Flowserve LPS Pneumatic Heavy-Duty Actuator Series - Manual (Page 26)

LPS Series Heavy-Duty Actuators FCD LFENIM0001-02-AQ – 5/15
26
Troubleshooting Table
Problem
Possible Cause Solution
The actuator does not move.
A moving part is seized up.
Check if any moving part is blocked. If so, follow
the maintenance instructions given in paragraphs
4.2, 4.3 and 4.4.
Leakages of the pneumatic cylinder.
A significant air leak may prevent the actuator
from operating. Ensure that there aren’t any
external leaks of the pneumatic cylinder. If
possible, detect them using a leak finder spray.
Check also that there are not leaks across the
piston. If leaks are present, follow the cylinder
maintenance instructions given in paragraph 4.3.
The actuator model is not the correct one,
or is not suitable for the plant conditions.
Check the actuator nameplate and the plant
requirements. If there are mismatches, contact
Flowserve Service Department.
Spring problems (if actuator is a single
acting model).
Check the proper functioning of the spring can.
If problems are found, contact the Flowserve
Service Department.
Perform the following test: disassemble the
actuator from the valve and measure the
minimum pressure values necessary to move
and compress the spring. Compare the measured
values with the ones reported on the Testing
Certificate. If there are significant differences you
should contact Flowserve Service Department.
A lockout device has been inserted and
forgotten in that position.
Disconnect the lockout module.
The valve does not shut off
properly and there are leaks.
The actuator is not correctly adjusted.
Adjust the end stops of the pneumatic cylinder
and of the spring can until the valve is leak-tight
across the seat. Follow the instructions given in
the paragraph about Travel-stop bolts (2.3).
The valve does not fully perform
the stroke, during opening or
closing.
The actuator is not correctly adjusted.
As above, check the position of the end stop
in opening and closing direction. If necessary,
adjust them. Follow the instructions given in
paragraph 2.3.
Exhaust port(s) obstructed.
Screw cap(s) must be disengaged. Ensure vent
ports are free. If not, clean them of any obstruc-
tions and clean the dust excluders, if present.
Actuator torque lower than required.
In order to do a check it is necessary to perform
the following test: disassemble the actuator from
the valve and measure the minimum pressure
values necessary to move and compress the
spring (if the actuator is a single acting model)
or the minimum values necessary to move the
actuator yoke and perform a stroke (for double
acting models). Compare the measured values
with the ones reported on the Testing Certificate.
If there are significant differences you should
contact Flowserve Service Department.
During the stroke the actuator
exhibits excessive amounts of
backlash.
Some components are excessively worn.
Identify and replace these components,
according to the procedure described in
paragraphs 4.2, 4.3 and 4.4.
In case of other problems not listed in this table, you should contact the Flowserve Service Department.