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Smoke free muriatic acid


Thank you for taking time to read our problem. Can anyone give us an advise on how to prevent smoke in muriatic acids? Anything to be added to make it smoke-free or near smoke free? We use them during pickling and pH control of our ammonium based zinc plating.

Andrew Kaw
- Manila, Metro Manila, Philippines


If you strip old work they will fume madly because zinc is so reactive with hydrochloric acid. If you only clean steel, you should have an inhibitor that limits attack on steel. Still, local exhaust ventilation is a necessity with muriatic acid. It is, after all, HCl dissolved in water and it "wants" to vaporize.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


Dilute it with water to a point that it does not "smoke" and will still do the job, if that is possible, otherwise it is a tradeoff. If you are talking about fumes from the bottle or drum of raw material, buy it about 2 baumé less strong and the fuming will be reduced greatly.

James Watts
- Navarre, Florida


The white "smoke" that you see is actually ammonium chloride. It is remarkable how even very small amounts of ammonia and hydrochloric acid fumes will cause this effect. Even amounts that are well within a tolerable range for breathing can cause this "smoke". The only way to prevent it is by ventilating one or both of the tanks, or by changing the airflow patterns in your plating room so that the HCl fumes and ammonia fumes don't get together.

Lyle Kirman
consultant - Cleveland Heights, Ohio


As a follow-up to Lyle and Ted's comments, local ventilation is your best bet for containing the fumes and smoke. But the containment is short lived to the exit of the exhaust stack. If used, a fume scrubber and high efficiency mesh pad will contain the HCl fumes and HCl mist (99% to a low single digit micron range) but the ammonium chloride (smoke) will pass right through the scrubber.

Rick Hall
- Hickory, NC

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