Spirax Sarco 37D, Installation And Maintenance Instructions Manual

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IM-P102-04 CTLS Issue 7
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To service or renew the main valve
and seat
Isolate the valve and zero the pressure. If the plant is
still in operation through a bypass valve or if the medium
surrounding the bulb is hot, withdraw the sensor bulb
and allow it to cool down, otherwise the control system
may be strained.
34. Unscrew the unions and release pipework.
35.
Unscrew the nuts.
36. Remove the pilot valve housing, complete with the
spring housing assembly.
37.
Remove the screen and clean.
38. Remove the main valve spring and the main valve
head.
39.
Remove the main valve seat. Examine the faces of
the main valve head and seat. If they are only slightly
worn both the main valve head and main seat may be
lapped on a flat plate using a fine grinding paste. If
either is badly worn or unfit for further use they will
need to be replaced.
40.
Refit the valve seat and tighten to the recommended
torque shown in Table 2. Where a new part has been
fitted it will be necessary to reset the main valve
push rod to give the correct valve lift. To do this it is
necessary to expose the main diaphragm plate and
push rod assembly.
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