Cashco DA8 Differential - Manual (Page 9)

IOM-DA8/9 9
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.
d. Type NO:
1. For “standard” fl ow direction ap pli ca -
tions, it is not ab so lute ly required that
a dynamic side seal (27) be installed.
(When included with the dy nam ic seal
(27), better guid ing of valve plug (20)
results.) Type “NO” dynamic seal (27)
means NO dynamic seal.
2. The more common “Reverse” fl ow
direction always requires a dynamic
side seal (27).
7. Place fl uid compatible thread anti-seize,
Locktite Corp., "Nickel Anti-Seize", or equal
on thread ed por tion of di a phragm cap screw
(7), sizes 1-1/4" and 1-1/2"; or, thread ed post
por tion of valve plug (20), sizes 1/2" – 1"
and 2-1/2" – 4". ( NOTE: Valves cleaned for
ox y gen ser vice should use Fisher Scientifi c
Co., "Fluorolube GR-362", or equal.)
8. Body sizes 2-1/2" thru 4".
a. Place o-ring lower stem seal (14.3) over
upper-end of plug (20) and into groove
in plug (20).
b. Place properly oriented piston/guide bear-
ing (13) over up per-end of plug (20) and
into po si tion on plug (20).
c. Place o-ring middle seal (14.2) over up-
per-end of plug (20) and into groove of
piston/guide bear ing (13).
9. Body sizes 1/2" thru 2".
Place new o-ring mid dle stem seal (14.2) into
groove of valve plug (20) upper surface.
10. Position lower diaphragm pusher plate (10)
on/over upper end of valve plug (20) properly
oriented. For composition diaphragm con struc -
tion the “tongue and groove” “ridge” should
be on upper side, “fl at” side down wards. For
metal diaphragm construction the “rounded”
surface of the lower diaphragm push er plate
(10) should be on upper side, “fl at” side down-
wards.
11. For composition diaphragm construction, place
new o-ring upper stem seal (14.1) on/over
upper end of valve plug (20) and into groove
of lower diaphragm pusher plate (10).
12. For metal diaphragm construction, place
com pat i ble gasket sealant on both sides and
place new lower pusher plate gasket (14.4)
on/over upper end of valve plug (20) and onto
lower diaphragm pusher plate (10). (Gasket
sealant is Federal Process Corp. “Gasoila” ,
or equal.)
13. Position new diaphragm(s) (9) on/over upper
end of valve plug (20). NOTE: For multiple
diaphragms (9) that include TFE material, the
TFE should be on the wetted side; for 6-ply
elastomeric TFE diaphragm (9), stackup is
TFE-TFE-HK-HK-TFE-TFE, be gin ning with
the low er wetted diaphragm (9) fi rst.
14. Position upper diaphragm pressure plate (8)
on/over upper end of valve plug (20) prop-
erly oriented. For composition di a phragm
con struc tion the "tongue and groove" "ridge"
should be on lower side, "fl at" side upwards.
For metal diaphragm construction the "round-
ed" surface of the upper diaphragm pressure
plate (8) should be on lower side, "fl at" side
upwards.
15. a. Body sizes 1/2" thru 1": Engage di a -
phragm lock nut (7) to thread ed post
por tion of valve plug (20) and torque
to 60-70 ft-lbs. by rotating CW.
b. Body Sizes 1-1/4" and 1-1/2": In sert
anti-seize coat ed di a phragm cap
screw (7) through stacked parts (8,
9, 10, 14.1, 14.4) and into upper end
of valve plug (20). Torque-tight en
diaphragm cap screw (7) to 120-130
ft-lbs.
c. Body Sizes 2-1/2" thru 4": En gage di-
a phragm lock nut (7) to threaded post
of valve plug (20) and wrench-tight en
fi rmly. While restraining valve plug
(20) from rotating by torque wrench
on upper end 3/4" hex, use another
wrench to tighten di a phragm locknut
(7) to a torque of 180 - 200 ft-lbs.
16. This completes assembly of ITA; remove from
vise.
F. Main Reassembly:
1. Place body (23) in a vise.
2. Fit the o-ring cage seal (15) into its body (23)
groove.
3. For metal diaphragm construction, place