The Low Potential Zinc Anode In Theory and Application

After a brief discussion of the principles of cathodic protection and the basic requirements of a galvanic anode, anode requirements are examined specifically in terms of the cathodic protection of iron or steel in an electrolyte of uniform characteristics. For sea water it is shown that it is desirable to limit the cathode polarization to a value less anodic than –1.1 v (vs Ag/AgCl). The advantages of a low potential anode for the cathodic protection of iron under these conditions are discussed in detail in terms of circuit resistance, self-regulation, and cunrent distribution on the cathode. Other desirable anode characteristics such as current efficiency, current capacity per unit volume, and the effect of anode shape on anode current output are examined mathematically. The practical advantages and implications of the above considerations are described. It is suggested that where cathode polarization controls current distribution on the cathode and regulates anode current output, a new concept can be advanced for the design of cathodic protection systems utilizing low potential zinc anodes. 5.2.2