Graco 965477 manual Determine the Ratio, Procedure 1 Base is not pre-reduced, Adjusting the Ratio

Determine the Ratio

Set the ratio based on your situation. If :

•The fluids are supplied at a ready–to–spray viscosity, simply set the ratio as explained under Adjusting the Ratio.

•The fluids are NOT supplied at ready–to–spray viscosity, the ratio must be determined after the reducer is added to the base, as instructed in Procedure 1, below.

NOTE: Evaporation of the reducer in the base causes changes in the ratio. To prevent evaporation, store the base in a closed container.

NOTE: Some reducers have very little ability to lubricate and many cause seals to dry out. To prolong the seal life, be sure your pump seals are compatible with the base’s reducer. Contact your Graco representative for the correct seals to use.

Procedure 1: Base is not pre-reduced

When adding the reducer to the base before proportioning with the VRHC system, determine the ratio of the base/reducer mixture to the catalyst in order to set the proper ratio.

Example:

The instructions on the can say “Mix 5 parts base to 1 part catalyst. Then reduce 3 parts of this mixture to 1 part reducer.”

1.Add the parts of the base and catalyst to find the parts mixture.

5parts base

+1 parts catalyst

6parts mixture

Fig. 5

2.The next statement on the can says, “Reduce 3 parts of the mixture.” So divide the parts of the mixture by 3 parts to reduce to find the parts reducer.

6parts mixture

/3 parts to reduce

2parts reducer

3.To determine the ratio of the secondary pump, add the appropriate parts of base and reducer to find the parts combined base/reducer.

5parts base

+2 parts reducer

7parts combined base/reducer to 1 part catalyst

The ratio of the pump is 7:1.

Relationship Between the Primary and Secondary Pumps

Moving the fulcrum point away from the primary pump reduces the secondary stroke length, reducing its fluid output. Moving the fulcrum point closer to the primary pump increases the secondary stroke length, increasing its fluid output.

Fig. 5 shows the relationship between the primary pump and the secondary pump.

Adjusting the Ratio

See Fig. 2. Use a wrench to rotate the ratio adjustment screw (S). Rotating the screw clockwise will increase the ratio. Rotating the screw counterclockwise will decrease the ratio. The indicator pin (V) will move along the ratio indicator scale (U) as the ratio adjustment screw is rotated. When the pin is above the desired ratio, remove the wrench and perform a ratio test as described on page 12.

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