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 44077
USE OF DI WATER IN WATER TREATMENT PLANT
FOR RINSING IN POWDER COATING PLANT [Pakistan]
February 20, 2007
Hi there!
I just want to know the importance of D.I water in chemical treatment
on ferrous surfaces prior to Powder Coating. We do have spray booth
type state of art equipments but the D.I plant isn't working properly
and was out of order for some time. I am wondering how important it
is to use this D.I water and what Impact does it make on the surface
finish. At the moment we are getting uneven Phosphating on our
products. It seams like some flood has passed by and have left some
bluish lines on it.
Can any one suggest some measures to be taken please!
Regards,
Raza
M. Ahsen Raza
- Karachi, Pakistan
February , 2007
Hi, Raza. I don't know quite what you mean by "suggest some
measures to be taken". Obviously, getting the DI unit back in service
is important. If you are asking whether parts that were not rinsed
need to be rejected, or even recalled from the field, I don't think
anyone has enough info to answer that.
Very good rinsing, either DI or with an additive, is necessary
between phosphatizing and painting for maximum corrosion resistance.
The usual procedure is to develop a robust treatment system, test
that it works as planned, and then carefully adhere to it.
Unfortunately , the question of the severity of the impact if you
don't adhere to the plan is generally not answerable. Sorry, I am not
personally familiar with a bluish "high water mark" effect, but maybe
another reader is.
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Ted Mooney, P.E.
finishing.com
Brick, NJ
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February 21, 2007
The answer to your DI questions depends on the quality of
your tap water. Some places have near DI quality tap water
and others have terrible water.
The typical reason for a DI system not working is simply
that it is not being taken care of per the DI system
manufacturers instruction sheet.
It is penny wise and pound foolish to run a system any
longer than it is supposed to before regeneration. You get
very bad water and sometimes it will damage the resin. Not
having a proper filter and carbon pack ahead of the resin
tanks will give much shorter regeneration times and probable
resin failure.
James Watts
- FL
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February 23, 2007
Mr. Raza,
The Powder Coat Institute sells books that will answer all of your
questions, you need more information than can be presented here. Your
chemical vendor should also be helping you set up your system.
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Sheldon Taylor
supply chain electronics
Wake Forest, No. Carolina
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April 4, 2007
Dear sir,
'getting uneven Phosphating on our products. It seams like some flood
has passed by and have left some bluish lines on it'
1. check the NOZZLE if your process is auto spray.
if you use zinc phosphate
2. check/add the conditioner to get the fine crystal phosphate
coating
3. check the free acid, total acid, accelerator. free acid have to in
range 1.0 to 1.2
Jaff
- Malaysia
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