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
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