Summary for anodising bath air agitation Discussion
Anodising bath air agitation is discussed as a practical design issue for a new aluminum anodizing tank. The original questioner, Abhijit kr. Datta, asked for the best technique to achieve good bath agitation. The first reply said air agitation can be used in an anodizing bath and is usually the most cost-effective approach, pointing to a related article on agitation air sizing and calculations. James Watts recommended using air from a regenerative blower through a sparger system, and said adding filtration can also contribute a small amount of agitation while extending bath life and reducing rejects. Freeman Newton agreed with James and suggested a simple PVC header-and-lateral layout, with 1/8-inch holes on about 12-inch centers, adjusting hole size at the ends if agitation is uneven. He also noted that compressor bleed-off can be used if flow is controlled with a valve.
Q. Dear Sir,
I am working as a chemist in an anodising plant in Kolkata, India. We are going to construct a new anodising(Al.) bath. Please suggest me the technique to achieve good bath agitation.
Thanking you,
Abhijit kr. Datta
– Kolkata, West Bengal, India
2002
A. There is no reason you can’t use air agitation
⇦ huh?
in an anodizing bath, and that is usually the most cost effective approach. There are any number of “how to” articles about air agitation in the plating journals and books, but thread 40886, “Agitation air sizing and calculations for plating & anodizing” should give you most or all of what you need.
Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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A. Dear Abijit,
To have uniform agitation you can either have a small twin lobe compressor . Alternatively if you have an acid circulating system using an acid pump then there are nozzles which could be fitted on the discharge line to ensure uniform acid agitation inside the bath.
Jothi Ramalingam
Abhinava Aluminium P Ltd – Chennai
A. We used air from a regenerative blower thru a sparger system. We later added a filtration system (which contributes a small amount of agitation) that allowed us to use the bath longer and have less rejects. I suggest both rather than just one.
James Watts
– Navarre, Florida
A. Hi Abhikit,
What James Watts says makes sense. A simple system. Use plastic pipe, i.e, PVC … the layout, i.e., headers and laterals, will depend upon the tank length and width.
To start with use 1/8″ dia holes (smaller ones tend to plug up during drilling) at say 12″ centers … and if you find, for instance, that the ‘end’ or ‘ends’ are not getting sufficient agitation and air bubbling, drill one slightly larger hole at the very end to relieve the pressure and get better distribution. … you could take a bleed-off from your air compressor but then use a valve (diaphragm or needle) to control/reduce the flow.
For superlative mixing, go to the archives thread #7718.
Freeman Newton [deceased]
R.I.P. old friend (It is our sad duty to
advise that Freeman passed away 4/21/12)