4
IOM-8311HP/LP
Model
Diaphragm
Material
Torque
Bolt Size
8311HP
ALL
45 ft-lbs (61 N-M)
5/8" Ø
8311LP
ALL
45 ft-lbs (61 N-M)
1/2" Ø
8. Examine the lower guide bushing (4) for wear;
determine if debris has gathered in lower guide
bushing (4) zone. Clean, if necessary. If unable
to clean then remove per Step 16. below.
9. Remove upper body gasket (6) and clean sealing
sur face thoroughly.
10. Install plug and stem assembly (12) into body (1)
and place new body gasket (6) onto body (1).
11. Align match mark and replace bonnet (2) on
body (1) and reinstall bonnet
fl
ange stud nuts (8).
Me chan i cal ly tighten nuts (8) in al ter nat ing cross-
ing pattern that allows bonnet (2) to be pulled up
evenly. Rec om mend ed torques are as fol lows:
12. Fully thread stem lock nut (19) and pusher plate (17)
on end of plug and stem assembly (12). Refer to
Figure 1 for correct orientation of the pusher plate
(17).
13. Calibrate diaphragm (20) setting and correct plug
and stem assembly (12) travel as follows:
a) Hand press plug and stem assembly (12) tight
into the seats (10 and 11).
b) Adjust the pusher plate (17) so that the gasket
surface face of the pusher plate (17) is
fl
ush with
the top of the diaphragm case (14)
fl
ange.
c) Draw the stem lock nut (19) up tight against
the pusher plate (17) by holding “
fl
ats” milled
on push er plate (17).
14. Grasp threaded end of plug and stem assembly
(12) by hand and ensure that the assembly moves
freely by lifting the plug and stem as sem bly (12)
in and out of the seats (10 and 11), making sure it
does not “stick”. If it does not move freely, rotate
plug and stem assembly (12) CW until new posi-
tion is found which allows optimum “free vertical
move ment” in and out of seats.
15. Proceed with diaphragm (20) assembly in struc tions
in accordance with Section IV.B., steps 10 through
18.
NOTE:
Do not rotate plug and stem assembly
(12) from optimum “free vertical move ment” po si tion
during
fi
nal as sem bly.
16. If necessary, remove bottom
fl
ange (3) bolting
(7)(8). Clean cavity. Examine lower guide bushing
for wear. Replace bottom bonnet if lower guide
bushing is worn or dam aged.
17. Replace bottom
fl
ange (3) on body (1) and re-
install bolting(7)(8). Mechanically tighten nuts (8)
in alternating crossing pattern that allows bottom
fl
ange (3) to be brought up evenly. Refer to Step
11. for recommended torques.
Regulator Size
Torque
Bolt Size
1-1/2" - 2"
50 ft/lbs (68 N-M)
1/2" Ø
3" - 4"
50 ft/lbs (68 N-M)
5/8"Ø
NOTE:
Never replace bolting (29) (30) with just
any bolting, if lost. Bolt heads and nuts are marked
with speci
fi
cation iden ti
fi
ca tion mark ings. Use only
proper grades as re place ments.
17. Reinstall adjusting screw (or T-bar) (32) with lock
nut (or lever) (33). Rotate number of revolutions
recorded in Step 2. above.
18. Pressurize inlet portion of valve. Soap solution test
around bolting (29)(30), di a phragm case (14), and
spring chamber (13)
fl
ang es for leakage. Ensure
that an inlet pres sure is maintained during this leak
test of at least mid-range spring level; i.e. 10-40
psig (.69-2.76 Barg) range spring, 25 psig (1.72
Barg) test pressure minimum.
C. Trim
Inspection:
1. To inspect the internal trim parts, refer to Section
VI.A. and B.1 through 9 for diaphragm re place ment
and proceed as follows.
2. Secure the “
fl
ats” on the threaded end of the plug
and stem assembly (12) with adjustable wrench
and remove pusher plate (17), stem lock nut (19)
by rotating CCW (viewed from above).
NOTE:
Do
not rotate the plug and stem assembly (12).
3. Draw or embed a match mark between body (1)
and bonnet (2).
4. Loosen and remove bonnet
fl
ange stud nuts (8)
CCW (viewed from top) and remove bonnet (2).
In spect the upper guide bush ing (4) for ex ces sive
wear. Replace, if worn.
NOTE:
DO NOT RE MOVE
BOTTOM FLANGE (3). The bot tom
fl
ange (3) acts
as a guide to align the plug and stem assembly
(12) into the seat rings (10 and 11).
5. Firmly grasp end of plug and stem assembly (12)
by hand and pull out of the body (1) cavity.
6. Inspect the seating surfaces of the plug (12.1) for
nicks or excessive wear.
7. Using a
fl
ashlight or other light source, ex am ine
the interior of body (1) cavity. Also, inspect the
seating surfaces of both the upper and lower seat
rings (10 and 11) for ex ces sive wear. If either the
plug (12.1) or the seat rings (10 and 11) are worn
and in need of re place ment, con tact the fac to ry
for au tho ri za tion to return unit for re pair.
NOTE
:
Over haul and replacement of trim parts is not easily
ac com plished by non-factory trained per son nel.
(29) and nuts (30) by hand tightening. Me chan i-
cal ly tighten bolting (29) (30) in a cross ing pat tern
that allows spring cham ber (13) to be pulled down
evenly. Rec om mend ed torques are as fol lows:
