Packing Lubrication; Factors Affecting Valve Life - Graco DV Series Instructions-Parts List Manual

Packing Lubrication

This valve has a primary seal, a pressurized
grease area, and a secondary seal. The key to
long seal life is that the secondary seal only
has to seal grease.
When dispensing filled materials this grease
should be refilled once a month. Complete the
following procedure to avoid pushing grease
into the fluid stream
1. Relieve the system pressure, page 11.
2. Remove one grease zerk fitting (111).
F . 5
IG
3. Use a grease gun (part no. 551189) to
pump a high quality grease (part no.
115982, high temperature moisture free)
into the zerk fitting (111) until fresh grease
comes out the other side.
4. Reinstall the grease zerk fitting (111) and
give the valve one more shot of grease to
pressurize the cavity through the grease
zerk fitting (111).
NOTE: Grease can enter the fluid section if
more than one shot is triggered after the
grease fitting or plug has been replaced.
3A1792A

Factors Affecting Valve Life

The maintenance tables should be used as a
guideline for frequency of maintenance tasks.
Additional factors that could affect valve life
include the following:
Process Fluid - Abrasive or fiber filled fluids
•
are much harder on seals, shafts, and seats
than non-abrasive fluids such as oil.
Pressure drop across the valve seat - As
•
the valve opens or closes, the fluid is acceler-
ated to a high velocity at the needle/seat con-
tact area. The rate of wear at the valve will be
much greater at 3000 psi than at 1000 psi.
Changing nozzle or tip size can have a sub-
stantial affect on wear.
Number of cycles - This has a much greater
•
affect on valve wear than number of gallons.
If you can do the same job with fewer on/off
111
cycles, the valve will last longer.
Speed of actuation - Opening and closing
•
the valve quickly will increase needle and
seat life. Use short air lines after the solenoid
to improve open and close speed. Avoid long
air tube runs after the solenoid.
Air pressure - This is what provides the
ti16958a
•
force to hold the carbide ball against the car-
bide seat to seal against fluid pressure.
NOTE: Any leakage on these hard parts, at high
pressure, will quickly "worm-hole" the parts and
cause the valve to wear out sooner.
Maintenance
13