Cashco DA4 - Manual (Page 10)

IOM-DA4 10
5. With the ITA held manually in the closed po si-
tion, insert ITA into body (23).
6. Properly align all three cage bolt (18) holes
as there is only one circumferential location
pos si ble for this align ment. If a lower piston
spring (22) is used, apply downward force to
the top of the cage (19) until the ITA is lowered
suf fi cient ly to engage the cage bolts (18) into
the body (23). Engage all of the cage bolts
(18), then evenly screw in the cage bolts in
one-half revolution increments to pull down
the ITA evenly, taking care NOT TO “AN GLE”
the ITA in the BODY. Torque the cage bolts
(18) to 13-15 ft-lbs (17.6-20.3 N-m).
7. Composition Diaphragm Designs:
a. For the following steps b.– h., the upper
end of valve plug (20) MUST be manually
held up if unit is not supplied with lower
piston spring (22).
b. Remove temporarily installed diaphragm
lock nut (7) and spacers of previous Step
E.5.c. this section.
c. Place new o-ring middle stem seal (14.2)
into groove of piston-guide bearing (13)
upper surface.
d. Position lower diaphragm pusher plate
(10) over upper end of plug (20) with
tongue and groove “groove” on up per
side.
e. Place new o-ring upper stem seal (14.1)
over upper end of valve plug (20).
f. Place diaphragm(s) (9) over end of valve
plug (20). NOTE: For multiple di a phragms
(9) that include TFE material, the TFE
should be on wetted side; for 3-ply TFE
elastomer diaphragm (9), stackup is TFE-
HK-TFE, beginning with lower wetted
diaphragm (9) fi rst.
g. Place upper diaphragm pressure plate (8)
over upper end of plug (20) with tongue
and groove “ridge” on lower side.
h. Place lubricant on valve plug (20) thread ed
end. Engage diaphragm lock nut (7) with
upper end of valve stem (20) as far as
possible manually.
i. Place a wrench on diaphragm lock nut (7)
and a torque wrench on the upper end
of valve plug (20). Hold torque wrench
sta tion ary and rotate diaphragm lock nut
(7) to the following torque values:
DO NOT allow valve plug (20) to rotate
against seat ring (21) during tightening.
j. This completes ITA reassembly.
8. Metal Diaphragm Designs:
a. Install new diaphragm gasket (37) onto
body (23) diaphragm fl ange.
b. Position diaphragm(s) (9) onto body's (23)
diaphragm fl ange with bolt holes aligned.
c. Position upper diaphragm pressure plate
(8) onto center top of diaphragm(s) (9)
with rounded side of plate (8) on bottom
next to diaphragm (9).
9. Aligning matchmarks and bolt holes, place
cover dome (25) onto body (23).
10. Reinstall all fl ange bolts (11) and nuts (12)
with nameplate (99) located under one bolt
head. Hand-tighten nuts (12).
NOTE: If a 3-ply diaphragm is being used,
it is important that the diaphragm (9) is “pre-
formed” – pulled together to remove as much
entrapped air as possible and allow formation
of a diaphragm (9) convolution. Starting with
the body bolts and nuts (11,12) hand tight ened,
“preforming” can be accomplished by any one
of the following techniques:
a. Apply 30 psig (2.1 Barg) pressure to the
valve outlet. OR
Block the valve outlet and apply 30 psig
(2.1 Barg) under the di a phragm through
the 1/4" (DN8) NPT (plugged) external
pres sure sens ing connection on the
valve di a phragm fl ange.
b. Leave pressure on through tightening
of bolt ing (11,12).
11. Evenly tighten the body bolting (11,12) in an
alternating cross pattern in one revolution
increments to the following torque values:
If supplied, remove pressure of previous Step 10.
Body Size
in (DN)
Torque Value
Ft-lbs (N-m)
1/2" - 1" (15 - 25) 60 - 70 (81 - 95)
1 1/4" - 2" (32 - 50) 120 - 130 (163 - 176)
2 1/2" - 4" (65 - 100) 180 - 200 (244 - 271)
Body Size
in (Dn)
Torque Value
Ft-lbs (N-m)
1/2" - 2" (15 - 50) 30 - 35 (41 - 47)
2 1/2" - 4" (65 - 100) 45 - 50 (61 - 69)
G. Units with Supported Diaphragm Designs:
1. A supported diaphragm (9) construction is
designated as Opt-81 High Outlet Pressure.
Both upwards and downwards directions
are protected against pressure reversal; i.e.
pres sure on one side of diaphragm (9) with
no pressure on other side of diaphragm (9).
2. Body Sizes 2" (DN50) and Smaller; Com po si-
tion Diaphragm. (See Figure 5.)