Emerson CROSBY Installation, Maintenance And Adjustment Instructions

Crosby style JCe safety ValVe
InstallatIon, MaIntenance and adjustMent InstructIons
1 InstallatIon
the valve must be installed with its main axis
perpendicular either on pipework or directly on
to the pressure vessel. the branch leading to
the valve shall be of sufficient size to prevent
a pressure drop in excess of 3% of the set
pressure when the valve is discharging its rated
capacity.
1.1 Drainage
If liquid can collect on the discharge side of the
valve, the drain plug (42) should be removed
and drain pipework connected so that the liquid
can be discharged at a point where it will not
cause injury to anyone.
1.2 Discharge pipework
In no case shall the nominal bore of the
discharge pipework be less than the nominal
bore of the valve outlet.
except for balanced bellows valves, pipework
should be as short as possible, and of sufficient
size to limit the pressure drop through the
pipework to 10% of the set pressure.
the pipework should be suitably supported
so as not to impose an excessive load on the
valve, and consideration should be given to the
reaction due to the valve discharging its rated
capacity.
1.3 Preparing for installation
Remove all packing material. Check that the
set pressure and other details on the valve
nameplate are correct. fit an inlet gasket and
ensure that it is properly located so that it does
not impede the flow to the valve. Connect up the
discharge piping, ensuring that an outlet gasket
is properly located.
note: fluid discharged from the bonnet vent
hole in the event of bellows failure on Balanced
Bellows valves is usually discharged to
atmosphere. If this fluid is toxic or inflammable,
it must be piped away to a safe place, however
atmospheric pressure within the casing must
be maintained.
note: Pipework leading to the valve should
be thoroughly cleaned to remove any foreign
matter, as this would cause the valve to leak if
trapped between the seat (4) and disc (5).
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2 PrEssurE aDjustMEnt
the valve has been factory set, but if it is found
necessary to make pressure alterations, it
is desirable to remove the valve from the
installation and use a suitable test rig. If this
cannot be done, the pressure may be altered
in situ by removing the cap (3), retaining the
compression screw in position by means of the
flats provided and slackening off the locknut
(13). the set pressure of the valve may be
increased by turning the compression screw
(12) in a clockwise direction, or decreased by
turning the screw in anti-clockwise direction.
note: On valves with packed or marine caps the
cap may be removed by following the procedure
in 4.4 or 4.5.
the set pressure should be checked by bringing
the pressure within the vessel or pipework
up to the required level gradually. a pressure
gauge must be installed so that the pressure
may be checked.
3 MaIntEnanCE
Before any maintenance work is carried out, all
pressure should be exhausted from the system.
If the work cannot be carried out in a satisfactory
manner by competent personnel, the valve
should be returned to the factory for service.
It is not always possible to carry out
maintenance work at the site, and we suggest
that the valve should be removed from the plant
and taken to a workshop.
4 DIsMantlIng
4.1 all valve types - refer to figure 1
Unscrew the cap (3), if a packed or marine type
cap is fitted refer to sections 4.4 and 4.5. slacken
the locknut (13) and remove all compression
from the spring (22) by turning the adjusting
screw (12) anti-clockwise. It is recommended
that the adjusting screw (12) is marked before
removal so that the valve can be approximately
reset to the correct pressure on reassembly.
slacken the body nuts (19) and remove
the cover (2). Remove the spindle (10)
from the guide plate (9), complete with the
lower spring plate (11) as an assembly.
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the lower spring plate (11) may then be lifted off
its split collar (69) and removed from the spindle
(10). Care should be taken not to lose the split
collar (69). If the valve is an 80 mm or 100 mm
high pressure model the 4 nuts (21) holding
the cover spacer (68) to the body (1) should be
removed and the cover spacer (68) lifted away
from the guide plate (9). the guide plate (9)
may now be removed from the body (1). It is not
recommended to release the guide plate (9) by
inserting a tool in the seat bore (4) as damage to
the disc (5) and seat (4) will result.
note: Care must be taken when removing the
guide plate (9) not to damage the bellows unit
(23) on balanced bellows valves.
4.2 Conventional valve - refer to figure 1
4.2.1 Remove the disc assembly from the
seat (4), being careful not to lose the
ball (31). examine the disc (5), re-lap as
necessary. If the valve is a resilient seated
model refer to next section.
4.2.2 Resilient seated valve - Refer to figure 4.
the resilient seat (53) may be replaced,
if necessary, by removing the circlip (65)
from the disc assembly along with the
retaining plate (66).
VCIoM-01087-En 17/11