Cashco DA6 - Manual (Page 10)

IOM-DA6 10
11. Evenly tighten the body bolting (11,12) in an
alternating cross pattern in one revolution
increments to the following torque value:
If supplied, remove pressure of previous Step
10.
G. Units with Supported Diaphragm Designs:
1. A supported diaphragm (9) construction is
designated as Opt-81 High Inlet Pressure.
Both upwards and downwards directions
are pro tect ed 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" and Smaller; Composition and
Metal Diaphragm. (See Figure 7.)
a. Body (23) is specially machined with a
shelf to capture a lower diaphragm sup-
port ring (35).
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support. Lower diaphragm support ring
(35) is captured by its location. Upon re-
moval of cover dome (25) and di a phragm
(9), the lower diaphragm support ring (35)
can be lifted upwards and out of the body
(23) cavity.
c. Reinstallation is a reversal of Step b.
above.
3. Body Sizes 2" and Smaller; Metal Di a phragm.
(See Figure 8.)
a. Body (23) is specially machined with a
shelf to capture a lower diaphragm sup-
port ring (35) and a groove for lower o-ring
diaphragm seal (65).
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support and a groove for upper o-ring
diaphragm seal (65). Lower di a phragm
sup port ring (35) is captured by its lo-
ca tion. Upon removal of cover dome (25)
and di a phragm (9), the lower di a phragm
sup port ring (35) can be lifted upwards
and out of the body (23) cavity.
c. Dual o-ring seals (65) replace the di a -
phragm gasket (37) normally supplied with
standard metal diaphragm con struc tion;
i.e. non-Opt-81.
d. Reinstallation is a reversal of Step b.
above.
4. Body Sizes 2-1/2" and Larger; Composition
Diaphragm. (See Figure 9.)
a. Body (23) is a standard body (23).
b. Cover dome (25) is specially machined to
provide a surface for the upper di a phragm
(9) support.
c. When disassembling valve unit, after low er
diaphragm pusher plate (10) is removed,
ac cess is provided to extended-length
cage cap screws (18). When screws (18)
are removed, both the cage (19) and the
lower diaphragm support ring (35) are
loose, and can be lifted upwards and out
of the body (23) cavity.
d. Upon reassembly of valve unit, after cage
(19) is positioned in body (23), lower
diaphragm support ring (35) is positioned
with cage (19) fl ange bolt holes (only one
orientation pos si ble) prior to engagement
and tightening of cage cap screws (18).
Torque screws to lev els indicated in Sub-
Section F.7.i., this Section.
H. Converting Internal/External Sensing:
1. Disassemble the regulator and remove the
diaphragm(s) (9) according to Steps 1-12 in
Part B – Main Regulator Disassembly.
2. To convert from internal to external sensing,
remove the drilled pipe plug (32) and install
a solid pipe plug. Reverse this step for con-
vert ing from external to internal sensing.
3. Reassemble the regulator according to Part
F – Main Regulator Reassembly.
I. Pressure Testing:
1. If a hydrostatic pressure test is performed,
pressure must be applied to all three of cover
dome (25), inlet and outlet of body at the same
level.
2. Inboard Leakage Test (Seat + Dynamic Seal
Leakage).
a. Release all loading pressure in cover
dome.
b. Pressurize inlet to 30 psig with air, GN
2
.
c. Tube outlet to a beaker of water to ob serve
number of escaping gas bubbles.
Inboard leakage path may be via plug/seat or
dynamic side seal.
CAU TION
DO NOT HYDROSTATICALLY TEST WITH OUT
COV ER DOME PRESSURIZED. NOT AD HER ING
WILL DO PHYSICAL INTERNALS DAM AGE THAT
COULD REN DER THE UNIT IN OP ER A BLE.
Body Size Torque
in. (mm) ft-lb (N-m)
1/2"-2" (DN15-50) 30-35 (41-47)
2 1/2"-4" (DN65-100) 45-50 (61-69)