Pilot Valve Assembly and Pilot Filters for DP27 Pilot Operated Pressure Reducing Valves

Pilot Valve Assembly and Pilot Filters for DP27 Pilot Operated Pressure Reducing Valves
IM-P470-06
4700034/2
CH Issue 2
Pilot Valve Assembly and Pilot Filter for
DP27 Pilot Operated Pressure Reducing Valves
Fitting Instructions
Warning
For full Installation and Maintenance Instructions, inclusive of safety information, see the
following: IM-P470-03 supplied with the product.
Note: Installation and Maintenance Instructions are available separately from Spirax Sarco.
1. How to renew the pilot
filter element
1.1 Isolate the reducing valve and zero
the pressure.
1.2 Unscrew the filter cap and carefully
withdraw the filter element.
1.3 Replace the element and tighten the
filter cap to 90 - 100 N m (66 - 74 lbf ft).
Note: The gasket is re-usable.
Filter
element
Filter gasket
Filter cap
Adjustment screw
2. How to renew the pilot
valve assembly
2.1
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.
Adjustment lock-nut
Spring housing
Top
spring
plate
4 off
spring housing
securing notes
Bottom spring
plate
2 x diaphragms
Pressure
adjustment
spring
IM-P470-06 CH Issue 2
© Copyright 2012
1
Printed in the UK
2.2 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.
2.3 Apply superlube grease to the threads before screwing the new pilot valve into the
housing. Torque 45 - 50 N m (33 - 37 lbf ft).
2.4 Check that there is a very slight clearance between the top of the plunger and a straight
edge placed across the diaphragm location recess.
Straight edge
Check that there is a
very slight clearance
2.5 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.
2.6 DP27, DP27E and DP27Y
Replace the bottom spring plate, pressure adjustment spring and top spring plate.
2.7 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 of IM-P470-03 which would have been supplied with the original product.
2
IM-P470-06 CH Issue 2
Adjustment screw
Adjustment lock-nut
Spring housing
Top spring plate
4 off spring housing
securing nuts
Pressure adjustment spring
Bottom spring plate
2 x diaphragms
Pilot valve assembly
Table 1
Recommended tightening torques for spring
housing / actuating chamber cover securing studs and nuts
Size of valve
Nut size
Tightening torques
½", ¾" and 1"
DN15, DN20, DN25 and DN32
M10
40 - 50 N m
(30 - 37 lbf ft)
DN40 and DN50
M12
45 - 55 N m
(33 - 41 lbf ft)
IM-P470-06 CH Issue 2
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IM-P470-06 CH Issue 2
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