BIFFI ALGA-EAC Series - Page 46

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June 2020
Installation, Operation and Maintenance Manual
MAN 564_EAC Rev. 2
Maintenance
Section 5: Maintenance
To replace the piston seal ring (9) and the O-ring (19) proceed as follows:
1. Remove the existing Teon seal ring (9) and the O-ring (19) from their groove.
2. Clean the groove carefully and lubricate it with a protective oil lm.
3. Assemble the new O-ring into its groove and lubricate it with a protective oil lm.
4. Assemble the new Teon seal ring (9) on its rubber O-ring (19) by introducing one
side of it into the groove and then enlarge it with your ngers so as to introduce
it into the groove: take care to enlarge it uniformly without any tools which could
possibly damage it. The elastic memory of the kind of Teon type the seal ring is
made of allows the ring to shrink back to its previous dimension after a short time.
If the o-ring (17) has to be replaced, measure the protrusion of the stop screw (11) with
reference to the end ange (13) surface, so as to be able to easily restore the setting of the
actuator mechanical stop in the open valve position, once the maintenance procedures have
been completed.
5. Loosen the stop setting screw cover (14) and unscrew the stop screw (11).
6. Remove the o-ring (17) from the stop screw (11). Carefully clean and lubricate
the stop screw thread and the surface of the end ange area, on which the
o-ring works.
7. Screw the new o-ring onto the stop screw until it touches the cover (14).
8. Screw the stop screw into the threaded hole of the end ange until it reaches
its original position (the same protrusion with reference to the ange surface).
9. Check that the o-ring (17) is inside the groove into the end ange and in contact
with the groove bottom surface.
Reassemble
1. Assemble the new gasket (item 36 - Figure 39) after cleaning the surfaces of
housing (item 8 - Figure 39) and head ange (item 2) which are in contact.
2. Assemble the head ange and tighten the screws (item 7 - Figure 39) to the
recommended torque.
3. Clean and lubricate the piston rod (item 6) surface, particularly that of the bevel,
with a protective oil or grease lm and introduce it into the head ange hole,
taking care not to damage the Teon seal ring (item 4): the piston rod bevel has
to enlarge smoothly the seal ring.
4. Carefully clean the threaded end of the piston rod and the threaded hole of the
adaptor bush (item 30 - Figure 39) of guide block (item 14 - Figure 39). Spread
some sealant LOCTITE 452, or equivalent, on the rod threaded end and screw
into the adaptor bush threaded hole and tighten.