Table 13 ALLOWABLE PRESSURE DROP RATINGS FOR 2700A CAGE CONTROL TRIM GRAFOIL PACKING, FLOW DOWN, No.16 Direct Actuator, 3 to 15 psi Spring Allowable Pressure Drops (PSI) Air Leakage Supply Trim Size Class Pressure 1" 1.5" 2" 3" 4" 18 18 18 20 20 20 22 22 22 24 24 24 27 27 27 30 30 30 33 33 33 36 36 36
II IV & VI V II IV & VI V II IV & VI V II IV & VI V II IV & VI V II IV & VI V II IV & VI V II IV & VI V
706 527
622 372
579 284
505 73
368
1,235 1,056 243 1,763 1,584 778 2,292 2,113 1,307 3,085 2,906 2,100 3,878 3,699 2,893 4,671 4,492 3,686 5,200 5,021 4,215
1124 875
1072 777
985 601
782 341
1,626 1,377 251 2,129 1,879 757 2,882 2,633 1,511 3,635 3,386 2,264 4,389 4,140 3,018 4,891 4,642 3,520
1,565 1,270
1,464 1,081
1,197 756
2,057 1,762 435 2,797 2,502 1,174 3,536 3,241 1,913 4,275 3,980 2,652 4,768 4,473 3,145
1,944 1,560
1,611 1,170
2,663 2,280 554 3,383 2,999 1,274 4,102 3,719 1,993 4,582 4,198 2,473
2,233 1,792 2,855 2,414 428 3,477 3,036 1,050 3,892 3,451 1,465
Usually direct acting actuators use a 3-15 psi spring. With an 18 psi air supply pressure, there is a 3 psi (18-15=3) net closure force on the trim, or for a 27 psi supply the net closure force is 12 psi. If a 6-30 psi spring is used in a direct acting actuator, add 15 to pressure in the air supply column.
ALLOWABLE PRESSURE DROP RATINGS FOR 2700A CAGE CONTROL TRIM GRAFOIL PACKING, FLOW DOWN, No.16 Reverse Actuator Allowable Pressure Drops (PSI) Initial Leakage Air Trim Size Class Pressure 1" 1.5" 2" 3" 4" 3 3 3 6 6 6 9 9 9 12 12 12
II IV & VI V II IV & VI V II IV & VI V II IV & VI V
706 527
622 372
579 284
505 73
368
1,499 1,320 514 2,292 2,113 1,307 3,085 2,906 2,100
1,375 1,126
1,318 1,023
1,224 841
990 548
2,129 1,879 757 2,882 2,633 1,511
2,057 1,762 435 2,797 2,502 1,174
1,944 1,560
1,611 1,170
2,663 2,280 554
2,233 1,792
The Initial air pressure is actuator diaphragm pressure when the valve begins to open. For example, a 315 has an initial pressure of 3 psi. The spring may have additional compression to provide the 6, 9 & 12 psi initial pressures.
//data/public/pdf/valve-sizing-maual.doc 20 of 43 Norriseal – P.O. Box 40525 Houston TX 77240-052–- Ph: (713) 466-3552, Fax: (713) 896-7386
10/10/2008