TECHNICAL MANUAL MT103
54
PM/819 MONITOR (FIG. 29)
1)
Disconnect the connection pipes between the regulator and monitor and the respective pilot units, and
between the latter and the downstream pressure take-offs.
2)
Remove the screws which secure the reduction assembly of the monitor to the body, making sure
that the weight of the reduction assembly itself can be sustained. When removing the assembly from the
body, the maximum care must be taken so as to avoid denting the sealing edge of the obturator .
3)
Lay the reduction assembly on one side.
4)
Slacken the lock nut, , fixing the obturator, to the rod , and remove the obturator,
from the obturator guide
.
5)
Completely slacken the spring, , by unscrewing the lock nut,
.
6)
Remove the screws and the nuts from the obturator guide .
7)
Raise the top cover with the flange and the indicator rod guide . To separate the three parts,
unscrew the screws .
8)
Separate the parts and making use of the flat faces on the piston guide and the holes on the
disc .
9)
Raise the assembly composed of the diaphragm and the discs , and ; disassemble the
diaphragm by removing the screws .
10) Remove the stem from the side of the cover.
11) Disassemble the bottom cover by removing the screws , and remove the stem guide .
Take the following precautions during reassembly:
- the bottom cover should be fixed to the obturator guide in such a way that the hole of the
motorization pressure passage mates with the similar hole on the obturator guide itself;
- when assembling the assembly consisting of the diaphragm and the guard discs, check that the
hole with the nozzle on disc is aligned with the hole on disc ; also check that the hole on nozzle
is free from dirt and foreign bodies;
- when assembling the assembly composed of the top cover with the flange and the indicator rod
ensure that the washer of the indicator rod is correctly fitted between the disc
and the piston
guide
and that it does not obstruct the hole in disc ; it should all be turned in such a way that the
indicator port is completely visible;
- before securing the lock nut , check that the spring is properly housed in the special centring beat
on the obturator guide .
DISASSEMBLING THE PILOT ASSEMBLY
1)
Disconnect the connection nipples between the pilot 204/A and the preregulator R14/A, unscrewing the
tapered seal connectors.
88
90
5
33
6
71
71
70
80
9
25
26
2
3
14
17
27
13
11
13
50
10
13
12
23
50
6
3
3
2
27
20
11
50
13
10
21
3
14
18
13
11
13
9
54
2
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