16 / Valve Maintenance
Note: The piston and needle assembly is replaced
as a unit and cannot be disassembled.
To reseat the needle and nozzle assembly:
1. Disconnect or shut off all air to the valve.
2. Rotate the stroke adjustment knob to
the closed position by turning clockwise.
3. Rotate the stroke adjustment further
clockwise one additional reference mark
to compress the needle into the nozzle.
4. Return the adjustment knob to normal
setting and cycle the valve a few times.
If there is still a slight leak, repeat steps
1 and 2 again.
5. If the leak continues, replace the nozzle.
To replace the piston and needle assembly or
the piston O-ring:
1. Remove the needle stroke control knob
by turning counterclockwise until free.
2. Remove the piston return spring and
thrust washers located on each end of
the spring.
3. Remove the snap ring using snap ring
pliers.
4. Pull the piston and needle assembly out
of the air cylinder using small pliers on
the spring pilot (at the top of the piston).
Note: The piston and needle assembly is replaced
as a unit and cannot be disassembled.
5. Clean the air cylinder body wall and
apply lubricant.
6. Reinstall a new O-ring on the piston,
apply lubricant to the needle and O-ring
then reinstall in the air cylinder.
7. Reinstall the snap ring.
8. To reinstall the piston return spring, first
put one thrust washer over the spring
pilot, then the other thrust washer into
the needle stroke control, followed by
the spring.
9. Reinstall the needle stroke control knob
by aligning the piston return spring with
the spring pilot. Turn the needle stroke
control clockwise until it stops and then
back it out to the desired setting.
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