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FMPRV41
7.9 Procedure to renew or clean main diaphragms: (Refer to Figure 17)
Isolate the reducing valve and zero the pressure.
1.
Undo the long union nut
(1)
and pull away.
2.
Undo the M12 nuts and bolts
(2)
.
3.
Drop away the lower diaphragm chamber
(3)
, the two main diaphragms
(4)
,
diaphragm plate
(5)
and the pushrod assembly
(6)
.
4.
Thoroughly clean the lower diaphragm chamber
(3)
making sure contact faces are
clean.
5.
Replace the diaphragm plate
(5)
and pushrod assembly
(6)
and loosely fit the lower
diaphragm chamber
(3)
on two bolts either side of the union connection
.
6.
Bring the two new diaphragms together and slide into position
.
If the diaphragms are not renewed, but cleaned only, care must be taken to replace the
diaphragms in their original order.
7.
Push the lower chamber
(3)
and tighten the M12 nuts and bolts
(2).
Progressively and
evenly tighten to a torque of 80 - 100 N m .
8.
Retighten the long union nut to ensure a steam tight seal
.
9.
Bring the valve back into commission, following as many steps as necessary in section 6
Figure 17: Main Diaphragms
17 (a)
Union nut (1)
M12 nuts
and bolts (2)
Push Rod
assembly (6)
Diaphragm Plate (5)
Main Diaphragms (4)
Lower Diaphragm
Chamber (3)
17 (c)
17 (a)
