Pollution Prevention and Control Technologies for Plating Operations
Section 2 - General Waste Reduction Practices
2.5 RINSEWATER REDUCTION
2.5.1 Optimal Rinse Tank Design
The key objectives with regard to optimal rinse tank design are
to attain fast removal of drag-out from the part and complete
dispersion of the drag-out throughout the rinse tank. When these
objectives are achieved, the time necessary for rinsing is reduced
and the concentration of contaminants on the part when it leaves
the rinse tank are minimized for a given rinse water flow rate.
The following are rinse tank design elements that help to achieve
fast drag-out removal and complete mixing. These methods can be
combined to develop an optimal rinse tank design for a given workload.
The optimal rinse tank design for different shaped parts, racks
and barrels will usually result in the selection of a different
combination of design elements. When parts with various configurations
are rinsed in the same tanks, it may be necessary to compromise
the design to provide adequate rinsing for all parts.
- Select the minimum size rinse tank in which the parts can
be rinsed and use the same size for the entire plating line.
- Locate the water inlet and discharge points of the tank at
opposite positions in the tank to avoid short-circuiting.
- Use a flow distributor/sprayer to feed the rinse water evenly.
- Use air agitation, mechanical mixing or other means of turbulence.
- Use spray rinsing for flat surfaced parts.
- Use ultrasonics, where applicable.
Air agitation was a relatively common element of rinse tank designs
used by survey respondents. A total of 185 (or 58.2%) of the respondents
reported its use. The average success rating was 3.71 (see Exhibit
Spray rinsing is used by 124 (or 39.0%) of the survey respondents.
The success rating for this method was 3.82.
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