Spirax Sarco DP27, Инструкция по установке и обслуживанию

Страница: 20 / 40

IM-P470-03 CH Issue 7
20
5.4 How to renew the pilot valve assembly
6. DP27, DP27E and DP27Y
Isolate the reducing valve and zero the pressure and proceed to unscrew the 4 off spring
housing securing nuts and remove spring housing, bottom spring plate and diaphragms.
DP27R
Isolate the actuating air supply and zero the pressure and proceed to unscrew the 4 off
actuating chamber nuts and remove the air control block and diaphragms.
7. Unscrew and remove the pilot valve assembly (19 mm A/F). The pilot assembly has an
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.
8. Apply superlube grease to the threads before screwing the new pilot valve into the housing.
Torque 45 - 50 N m.
9. Check that there is a very slight
clearance between the top of the plunger
and a straight edge placed across the
diaphragm location recess.
10. Refit the two diaphragms making sure
that they are fitted the same way round
as they were removed and that all
contact faces are clean. Diaphragms
showing signs of wear or damage should
be replaced.
11. DP27, DP27E and DP27Y
Replace the bottom spring plate.
12. DP27, DP27E and DP27Y
Assemble the spring housing and tighten the nuts to the recommended torques shown
in Table 1.
DP27R
Assemble the air control block and tighten the nuts to the recommended torques shown
in Table 1.
Bring the valve back into commission, following as many Steps as necessary in Section 4,
page 14.
9
Straight edge