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Series NKS-N, NKSP-N
9
Maintenance
♦ All repair work is to be performed by qualified
personnel using the appropriate tools.
♦ For the arrangement, designation and item
numbers of all parts of the valve, see Section 10.
♦ Spare parts are to be ordered with all the details in
acc. with the valve identification.
♦ Only original spare parts may be installed.
♦ To prevent leaks, a regular check of the connection
screws should be made in line with the operating
requirements.
For tightening torques, see Section 1.2.
♦ When disassembling and assembling the valve,
attention is to be paid to the tables and drawings in
Section 1 and 9.
♦ As the body lining 409 is drawn over the disc/stem
unit 221 while warm, this work should only be
carried out by the manufacturer.
♦ Has the valve been shut down, drained and
flushed in accordance with the regulations?See
also Section 6.3.
If
assembled
components of the valve may be damaged
and this can result in malfunctions during
operation.
9.1
Notes on dismantling
Improper dismantling can cause injuries
if the shell halves spring apart.
The
body
screws
914/1
unauthorised removal by the works sealing.
For residual spring travel values and residual spring
forces through unscrewing of the body screws, see
the table in Section 1.7.
9.1.1 Dismantling of the valve
♦ Remove sealing from the screw heads.
♦ Undo one body screw 914/1 from the shell.
♦ Replace this screw with a completely screwed
longer dismantling screw (not in the product
range).
♦ For the required minimum length of the dismantling
screw, see table in Section 1.7.
9520-021-en
Revision 17
TM 10477
Edition
05/2022
incorrectly,
individual
are
secured
against
♦ Remove the opposite body screw 914/1.
♦ Replace this screw as well with a longer disman-
tling screw.
♦ Undo both dismantling screws uniformly until the
screw springs 952/1 are completely relieved (re-
sidual force = 0).
9.2
Notes for assembly
♦ The flexible inlay 521 expands during assembly.
Do not cut off the overhang, but push back into the
lower and upper part of the shell 120.
♦ Before tightning the body screws 914/1 align the
disc/stem unit 221 centrally in the closed position.
♦ Mark the position of the disc/stem unit 221 against
body lining 409 at the hub, so permitting switching
only to this point during later test switching.
♦ With disc/stem unit in closed position, tighten the
body screws 914/1 until the gap between the upper
and lower part of the shell 120 is ca. 5 mm.
♦ Open the valve several times counterclockwise
(when viewing the stem unit) and close again in
the opposite direction. A sealing edge can form in
this way.
Never switch in the other direction of
rotation over the sealing edge!
♦ Tighten the body bolts 1-2 mm when disc in closed
position.
♦ Repeat the previously described process once or
twice.
♦ When finally tightening the body bolts, pay
attention to the torques provided in Section 1.2.
9.2.1 Assembly of the valve
During assembly of the valve the shell halves are
screwed together in reverse sequence.
The screw heads are then sealed again with:
Diamant Plastic Ferro #0067, Superior Dunkel 2-
component metal sealing compound.
Diamant Metallplastic GmbH, POB 200308, D-41203
Mönchengladbach
Page 13
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