø 2 3,5 6,2 911,814,5

Ø 41935506682

1/8’’Ø 6 53 97140185230

1/4’’Ø 8110200290380470

3/8’’Ø 10190350500660820

Ø 12 300 550 80010501300

1/2’’Ø 15 370 700100013001600

3/4’’Ø 20 7501400200026003250

1’’Ø 2513502400350045005700

1 1/4’’Ø 32 2500 4500 6500 850010500

1 1/2’’Ø 40 4300 7800115001500018500

TABLE 9 - INDICATIVE AIR CONSUMPTION FOR DIFFERENT TYPES OF EQUIPMENT

Type of equipment

6 mm Ø drill12 mm Ø drill20 mm Ø drill45 mm Ø drillM6 screwdriver or bolt screwerM10 screwdriver or bolt screwerM16 impulse screwerM25 impulse screwer1” Ø wheel grinder6” Ø disk grinder9” Ø disk grinderPolishing machine1000 kg hoistSpot welder

Consumptionat full load Nl/min.

300 50011501650 300 40011501650 3501500210012002150 300

Type of equipment

Bench tamper8 kg tamper10 mm Ø riveting machine20 mm Ø riveting machine4 kg chisel6 kg chiselSmall paint-spray gunIndustrial paint-spray gun1 mm Ø cleaning bellows2 mm Ø cleaning bellows5 mm Ø nozzle sandblasting machine8 mm Ø nozzle sandblasting machinePlaster sprayerHeavy-duty concrete vibrator35 kg concrete breaker18 kg breaker30 kg breaker

Consumptionat full load Nl/min.

350 700 4501000 380 500 160 500 65 25016004200 5002500165018502850

Norma EN 60529 e CEI 529

IP 6 5

DEGREE OFPROTECTIONAGAINST THEPENETRATION OFLIQUIDS

DEGREE OF PROTECTIONAGAINST THE PENETRATIONOF FOREIGN BODIESCOMING INTO CONTACTWITH LIVE PARTS.

DEGREE OF PROTECTION

0

1

2

3

4

5

6

0

1

2

3

4

5

6

7

Not protectedProtected against solid bodiesgreater than ! 50 mm

Protected against solid bodiesgreater than ! 12 mm

Protected against solid bodiesgreater than ! 2.5 mm

Protected against solid bodiesgreater than ! 1 mm

Protected against dust

Totally protected against dust

Not protectedProtected against water fallingvertically (condensate)

Protected against drops of waterfalling up to 15° off the vertical

Protected against rain water upto 60° off the vertical

Protected against sprays of waterfrom any direction.

Protected against jets of waterfired from any direction

Protected against sea waves orthe like

Protected against the effects ofimmersion

1st No. DESCRIPTION 2nd No. DESCRIPTION

6.1/08

Pneumatic products include elastomer gaskets that are made of acryl-nitrile butadiene (NBR), polyurethane or fluorocarbonrubber (FKM/FPM).It is important for them not to come into contact with incompatible substances, which could cause them to swell or crackand subsequently malfunction.

In particular, it is necessary to check compatibility of:• the oil used in the air compressor• any oil used in the lubricator• the oil or cutting fluids used on the machine, which could get into the cylinders and from there the valves.

We have drawn up a compatibility table containing a list of chemicals and elastomers, and also Hostaform®, thetechnopolymer most commonly used in our products. Please refer to the English webpagewww.metalwork.it/eng/materiali_compatibilità.html or the Italian webpagewww.metalwork.it/ita/materiali_compatibilità.htmlThe website www.parker.com/o-ring/fcg/fcg.asp of Parker Pradifa, one of our gasket suppliers, contains an interactivetable defining incompatibility.

Below are some the oils that are definitely compatible with all the elastomers used with our products:• UNI and ISO FD 22 lubricants (Energol HPL, Spinesso, Mobil DTE, Tellus Oil).• low pressure compressor oil: SHELL CORENA OIL D 46• high pressure compressor oil: SHELL RIMULA X OIL 40.

Please note that some ester-based synthetic oils used in compressors are extremely incompatible with NBR andpolyurethane. ROTOROIL 8000 F2 is one of them.

Metal Work can provide you with further information or carry out research and tests if required.

CHECK COMPATIBILITY

6.1/09

6

PNEUMATIC SYMBOLSDISTRIBUTION AND REGULATION

2-way/2 positions valve(2/2)normally closed

2-way/2 positions valve(2/2)normally open

3-way/2 positions valve(3/2)normally closed

3-way/2 positions valve(3/2)normally open

3-way/2 positions valve(3/2)NC-NO

5-way /2 positionsvalve(5/2)

5-way/3 positions valve(5/3)pressurized centres

5-way/3 positions valve(5/3)open centres

5-way/3 positions valve(5/3)closed centres

Unidirectional valve

Check valvewith spring

Circuitselector valve(OR element)

Quick-release valve

Flow regulatorwith variable choke

Unidirectionalflow regulator withvariable throat

Sequence valve

Pressure reducerwithout blowoff valve

Pressure reducerwith blowoffrelief valve

Pressure pilotedreducer withblowoff relief valve

Shutoff valve

Dual pressure valve(AND element)

Progressivepneumaticstarter (APR)

Progressivesolenoidstarter (APR)

Progressivepneumatic starter(APR) (SK 100 only)

Progressivesolenoid starter(APR) (SK 100 only)

3-way shutoffvalve (V3V)with lockable control

3-way shutoffvalve (V3V)with pneumatic control

3-way shutoffvalve (V3V)with solenoid control

2/2 progressivepneumatic valve(VAP) (SK 100 only)

2/2 progressivesolenoid valve(VAP) (SK 100 only)

2

12

1

31

2

2

31

1 3

2

2

1

4

35

5

4

3

2

1

5

4

3

2

1

15

4

3

2

6.1/10

CONTROLS

Manual control

Manual pushbuttoncontrol

Manual levercontrol

Manual controlwith 2-position lever

Manual controlwith 3-position lever

Manualpedal-operated control

Mechanical controlwith ferrule

Mechanical controlwith sensitive ferrule

Mechanical controlwith spring

Mechanical controlwith roller lever

Mechanical control withsensitive roller lever

Mechanical control withunidirectional roller lever

Mechanical controlwith drawer

Electrical control

Solenoid control

Solenoid,pilot-assisted control

Piezoelectric control

Pneumatic control

Mechanical stop

Release device

6.1/11

6

TRANSMISSION AND PREPARATION

Pneumaticpressure source

Operating line

Pilot line

Discharge line

Flexible lineconnection

Electric cable

Line connection(welding, screwing)

Line connection(welding, screwing)

Crossing ofunconnected lines

Discharge point

Discharge holewithout connection

Discharge holewith connection

Power pick-up pointwith closing cap

Power pick-uppoint with port

Quick-fit coupling withoutunidirectional valve

Quick-fit coupling withunidirectional valve

Quick-fit coupling(de-coupling with openterminal section)

Quick-fit(de-coupling with closedterminal section)

1-way swivelcoupling

3-way swivelcoupling

Silencer

Tank

Filter

Condensate separatorwith manual discharge

Condensate separatorwith automatic discharge

Filter with condensateseparator withmanual discharge

Filter with condensateseparator withautomatic discharge

Lubricator

Pressure gauge

Pressure switch

Optical tester

FRL+pressure gaugemaintenance unit

FRL+pressure gaugesimplifiedmaintenance unit

FR+pressure gaugemaintenance unit

6.1/12

TRANSFORMATION

DE magnetic cylinderwith adjustablebilateral cushioning

DE magnetic twin-rodcylinder with adjustablebilateral cushioning

DE magnetic twin-rodcylinder with adjustablebilateral cushioningDE magnetic twin-rodcylinder with adjustablebilateral cushioning-singlethrough rodDE magnetic cylinder withadjustable bilateral cushioning+ DZB mechanical lock

DE magnetic cylinder withadjustable bilateral cushioning+ DZBA mechanical lock

DE cylinder withadjustable bilateralcushioning, through-rod

DE through-rod cylinder

DE magnetic cylinderwith adjustable bilateralcushioning, through-rod

DE magnetic cylinder,through-rod

DE cylinder

DE cylinder with cushioning

DE magnetic cylinder

SE cylinder

SE magnetic cylinder

Hydraulic brake withadjustment in onedirection only

Hydraulic brakewith adjustmentin both directions

Cushion

Pressure multiplierfor fluids withidentical characteristics

Pressure multiplierfor fluids withdifferent characteristics

Pneumatic/hydraulictransducer

Constant volumecompressor

Constant volumepneumatic motor,unidirectional flow

Constant volumepneumatic motor,bidirectional flow

Variable volumepneumatic motor,unidirectional flow

Variable volumepneumatic motor,bi-directional flow

Rotary pneumatic motor

Cylinder with adjustablesingle cushioning

Y X

Y X