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Electric Heaters for Plating Tanks are Becoming Plated

adv.    industrial heating systems


Q. We recently did the electrical connections for a new plating room for one of our customers. The tank heaters are plating and my customer thinks it is the way we connected them. The heater manufacture says it a grounding problem. I am also told this is a common problem. We connected this equipment correctly, including proper ground connections. All grounds are common in the electrical panel. The only time the heaters do not plate is when the ground is not connected. What am I missing here?

Ron Byrd
- Cameron Park, California
2001


A. Hi, Ron.

The problem isn't that the heaters are grounded, it's that the anodes or cathodes are :-)

Electric heaters must be grounded for safety reasons, but this necessitates that everything else must "float", i.e., be isolated from ground; otherwise current will flow to or from the grounded heater to whichever side of the circuit is not grounded.

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


A. Make sure the heater surface is non conducting. If it is an electrical heater, they are usually covered with a teflon surface. If this surface is punctured somehow, an earth leakage will occur and trip the fuse if present. I have seen in the past that if the earth leakage system is not working, a small AC current flow is going through the chemical solution and starts a deposit on the heater.

Do not worry too much about the rectifiers, since those are DC.

Jelle JüNgeling
- The Netherlands


A. We run heat and cool through coil pacs utilizing LP steam and a cooling tower. It negates the issue of electrical problems from electric heaters. I believe it's more efficient also. Solution temps must be maintained at specific temps. Ambient temperature plays a large role on which temperatures stabilize at and temperatures like to bounce up and down with the ambient temperature. So much where I live that the temperatures are computer controlled.

Victor L. Firman
Plating - St. Louis, Michigan, USA
2005




Shock from electric heaters in plating & cleaning solution

Q. Dear sir,
I am an anodizer, and we are doing anodizing of different aluminum alloys.

During cleaning of parts we use sodium hydroxide and some other chemicals at specified temperatures. For this temperature we use electrical heaters of titanium (direct heating). The problem is when we hang the component by a jig of titanium or aluminum then to avoid electrical shock, we have to shutdown the electrical heaters. But it reduces the temperature, so reduces production again & again.

So I want to resolve this problem. Is there any method to avoid electrical shock during parts processing? I mean to say is there any method by which during processing of parts electrical heater can be in running condition? So please guide me in this regard.

Mahboob Alam
A E R O - ISLAMABAD,PAKISTAN
2005


A. Hi Mahboob. Something is desperately wrong with that electric heater! Heaters are supposed to be completely sealed so that there is no possibility of shock short of physically damaging the heater, and they should be grounded for safety as well.

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



A. Hi Mahboob,

What Ted says sounds right ... but then he's a plater, and I sure ain't.

But why don't you use a liquid filled heat exchanger? Such as made of PVDF which is good for 140 °C? Then you could pump hot water through it till the cows come home without any shocks.

Just a thought.

freeman newton portrait
Freeman Newton [deceased]
R.I.P. old friend (It is our sad duty to
advise that Freeman passed away 4/21/12)




Q. DEAR TED
Thanks FOR YOURS ANSWER BUT I HAVE THIS PROBLEM WITH ALL OF MY BATHS AND ALL OF HEATERS EVEN IF THEY ARE NEW.
SO MY QUERY IS WHAT SPECIAL ARRANGEMENTS WITH A HEATER IS MADE WHEN INSTALLED IN A PLATING BATH TO AVOID ELECTRIC SHOCK?

Mahboob Alam [returning]
A E R O - ISLAMABAD,PAKISTAN


A. Hello again, Mahboob. Please try to contact a local (Pakistan or India) plating equipment supplier who can show you proper electric heaters for electroplating operations. These commercially available units are completely sealed so that no liquids can make contact with the electricity, and they are grounded as a safety precaution so that if a leak occurs and the internal parts which carry electricity get wet, the fuses will blow.

Unfortunately I cannot fully describe in detail the entire procedure for designing and building a proper electric heater from scratch; it is something you have to buy, not something you make. But once you see one you will understand exactly what is wrong with your present dangerous heaters.

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



Ted is right. If heaters are being used correctly they will not give an electric shock. It sounds like your whole wiring system is faulty. I suggest you get a qualified electrician to check out the whole system before someone gets seriously injured. Electricity, chemicals and people really don't make a safe combination!

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK




Help with Temperature Controllers

Q. I am with a plating shop in Austin, Texas and I have some controllers and they will not work. I have done everything in my power, i.e. what the book says; I've talked to the manufacturer and nothing seems to work. I have replaced the controller, probe, and checked all wires for power. Everything shows the controller to be working but the heater will not turn on and allow the tank to heat up. <>If anyone knows what could be wrong or knows of anyone in the central Texas area that could offer assistance or come by my shop and show me what is going on with this thing I would greatly appreciate it. Thank you to anyone that could help.

Richard Sulanka
Plating Shop - Austin, Texas
2006


A. We deleted the brand name of the controllers, but they are single-phase electronic type with RTD temperature probe and LED readout. Richard, the manufacturer must have a distributor in your area who can help you. Unfortunately, it can be tricky, but have your electrician start by making sure you have power in, that the DIP switches are set for RTD control, and by wiring a light bulb to the power out terminals of the controller. The light bulb doesn't need protection by level control or over-temperature and will let the electrician get the controller itself going.

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


A. I hate to point out the obvious, but are you sure the problem is in the controller and not the heater?

James Totter
James Totter, CEF
- Tallahassee, Florida


A. Mr Totter has a good point. I have had a few electric heaters overheat. A popular heater/controller supplier here in the US (name deleted, but I do kind of like them) that I bought them from pointed out that they have an overheat protection fuse in them (not a good idea to shut one off and then pump the tank out right away). The fuse once blown will not allow the circuit to be complete (i.e., no power to heater until you make the circuit complete). A competent electrician (or a handy maintenance man) should be able to tell pretty quick. DIP switch is also an easy check if you have the manual in front of you. It is pretty straight forward.

Good Luck I've Been There

Trent Kaufman
Trent Kaufman
electroplater - Galva, Illinois




Heaters gassing in electrocleaner

Q. Hello, I have just installed a new 316L stainless electric immersion heater in my electroclean tank. The heater gasses whenever the rectifier is on. I have isolated the anode bar, still gasses, isolated the heater with plastic from the tank, still gasses. Shut off power to the heater and turned rectifier on still gasses. Kind of at a loss here? Any help would be appreciated thanks.

Justin Hankins
plating shop - Tennessee
July 5, 2016



bipolar anode
From Lowenheim; item DE is a bipolar anode.

A. Hi Justin. For safety the heater must be grounded. There are only two possibilities I think:

1. Either the heater is functioning as a bipolar anode, or
2. The rectifier bussing is grounded on one side or the other.

If your heater or any metal object is positioned between the anode and the cathode, the plating or electrocleaning current prefers to travel through it, rather than through the solution, because the resistance of metal is much less than the resistance of the electrocleaning solution. Please see topic 829 for further details. This bipolar effect causes the metal object to release hydrogen on the side nearest the anode and oxygen on the side nearest the cathode.
Still, I'd expect this gassing to be relatively minor, and to probably not hurt anything.

I think it's more likely that one side or the other of your bussing is grounded. If so, the heater draws electricity just as if it were whichever electrode is grounded. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 2016




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