Article Contents

1. Introduction
2. Example 1
3. Examples 2 and 3
4. Lessons Learned
5. Other Improvements
6. Dragout Tank
7. Sprays
8. Counterflowing Sprays
9. The Bottom Line

Ten Minutes to Better Rinsing
(p. 2)

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Example No. 1. Plated work drags one gallon of processing solution per hour into a single rinse tank that uses 99 gallons per hour of fresh water. The dilution of the dragout is 100:1. The solution in the rinse tank will be 100 times more dilute than in the process tank.

Mixing or agitating the rinse water ensures the highest dilution ratio. Work can be moved up and down, or air-agitation can be used. In barrel plating or processing, it is particularly important to "double-dip" the barrel in the rinse tank, allowing a short drain time over the tank. This exchanges the rinse water in the barrel, providing increased dilution in each rinse tank.

In example No. 1, 99 gallons per hour of water is a rather large flow rate, and a 100:1 rinse ratio is not good rinsing. A good rinse ratio for plated work is generally 5,000:1, or even 20,000:1 after chromium plating. But nobody wants to run 5,000 or 20,000 gallons per hour of water through a single rinse.

When two rinses are connected so that water flows from rinse number two to rinse number one (Figure 1), some beneficial math results. The dragout from rinse number one to rinse number two is rediluted so that the total dilution is almost the multiplication of the dilution in each rinse tank.

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