Cashco DA8 Differential - Manual (Page 11)

IOM-DA8/9 11
10. 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 14.
G. Units with Supported Diaphragm Designs:
1. With composition diaphragm construction,
a supported diaphragm (9) construction is
des ig nat ed as Opt-81 High Inlet Pressure, and
comes with the highest range spring se lec tion
for sizes 2" and smaller.
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 per formed,
pressure must be applied to all three of spring
chamber, inlet and outlet of body at the same
level.
2. Inboard Leakage Test (Seat + Dy nam ic Seal
Leakage).
a. Determine test pressure. If upper value
of range spring is less than 55 psig, use
test pressure of 5 psig less than upper
value of range spring. If upper value of
range spring is greater than 55 psig, use
test pressure of 50 psig.
b. While applying GN
2
or air pres sur iza tion
fl uid, engage adjusting screw inwards
until valve appears to be closed. Add one
additional revolution in wards to adjusting
screw.
c. Tube outlet to a beaker of water to ob serve
number of escaping gas bubbles.
3. Pressure Containment Test.
a. Pressurize inlet and outlet to 1.0 x Upper
Value of Range Spring or 30 psig with air
or GN
2
, whichever is higher.
b. Soap solution test all external leak points;
plugged connections, diaphragm fl ange,
di a phragm bolting and spring chamber
vent open ing.
4. Excessive leakage will require disassembly,
examination of sealing elements, correction
of problem, reassembly and retesting. NOTE:
This valve is NOT a bubble-tight shutoff de-
vice. See DAG-TB, Table DAG-10 for leak age
classes.
Body Size
in (mm) Torque
ft-lb (N-m)
1/2" - 2" (DN15-50) 30-35 (41-47)
2 1/2" - 4" (DN65-100) 45-50 (61-69)
CAUTION
DO NOT HYDROSTATICALLY TEST WITHOUT SPRING
CHAMBER PRESSURIZED. NOT ADHERING WILL DO
PHYSICAL INTERNALS DAMAGE THAT COULD REN-
DER THE UNIT INOPERABLE.