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Chrome plating mist /fume control: PFOS, fume suppressants, surface tension reducers

(2004)

Q. 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)

A. 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 I think it indicates that every inch of freeboard makes a big difference in emissions.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2004)

A. 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 portrait Freeman Newton
- White Rock, British Columbia, Canada

freeman newton died


(2004)

A. 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
process supplier - Great Neck, New York


(2004)

A. 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 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?

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

(2004)

A. 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)

thumbsup2Thanks Jeff! We're never too old to learn.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

(2004)

A. 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)

thumbsup2Dear 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)

Hello,

Q. 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 Corbeil
hard chroming - North Bay, Ontario, Canada


(2004)

A. 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
process supplier - Great Neck, New York


(2006)

Q. Hello

I work as an environmental engineer for a customer, operating a traditional hard chrome plating line. At this moment, he uses a mist suppressant based on PFOS (a fluorinated compound). Products based on PFOS will be either banned or heavily regulated in Europe.

We are comparing two options:
- stop using mist suppressants and build a expensive exhaust system for evacuation of the chromic acid mist
- continue to use PFOS, but remove the PFOS from rinsing water before (or right after) the sulphite treatment (conversion of Cr(VI) to harmless Cr(III)).

Does anyone have experience with removal techniques for PFOS. For example: does active carbon adsorption work ? (We found out that 3M uses active carbon to remove PFOS from polluted ground water, but does it work on highly acid rinsing waters ?) Suggestions and ideas are most welcome.

Bert GIELEN
- Gent, BELGIUM


(2006)

A. If it is possible, what I would do is plan for a large amount of freeboard plus the exhaust system. Chromium mist droplets are heavy, and with extravagant freeboard much of the chrome will fall back into the tank.

We're going through the same issue in the USA. With only a little exaggeration, EPA no sooner claimed that chrome MACT standards were achievable and affordable through the use of fume suppressants than it began banning them.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

(2006)

A. Hi Bert,

What Ted said about banning suppressants is news to me ... but his remarks about 'freeboard' are interesting ... I used to think that a 6" (sorry! 15 cm) freeboard was OK.

On the subject of, you say, an expensive exhaust system ...
why expensive?

Welded mild steel ducting and hoods. Anyhow, go into the fin.com library for more data on that.

POLLUTION ... Back in the early 80's, the allowable specs for chrome in B.C. were ll grains/l000 cfm of chrome sulphuric acid. Using a well designed (and made) ordinary 2 stage PVC mist eliminator, horizontal design with sine curved blades, tests indicated that these were 30 times LOWER than the then acceptable limits.This is a l2 micron eliminator...but in your terminology that is 0.7 mg/M3

My 1974 design followed that route but was a good 3 micron inertial scrubber.

Freeman Newton
- White Rock, British Columbia, Canada

(2006)

Q. Ted, Freeman,

Thanks for the input.

Increasing the freeboard is a nice idea; in this particular case, the freeboard can be increased by ~25 cm (some 10") just by lowering the level of the tank.

Also thanks for confirming that a well designed mist eliminator will do the job. (This still leaves us with the cost of a new exhaust system).

Does anyone has experience with e.g. ACTIVE CARBON ADSORPTION of the chlorinated mist suppressors ?

Best regards

Bert

Bert GIELEN
- Gent, Belgium


(2006)

A. Activated carbon might work. But, frequently, charged ions like the salts of anionic surfactants have a higher affinity for anionic ion exchange resins. These compounds are going to be even more acidic than non-fluorinated surfactants of this type and will only be present as the free acid at very low pH values.

dave wichern Dave Wichern
- The Bronx, New York


(2007)

Q. What is the status of chrome plating fume suppressants / mist suppressants that do not contain PFOS (perfluorooctane sulfonate) or fluorinated surfactants?
Are they available?
what is their performance like?
What surfactants are they based on?
what are their strengths and weaknesses.
Is anyone using one and willing to share their experience with it.

A MN plater was identified as the primary source of PFOS going through a medium sized POTW, causing the POTW effluent to exceed a "health based value" set by the state health department.

As a result there is some interest on the part of local platers to begin looking at alternatives if they exist.

Karl DeWahl
resource to the MN metal finishing industry - Minneapolis, MN, USA


(2007)

A. Based on the usage of the fluorinated products, I can't figure out how so much got to the POTW that the POTW was high!

Gene Packman
process supplier - Great Neck, New York


(2007)

Q. We are talking very small amounts here.
The health department standard is 75 ppt for PFOS.
The POTW effluent was 12 times higher than that
There was no attenuation in the POTW, and
The plating shop effluent was 58 time higher than the POTW effluent.

All this is based on a relatively few samples.

Karl DeWahl
MnTAP / University of Minnesota - Minneapolis, Minnesota USA


(2007)

A. Since this product is getting into the effluent via drag out from the plating solution, the most effective way to limit this is to reduce the drag out in the plating facility by implementing waste reduction methodology.

Gene Packman
process supplier - Great Neck, New York


November 6, 2010

Q. We know wetting agent in Bright Nickel is SLES (sodium lauryl ester sulphate),
Can we use it in bath of Chrome plating as wetting agent?
Thank you, Good luck

ASAD SHAHBAZI
plating shop employee - ARAK, IRAN

November 9, 2010

A. Nope, chrome solutions would destroy that in no time. If you use surface tension reducers in your chrome bath, you need the ones that are specifically designed for chrome plating. The chemical suppliers that offer these additives have spent big bucks on R&D to solve this particular issue for you, so the additives are expensive. Until recently most suppliers offered PFOS or similar compounds, but those chemicals are becoming banned, so they are now offering brand new proprietary additives.

Jon Barrows, MSF, EHSSC
Springfield, Missouri



January 4, 2011

A. 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 Clark
Aerospace - Monrovia, California, USA


April 7, 2011

Q. 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 Kiminki
plating shop - Dallas, Texas

April 10, 2011

A. 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.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


December 28, 2011

Q. 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.

Jeremy Horn
- Portland, Oregon, USA


January 4, 2012

A. 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


March 4, 2013appended

Q. Dear sir,
Which chemical is used to control the hydrogen gas in hard chrome plating? Please suggest to me. I use Mistolin but it is not working truely and its price is very high. Please tell me about other chemicals which are used to control the hydrogen gas.

Narendra parmar
hardchrome electroplater - vadodara,gujrat,india.



April 4, 2013

Q. I support the Plating Shops at a Naval aircraft overhaul facility in Jacksonville, Florida. While researching ways to reduce chromium air emissions (due to misting), I found this page. The first response is Ted Mooney's:

". . . 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 naval 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 I think it indicates that every inch of freeboard makes a big difference in emissions."

Can anyone provide more information about the plant mentioned above that implemented this change? Could you give any POCs there that may be able to answer questions about what they did and how their EPA- and Permit-types reacted?

Our hard chrome workload has changed to primarily small parts, possibly allowing us to get away with lowering the solution levels in our 8-foot deep tanks to give the ~36-inch freeboard. And possibly eliminate/reduce the costs and problems with our chrome scrubber system.

Can anyone offer advice or suggestions about any of this? Has anyone other than the above plant implemented such a change? If so, what were your results?

Thanks,

Bob Vines
Plating Shop Process Engineer - Jacksonville, Florida, United States
  ^- Privately contact this inquirer -^


April 4, 2013

A. Hi Bob. It was a very long time ago, mid 1970s, and I was not involved in the chrome fume control. I was visiting on another matter but inquired when I noted the very low solution level. One of the plant's engineers explained the situation and demonstrated it by holding a white handkerchief over the tank. But I have no data or history on it. I sent you the name of the shop in private.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
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