Cashco DAP - Manual (Page 5)

IOM-DAP 5
7. Place the seat ring (21) properly ori ent ed onto
the lower ledge of the cage (19).
8. Carefully insert the cage (19) and seat ring
(21) into the body (23) cavity, around the plug
(20).
9. 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 plug (20) is
lowered suf fi cient ly to engage the cage bolts
into the body (23). Engage threads of all the
cage bolts into the body, then rotate the cage
bolts CW in one-half revolution increments to
pull the plug (20) down evenly, taking care
NOT TO “COCK” THE PLUG (20) IN THE
BODY. Torque the cage bolts to 13-15 ft-lbs
(17.5-20 N-m).
10. Insert lower retainer ring (109) over the
threaded end of the plug (20) and down around
the stem seal (14).
11. Place piston (77) into a vise, use the jaws to
secure that portion of the piston's un der neath
side that does not insert into the cage (19);
i.e., the larger diameter "hub".
12. Stretch a new properly oriented upper dy nam ic
actuator seal (78) onto the piston (77) groove.
NOTE: The open-end of the u-cup seal should
be upwards such that the loading pressure
fl uid "fi lls" the cup por tion of the seal (78).
13. Position upper retainer ring (108) onto piston
(77). Engage threads of all retainer screws
(110) and tighten each securely in an al ter nat-
ing crossing-pattern.
14. Remove piston (77) from vise.
15. Stretch properly oriented lower dynamic bal-
anc ing side seal (27) over the lower end of
the pis ton (77). (NOTE: The open-end of the
u-cup seal (27) should be downwards such
that the P1 inlet pressure fl uid "fi lls" the cup
por tion of the seal.
16. Position piston (77) with the dynamic side
seal (27) over the threaded end of the plug
(20) and slide down to the upper edge of
the cage (19). Try to "tilt" the piston (77), as
much as possible, to one side while placing
a downwards force to engage the lip of the
dynamic side seal (27) into the cage (19);
using a thumb, press the outer edge of the
dynamic side seal inwards to aid the in ser tion,
move circumferentially around the seal until it
slides downwards into the cage fully.
17. Engage threads of lock nut (7) on threaded
end of plug (20). Hand-tighten as far as pos-
sible.
18. Place a deep offset box end wrench onto the
lock nut (7). Place a torque wrench on the
protruding end of the stem. Tighten the lock
nut (7) to the following torque levels:
Body Size
in (mm) Torque Value
Ft-lbs (N-m)
1/2" - 1" (DN15 - 25) 60 - 70 (81 - 95)
1 1/2" - 2" (DN40 - 50) 120 - 130 (163 - 176)
19. 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 sensing drilled plug (32)
for units equipped with internal sensing.
For units with external sensing, it will be
necessary to remove the internal 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,
leather), sharply rap the top end of the
plug (20). (Note: Gas will escape as the
plug (20) opens at the seat ring (21). Al-
low suffi cient time for leakage pressure
on outlet to bleed-off.) The hammer rap
should be strong enough to "bounce" the
plug (20) into the seat ring (21), leaving
the "coined" indentation.
e. Repeat d. a minimum of 2 times until the
best possible seat leakage is obtained.
f. After "coining" completed, remove gas
pressure source, remove outlet closure,
and re in stall plug (33) if removed.
20. Place new o-ring fl ange seal (65) into groove
of body (23) fl ange.
21. Position cover dome (25) matchmarks cor-
rect ly, then bring cover dome (25) down to
large piston (77). Tilt the cover dome (25) ap-
proximately 20° from vertical and press down
on the cover dome (25) while using thumb to
press the actuator seal (108) into the cover
dome (25). When seal (108) is fully inserted,