Flowserve NAF-Turnex pneumatic actuators - Manual (Page 4)

4
2.2 Checking for damage and wear
Size 0
The following parts should always be replaced:
Lever bearings (38)
O-rings (3, 7, 17, 27, 37)
If the air consumption of the actuator is abnormally high,
this may be due to wear of the O-ring (27). Always replace
it as stated above. The following parts should also be
inspected:
Cylinders (1, 16). Clean the cylinders with white spirit and
blow them dry with compressed air. Inspect the cylinder
bore for scratches and other internal damage. Fit a new
cylinder if the existing one is damaged.
Pistons (25). Inspect the sealing lips of the piston. If
these are damaged or heavily worn, fit a new piston.
If one of the pistons is still on the piston rod, it can be
removed by fitting two nuts to the opposite end of the
piston rod (26) and locking them against one another.
The inner of the two nuts can then serve as a restraint
when the nut (24) at the opposite end of the piston rod is
released with a ring spanner. Take care not to damage the
piston rod surfaces.
Piston rod (26). If the piston rod has deep longitudinal
scratches, the piston rod and piston rod bushes (28)
must be replaced. However, minor scratches on the piston
rod can be removed by carefully rubbing down with very
fine emery cloth.
Size 1-3
The following parts should always be replaced:
Lever bearings (38)
O-rings (3, 7, 17, 37)
If the air consumption of the actuator is abnormally high,
check the following parts:
Cylinders (1, 16). Clean the cylinders with white spirit and
blow them dry with compressed air. Inspect the cylinder
bore for scratches and other internal damage. Fit a new
cylinder if the existing one is damaged.
Pistons (25). Inspect the sealing lips of the piston. If
these are damaged or heavily worn, fit a new piston. If
one of the pistons still remains on the piston rod, it can
be removed by fitting two nuts to the opposite end of the
piston rod (26) and locking them against one another.
The inner of these two nuts can then serve as a restraint
when the nut (24) at the opposite end of the piston rod is
released with a ring spanner. Take care not to damage the
piston rod surfaces.
Piston rod seals (27). Inspect these for damage or find
out whether the piston rod (26) moves very freely in the
seals. If the seals are damaged or leaking, fit new seals.
See section 2.4
Piston rod (26). If the piston rod has deep longitudinal
scratches, a new piston rod must be fitted. Minor
scratches can be removed by carefully rubbing down with
very fine emery cloth.
Sizes 4-5
The following parts should always be replaced:
Lever bearings (4, 16)
O-rings (7, 17, 30, 43)
If the air consumption of the actuator is abnormally high,
check the following parts:
Cylinders (35). Clean the cylinders with white spirit and
blow them dry with compressed air. Inspect the cylinder
bore for scratches and other internal damage. Fit a new
cylinder if the existing one is damaged.
Lever (6) bearings (3, 4,10 and 16). Clean the bearings
with white spirit, and fit new bearings if there is play in
the existing bearings. Inspect the O-rings (7 and 17). Fit
new O-rings if necessary. Grease the O-rings and bearings
surfaces. Re-assemble.
Pistons (32). Inspect the piston guide ring (33) and
faced O-ring (34). Fit new rings if the existing ones are
scratched or haved damaged edges, or if they are heavily
worn. If no damage is visible, test the outside dimensions
of the sealing ring by threading the cylinder onto the
piston. If this is easy to do without significant resistance,
this indicates that the O-ring and guide ring are heavily
worn and new ones must be fitted.
Use a small screwdriver to prise carefully the old guide
ring and faced O-ring. Place the new rings for 3-4 minutes
in water at 60 °C to soften them. Then quickly prise the
ringsover the guide edge of the piston and down into the
groove. Don´t use tools with sharp edges, and don´t stretch
the rings more than necessary, since they could otherwise
be permanently deformed. The simplest procedure is to fit
a spare piston and send the damaged piston back to NAF
for replacement of the rings. This has the added benefit of a
factory guarantee.
Piston rod seals (42). Inspect these for damage or find
out whether the piston rod (31) moves very freely in the
seals. If the seals are damaged or leaking, fit new seals.
See section 2.4
Piston rod (31). If the piston rod has deep longitudinal
scratches, a new piston rod and piston rod bearings
(44) must be fitted. Minor scratches can be removed
by carefylly rubbing down the piston rods with very fine
emery cloth.
Sizes 0-3 and 4-5
After a long period of service under difficult
conditions, it may be necessary to change other
component parts. Check the following:
Piston rod bearings (item 28 of sizes 0 and 1-3, and
item 44 of sizes 4-5). If the internal PTFE coating is
damaged so that the metal to which it has been applied is
visible through the coating, fit new bearings. See section
2.3.
Linkage mechanism - Fig. 1. This consists mainly of
pins, links, lever and coupling. If play can be felt in the
mechanism or if there is reason to suspect that some part
may be damaged, the mechanism should be dismantled.