Controller in Open (Reset) Position
(Figure 13)
When the controller is in the open position, the trip indicator
(key 27) is visible and rm when pressed with a nger.
Controller in Closed (Tripped) Position
(Figure 14)
When the controller is in the closed position, the trip indica-
tor (key 27) is not visible and easily moved when pressed
inward with a nger.
Maintenance
WARNING
Only a competent and qualied person may
perform maintenance procedures. If necessary,
contact your local Sales Ofce for assistance.
Failure to test the controller for proper shutoff
can result in a hazardous condition. Test the
controller for operation per applicable federal,
state and local codes, rules and regulations
and Emerson instructions.
Due to normal wear or damage that may occur
from external sources, the controller should
be inspected and maintained periodically.
The frequency of inspection and replacement
depends on the severity of service conditions
and on applicable codes and regulations.
In accordance with applicable National or
Industry codes, standards and regulations/
recommendations, all hazards covered by
specic tests after nal assembly before
applying the CE marking, shall also be
covered after every subsequent reassembly
at installation site, in order to ensure that
the equipment will be safe throughout its
intended life.
Periodic inspection must be performed on the
VSX4 and VSX8 Series. The controller should
be tested for both under and overpressure
shutoff activation and pressure tight shutoff
annually with test intervals not to exceed 15
months but at least once each calendar year.
If the controller does not close at the desired
pressures or leaks gas after closure, repair and/
or replace the controller. For the verication of
internal parts and replacement of worn parts,
the controller should be disassembled every
3 years minimum.
Disassembly and Reassembly
Note
User should only disassemble the controller
to replace the Valve Plug (Disk), change
registration from Internal to External and
Spring and Diaphragm Replacement as
described below.
All other internal disassembly requires
special tooling and should be done only at
the factory; for example the cam and reset pin
assembly (key 4, Figure 15).
WARNING
Only parts manufactured by Emerson
should be used for repairing the VSX4 and
VSX8 Series Slam-shut Device.
Valve Plug (Disk) Replacement
WARNING
To avoid personal injury or equipment
damage, do not attempt any maintenance
or disassembly without rst isolating the
regulator/controller from system pressure
and relieving all internal pressure.
Installation of an incorrect size valve plug
(disk) will prevent the controller from shutting
off the ow of gas in an overpressure or under
pressure scenario resulting in a hazardous
condition. A 39 mm / 1.54 in. diameter valve
plug must be installed in VSX8 Series
controllers for proper operation. VSX4 Series
controllers require the use of the 24 mm /
0.94 in. diameter valve plug.
• Refer to Figure 15 when following this procedure. Remove
the body ange screws (key 34) and the two half anges
(key 36). Remove the controller from the body.
• For VSX4 Series disk replacement, remove the fastening
ring (key 44). For VSX8 Series disk replacement, remove
the travel stop/cotter pin (key 53) and the safety nut (key 58).
For specic tools needed for this step, see Table 7.
• Remove and replace the valve plug (disk) (key 47).
• Replace the fastening ring (key 44) or safety nut (key 58)
and cotter pin (key 53). To replace the safety nut (key 58)
screw the nut onto the plug support until it stops and
then reverse the nut until the cotter pin (key 53) can
be assembled.
• Reassemble in reverse order, taking care to follow the
steps outlined in the General Controller Reassembly
Procedures section.
• Test the controller for proper operation at the desired OPSO
and/or UPSO set points. Readjust set point(s) if needed.
Changing from Internal to
External Registration
WARNING
To avoid personal injury or equipment
damage, do not attempt any maintenance
or disassembly without rst isolating the
regulator/controller from system pressure
and relieving all internal pressure.
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