Zinc Anodes
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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 |
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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. |
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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)
A
B |
Anode Thread |
Plug NPT Size |
Plug Type |
|
P375 |
.375 |
1"-6" |
3/8-16 NC |
1/4" |
PP250-B |
|
P500 |
.500 |
1"-6" |
3/8-16 NC |
3/8" |
PP375-B |
|
P625 |
.625 |
1"-6" |
3/8-16 NC |
1/2" |
PP500-B |
|
P750 |
.750 |
1"-6" |
5/8-11 NC |
3/4" |
PP750-B |
|
P840 |
.840 |
1"-6" |
5/8-11 NC |
3/4" |
PP750-B |
|
P1050 |
1.05 |
1"-6" |
3/4-10 NC |
1" |
PP1000-B |
Dimensions: Zinc Condenser Anodes
|
Type |
Weight (lb.) |
Diameter |
Cores |
|
CZ-2 |
1 |
2" |
1 |
|
CZ-3 |
2 |
3 |
1 |
|
CZ-4 |
3 |
4 |
1 |
|
CZ-5 |
5 |
5 |
1 |
|
CZ-6 |
7 |
6 |
1 |
|
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. Brance-Krachy Co.,
Inc. has provided industry with quality cathodic protection equipment for over
65 years.
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