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topic 7014

Heaters for Plating Tanks are Becoming Plated


(2001)

Q. We recently did the electrical connections for a new plating room for one of our customers. The tank heaters plating 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 the grounding of the heaters, it's the grounding of the anodes, cathodes, or rectifier.

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


(2002)

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 some how, 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

(2005)

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 temp plays a large role on which temps stabilize at and temps like to bounce up and down with the ambient temperature. So much where I live that the temps are computer controlled.

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



Heaters gassing in electrocleaner

July 5, 2016

Q. Hello, I have just installed a new 316L stainless electric immersion heater in my electro clean 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
  ^- Privately contact this inquirer -^


bipolar anode
From Lowenheim; item DE is a bipolar anode.
July 2016

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 letter 829 for 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
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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