Graco PR70e, Instructions Manual

Page: 31 / 70

Setup
334135B 31
Adjust Dispense Valve Snuff
Back
At the end of a shot, a small amount of material is drawn
back into the static mixer to prevent extra material from
being dispensed. If too much snuff back occurs, air will
enter the static mixer and can travel up into the dispense
valve. If too little snuff back occurs, the materials may
drip out of the static mixer and affect dispense quantity.
It is most efficient to adjust the snuff back while material
is dispensing, but it can also be adjusted when there is
no air pressure in the system.
1. Navigate to the Shot Mode Screen or Operator
Mode Screen .
2. Select a small size shot.
3. If a static mixer is not in place, install one, then
prime the machine. See
Prime the Dispense Head ,
page 28.
4. Place a waste container under static mixer.
5. Press the Dispense Request button ( ).
6. Inspect the tip of the static mixer for dripping mate-
rial or for air bubbles traveling up the mixer.
7. Perform another shot and, while dispensing, adjust
the snuff-back adjustment knob as follows.
• If an air bubble is moving up the mixer, turn the
knob clockwise to decrease snuff back.
• If material is hanging from the tip of the mixer,
turn the knob counterclockwise to increase
snuff back.
8. Repeat step 7 until snuff back is adjusted as
desired.