Cashco DA8 Differential User Manual

Page 11

IOM-DA8/9

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

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

, 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.