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topic 2674

Rinse Dilemma


My company is entering into the electroless nickel business. Most of my equipment is in, and I have been practicing for months with very good results. Our problem is one of logistics. The shop area is simply NOT large enough to support all the rinse tanks needed. I have room for only two rinse tanks. RO and DI are both available to me. How can I set these tanks up so as to get the best results with what I have to work with? Your advice is appreciated.

Paul Norman
Paul Norman
- Odessa, Texas


The simplest approach is to add top sprays upon exit. This gives an additional counterflow stage to any tank.

More complex is to purchase a system that has external reservoirs for 3 or 4 gradients of rinse water. These systems subject the parts to the dirtiest water, then pump that dirty water to a reservoir for later use as a first rinse again; then they pump in mid-quality water, and pump it back to the mid-quality water reservoir; finally the parts are exposed to the cleanest water, which is then pumped to the clean water reservoir so the rinse tank can be refilled with the dirty water for the next load.

I've read good ad copy about such systems, but haven't seen them in operation, and remain rather unimpressed with the concept. If somebody has used them and is happy with them, please tell us about it.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


Do you mean 2 rinse tanks for the whole line or 2 rinse tanks after the EN. If it is the first, you are going to spend a lot of money on water or expect rejects. Ted's comment is certainly correct. I have used variations of this and it is better than two tanks that are cascade counter flow which is better than two flowing tanks.

James Watts
- Navarre, Florida


If you have restricted space but can set up at least a pair of counterflow rinses, start with the sprays. Ted is right.

Also look into the book "Water and Waste Control for the Plating Shop". The Kushners (advertisement on this web site) have done a great job in covering the theory and practice of rinsing.

Finally, consider closing the loop on the new rinses by processing through ion exchange or RO. You can size a system to get really good flow and therefore exceptional quality water, but never run into the problems of chelators, etc. and never have to dump much, if any, water. There are companies that will even provide regeneration services if you want to use ion exchange but don't want to have to deal with regeneration yourself. If you go the rental route there is little or no capital investment, although your monthly payments will be more.

bill vins
Bill Vins
microwave & cable assemblies
Mesa (what a place-a), Arizona 



in addition to top sprays suggested by Ted (a very good approach that can be implemented as a simple hand-held spray nozzle), you can circulate your rinse tanks through mixed bed IX columns. This way, the rinses will stay clean for as long as your IX columns will last, and those are pretty inexpensive to regenerate (Culligan or other vendors offer this service all over the country).

Good luck from PlaterB

berl stein
berl sig
"PlaterB" Berl Stein
NiCoForm, Inc.
supporting advertiser
Rochester, New York



Be sure if you go with IX and plan on getting the columns regenerated by an outside service that they know how to legally handle the columns and regenerant. This stuff could be classified as a hazardous waste. Spent columns are usually manifested as F006 wastewater treatment sludge.

bill vins
Bill Vins
microwave & cable assemblies
Mesa (what a place-a), Arizona 

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