Ratio Adjustment - Graco 8900 Installation And Operation Manual

Installation and Operation of Model 8900 VR
5. RATIO ADJUSTMENT FOR MODEL 8900VR
The ratio of this unit is produced in part by the difference in the area of the
metering cylinders and in part by the position of the adjustable fulcrum point in
the Unibar linkage assembly. With the fulcrum in the center (next to stop at left
of center), each meter cylinder strokes 4". In this center position, the dispense
ratio is the same as the meter cylinder ratio.
The linkage is adjustable from 1:1 to 4:1 depending on the location of the
fulcrum point. The linkage must be adjusted for each material application so that
the combination linkage and meter cylinder ratio equals the desired material mix
ratio by volume. The ratio may be checked by weight, but the machine meters
by volume and that ratio must be known before proceeding.
The initial linkage adjustment point may be determined through a simple
mathematical calculation by inserting known values in the formula on the
following page. The answer given will be the distance in inches from the center
of the fulcrum point to the center of the minor volume (catalyst) meter cylinder.
For convenience, measure the distance between the grease fitting on the top of
the fulcrum and the center of the catalyst cylinder meter rod.
5