9
Rebuilding procedure:
The use of Molykote 111 "O" ring lubricant is recommended during the rebuild.
1. Locate secondary diaphragm (22) with convolution uppermost on to the body (2). Ensure screw holes and impulse tube
holes are aligned correctly.
2. Secure secondary diaphragm (22) in position using screws (21).
3. Place diaphragm spacer (6) on secondary diaphragm (22) ensuring diaphragm bead is located correctly in the groove.
4. Place main diaphragm (7) with convolution uppermost, ensuring that the bead is located in the groove in the body (2).
5. Locate the top diaphragm plate (20) ensuring raised edge is uppermost.
6. Insert the valve spindle (19) through the centre hole in top diaphragm plate (20), main diaphragm (7) and diaphragm
spacer (6).
7. Locate valve spacer (5) on to valve spindle (19) through bottom plug opening.
8. Assemble valve disc (4) on to valve disc holder (3) with bead uppermost.
9. Screw valve disc holder (3) complete with valve disc (4) on to threaded end of valve spindle (19) through bottom plug
opening. DO NOT TIGHTEN.
10. Restrain valve disc holder (3) with suitable box spanner and tighten valve spindle (19).
11. Place "O" ring seal (24) into "O" ring seal groove in bottom plug (1), outlet adaptor bush (28) or meter union assembly
(29).
12. Replace the component (1), (28) or (29) complete with "O" ring over centre shaft of valve disc holder (3) into body (2) and
screw tightly in position.
13. Carefully replace top cover (10) on to body (2) with vent facing the outlet and secure with top cover screws (8).
14. Insert loading spring (17) over spring location ridge in top diaphragm plate (20).
NOTE: If adjusting bush assembly (35) has been dismantled follow procedure, if it has been left assembled then proceed to
instruction number 21.
15. Slide "O" ring seal (16) over slotted end of spring adjusting screw (36) into second groove. (i.e. groove nearest thread).
16. Replace washer (34) over slotted end of spring adjusting screw (36) and slide down until it sits on shoulder of adjusting
screw.
17. Slide "O" ring seal (14) into "O" ring groove on adjusting bush (35).
18. Push spring adjusting screw (36) into hole in the bottom of the adjusting bush (35) until parts are firmly together.
19. Position key hole slot in locking lever (13) over slotted end of spring adjusting screw (35) and slide over slopping peg in
adjusting bush (35) until firmly locked in position.
20. Screw top spring holder (33) anti-clockwise to within 10mm of underside of adjusting bush (35).
21. Position underside of top spring holder (33) on to loading spring (17).
22. Align slots in top spring holder (33) with splines in top cover (10) and push adjusting bush (35) assembly into top cover
(10) as far as possible.
23. Turn adjusting bush assembly (35) clockwise until locking lever (13) snaps into any of the three locking castellations in
top cover (10).
24. Set units to required pressure.
25. Replace top cap (12) by aligning slot in cap with sealing wire lug and push over until it clicks into position, and seal if
necessary.
J48Z and P: Maintenance Instructions
For all units after October 1997
