Emerson Fisher OS2 Instruction Manual page 11

MECHANISM BOX
SLIDING CLEVIS
(KEY 16F)
SCREW (KEY 39) AND
FLAT WASHER (KEY 40)
W8128A
The cover is held on by one screw which can be unscrewed
manually or by using a socket (maximum recommended
torque is 1.8 ft-lbs / 2.4 N•m).
1. Open the mechanism cover and replace the cover screw
O-ring (key 16J) by removing the circlip.
2. Trip the mechanism by carefully turning the tripping
plate (Pins D1 and D2) clockwise (refer to Figures 5
and 6).
3. Remove the clip (refer to Figure 8). Turn and detach the
clevis (key 16F) from the stem by pulling the pin from
the sliding clevis.
4. Remove the two cap screws (key 39) holding the
mechanism box (key 16) to the bonnet (key 15) and
remove the mechanism box.
5. Remove the nuts (key 23, for NPS 4 and 6 / DN 100
and 150 only) or cap screws (key 21) holding the bonnet
(key 15) to the body (key 1).
6. The bonnet (key 15), valve plug (key 5H) (with equalizer
bypass, key 5A in NPS 1 through 6 / DN 25 through
150 body sizes), main spring (key 12) and small stem
bushing (key 24) will lift out of the body as a unit. Set the
unit on a hard flat surface with the valve plug (key 5H)
at the bottom and press down on the bonnet (key 15) to
compress the main spring (key 12), allowing the stem to
be unhooked from the coupling head.
7. Use a spanner wrench (a wrench is supplied with one
of the replacement parts kits) to unscrew the equalizer
bypass (key 5A) from the valve plug (key 5H). The
NPS 1 / DN 25 body size equalizer bypass (key 5A)
holds the plug O-ring (key 5J) to the valve plug (key 5H).
On the NPS 2 and 3 / DN 50 and 80 body sizes, the
equalizer bypass (key 5A) holds the plug disk (key 5N)
and the plug O-ring (key 5J) to the valve plug (key 5H).
The NPS 4 and 6 / DN 100 and 150 body sizes valve
plug disk and valve plug are held together by six cap
(KEY 16A)
CLIP
STEM
(KEY 24)
Figure 8. Type OS2 Internal Parts
LOCATION FOR
SWITCH (KEY 27)
RESET PIN WITH WHITE DOT
screws. On these body sizes, remove the cap screws
and valve plug disk to replace the plug O-ring.
The equalizer bypass (key 5A) is a common
part between valve plug sizes from NPS 1
through 6 / DN 25 through 150 body sizes.
The equalizer bypass (key 5A) is not
serviceable and must be replaced as a unit.
8. To remove the equalizer bypass (key 5A) from the
coupling (key 5L) and coupling head (key 5M), drive out
the roll Pin (key 5K) on the coupling.
Disassembly for NPS 8 and 10 / DN 200 and 250
Body Sizes (Refer to Figure 13)
1. Remove the mechanism box (BM) cover (key 96).
2. Remove the travel stop (see Figure 13).
3. Unscrew the nuts (keys 97 and 98).
4. Remove the resetting latch (key 100).
5. Remove the bolt (key 113) and the spacer (key 114).
6. Remove the cam (key 121) and yoke (key 108).
7. Unscrew the two screws (key 117).
8. Retain the square nut (key 53) situated at the extremity
of the stem valve (key 20).
9. Unscrew the cap screws (key 21).
10. Remove the O-ring (key 11).
11. For NPS 8 / DN 200, insert a spacer (key 114) between
the cam (key 121) and square nut (key 53) or a stack
washer (key 99) between the bolt (key 113) and square
nut (key 53).
12. Remove the bonnet (key 15) / valve plug assembly
(key 13).
Type OS2
TRIPPING PLATE
(KEY 16B)
MANOMETRIC SENSING
DEVICE (TYPE BMS1, KEY 17)
MANOMETRIC DEVICE
THREADED STEM
SECOND STAGE RELEASING SHAFT (KEY 16D)
TRAVEL STOP
RESETTING TOOL
(KEY 3)
CAP SCREW
(KEY 21)
BONNET (KEY 15)
Note
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