19
FMPRV41
7.5 Procedure to renew the pilot valve assembly FMPRV41steam: (Refer to Figure12)
1.
Unscrew the unions of balancing pipe and controlling pipe
(1)
and release the pipe work.
2.
Unscrew spring housing securing nuts and bolts
(2)
, thereby releasing the spring housing,
spring
(3)
, top spring plate
(4)
, bottom spring plate
(5)
and pilot diaphragm
(6)
3.
Unscrew and remove the pilot valve assembly
(7)
(19 mm A/F). The pilot assembly hasan
integral PTFE seal.
The following handling precautions should be observed.
Handling precautions for PTFE
Within its working temperature range PTFE is a completely inert material, but
when heated to its sintering temperature it gives rise to gaseous decomposition
products or fumes which can produce unpleasant effects if inhaled. Fumes can be
produced during processing: for example, when the material is heated to sinter
it, or when brazed connections are being made to cable insulated PTFE. The
inhalation of these fumes is easily prevented by applying local exhaust
ventilation to atmosphere as near to their source as possible.
Smoking should be prohibited in workshops where PTFE is handled because
tobacco contaminated with PTFE will during burning give rise to polymer fumes.
It is therefore important to avoid contamination of clothing, especially the
pockets, with PTFE and to maintain a reasonable standard or personal cleanliness
by washing hands and removing any PTFE particles lodged under the fingernails.
4.
Screw the new pilot valve into the housing and tighten the nuts to the recommended
torque (Refer Table1).
5.
Check that there is a very slight clearance between the top of the plunger and a
straightedge placed across the diaphragm location recess.
Figure 12: Pilot valve assembly FMPRV41 steam
Straight edge
Plunger (8)
Top spring plate (4)
Spring (3)
Unions of
balancing pipe (1)
Pilot Valve
Assembly (7)
Spring Hsg.securing nuts and
bolts (2)
Bottom Spring Plate (5)
Pilot Diaphragms (6)
Unions of balancing
pipe (1)
