IOM-DA8
8
wards, place into a vise, grasping the seat
disc nut (30); tighten the vise lightly, only
enough to "hold" the plug (20) from ro tat ing
out of the vise.
Caution:
Over-tight en ing
the vise can distort the seat disc nut (30)
and give bad final torque values.
b. Place a torque wrench on the 3/4" hex
upper end of the plug (20); tighten the
seat disc nut (30) to 40-60 ft-lbs by ro tat-
ing CW.
6. Installation of dynamic side seal (27) (See
Figure 1):
NOTE:
Dynamic side seal (27) for
sizes 2-1/2"-4" is located on the pis ton/guide
bear ing (13). The dynamic side seal can be
in stalled on a work bench without need of a
vise.
a. Type
CP:
1. Stretch o-ring energizer/seal (27.2)
over low er cir cum fer ence of piston-
guide bear ing (13) or valve plug
(20), tak ing care not to “cut” o-ring
energizer/seal (27.4). Using thumbs,
work the o-ring energizer/seal (27.4)
up and into the groove of the piston-
guide bear ing (13) or valve plug
(20).
NOTE:
A very slight amount
of fluid and elas tomer compatible o-
ring lubricant is rec om mend ed as an
installation aid.
2. For metal diaphragm construction,
insert cam ber adjusting washer (17.2)
into cage (19) and allow to rest in the
bottom of the cage (19).
3. Position TFE cap seal (27.1) ring with
rectangular cross-section at end of
pis ton-guide bearing (13) or valve
plug (20). Stretch cap seal (27.1) over
lower end of piston-guide bear ing
(13) or valve plug (20) using thumbs
to work the cap seal (27.1) onto the
piston-guide bearing (13) or valve plug
(20). DO NOT USE A TOOL FOR THIS
STEP. Continue pressing cap seal
(27.1) up wards towards the groove
until the cap seal (27.1) “snaps” into
the groove of the piston-guide bearing
(13) or valve plug (20).
4. Position piston-guide bearing (13) or
valve plug (20) over and into upper end
of cage (19) until the cap seal (27.1)
edge touches the upper lip of the cage
(19). While gently applying force to
press the piston-guide bushing (13)
or valve plug (20) into the cage (19),
simultaneously use fingers to lightly
press the cap seal (27.1) inwards into
the groove of the pis ton-guide bearing
(13) or valve plug (20) until the cap
seal (27.1) “slips into” the cage (19).
DO NOT USE TOOLS, LUBRICANT,
OR HEAVY FORCE TO EN GAGE
THE CAP SEAL (27.1) INTO THE
CAGE (19).
b. Type
PR:
1.
NOTE:
A piston ring assembly (27.5)
consists of one metal corrugated
energizer and two piston ring seals.
Wrap corrugated metal piston ring
energizer into the groove of piston-
guide bearing (13) or valve plug (20).
2. Spread a piston ring seal and slide
over lower circumference of piston-
guide bearing (13) or valve plug (20).
Using thumbs and fingers, work the
piston ring seal into the groove of the
piston-guide bearing (13) or valve
plug (20). Repeat this procedure with
a second piston ring seal. Orient the
Z-cuts in the piston ring seals 180
degrees apart to minimize leakage
by the piston ring assembly.
3. Position piston-guide bearing (13) or
valve plug (20) over and into upper
end of cage (19) until the lower piston
ring seal touches the upper lip of the
cage (19). While gently applying force
to press the piston-guide bearing (13)
or valve plug (20) into the cage (19),
simultaneously use fingers to lightly
circumferentially press the piston
ring assembly (27.5) inwards into the
piston-guide bearing (13) or valve
plug (20) groove until the piston ring
assembly (27.5) “slips into” the cage
(19).
c. Type
UC:
1. Stretch u-cup seal (27.3) over upper
cir cum fer ence of valve plug (20), tak-
ing care not to “cut” u-cup seal (27.3)
on the protruding shelf that is part of
the valve plug's (20) groove. Ensure
that the u-cup seal (27.3) is oriented
with the cen ter-open-up wards as
shown in Fig ure 1, as the u-cup seal
(27.3) depends upon the P1-Inlet
Pres sure to pres sure ac ti vate the seal
for prop er seal ing ac tion.
