IOM-3381/4381
4
pressure is maintained during this leak test
of at least mid-range spring level; i.e. 20-80
psig (1.4-5.5 Barg) range spring, 50 psig
(3.4 Barg) test pressure minimum.
C. Diaphragm Replacement - Model 4381:
1. Procedures are the same as Model 3381,
except that the 4381's lower diaphragm flat
gasket (14) is replaced with an O-ring type di-
aphragm gasket (24). The O-ring diaphragm
gasket (24) is used with both metal and com-
position diaphragms (13).
2. For SST body (1) and SST spring chamber
(2), place thread lubricant to minimize po-
tential of seizing threads.
11. For metal diaphragm(s) (13), place lower
diaphragm gasket (14) into body (1) recess
(none required for composition diaphragm
(14)). Insert diaphragm subassembly into
the body (1). Place upper diaphragm gasket
(14) into recess of body (1).
12. Place the range spring (17) over the pusher
plate nut (10) of the diaphragm subassembly.
13. Place multipurpose, high temperature grease
into depression of spring button (5) where ad-
justing screw (8) makes contact. Set spring
button (5) onto range spring (17); ensure
spring button (5) is laying flat.
14. Rotate the spring chamber (2) CW by hand
into the threaded portion of the body (1) en-
suring not to cross thread. Continue hand ro-
tating CW until firmly seated against the upper
diaphragm gasket (14). Tighten to 30-35
ft-lbs (41-47 N-m) torque value.
15. Reinstall adjusting screw (8) with locknut (11)
into the spring chamber (2).
16. Pressurize with air and spray liquid leak
detector to test around body (1) and spring
chamber (2) for leakage. Ensure that an outlet
1. Install body (1) in a vise with the body cap
(6) on top and the spring chamber (2) down-
wards.
2. Loosen and remove body cap.
3. Remove piston spring (7), and piston (16).
Note that the seat and piston guide are in-
tegral parts of the body (1) casting. Inspect
integral seat and parts for excessive wear,
espe cially at seat surfaces. Replace if worn,
nicked or depressed. If integral seat is nicked,
use seat lapping compound to remove. Valves
8. Remove diaphragm(s) (13), and diaphragm
gasket(s) (14).
9. Clean body (1) and diaphragm flange. Do not
scratch diaphragm gasket seating surface.
NOTE:
On regulators originally supplied as
“oxygen clean”, Option s 3381-5 & -55, 4381-
36 & -55, main tenance must include a level
of cleanliness equal to Cashco's cleaning
standard #S-1134. For regulators originally
supplied as “cleaned for Pharmaceutical and
Food applications” Options 4381-37 and
4381-37S, maintenance must include a level
of cleanliness equal to Cashco cleaning stan-
dard #S-1576.
Contact factory for details.
10. Reassemble diaphragm subassembly
by placing pusher plate gasket (15) over
threaded post of pusher plate (4), placing
diaphragm(s)(13) and pressure plate (3)
over the threaded post. Assure the pressure
plate (3) is placed with curved outer rim down
next to the diaphragm (13) surface. Place a
thread sealant compound on the threads of
the pusher plate post (4) prior to tightening the
pusher plate nut (10) to the following torque
values:
Sizes
Diaphragm
Torque
In-lbs (N-m)
ALL
Metal
60
(6.8)
Composition
15
(1.7)
CAUTION
To prevent damage to body, use soft jaws when placing
body in a vise. Position so that vise closes over inlet and
outlet of the body.
CAUTION
Option-1+6 contains single diaphragm construction. In
the event of diaphragm failure, the process fluid will mix
with the loading fluid. Please alert your representative so
an alternative product can be selected.
D. Special Instructions for Diaphragm Removal:
1. If the TFE coated diaphragm (13) is utilized
on the Model 4381, the TFE coating is the
wetted side of the diaphragm.
2. If the Option-2 handwheel is utilized, the ad-
justing screw (8) and locknut (11) are re placed
with a handwheel (18) and lock nut (11). With
the Option-22 panel mounting w/handwheel,
the adjusting screw (8) and lock nut (11) are
replaced with a handwheel (18), lock nut (11)
and a panel mounting nut (19).
3. Use only those gaskets manufactured and
supplied by Cashco, Inc. for these products.
E. Trim Replacement:
