Cashco DA1 - Manual (Page 10)

IOM-DA1 10
values. DO NOT ALLOW PLUG (20) TO
ROTATE AGAINST SEAT RING (21)
DURING TIGHTENING. plug (20). NOTE: For multiple di a phragms
(9) that include TFE material, the TFE
should be on wetted side; for 6-ply TFE
elastomer diaphragm (9), stackup is TFE-
TFE-HK-HK-TFE-TFE, beginning with
lower wetted diaphragm (9) fi rst.
g. Place upper diaphragm pressure plate
(8) over upper end of valve 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 reassambly.
8. Units with V-TFE & CTFE seat ring (21): Due
to the relative "hardness" of the V-TFE & CTFE
ma te ri al, to obtain the best possible shutoff
it is nec es sary to "coin" the V-TFE & CTFE
with a per ma nent in den ta tion.
a. Close-off the outlet connection.
b. The level of seat leakage can be
quantifi ed at the internal sens ing drilled
plug (32) for internal sensing units. For ex-
ternal sensing units, it will be nec es sary to
re move the in ter nal sensing plug (33).
c. Place 50 psig (3.5 Barg) of gas pressure
to the valve's inlet.
d. Using a soft-headed mallet (rubber,
leath er), sharply rap the top end of the
plug (20) for composition di a phragm de-
signs, or the pis ton-guide bear ing (13) for
metal di a phragm designs. (Note: Gas will
escape as the plug (20) opens at the seat
ring (21). Allow suffi cient time for leak-
age pressure on out let to bleed-off.) The
ham-mer rap should be strong enough to
"bounce" the plug (20) into the seat ring
(21), leaving the "coined" in den ta tion.
e. Repeat d. a minimum of 2 times until the
best possible seat leakage is ob tained.
f. After "coining" completed, remove gas
pressure source, remove outlet clo sure,
and re in stall plug (33) if removed.
e. This completes ITA reassembly.
F. Main Reassembly:
1. Place body (23) in a vise.
2. Reinstall internal sensing drilled plug (32) with
compatible thread sealant.
3. Insert the lower piston spring (22) into the
body (23), if supplied.
4. Fit the o-ring cage seal (15) into its body (23)
groove.
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, taking care NOT TO “COCK” THE ITA
IN THE BODY. Torque the cage bolts (18) to
13-15 ft-lbs (18-20 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
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 valve 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
Recommended Torque Values are:
Body Size Torque
in. (mm) ft-lbs (Nm)
1/2"-1" (DN15-25) 30-50 (41-68)
1 1/4"-2" (DN32-50) 45-70 (61-95)
Body Size Torque
in (mm) ft-lbs. (Nm)
1/2"-1" (DN15-25) 60-70 (81-95)
1 1/4"- 2" (DN32-50) 120-130 (163-176)
2 1/2" - 4" (DN65-100) 180-200 (244-271)