Cashco 5100 - Manual (Page 6)

6 IOM-5100
SECTION VII
VII. VENT VALVE MAINTENANCE:
A. General:
1. The Model 5100 POVV does not require
routine lubrication or adjustments. It
should be checked periodically, at least
twice a year, to conſ rm that the vent is
functioning properly and that the set point
is correct.
2. The pilot valve is designed to function in a
failsafe manner. The failure of a seal or a
diaphragm will cause pressure to be vent-
ed to the atmosphere; the resulting loss in
pressure will cause the main valve to open
under rising pressure.
3. Periodic inspection for seat tightness
should be done to ensure compliance with
local air pollution control requirements. If
the vent relieves to the atmosphere, this
maybe accomplished with a gas detector
calibrated for the principle product in the
system.
4. The vent valve will need to be removed
from the tank for inspection of diaphragms,
gaskets and seals. When this is done, the
vent must be handled carefully using the
lifting lugs and the body.
5. The main and pilot valve housings, bodies,
pallet assemblies and other components
are exposed to the process vapor.
B. Disassembly:
1. Disconnect the tubing connections (pilot to
main Valve) (48, 57 and 244) and remove
the pilot by rotating the pilot body (201) as-
sembly CCW from nipple (53).
Actuator Diaphragm Replacement:
a. Paint or embed a match mark between
upper case (33) and lower case (32) along
ƀ anged area.
b. Loosen and remove nuts (35), lock
washer (37), ƀ at washer (36) and cap screw
(34).
c. Lift up and remove the upper case (33)
assemby and set aside.
d. Remove diaphragm (41) and replace
with new diaphragm. Position and align bolt
holes in the circumference of the diaphragm
with the holes in the lower case (32).
e. Reposition upper case assy (33) on dia-
phragm (41). Align marks of a. above.
f. Install cap screws (34), ƀ at washer (36),
lock washer (37) and nuts (35) and tighten.
g. Install pilot body assembly on nipple (53)
tight with CW rotation. Ensure straight con-
nector (244) of the pilot valve assembly is
directly above sensing tube connector (48)
of the main valve assembly.
h. Reconnect tubing (57) to ſ ttings
(48),(244). Refer to Section IX for Calibra-
tion and Testing.
Pressure Pallet Diaphragm Replacement:
a. Paint or embed a match mark between
weatherhood (17) and body (1) along ƀ anged
area.
b. Rotate jam nuts (55) CCW coming to
rest against top of jack screw (7). Rotate
jack nuts (54) CCW coming to rest against
nuts (55).
c. Rotate jack screw (7) CCW and remove
from threaded end of pallet guides (16).
d. Grasp the case assy (AA) (32/33) and lift
straight up to remove (AA) and weatherhood
assy (17) from pallet guides (16).
CAUTION
If the vent valve must be removed from the tank for
any reason, make sure that all pressure has been re-
leased before the ƀ ange fasteners are loosened. Refer
to your company procedures before venting the tank
pressure and when handling toxic or otherwise haz-
ardous materials. Observe all standard safety precau-
tions as speciſ ed on Material Safety Data Sheets for
the product(s) in the system while removing the valve
and during the repair.
CAUTION
Do not grasp weatherhood around the bottom edge,
it maybe sharp.