Cashco 3100 - Manual (Page 4)

4 IOM-3100
V. MAINTENANCE
Tank or system protection is the primary function
of the weight loaded Pressure and/or Vacuum
Relief Vent. As a safety device, it is very important
that maintenance/inspection be done on a regular
interval. Maintenance should only be done by a
qualifi ed technician. Valve Concepts recommends
that all service be performed at the factory or a
factory authorized repair center. For information on
repair centers in your area, please contact factory.
To Dis-assemble: Remove the weatherhood wing
nuts (7) and washers (72) and lift off weatherhood
(17) and bug screen (27).
Remove vacuum cover bolts (22), vacuum cover (2)
and vacuum cover gasket (12).
Inspect weatherhood, bug screen, and cover for
corrosion, damage, or product build up. Clean with a
suitable solvent, replace as necessary.
NOTE: During re-assembly, install new cover gasket
(12) (5/32-inch diameter Gortex rope joint sealant).
For FRP material - bolting (22) for cover (2) should
be tightened to 50 in. - lbs. (5.6 Nm).
Remove pressure and vacuum pallet assemblies,
including any loading weights (18) that may be on
the pallets (4). NOTE: As the pallet(s) are removed
from the vent, identify each assembly (including the
stack of weights) by tagging as “pressure” side or
“vacuum” side.
Clean and inspect pallet assemblies. Inspect the
diaphragms (5) and replace if necessary.
To Replace Diaphragms: Place stems (9,10) in a
vise with threaded end up. Remove cotter pin (61),
nut (23), lock-washer (19) and washer (24).
Lift up to remove diaphragm plate (6,28) and
diaphragms (5). NOTE: Apply TFE paste to threads
of the stem and around hole on the pallets (4).
Install new diaphragms (5). Re-install diaphragm
plate (6,28), washer (24), lock-washer (19) and
tighten nut (23) on stem. Insert cotter pin (61)
through hole in stem and secure.
Inspect and clean pressure / vacuum seat ring(s)
(3). Check seat surface for any nicks, corrosion,
pitting or product build up. Seat surfaces must be
clean and smooth for vent to perform properly.
To Remove Seat Rings/Gaskets: Rotate bolts (11)
CCW and remove. Remove guides (8) and supports
(16), spacers (69) (Use fl ats on the supports or the
slot on top of guides and rotate CCW.) Mark the
location of these items on the seat ring(s) (3) for
reference at re-assembly.
Lift up to remove seat rings (3) and gaskets (13).
Inspect guides (8) and supports (16) and inside of
the body cavity (1) for any corrosion or product build
up. Clean if necessary.
Apply TFE paste to both sides of new gaskets and
install in body (1).
Re-assemble vent in reverse order, making sure
that the pressure and vacuum pallet(s) and loading
weights are in their proper location. Tighten bolts
(11), guides (8) and supports (16) to 15 ft. lbs. (20.3
Nm). When installing the weatherhood and vacuum
cover, ensure the pressure stem (10) and vacuum
stem (9) are inserted in the stem guides.
To Remove Inlet Screen: Rotate bolts (15) CCW
and remove. Inspect and clean screen (14) and
reinstall to body (1).
WARNING
When assembling a P/V vent, always put the
p r e s s u r e ( l o n g s t e m ) a n d v a c u u m ( s h o r t
stem) pallet assemblies back in their original
location and ensure that the stem is straight and fi ts
into the guide in the cover or weatherhood.
If the pressure and vacuum pallet assemblies are mixed
at assembly, the settings will be changed and the fl ow
for the vacuum side will be restricted.
If the stem is cocked at an angle, pallet lift may be com-
pletely blocked. An over-pressure can occur if any of
these three conditions happens. This can cause a tank
failure, severe personal injury and material damage.
SECTION V