Manual

4
IOM-5200
SECTION VI
VI. PILOT MAINTENANCE:
A. General:
1. Maintenance procedures herein after are
based upon removal of the pilot/vent valve
unit from the vessel/piping where installed.
2. Owner should refer to owner’s procedures for
re mov al, handling and cleaning of non re us-
able parts; i.e. gaskets, suitable solvents,
etc.
3. All indicated Item Numbers that are with
respect to the Pilot Assembly will be in
pa ren the sis and un der scored; i.e. (205). All
Item Numbers that are with respect to the
Vent Valve are not un der scored; i.e. (6).
B. Separation from Main Valve and Disassembly:
1. Disconnect sense tube (57) from  ttings
(48) and (244). Remove the pilot valve as-
sembly from the nipple (53) by rotating the
pilot body (201) CCW.
2. Secure body (201) in vise with ‘sensing”
port facing front. Disconnect tubing (243)
from connectors (232),(234).
3. Paint or embed a match mark between
upper case (202), spacer (245) and lower
case (203) along  anged area. NOTE lo-
cation of 1/8” NPT tap from elbow (234) in
relation to body sensing port and straight
connector (232).
4. Rotate the closing cap (205) CCW for
removal. Loosen the adjusting screw nut
(214) two revolutions. Rotate Adjusting
screw (213) CCW and remove.
5. Remove diaphragm case nuts (209),
lockwashers (210),  at washers (221) and
cap screws (220). Grasp spring bonnet
(204) and lift up until diaphragm case (202)
clears top of spring button (212).
6. Secure spring bonnet (204) in a vice with
the upper diaphragm case (202) orientated
upwards.
7. Use 5/32” allen wrench to remove cap
screws (237) and lock washers (239) to
separate the bonnet (204) from the upper
case (202). Replace bonnet gasket (222)
and reassemble item numbers (202, 204,
237 and 239). Remove bonnet from vice
and set assembly aside.
8. Lift range spring (215) and spring button
(212), up and set aside.
9. Grasp the  at surfaces of wrench washers
(228) with a wrench and rotate piston stud
nut (235) CCW to remove nut, lock washer
(241), spring guide (211), washers (228).
10. Remove pressure ring (250), upper
pressure plate (246), upper diaphragm
(207) and spacer (245).
11. Remove upper diaphragm washer (219),
upper diaphragm gasket (226), and
diaphragm spacer (247).
12. Remove lower pressure plate (206), lower
diaphragm (207), lower diaphragm washer
(219) and lower diaphragm gasket (226).
13. Rotate 7/16” hex head cap screws (238)
CCW and remove lock washers (240).
Lift up on lower diaphragm case (203) to
remove. NOTE the alignment of the four
bolt holes and the sense hole in case (203)
with the holes in the body (201).
14. Grasp the cylinder (227) / piston (208)
assembly and lift upwards to extract this
assembly from the body (201). Remove
upper and lower body gaskets (225).
15. From top of assembly, press piston stud
(230) / piston (208) downward through
the center of the cylinder (227) to remove.
Apply Dow Corning 111 lubricant in o-ring
grooves and install new piston O-rings
(224).
WARNING
SPRING UNDER COMPRESSION. Prior to re mov ing
 ange bolts, relieve spring com pres sion by backing
out the adjusting screw. Failure to do so may result
in  ying parts that could cause personal injury.
For Intermediate & High Pressure Pilots Only:
Remove diaphragm case gasket (255)
and pressure ring (251).