Oce Arizona 550 GT User Manual page 88

The Media Vacuum System
see dimples on the media that are the same size and location as the vacuum table punched
holes, introduce bleed until the dimples disappear from the media.
The bleed valve is off when its handle is in the horizontal position. To activate the bleed
valve, turn the handle to the vertical position. The closer the handle is to the vertical po-
sition, the more vacuum pressure is reduced.
The vacuum guage is located on the side of the table above and to the left of the bleed
valve handles. It provides a visual representation of the actual pressure in the vacuum table
system.
Note:
Use the vacuum gauge to determine if a zone is properly masked. When the active zone
is properly masked the gauge will read at 20"Hg (68 kPa) or higher. Small leaks can re-
duce this number and therefore the efficiency of the vacuum. Porous media can also
degrade the vacuum effect.
If the vacuum gauge for an active zone reads below 10"Hg (34 kPa) and you have ensured
that the area is properly masked and taped off, you may have a leak in the vacuum system.
Place a service call only if you determine that the zone is correctly masked and the gauge
reads consistently low.
How to Maintain the Vacuum Overlay Sheet
If an overlay sheet is damaged, replace it. The overlay is an optional commercial item and
can be ordered from your local sales representative. You may want to purchase multiple
overlays if you need multiple common material sizes or a regular, repeating job that is
non-square or unusually sized.
If ink build-up occurs on the overlay sheet, remove the ink. If it is not removed, the print
gap could be affected and this may affect the vacuum table's ability to secure the media
properly. To remove ink we recommend that you use a paint scraper containing a straight
edge razor blade (these can be found at a local hardware store). Refer to the Maintenance
section for more detailed instructions.
88 Chapter 5 - How to Operate the Océ Arizona 550 GT