HOMEFAQsBOOKS JOBS: Help WantedSuggestions you are here: Hotline/Forum => Letter 32578
Hard chrome fume suppressants and other misting measures
(2004)
Dear all,
I work for a plating shop and currently we are facing problems with the fume suppressant. In detail we have used fume suppressants in a hard chrome bath from two different suppliers, one of which is a major international chemicals company. Both liquids do not perform as good as expected. For example, after no more than 14 hours of operation everything near the bath is full of this dark red/brown chrome layer. If you leave a white page of paper in the afternoon on a table 2 m from the bath, next day it has become brown.
Should you have any suggestions, please reply.
Thank you in advance.
Christos Sigalas- Athens, Attica, Greece
(2004)
Personally, I don't feel that fume suppressant is an adequate substitute for an exhaust ventilation system. But try dropping the solution level in the chrome tank to whatever extent is possible as well -- it can make a very big difference. I once visited a plant that had been built with very deep tanks for vertically chrome plating navel gun barrels. When they no longer processed parts that long, they decided to drop the solution level to about 36 inches. Without fume suppressants or a ventilation system, they had no detectable chrome emissions! Apparently, in the absence of drafts, the chrome mists fell back into the tank before rising 36 inches. 36" freeboard is impractical for most shops, but it indicates that every inch of freeboard makes a big difference in emissions.
|
 Ted Mooney, P.E. RET finishing.com Brick, New Jersey |
(2004)
We have used a fume suppressant for ten years, and it works very well. There are no fumes you can see or smell, and there are no chrome stains on or near the tanks. The one we use is available from Atotech USA.
|
Jeffrey Holmes, CEF - Spartanburg, South Carolina |
(2004)
Thanks, Jeffrey. To be clear, you do hard chrome plating with no local exhaust on the tank, and do not have an unusually low solution level in the tank, and need nothing but fume suppressant for control? I worked for M&T Chemicals and Harshaw Chemical Co., the two components of Atotech, and am happy but a bit surprised that the development efforts were that successful! If you are at liberty to say, do you use conventional sulfuric catalyzed, fluoride, or high efficiency etch free chrome?
|
|
Ted Mooney, P.E. RET finishing.com Brick, New Jersey |
First of three simultaneous responses -- (2004)
I tend to disagree & agree with Ted. Fume suppressants (foam blankets) are not very effective and short lived however, surface tension reducers are very effective in eliminating chrome mist and spray (as has been proven in several tests by U.S. EPA et.al.) If you are using one of the modern fume suppressants/surface tension reducers check to see if your surface tension is below 45 dynes ( I prefer 35). This may be done with some accuracy using a relatively inexpensive piece of glassware called a stalagmometer.
Gene Packman- Syosset, New York
Second of three simultaneous responses -- (2004)
Hi Christos,
What Ted said about ventilation hit the nail on the head ...and yes, the lip of the tank should be min. 6" (sorry, I forgot ... 15 cm!) from the liquid level.
I have seen very poorly designed fume hoods inefficiently exhausting a chrome tank but with the addition of some surfactants, they became 'efficient' !
If this Atotech material works that efficiently, ... doesn't cause any side effects, is reasonably priced, then it will prove a huge benefit to platers.
But as a typical Doubting Thomas, me thinks it ain't so.
|
Freeman Newton - White Rock, British Columbia, Canada | Ed. note: It is our sad duty to advise that Freeman passed away on April 21, 2012. R.I.P. old friend. I know that his wife Nancy would appreciate your kind thoughts at |
Third of three simultaneous responses -- (2004)
Ted: Our chrome bath is sulfuric/boric acid catalyzed, no fluoride. approx. 32 oz/gal, solution level 4" from top. No ventilation of any kind. We have done 8-hour employee air monitoring with no Cr+6 detected. Also installed a temporary exhaust system, no scrubber, just a blower and ductwork, and passed the Cr emission test by a factor of 10. You can lay a white paper on the anode/cathode bars, and no yellow stain @ 2000 amps. The product is Fumetrol 140. Worth it's weight in gold, which is almost what it costs.
|
|
Jeffrey Holmes, CEF - Spartanburg, South Carolina |
(2004)
Thanks Jeff! We're never too old to learn.
|
 Ted Mooney, P.E. RET finishing.com Brick, New Jersey |
(2004)
Dear friends,
Thank you all for responding. In fact, one of the two products I mentioned is Fumetrol 140!
We do use an exhaust system and the space above the solution level is about 30 to 40 cm.
Well, the problem probably seems to be that the filters of the exhaust system, which is situated at the basement of the shop (under the bath), have to be changed more often because they were blocked.
Anyway, thanks again, pretty interesting discussion.
Chris Sigalas- Athens, Greece
(2004)
I have had the same results as Jeffrey in our shop.
Ted it has nothing to do with you or being too old to learn. The problem is companies want to keep on selling scrubbers, regulators want more regulations, and a plating society was willing to go along for the ride. Scrubbers were embraced, surface tension reducing agents were shunned. It was an excellent job as people to this day will denounce surface tension reducing agents.
Todd Osmolski
- Charlotte, North Carolina, USA
(2004)
Hello,
Is there a good combination of F/S, and surface reducing agents. I have 10" of freeboard, use Fumetrol 208 and have an exhaust system. After a night load I get the "Red Mist" on all my bars. Tried the balls, sank. thanks
Jamie Corbeilhard chroming - North Bay, Ontario, Canada
(2004)
Jamie,
If memory serves me correct Fumetrol 208 is a cost engineered product that contains less of the surface tension reducer and more surfactant. Switch to a product which is mostly surface tension reducer. These are relatively quite expensive ($85-160 U.S. depending upon vendor/manufacturer) but are based on fluorocarbon technology.
Gene Packman- Syosset, New York
January 4, 2011
We were just asked by the Air Quality folks to lower the emissions of our chromic acid anodizing tank. We are looking into some of the Fumetrol products. I see that they have a new product that is PFOS free.
Kevin ClarkAerospace - Monrovia, California, USA
April 7, 2011
What is the best way to stop evaporation from my chrome plating tanks? If it is to be purchased, where do I get the product?
Dave Kiminkiplating shop - Dallas, Texas
April 10, 2011
Hi, Dave.
Evaporation, per se, from a chrome plating tank is usually considered good rather than bad as it allows the return of some chrome-contaminated dragout.
The normal problem is chrome fumes or mists evolving from the tank. These can be addressed with a lowered solution level in the tank, wetting agents, and fume suppressants. Some people use "chroffles" (polypropylene ping pong balls), but I am not convinced they are worth the effort.
You might also see www.pfonline.com/articles/reducing-hexavalent-chromium-emissions about a special membrane cover which purportedly allows hydrogen and oxygen to escape from chrome plating tanks while containing the chrome fumes. Good luck.
|
|
Ted Mooney, P.E. RET finishing.com Brick, New Jersey |
December 28, 2011
According to ASTM D 1331, you must calculate the correcting factor F, when using a tensiometer. How do I obtain the value of "d", which is defined as the "density of air saturated with vapor of the liquid"?
The ASTM spec says the value of "d" can be obtained from published data, but I have not found anyone who knows this data or how to get it?
This is in regards to decorative chrome solutions.
Thank you, Jeremy.
- Portland, Oregon, USA
January 4, 2012
You might have better luck using a stalagmometer. There are several companies that sell this instrument and I'm sure they could provide you with a procedure that would work for you. Tensiometers are a big pain to use because there are many sources for error. And as for a literature source, I would check the International Critical Tables for a value, it might be in there.
Aimee Longacre- Savannah, Georgia, USA