Specialty Item Dielectric Fittings
When two dissimilar metals are placed in an acidic solution, they will form a battery and generate a voltage through a chemical process called electrolysis. The flow of current from one metal to the other will cause a movement of ions from one to the other, dissolving one metal and depositing on the other. While electrolysis is necessary for a car battery to function, it is undesirable in other applications such as piping. Even tap water or rain water is mildly acidic and causes electrolysis between dissimilar piping materials.
Dielectric fittings are used to separate dissimilar metals (such as copper and galvanized steel) to avoid the damaging effects of electrolysis. A dielectric fitting is constructed in two halves, with each half made of one of the two different piping materials to be connected. The fitting breaks the electrical current with a plastic liner between two halves of the fitting. The spacer is designed to be suitable for the system operating pressure and temperature.