Summary for plating shop ventilation Discussion
Ventilation requirements for plating shop are the main issue in this thread. David Darrow describes a 2,000 sq. ft. processing room with two lines: alkaline zinc plating for steel and chem film/anodize for aluminum, with large heated tanks, and says California code is pushing him toward 24/7 ventilation with backup power. He wants a good reason to ask the fire marshal for a modification because local shops do not seem to use that level of continuous exhaust. Ted Mooney, P.E., replies that plating “fumes” are really mists from hydrogen bubbles and are not known to be flammable. He adds that, based on his experience with insurance fire claims, running ventilation systems during unattended hours has contributed to major fires. His practical advice is to cover tanks when not in use and shut off or greatly reduce ventilation when the shop is unattended, since he sees no fire danger from the system being off.
Q. Hello,
I am designing a processing room to support our manufacturing, approx. 2000 sq. ft. The processing will consist of two lines, one for steel and one for aluminum. Alkaline Zinc plate for steel and chem film and anodize for aluminum, both lines tank size will be 600 gal ea. (zinc plate will be 1200 gal.) This area of the facility will be classified as an H-4 occupancy in accordance with California Building Code section 307.6. ventilation is required in accordance with California Fire Code 2705.1.19, 2704.3.1. the requirement is for 24/7 ventilation and back-up power. We planned on providing source ventilation for the heated tanks, but not 24/7 with back-up power. This ventilation requirement seems excessive for our use. I’ve not seen this in any local plating shops. I need to give the fire marshal good cause to modify the ventilation requirements, any suggestions?
David Darrow
special projects – San Diego, California, USA
May 5, 2010
May , 2010
A. Hi, David. Plating “fumes” are not fumes, they are mists produced primarily by the hydrogen bubbles evolved during plating — and I know of no case where they are flammable.
As the “plating shop guy” for a service company which handled dozens of fire claims for the insurance companies I do know of multi-million dollar fires spread by (it might be fair to say ‘partially caused by’ the fact that ventilation systems were running during unattended hours. Ventilated tanks should be covered when not in use, and the ventilation system turned off or at least powered way down.
Since the system being off poses no danger of fire, I think the fire marshall will agree.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Q. Hi Ted, Yes he knows the “mists / vapors” are not flammable. His concern is the for safety of occupants and first responders involved in an emergency situation. Our HMIS we submitted shows that we will exceed the exempt amounts of corrosive liquids in open use, this requires the H4 occupancy. The fire marshal is concerned that if our tanks were left uncovered a cloud of corrosive or toxic vapor may develop that continuous ventilation would prevent. To drop the 24/7 ventilation and back-up power requirement we would need a fail-safe engineered system were the covers would close automatically upon loss of power, and battery backup to provide some ventilation after loss of power. Although I’m happy he is willing to work with us, it seem excessive and unnecessary. Are the mists from these solutions is requiring a re-think. My problem is how do I show the that continuous ventilation and back-up power isn’t necessary?
David Darrow [returning]
– San Diego, California, USA
May 7, 2010
A. Hi, David. Of course it’s expensive and unnecessary and you haven’t seen it in any local plating shops. I personally never saw it in a career of 45 years in plating equipment and plating shop design spanning the world, so it’s not very common if it exists at all. Maybe another reader can point to examples though. Simple covers can be put in place by hand; this failsafe aspect is just silly — the automated controller is certainly not failsafe (Stuxnet anyone?).
Until the world economy crashes from unrealistic resources being wasted towards the elimination of all risk, we continue on this path where winning the argument is impossible because there is always “some” minuscule amount of danger of a worker or first-responder being temporarily exposed to an acid fume that exceeds some artificial limit. I know from my personal experience that running the ventilation system when nobody is there greatly increases the dangers rather than decreasing them; and a fire marshall — who is much more familiar with fires than you or I, but far less familiar with the ludicrously low danger of acid fumes in a plating shop — will surely recognize that high rate air flow is not the path to reducing the spread of fire. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
May 7, 2010