Interrupted power during Hard Chrome Plating
A discussion started in 2004 but continuing through 20172004
Q. Our environmental department would like to put tank covers on our hard chrome tanks. A supplier has Zero emission tank covers that will allow us to eliminate our chrome scrubber ventilation system.
We have 5 plating tanks with 31 rectifiers supporting them. With the covered tanks you must turn off all rectifiers going to that tank before you open the cover to prevent a hydrogen explosion.
My question is, when plating several different parts with several different rectifiers in the same tank that require different thicknesses of chrome applied to each part. Can the rectifiers be turned off before desired amount of chrome has been applied (to remove 1 finished part) and then turned back on again to continue plating the rest of the parts in the tank?
It's possible that 1 part could have the power turned on and off 4 or 5 times before completed.Larry Lausin
Equip. Manager, Plating Shop - San Diego, Calif., USA
A. Hi Larry. There is very little chance of that plan working because chrome must be reactivated if the current is interrupted. Since you have 5 tanks though, perhaps a rearrangement of your processing, so that full batches can be processed without interruption is possible, however.
The concept is a great one and I hope you can get the logistics sorted out so you can do it.
Ted Mooney, P.E.
Pine Beach, New Jersey
December 3, 2017
A. I have been in this business for half a century and tried many things, you CANNOT operate a chrome plating tank with hoods and not have leaks or contaminations no matter how good you calculate this arrangement and specially if you are doing flash chrome. The only thing that works are the dry fume scrubbers with BE Gone filters.
However even if you were to install a double system, still that will never, never give you zero emissions, ZERO EMISSIONS CAN ONLY BE ACHIEVED BY ELIMINATING CHROME ALL TOGETHER. Chrome is not different from a lot of other poisonous substances that are also noxious to humans: you control it to the best of your ability to reduce emissions to a maximum that the best filtration permits and if this will not satisfy us then we should get rid of it altogether.
- Toronto, ON, Canada
Hi Giovanni. The same comment applies to "zero discharge" of waste products, and "zero tolerance" in the social milieu. It's an analog world, and in most situations here is no such thing as zero.
But still, there are terrible ideas & approaches, poor ones, good ones, and excellent ones. Excellent ideas for control of chromium fumes include extremely large freeboard and efficient ventilation. My own belief is that freeboard of 15" instead of the usual 3" will make a huge difference; I saw 36" ± freeboard in an old plant that chrome plated naval gun barrels and the result was amazing. My recollection is that there was no need for fume suppressants or significant exhaust because almost all of the chrome mists simply collapsed and fell back into the tank.
Pine Beach, New Jersey
Striving to live "Aloha"
December 11, 2017
A. Some minimal ventilation is recommended on the covered tanks to keep the hydrogen / oxygen mixture below the LEL (lower explosive limit).Lyle Kirman
Consultant - Cleveland Heights
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