Elster J125B Training manual

J125B
Service Regulator
Inlet Pressure up to 8.6 bar
Commissioning Instructions
General Arrangements
Parts Lists
Maintenance Instructions
For: J125 MKII Regulator with balanced valve
1 ½”, 2” and 50mm size

2
J
125B: Commissioning Instructions
FITTING REGULATOR INTO PIPEWOR
K
•Ensure that this product is suitable for the chosen application.
•Installation, adjustment and maintenance by authorised, trained personnel only.
•When being fitted to an appliance, refer to the appliance manufacturers
instructions.
1. The unit should not be installed in a corrosive environment.
2. The ambient temperature (surface temperature) should be within the
limits stated on the regulator catalogue.
3. Check the maximum allowable pressure on the regulator nameplate
against the installation specification.
4. Remove the protection plugs from inlet and outlet ports.
5. Ensure that installation pipework is thoroughly clean.
6. The direction of gas flow must be the same as the arrows on the
regulator body. See Fig. 1.
7. Install the regulator into pipework using jointing compound approved
to national standards.
8. In order to fit the regulator into confined spaces it may be necessary
to rotate the diaphragm case. This is achieved by slacking off the two
cap screws, rotating the diaphragm case, and then re-tightening the
cap screws evenly. See Fig. 2.
9. For units with no OPSS fitted it is advised that a slam shut device is
fitted to protect downstream equipment.
INSTALLATION OF VENT LINE.
1. Remove clip and vent screen from regulator top cover.
2. Connect the vent line (2"), using a jointing compound approved to
national standards, and lead to atmosphere in accordance with
national standards. Ensure that no water can penetrate vent pipeline.
See Fig. 3.
3. If the regulator is fitted with an internal relief valve, ensure that the
vent line is of sufficient diameter to carry gas vented by the relief valve
to a safe outside location. Reference to any national standard
INSTALLATION OF IMPULSE LINE
1. Remove the plastic protection plug.
2. Connect the impulse line (½"), using a jointing compound approved
to national standards, and lead to a point downstream not less than
fifteen times the nominal pipe diameter from the outlet. See Fig. 4.
FOR PRE-SET UNITS ONLY.
1. Turn off downstream valves.
2. Slowly turn on inlet supply.
3. If safety shut-off device is not fitted, go to instruction 6.
Warning! Incorrect installation, adjustment, modification, operation and maintenance may
cause injury or damage.
Read the instructions before use. This control must be installed in accordance with the rules in
force.
Fig. 1
Fig. 2
Fig. 3
Fig. 4

3
J125B: Commissioning Instructions
4. If safety shut-off device is fitted unscrew reset spindle end cap and
firmly pull. Hold in this position until the outlet pipework is fully
pressurised, then release reset spindle end cap gently. See Fig. 5.
5. Re-screw reset spindle end cap into body, ensuring not to jam reset
spindle.
6. Commission downstream appliances.
WARNING: DO NOT UNDER ANY CIRCUMSTANCES WEDGE OPEN SAFETY
SHUT-OFF RESET END CAP AS THIS WILL NOT ALLOW THE SAFETY DEVICE(S)
TO FUNCTION IN ADVERSE PRESSURE CONDITIONS.
SETTING THE REGULATOR & SAFETY
SHUT OFF DEVICE PRESSURES.
OPSS = Over Pressure Safety Shut-off.
UPSS = Under Pressure Safety Shut-off.
1. Turn off inlet and outlet valves.
2. Remove top cap from regulator cover.
3. Insert an 11/4" A/F socket over the top of the adjustment screw.
4. Turn anticlockwise (-) to reduce loading on regulator spring to
minimum. See Fig. 6 (If no safety devices are fitted go to instruction 10).
5. Remove top cap from safety shut-off device cover (If UPSS only go to
instruction 8).
6. Insert a flat bladed screwdriver into one of the partial slots on the
OPSS spring holder. See Fig. 7.
7. Turn clockwise (+) to increase loading on OPSS spring to maximum.
8. If UPSS fitted, insert a pozidriv screw driver (No.2 point) into UPSS
adjusting screw in bottom spring holder. See Fig. 8.
9. Turn anticlockwise (-) to reduce loading on UPSS spring, making sure
screw head does not protrude from the bottom spring holder.
10. Slowly open inlet valve(s).
11. If safety device fitted, re-cock by unscrewing reset spindle end cap
and pulling firmly. Hold in this position until the outlet pipework is fully
pressurised, then release reset spindle end cap gently. Re-screw
reset spindle end cap into body. See Fig. 5.
12. Turn regulator adjustment screw clockwise (+) to increase the loading
on the spring until the required outlet pressure, plus approximately
2.5mbar (1"wg) is obtained. (This is an allowance for the regulator
being set with zero flowrate).
If UPSS only go to instruction 20, if no safety device go to instruction 27.
13. Block vent valve opening to prevent relief valve from operating.
14. Apply external pressure source to a suitable point on the outlet
pipework. Increase pressure to that required for OPSS trip-off.
Note: If pressure test point on underside of slam shut unit is used as
external source point, care must be taken to ensure pressures are
equalised across restricted orifice within test point.
15. Slowly turn OPSS spring holder anticlockwise (-) until OPSS device trips
off. See Fig. 7.
16. Reduce external pressure source to level set in instruction 12.
Fig. 5
Fig. 6
Fig. 7

4
J125B: Commissioning Instructions
17. Re-cock OPSS device by unscrewing reset spindle end cap and firmly
pull. Hold in this position until the outlet pipework is fully pressurised,
then release reset spindle end cap gently. Re-screw reset spindle end
cap into body. See Fig. 9.
18. Slowly increase external pressure to check for OPSS trip-off. Trim
adjustment if necessary and repeat instructions 16 - 18.
19. Remove external pressure source.
NOTE: OPSS device is now set.
20. Close inlet valves.
21. Reduce inlet pressure to approximately 140mbar (2 PSI).
22. Reduce outlet pressure by introducing a slow controlled bleed until
the required UPSS trip-off pressure is obtained and close bleed.
23. Slowly turn UPSS adjusting screw clockwise (+) until UPSS device trips
off. See Fig. 8.
24. Slowly open inlet valve to regain inlet pressure up to approximately
140mbar (2 PSI), then close inlet valve.
25. Re-cock UPSS device by unscrewing reset spindle end cap and firmly
pull. Hold in this position until the outlet pipework is fully pressurised,
then release reset spindle end cap gently. Re-screw reset spindle end
cap into body. See Fig. 9.
26. Slowly reduce outlet pressure to check for UPSS trip-off. Trim
adjustment if necessary and repeat instructions 24 – 26.
NOTE: UPSS device is now set.
27. Commission installations.
28. Trim the regulator outlet pressure if necessary once normal flow rates
have been achieved.
29. Unblock vent opening.
30. Replace all top caps (seal if necessary).
WARNING: DO NOT UNDER ANY CIRCUMSTANCES WEDGE OPEN SAFETY
SHUT-OFF RESET END CAP AS THIS WILL NOT ALLOW THE SAFETY DEVICE(S)
TO FUNCTION IN ADVERSE PRESSURE CONDITIONS.
Fig. 8
Fig. 9

5
J125B: Commissioning Instructions
IF THE REQUIRED REGULATOR OUTLET PRESSURE CANNOT BE
ACHIEVED WITH THE SPRING FITTED
31. Remove top cap from regulator cover.
32. Choose a loading spring from catalogue or page 17 that will give the
required outlet pressure range.
33. Fully unscrew and remove the adjustment screw, See Fig. 11.
34. Remove spring and replace with new one. See Fig. 10.
35. Screw adjustment screw back in place.
36. Adjust the outlet pressure as described previously.
37. Replace the top cap (seal if necessary).
NOTE: Outlet pressure is now set
IF THE REQUIRED TRIP-OFF PRESSURES CANNOT BE ACHIEVED WITH
THE SPRINGS FITTED
A) OPSS spring
38. Remove top cap from the safety shut-off device cover.
39. Choose an OPSS spring from the catalogue or page 17 that will give
the required pressure range.
40. Fully unscrew and remove top spring holder. See Fig. 12.
41. Remove spring and replace with new one. See Fig. 10.
42. Screw spring holder back in place, ensuring that castellated spigot is
uppermost in chimney. See Fig. 12.
43. Adjust the trip-off pressure as described previously.
44. Replace the top cap (seal if necessary).
NOTE: OPSS pressure is now set
B) UPSS spring.
45. Remove top cap from the safety shut-off device cover.
46. Choose an UPSS spring from the catalogue or page 17 that will give
the required pressure range.
47. Fully unscrew and remove top spring holder. See Fig. 12.
48. Remove OPSS spring (or spacer tube if UPSS only).
Fig. 10
Fig. 11
Fig. 12

6
49. Remove bottom spring holder and UPSS top spring holder.
50. Remove UPSS spring and replace with new one. See Fig. 13.
51. Replace UPSS spring holder, ensuring that spigot locates in UPSS
spring.
52. Replace bottom spring holder locating three webs into slots in bottom
of cover, ensuring not to disturb UPSS spring and UPSS spring holder.
53. Replace OPSS spring (or spacer tube if UPSS only).
54. Screw top spring holder back in place, ensuring that castellated
spigot is uppermost in chimney. See Fig. 11. (If UPSS only ensure that
spacer tube is firmly clamped)
55. Adjust the trip-off pressure as described previously
56. Replace the top cap (seal if necessary).
NOTE: UPSS pressure is now set.
Fig. 13
J125B: Commissioning Instructions

7
J125B: General Arrangement
S1, S2, S3 Assembly – Fig 14
S1 VERSION
(NO RELIEF VALVE)
S3 VERSION
(LIMITED RELIEF VALVE)
DIAPHRAGM CASE
ASSEMBLY
SEE FIG. 17
S2 VERSION
(FULL CAPACITY RELIEF VALVE)
41 38
39
40
42
44 46
16
94
43

8
J125B: General Arrangement
S4, S5, S10 Assembly- Fig 15
DIAPHRAGM CASE
ASSEMBLY
SEE FIG. 17
S4 VERSION
(FULL CAPACITY RELIEF VALVE)
41 38
39
40
44 46
16
94
S10 VERSION
(NO RELIEF VALVE)
S5 VERSION
(LIMITED RELIEF VALVE)
OPSS
SAFETY
SHUT OFF
ASSEMBLY
SEE FIG. 18

9
J125B: General Arrangement
S6, S7, S8, S9, S11, S12 Assembly- Fig 16
DIAPHRAGM CASE
ASSEMBLY
SEE FIG. 17
S8 VERSION
(FULL CAPACITY RELIEF VALVE)
41 38
39
40
44 46
16
94
S11 & S12 VERSION
(NO RELIEF VALVE)
S7 & S9 VERSION
(LIMITED RELIEF VALVE)
OPSS/UPSS
SAFETY
SHUT OFF
ASSEMBLY
SEE FIG. 19
S6, S7 & S11 VERSIONS
UPSS ONLY
SEE FIG. 20

10
J125B: General Arrangement
Diaphragm Case Assembly – Fig 17
S1, S10, S11 & S12
VERSIONS
(NO RELIEF VALVE)
S3, S5, S7 & S9
VERSIONS
(LIMITED RELIEF VALVE)
33
34
35
36
11
95
35
36
37
S2, S4, S6 & S8
VERSIONS
(FULL RELIEF VALVE)
13
97
10
96
15
12
14
45
7
8
9
95
6 5 4 3 2 1 32 31 30 29 28 27
26
25
24
23
22
21
20
19
18
16
17

11
J125B: General Arrangement
OPSS Safety Shut Off Assembly – Fig 18
83
82
81
80
79
65
50
87
86
85
78
84
47
61
62
63
64
65
66
67
68
69
71
77 72 76 75 74 65 73 72 70
88 49 89
90
91
TOP COVER TO BODY
FIXING
OPSS BODY TO
ADAPTOR PLATE
FIXING
ENLARGED VIEW OF
VALVE DISC
52 53 54 55 57 58 92 60
48

12
J125B: General Arrangement
OPSS/UPSS Safety Shut Off Assembly – Fig 19
83
82
81
80
79
65
50
87
86
85
78
84
47
61
62
63
64
65
66
67
68
69
71
77 72 76 75 74 65 73 72 70
88 49 89
90
91
TOP COVER TO BODY
FIXING
OPSS BODY TO
ADAPTOR PLATE
FIXING
ENLARGED VIEW OF
VALVE DISC
51 52 53 54 55 56 57 58 59 60
48

13
J125B: General Arrangement
UPSS Safety Shut Off Assembly – Fig 20
83
82
81
80
79
65
50
87
86
85
78
84
47
61
62
63
64
65
66
67
68
69
71
77 72 76 75 74 65 73 72 70
88 49 89
90
91
TOP COVER TO BODY
FIXING
OPSS BODY TO
ADAPTOR PLATE
FIXING
ENLARGED VIEW OF
VALVE DISC
48
51 52 53 54 55 56 93 58 59 60

14
ITEM DESCRIPTION PART NUMBER No. Off
1 TOP CAP I70103P001 1
2 "O" RING (TOP CAP) JOBS133 Ï1
3 ADJUSTMENT SCREW I73183P001 1
4 ROD STOP I73056P001 1
5 FLANGE STOP ROD I73174P001 1
6 SPRING ADJUSTING NUT (Full Relief) I71533P001 1
7 LOADING SPRING SEE TABLE 1
8 RELIEF VALVE SPRING J12509-099 1
9 RELIEF VALVE STEM I73058P001 1
10 "O" RING (BVO PISTON) JORM0295-30 Ï1
11 FLAT WASHER (No Relief) I13981P076 1
12 BVO SENSING SCREW J12509-118 1
13 BVO PISTON J12509-117 Ï1
14 BVO PISTON HOLDER J12509-119 1
15 BVO VALVE SEAT DISC J12509-121 Ï1
16 SOCKET GRUB SCREW JSA1012S0NSS 3
17 REGULATOR DIAPHRAGM CASE J12509-123 (+ if tapped) 1
18 PLUG (C/Sunk Recess ½" BSP Galvanised) JMFP2G04 (if fitted) 1
PLUG (C/Sunk Recess ½" NPT Galvanised) I11970P031 (if fitted) 1
19 LEVER ASSEMBLY I72626G001 1
20 DIAPHRAGM STEM I72629P005 1
21 HEXAGON NUT JNA8FZD 12
22 SCREW HEX HEAD JSA825HHNZG 12
23 DIAPHRAGM (Full Relief) J12509-116 Ï1
24 DIAPHRAGM PLATE (Full Relief) I73057P002 Ï1
25 VENT VALVE SEAT J12509-028 1
26 VENT VALVE DISC J12509-029 1
27 VENT SCREEN SPRING CLIP J12509-038 1
28 VENT SCREEN J12509-037 1
29 VENT VALVE SPRING J12509-060 1
30 TOP COVER J12509-079 + 1
31 VENT VALVE GUIDE PIN J12509-042 1
32 NAMEPLATE J8112-124 1
33 HEX CAP SCREW JSNEIHHNZR 1
J
125B: Parts List

15
ITEM DESCRIPTION PART NUMBER No. Off
34 SPRING GUIDE I72272P001 1
35 DIAPHRAGM PLATE (No / Limited Relief) I70012P052 Ï1
36 DIAPHRAGM (No / Limited Relief) J12509-115 Ï1
37 RELIEF VALVE CUP I73054P002 1
38 SCREWED BODY 1½" J12508-080 + 1
SCREWED BODY 2" J12509-080 + 1
FLANGED BODY 50mm J12509-081 + 1
39 VALVE SEAT (31.8mm) J12509-108 1
40 IMPULSE TUBE SCREWED J12509-112 1
IMPULSE TUBE FLANGED J12509-111 1
41 "O" RING JORM0195-30 Ï1
42 BLANKING PLATE J12509-083 1
43 SCREW (Blanking Plate) JSA616SANSS 4
44 "O" RING JORM0495-30 Ï1
45 "O" RING JOBS111 Ï1
46 "O" RING JOBS338 Ï1
47 ADAPTOR PLATE (USSA) J12509-082Z02 1
48 SCREW (Adaptor Plate/Regulator Body) JSA620SANSS 4
49 SCREW (OPSS Body/Adaptor Plate) JSA516SANSS 4
50 SCREW (Shut-off Diaphragm) JSA412XPTZ 1
51 UPSS SPRING SEE TABLE 1
52 SAFETY SHUT OFF SPRING HOLDER J12506-248 1
53 "O" RING (Safety Shut Off Top Cap) JORM0251-16D Ï1
54 BOTTOM SPRING HOLDER J12506-250 1
55 SAFETY SHUT OFF TOP CAP J12506-142 1
56 SCREW (UPSS Adjustment) JSA412XPTZ 1
57 OPSS SPRING SEE TABLE 1
58 SAFETY SHUT-OFF NAMEPLATE J150D-076 1
59 UPSS SPRING HOLDER J12506-249 1
60 SAFETY SHUT-OFF TOP COVER J12506-240 + 1
61 TRIP-OFF LEVER RETAINING PLATE J12506-243 1
62 TRIP-OFF LEVER J12506-242 1
63 "O" RING (Impulse Passage) JOBS011D Ï1
64 VALVE SPRING J12506-049 1
J125B: Parts List
Continued

16
ITEM DESCRIPTION PART NUMBER No. Off
65 CIRCLIP VALVE SPINDLE JCIR1500-015B Ï4
66 VALVE DISC (Moulded) J12509-109M Ï1
67 VALVE SPRING CUP J12506-251 1
68 "O" RING (Safety Shut off /Adaptor Plate) JORM0276-24D Ï1
69 CIRCLIP (Front "O" Ring Washer) JCIR2000K-17B Ï1
70 SAFETY SHUT OFF BODY J12506-239 + 1
71 FRONT "O" RING RETAINING WASHER J12506-252 1
72 "O" RING for Shut-Off Spindle (to end of 2005) JOBS105D Ï2
"O" RING for Shut-Off Spindle (from start 2006) JO4-25 Ï2
73 SAFETY SHUT-OFF VALVE SPINDLE J12509-110 1
74 PRESSURE TEST NIPPLE JPTN01-0.71 1
75 TRIP-OFF BUSH J12506-244 1
76 NEEDLE ROLLER JNR02S 1
77 STARLOCK WASHER JCIR1305-043B 1
78 RESET SPINDLE END CAP J12506-254 1
79 COVER (Spindle End Cap) J12506-255 1
80 INDICATOR CAP (Safety Shut Off) JCLOSEMC4 1
81 WASHER-REAR (circlip protection) J12506-292 1
82 REAR "O" RING RETAINING WASHER J12506-253 Ï1
83 TRIP-OFF LATCH J12506-241 1
84 LOWER DIAPHRAGM PLATE J12506-247 1
85 SAFETY SHUT-OFF DIAPHRAGM J12506-246 Ï1
86 VENT SCREEN J12506-277 1
87 TOP DIAPHRAGM PLATE J12506-245 1
88 SCREW (Top Cover/Body) JSA512XPTS 4
89 "R" CLIP VALVE J12506-274 Ï1
90 "O" RING SEAL JO200606-4475D Ï1
91 GASKET VALVE J12506-267 Ï1
92 NEEDLE ROLLER (OPSS only) JNR02S 1
93 UPSS SPACER TUBE J12506-279 1
94 BONDED SEAL JBSMB45017 Ï1
95 SPRING LOCATOR ASSEMBLY I73175G001 1
96 BVO LOADING SPRING J12509-120 1
97 "O" RING SEAL JOBS230 Ï1
NOTES: Items marked Ïare contained in spares kits (See table below). Part Numbers ending with + require connection information.
J125B: Parts List
Continued

17
J
125B: Spring Tables
REGULATOR SPRINGS
mbar. "w.g. PART NUMBER COLOUR
8.8 - 15 3.5 - 6 J12509-091 RED
14 - 20 5.5 - 8 J12509-092 ORANGE
21 - 35 8.5 - 14 J12509-093 YELLOW
36 - 70 14.5 - 28 J12509-094 GREEN
69 - 138 1 - 2 PSI J12509-095 ROYAL BLUE
104 - 173 1.5 - 2.5 PSI J12509-096 BROWN - ROYAL BLUE
138 - 207 2 - 3 PSI J12509-097 BROWN - GREEN
207 - 350 3 - 5 PSI J12506-098 BLACK - GREEN
OVER PRESSURE SLAM-SHUT SPRINGS
mbar. "w.g. PART NUMBER COLOUR
18 - 60 7.5 - 24 J12506-281 BLACK
50 - 80 20 - 32 J12506-282 ORANGE
60 - 110 24 - 44 J12506-283 RED
100 - 210 40 - 84 J12506-284 DARK GREEN
200 - 350 3 - 5 PSI J12506-287 YELLOW
280 - 500 4 - 7 PSI J12506-288 WHITE
UNDER PRESSURE SLAM-SHUT SPRINGS
mbar. "w.g. PART NUMBER COLOUR
8 - 16 3 - 6 J12506-285 LIGHT BLUE
16 - 60 6 - 24 J12506-286 BROWN
60 - 150 24 - 60 J12506-289 PURPLE
NOTE: A minimum differential of 30mb must be maintained between OPSS and UPSS set pressures
SPARES KITS
REGULATOR TYPE SPARES KIT PART NUMBER
J125B-S1 & S3 SK2529-08
J125B-S2 SK2529-09
J125B-S4, S6 & S8 SK2529-10
J125B-S5, S7, S9, S10, S11 & S12 SK2529-11

18
J125B: Maintenance Instructions
Regulator Body
Drawing Reference: Figs. 14, 15 & 16
NOTE: Numbers in brackets identify items on drawings
Regulator Dismantling Procedure.
1. Check external surfaces for excessive corrosion.
2. Disconnect diaphragm case assembly from regulator body (38) by removing the three grub screws (16),
gently pull out the case from the regulator body (38).
3. Disconnect the safety shut-off unit assembly, or blanking plate (42), from the regulator body (38) by removing
the four cap screws (43) or (48).
4. Remove valve seat (39) assembly from the regulator body (38).
5. Remove bonded seal (94) or gasket (45) from valve seat (39) assembly. Note: the old design valve seat
assembly with gasket (45) was glued into body (38).
6. Wipe clean the valve seat (39) assembly, check for any damage and take note of whether bonded seal (94)
or aluminium gasket (45) is fitted to the valve seat.
7. Check that the impulse tube (40) is clear. DO NOT REMOVE TUBE FROM BODY.
Regulator Rebuilding Procedure.
NOTE: Inspect all sealing "O" rings, and replace where necessary
(a soft spares kit is available for this purpose, see page 17).
The use of Molykote 111 "O" ring lubricant is recommended during the rebuild- unless for use with oxygen
when no lubricant should be used.
1. If, when the valve seat (39) assembly was dismantled, the bonded seal (94) was fitted, then replace with a
new bonded seal (94). DO NOT USE ALUMINIUM GASKET (45).
2. If, when the valve seat (39) assembly was dismantled, the aluminium gasket (45) was fitted, then replace
with new aluminium gasket (45). DO NOT USE WITH BONDED SEAL (94). Note: The bonded seal (94) and
aluminium gasket (94) CANNOT be interchanged with each other, due to valve seat (39) being a different
length and this may affect unit performance and safety.
3. Refit valve seat (39) assembly into regulator body (38) by screwing it in until metal contact is made.
4. Fit new "O" ring (46) onto diaphragm case assembly and apply "O" ring lubricant.
5. Insert diaphragm case assembly into regulator body (38) being careful not to damage the "O" ring, secure in
place with three grub screws (16).
6. Replace "O" rings (41) and (44) into regulator (38) making sure the contact surfaces are clean and the "O"
rings are lubricated.
7. Locate and secure the safety shut-off assembly, or blanking plate (42), in place using four cap screws (43) or
(48).
8. Test unit for gas tightness.
9. Commission unit as described on pages 2 - 6.

19
J125B: Maintenance Instructions
Diaphragm Case
Drawing Reference: Figs. 17
NOTE: Numbers in brackets identify items on drawings
Diaphragm Case Dismantling Procedure.
1. Unscrew top cap (1) and remove "O" ring (2).
2. Unscrew and remove adjusting screw (3) and loading spring (7).
3. Remove top cover (30) by unscrewing the 12 nuts (21) and screws (22).
NOTE: It is not recommended to strip down the Vent Valve Assembly items: (25), (26), (29) & (31).
For Relief Versions go to instruction (6).
4. Remove diaphragm assembly (35), from the diaphragm case (17).
5. Unscrew the hexagon cap screw (33) from the diaphragm assembly (35) to allow assembly to be
dismantled.
For No Relief Version go to instruction (9).
6. Prior to dismantling the relief valve assembly, measure the height "h" of the relief valve spring (8). The spring
will have to be compressed to the same dimension on reassembly.
7. Remove diaphragm assembly (Full Relief) (23) or (Limited Relief) (35), and relief assembly from the diaphragm
case (17).
8. Unscrew spring adjusting nut (6) from diaphragm assembly (23) or (35) to allow dismantling.
9. Lift lever assembly (19) to disengage with BVO piston (13).
10. Withdraw BVO valve assembly (10, 12, 13, 14, 15, 45, 96 & 97) from the diaphragm case (17).
11. Take BVO piston (13) and BVO loading spring (96) from BVO piston holder (14) and remove “O” rings (10, 45 &
97).
12. Unscrew BVO sensing screw (12) and check hole for dirt.
13. Remove lever assembly (19) from the diaphragm case (17).
Diaphragm Case Rebuilding Procedure.
NOTE: Inspect all sealing "O" rings, diaphragms and gaskets and replace where necessary (a soft spares kit is
available for this purpose see page 17).
1. Check main diaphragm (23) or (36) for signs of damage, if necessary replace with a new diaphragm
assembly (23) + (24) or (35) + (36).
2. Check that the sealing surfaces on the diaphragm (23) + (36) and diaphragm stem (20) are clean.
For Relief versions go to instruction 7.
3. Push cap screw (33) through centre hole of spring guide (34) with lip facing screw head.
4. Now push cap screw (33) through centre hole of diaphragm assembly (35) + (36), with diaphragm plate lip
facing spring guide (34).
‘h’

20
J125B: Maintenance Instructions
Diaphragm Case, Continued
Diaphragm Case Rebuilding Procedure continued..
5. Replace flat washer (11) over cap screw (33).
6. Screw diaphragm stem (20) onto cap screw (33) securing diaphragm assembly
For No Relief version go to instruction 14.
7. (Limited Relief Version): Replace relief cup (37) with projections facing upwards, over centre hole of the
diaphragm stem (20).
8. Screw relief valve stem (9) into diaphragm stem (20).
9. (Limited Relief Version): Place diaphragm assembly (35 & 36) with diaphragm plate lip facing upwards, on
top of relief cup (37).
10. (Full Relief Version): Place diaphragm assembly (23 & 24) with diaphragm plate lip facing upwards, on top of
relief valve stem (9).
11. Replace spring locator (95) with convolution facing upwards, over relief valve stem (9).
12. Place relief spring (8) over relief valve stem (9).
13. Screw relief spring adjusting nut (6) with spigot located in relief spring (8), onto relief valve stem (9). Screw
relief adjusting nut (6) to the required height "h", as measured during dismantling, see instructions (page 19).
14. Place lever assembly (19) into the slot in the diaphragm case (17).
15. Check valve disc (15) and BVO piston (13) for damage and excessive wear, if necessary replace with a new
assembly.
16. Insert BVO sensing screw into BVO piston and tighten.
17. Fit “O” rings (10 & 45) onto BVO Piston (13) and with BVO loading spring (97) in place, insert into BVO piston
holder (14).
18. Replace “O” ring (97) to outside of BVO piston holder (14).
19. Carefully push BVO piston assembly (10, 12, 13, 14, 15, 45, 96 & 97) through hole in the diaphragm case (17)
and engage grooves into teeth in lever assembly (19).
20. Relocate the main diaphragm / relief valve assembly into position. Make sure of the following:
(a) The lever assembly (19) is fitted correctly into the slot in the diaphragm stem (20).
(b) The holes in the diaphragm (23) or (36) and diaphragm case (17) are aligned correctly.
21. Check that the vent valve in the top cover (30) moves freely.
22. Replace top cover (30) on top of diaphragm case (17) taking care not to damage diaphragm (23) or (36), and
secure in place using 12 screws (22) and nuts (21).
23. Place loading spring (7) into chimney of top cover (30).
24. With slot in adjusting screw (3) facing upwards, screw adjusting screw (3) into the chimney of the top cover
(30), so that it locates on loading spring (7).
25. For Full Relief Version only: Screw rod stop assembly (4) and (5) into top cap (1).
26. Replace "O" ring (12) onto top cap (1).
27. Screw top cap (1) into chimney of top cover (30).
28. Screw 3 grub screws (16) into case (17).
29. Refit screen (28) and clip (27) into vent.
For reassembly to body see page 18.