KSB BOAX- B, Operating Instructions Manual

Page: 43 / 48

41
DYNACTAIR NG: 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

for each full turn of the adjusting screw (28)
Actuator type
Shaft variation angle

after
adjustment
DYNACTAIR NG 2 2 °
26’
DYNACTAIR NG 4 2 °
DYNACTAIR NG 6 2 °
14’
DYNACTAIR NG 8
1
°
54
’
DYNACTAIR NG 12 1 °
40’
DYNACTAIR - NG 16
1 °
54’
- 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 NG
28
22 2 4
24 18
ACTAIR NG / DYNACTAIR NG
Closed
--1 °
Open
91 °
9 °
92
°