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CROSBY SERIES HE ISOFLEX
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
Nozzle ring and guide ring adjustment
The nozzle ring location and guide ring location
are determined at the factory and their locations
are stamped on the valve bonnet where the cap
is seated. However, if the desired blowdown is
not obtained, it will be necessary to adjust the
rings. The following steps should be taken:
CAUTION
Never make any ring adjustments with the vessel
under pressure without gagging the valve properly.
Care should be taken to use only sufficient torque
on the gag to hold the valve closed. Overgagging
may damage the valve internals.
• Guide ring adjustment
The guide ring (10) is the principal blowdown
control ring in the valve. To change the guide
ring position, remove the guide ring set screw
(11) from the body (1A). Insert a screwdriver
or similar tool and engage one of the notches
(these can be seen through the set screw hole).
The guide ring can then be turned to the right
or left as desired.
NOTE
Turning the guide ring to the right (counterclockwise)
decreases the blowdown. The guide ring should never
be turned more than five notches either way without
retesting the valve. After each adjustment always
replace, tighten and lock wire the set screw being
careful that its point engages a notch.
• Nozzle ring adjustment
The nozzle ring (3) is necessary in obtaining
the pop action of the valve. This ring setting is
determined carefully by factory test and rarely
needs any further adjustment. However, in case
the guide ring (10) adjustment does not give the
described operating characteristics under all
conditions of operation, the nozzle ring may be
adjusted to control the valve operation for very
fine adjustment.
The nozzle ring is adjusted by removing
the nozzle ring set screw (4) from the valve
body (1A). Moving the ring to the right
(counterclockwise) results in a strong 'pop'
action and will increase blowdown. Moving the
ring to the left (clockwise) lowers the ring and
decreases the blowdown. Warn or simmer may
result if lowered too far.
The range of adjustment of this ring is limited
and it should not be moved more than one
notch at a time from its set position. The valve
performance should be checked after each
adjustment.
After each adjustment, always replace, tighten
and lock wire the set screw, being careful that
its point engages a notch.
Whenever ring adjustments are changed, a
record should be kept of the number of notches
and the direction in which the ring was moved.
This will make it possible to return to the
original setting in case of error.
SELF-ACTUATED SAFETY VALVES
®
After the valve has been adjusted to open and
close at the desired pressures, make sure the
adjusting bolt locknut and the set screws are
installed properly and tightened. If different ring
locations are obtained from testing, restamp the
valve bonnet with the new ring settings. Install
the cap, forked lever and lever making sure
there is a
inch (1.59 mm) clearance between
1
/
16
the spindle nut and forked lever.
7 VALVE MAINTENANCE
The functioning and life of a safety valve
depends primarily on methods used in its
maintenance. For this reason, the following
recommended steps for maintenance should
be followed:
General information
When possible remove flanged inlet valves from
the system before dismantling. In any case,
there should be no system pressure when a
valve is either dismantled in place or removed
for shop repair.
Nozzle and guide ring set screws are
custom fitted to each valve and are not to be
interchanged. The spring washers are fitted to
each end of the spring. The spring and washer
are to be kept intact as a unit.
The piston (13) is retained on the spindle
assembly (12) by means of a piston ring (14).
The piston (13) has labyrinth grooves which
should be oriented downward toward the nozzle
when assembled on the spindle.
Before disassembly, spare parts and service
equipment (such as lapping compound, lapping
blocks and jacking gear) should be available.
FIGURE 7 - Crosby hydraulic jacking device
Bleed
hole
¼-18 NPT
Parts list
1
Housing
2
Piston
3
O-Ring
3A
O-Ring
4
Backup ring
4A
Backup ring
5
Bonnet spacer
6
Spindle adapter
7
Hydraulic pump
8
¼" Hose
12
Valve spindle
17
Bonnet
26
Adjusting bolt
27
Adjusting bolt nut
Piston stroke indicator
9
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