KSB BOAX-B Instructions De Service page 35

DYNACTAIR- - B: Stroke closing adjustment
Single acting with spring return actuator is provided as standard with
10 ° stroke adjustment from 0 ° to 10 ° .
The stroke adjustment of the actuator mounted onto valve should be
done with the valve free of any flow pressure or friction impediments,
the actuator must be disconnected from air supply and equipment.
This operation must be done with the valve/actuator fitted on pipe line
or in a vice.
- - Remove the nuts (18) and its O- -rings (24)
- - Supply air pressure to port 4 to open the valve and to push the
actuator pistons outward.
- - Unscrew, counter clockwise direction, the adjusting screw (28) (see
table below). This table defines the average drive variation angle a
for each full turn of the adjusting screw (28)
Actuator type
DYNACTAIR- -B2
DYNACTAIR- -B4
DYNACTAIR- -B6
DYNACTAIR- -B8
DYNACTAIR- -B12
DYNACTAIR- -B16
- - Stop to supply air pressure to port 4, and due to the spring action the
pistons moves to inward position up to the limits determinate to the
adjustment screws on the springs cylinder (22).
Warning: The spring return close adjustment is not a mechanical
stop that acts against the pistons travel or the shaft rotation, but the
screws limit the spring travel and the pistons without any force
standstills. In this condition the shaft is not stopped and theoretically
could be moved to the total closing position with compressed air in
port 2. The valve disc friction prevents the disc to rotate.
- - Check the valve close position, if it is over closed repeat the
operation from the beginning until the desired valve closure position
is achieved.
- - In opposite case, with the valve to much open, with the air supply to
the port 4, move both adjustment screws inward, clockwise. A valve
too closed may not open if the air pressure is too low.
- - To obtain a good operation, the 2 adjusting screws (28) must be in
contact and under stress. If it is not the case, unscrew one adjusting
screw (28) by hand until contact against the springs. Unscrew it,
counter clockwise direction, by hand, and 1/8 turn more with a
spanner.
- - Without pressurised air supply, tighten the nuts (18) with its sealing
O- -ring (24) on the plugs.
- - The actuator is now ready to operate correctly
DYNACTAIR- - B
22
2
ACTAIR- - B / DYNACTAIR- - B
92 °
Open
91 °
Shaft variation angle a after
adjustment
2° 26'
2°
2° 14'
1° 54'
1° 40'
1° 54'
28
24 18
4
Closed
- -1°
9 °
35