3
TABLES AND CONVERSION FACTORS IN PNEUMATICS
VALVES
Frequently asked questions in pneumatics typically concern: air quality, cylinder forces, loading and bending, air consumption plus valve flow and lubrication. The tables on this page can be used in combination with the guidance and golden rules stated on the previous page. For sizing cylinders and air consumption go to page 17.
AIR QUALITY
ISO 8573-1 specifies quality classes for compressed air. A class number is made up from the individual maximum allowable contents of solid particles, water and oil in air and can be used to specify air quality for use with valves and other pneumatic applications. Class
Solids particle size max μm
1 2 3 4 5 6
0,1 1 5 15 40 –
concentration maximum mg/m3 0,1 1 5 8 10 –
Water Max. Pressure Dew Point °C
Oil concentration mg/m3
-70 -40 -20 +3 +7 +10
0,01 0,1 1 5 25 –
For general applications where ambient temperature is between +5 and +35°C, air quality to ISO8573-1 class 5.6.4 is normally sufficient. This is 40 µm filtration, +10°C maximum pressure dew point and 5 mg/m3 maximum oil content. Pressure dew point is the temperature to which compressed air must be cooled before water vapour in the air starts to condense into water particles.
LOAD AND BUCKLING For applications with high side loading, use pneumatic slide actuators or standard cylinders fitted with guide units. Alternatively external guide bearings should be installed. When a long stroke length is specified, care must be taken to ensure the rod length is within the limits for prevention of buckling. The table shows the maximum stroke length for a variety of installation arrangements.
1]
2]
152
Cylinder Ø mm (inch)
Piston rod Ø mm (inch)
8 10 12
3 4 4 6 6 8 8 10 10 12 12 12 16 14 16 16 20 20 20 25 25 25 25 32 32 38,1 (1,5) 38,1 (1,5) 40 40 44,45 (1,75) 50 57,15 (2,25) 57,15 (2,25) 63 57,15 (2,25)
16 20 25
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31,75 (1,25) 32 40 44,45 (1,75) 50 50,8 (2) 63 63,5 (2,5) 76,2 (3) 80 100 101,6 (4’) 125 127 (5’) 152,4 (6’) 160 200 203,2 (8) 250 254 (10) 304,8 (12) 320 355,6(14)
Load case 1 Pressure (bar) 4 6 270 220 380 300 310 250 730 590 540 440 980 790 780 620 1200 1000 970 790 1400 1100 1100 890 1100 860 2000 1600 1200 960 1600 1200 1400 1100 2000 1600 1900 1600 1500 1200 2400 2000 2000 1600 1900 1500 1500 1200 2400 2000 2000 1600 2800 2200 2300 1800 2400 1900 1900 1500 2300 1900 2400 1900 3100 2500 2500 2000 3000 2400 2100 1700
10 170 230 180 450 330 600 470 760 600 880 680 650 1200 730 950 870 1200 1200 930 1500 1200 1100 880 1500 1200 1700 1400 1500 1100 1400 1400 1900 1500 1800 1300
3]
16 130 170 140 350 250 470 370 590 460 680 520 500 960 570 730 670 930 930 720 1200 950 880 670 1100 910 1300 1100 1100 860 1100 1100 1400 1200 1400 970
Load case 2 Pressure (bar) 4 6 130 100 170 140 140 110 350 280 250 200 470 370 370 290 590 470 460 370 680 550 520 420 500 390 960 770 570 450 730 580 670 540 930 740 930 740 720 570 1200 930 950 760 880 700 670 520 1100 910 910 710 1300 1000 1100 830 1100 880 860 670 1100 840 1100 850 1400 1100 1200 920 1400 1100 970 760
VALVE FLOW
There are a variety of standards and methods for the measurement and display of valve flow performance. These can give rise to confusion and difficulty when comparing the published performance of different valves. The table below provides conversion factors as a guide to expressing valve performance in different units.
HOW TO USE:
There Select the unit of measurement that is known in the left hand column and multiply by the factor given in the column of the required unit of measurement. ‘Cv’ is specified by ANSI/NFPA ‘Kv’ used in Germany and based on water flow ‘C’ sonic conductance in dm3/s/bar specified by ISO 6358 ‘A’ effective area in mm2 specified by ISO 6358 ‘S’ effective area in mm2 according to the Japanese standard JIS B 8375 A further measurement is the NW value. This gives the equivalent diameter in mm2 of the smallest path through a valve. This is non-comparable and not in the table.
10 80 100 80 210 150 280 220 350 270 410 310 290 580 340 430 400 550 550 420 700 560 510 380 670 520 760 610 640 480 610 620 840 660 780 540
16 60 70 50 160 110 210 160 270 200 310 230 210 450 250 320 300 420 420 310 530 420 380 270 500 380 570 440 480 350 440 440 620 480 570 380
Load case 3 Pressure (bar) 4 6 170 130 230 180 180 140 450 360 330 260 600 480 470 380 760 610 600 480 870 700 680 540 650 520 1200 990 730 580 940 750 860 690 1200 960 1200 960 930 740 1500 1200 1200 980 1100 910 880 690 1500 1200 1200 940 1700 1300 1400 1100 1400 1200 1100 890 1400 1100 1400 1100 1900 1500 1500 1200 1800 1400 1300 1000
4]
10 100 130 100 270 190 360 280 460 360 530 410 380 750 440 560 520 720 720 550 900 740 680 510 890 690 1000 810 860 650 810 830 1100 890 1000 730
16 80 100 80 210 150 280 210 350 270 410 310 290 580 330 430 400 550 550 420 690 560 510 370 670 520 760 600 640 480 600 610 830 660 780 540
Load case 4 Pressure (bar) 6 6 190 160 260 210 220 170 520 420 380 300 700 560 550 440 880 710 690 560 1000 820 790 630 760 600 1400 1100 850 680 1100 880 1000 810 1400 1100 1400 1100 1100 860 1700 1400 1400 1100 1300 1100 1000 820 1700 1400 1400 1100 2000 1600 1600 1300 1700 1400 1300 1000 1600 1300 1700 1300 2200 1700 1800 1400 2100 1700 1500 1200
10 120 160 120 320 230 430 330 540 420 620 480 450 870 510 660 610 840 840 650 1100 860 800 600 1000 820 1200 950 1000 770 960 980 1300 1100 1200 870
16 90 120 90 240 240 330 250 410 320 480 360 340 680 390 500 470 640 640 490 810 660 600 450 790 620 900 720 760 580 720 730 990 790 930 650
FLOW FACTOR CONVERSION TABLE Factors Flow * Orifice Size Cv Kv C m3/h l/min A S Cv 1 0,869 4,08 59,1 985 16,3 21,5 Kv 1,15 1 4,69 67,9 1132 18,7 24,7 C 0,245 0,213 1 14,5 241 4,11 5,27 3 0,017 0,015 0,069 1 16,67 0,276 0,364 m /h l/min 0,001 0,0088 0,0041 0,06 1 0,016 0,022 A 0,061 0,053 0,243 3,62 60,4 1 1,31 S 0,046 0,04 0,189 2,75 45,8 0,761 1 * Flow parameters are 6 bar inlet and 5 bar outlet at 20°C, 1013 mbar and 65% humidity.
LUBRICANTS
When to lubricate, via an oil-fog or micro-fog lubricator, is generally explained in this catalogue. However the oil recommended is very much dependant on the local conditions and not least availability of various brands and labels. In each country IMI Norgren can recommend equivalent products, based on the information from the suppliers.
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