25
DP17R
Remove the pilot valve housing, complete
with the air control block.
47. Remove the main valve, screen and
clean.
48. Remove the main valve spring and the
main valve head. Clean to remove dirt
or scale as is necessary.
49. Remove the main valve seat. Clean and
remove dirt and scale as is necessary.
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. Clean
to remove dirt or scale as necessary.
DP17G
If there is any wear or damage to the
nitrile face then the head assembly must
be replaced.
50. Refit the valve seat applying jointing
compound to the seating faces and
tighten to the recommended torque
shown in Table 2, page 26.
Where a new part has been fitted it will
be necessary to reset the main valve
pushrod to give the correct valve lift.
To do this it is necessary to expose
the main diaphragm plate and pushrod
assembly.
51. Undo the long nuts and pull away.
52. Undo the M12 nuts and bolts.
53. Drop away the lower diaphragm chamber,
the two diaphragms, diaphragm plate
and the pushrod assembly.
52
53
51
50
48
49
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