Flowserve LPS Pneumatic Heavy-Duty Actuator Series - Manual (Page 18)

LPS Series Heavy-Duty Actuators FCD LFENIM0001-02-AQ – 5/15
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3.2.2 Measure the position of the spring can end stop (7) before removing it, and then lock the spring in the
compressed position by means of a specifically designed locking tool (provided by Flowserve upon request)
for this maintenance. This tool shall be installed in the opening of the spring can end flange (11) where the
spring-end travel-stop (7) has been removed. Screw the special tool to the spring shaft and follow other
detailed instructions provided with the special tool. Then remove pressure from the pneumatic cylinder.
a WARNING: At this point the spring is compressed and the spring module contains a large quantity of stored
energy. Failure to properly engage the specifically designed locking tool or failure to handle the spring carefully
could result in release of the spring with potential damage to equipment or injury to personnel.
3.2.3 Unscrew and remove the travel-stop of the pneumatic cylinder (25). For removing the stop, refer to
paragraph 2.3. Feed the pneumatic cylinder from the port on the head flange (19) at minimum necessary
pressure up to totally retract the piston rod (20).
3.2.4 Remove the cover (46) from the Scotch yoke housing by unscrewing all of the locking components: hex screw
(45), hex head shoulder bolts (44) and eyebolts (42) plus upper nuts (43). Leave the studs (41) screwed into
the Scotch yoke housing (51).
3.2.5 Remove the spring can, carefully following the instructions given in paragraph 4.2.
3.2.6 Locate the studs (57) that connect the Scotch yoke housing to the cylinder. With the Scotch yoke (36)
rotated 45°, it is possible to easily access these studs. Carefully unscrew the nuts (56). Pull out the whole
pneumatic cylinder. The stem has to be is fully retracted.
NOTE: Take care during removal, so as not to damage the piston rod or the stud threads.
3.2.7 Change the adapter kit. Replace the adapters (54 and 55) designed for fail close (open) action, with the new
ones designed for the opposite action. Take care to choose the adapter kit suitable for the Scotch yoke type
in use (symmetric or canted). The guide
block (48) of the symmetric Scotch yoke is
marked with the “S” letter on the top face,
while the guide block of the canted Scotch
yoke is marked with a “C” letter on the top
face, as shown in the pictures at right.
NOTE: The spring can adapter (55) and cylinder adapter (54) can be inserted in the guide block in one way
only, pending on the Fail Close (CW) or Fail Open (CCW) configuration. Component numbers are referred to
in Figures 26 and 27.
3.2.8 Reassemble the spring can, as instructed in paragraph 4.2.
3.2.9 Reassemble the pneumatic cylinder with adapter, following the reverse procedure as described in point 4.3.
3.2.10 Apply the minimum pressure necessary to the pneumatic cylinder from the port on the end flange (27) until
the piston rod moves the guide block (48) and partially compresses the spring. In this condition it will be
possible to remove the special tool from the spring can.
3.2.11 Remove the pressure, checking that the actuator goes in the correct new fail safe position.
3.2.12 Reposition the cover, taking care to replace the cover gasket (47).
3.2.13 Readjust the travel-stops, as instructed in paragraph 2.3.