Ratio Adjustment Calculation - Graco 8900 Installation And Operation Manual

6.

RATIO ADJUSTMENT CALCULATION

STEP 1: Determine Required Linkage Ratio
Required Mix Ratio By Volume (X:1)
Selected Meter Piston Ratio (Y:1)
(400 cyl/80 cyl = 5:1)
Mix Ratio By Volume is computed as 1000 parts base divided by the parts of
catalyst, i.e., 80 part catalyst per 1000 parts base - 1000/80=12.5:1 ratio (12.5
parts base to 1 part catalyst).
STEP 2: Compute Linkage Distance
14.850" (Total Length of Linkage Arm) =
Z (From above) + 1 (Linkage ratio +1)
The length established with the calculation should be the approximate distance
in inches from the center of the catalyst meter cylinder piston rod to the fulcrum
center point.
Linkage Adjustment Example
The required mix ratio by volume is 80/1000 or 12.5:1. The selected meter
piston ratio is 400/80 or 5:1.
STEP 1
12.5:1
5:1
STEP 2
14.85"
2.50 + 1
Hence, to establish the correct ratio with the 12.5:1 meter cylinders, the center of
the fulcrum must be situated 4.24" (approximately) form the center of the meter
cylinder piston rod. Further adjustments that are required are discussed on the
following page.
Installation and Operation of Model 8900 VR
= 12.5/5 = 2.50:1
= 4.24"
= Required Linkage Ratio (Z:1)
Length in inches fro fulcrum
center to meter rod center
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