Zinc anodes are usually applied in low resistivity soils below 1000 ohm-cm and in seawater or produced brines. Zinc is excellent for use as an electrical grounding material. Special 99.99% pure zinc electrodes are used as permanent references under tanks and inside vessels.
Zinc has a density of 446 lb/ft3 which is over 4 times the density of magnesium and 2.6 times the density of aluminum. The higher density means that zinc anodes will be much smaller and have a higher resistance to electrolyte, than magnesium or aluminum anodes of the same weight. Zinc has an open circuit potential to a copper/copper sulfate half cell of -1.1 volts, giving it a net driving potential of only 0.25 volts against a steel structure protected to 0.85 volts. Due to the low net driving potential and high density, zinc anodes for earth burial should have a long slender shape.
Zinc has a high conversion efficiency of 90% compared to 50% for magnesium; however, it has an electrochemical equivalent of 23.5 pounds per ampere year or 372 ampere hours per pound compared to 17 pounds per ampere year or 500 ampere hours per pound for magnesium.
Zinc should not be used when the electrolyte temperature is 135°F or higher. At approximately 140°F, zinc becomes passive and can become cathodic to the structure being protected.
|Dimensions: Zinc Pencil Anodes|
|Type||Pencil Dimensions (in)||Anode Thread||Plug NPT Size||Plug Type|
|Dimensions: Zinc Condenser Anodes|
|CZ-9||16||9||2 on 3 1/2 " centers|
|CZ-11||24||11||2 on 3 1/2 " centers|
Background: Galvanic Anode Cathodic Protection System
The galvanic system uses the natural difference in potential between metals to cause a direct electrical current from an anode through the soil or water to the structure being protected. BK Corrosion has provided industry with quality cathodic protection equipment for over 65 years.