AquaTechnic Nylon pipe bushings are designed specifically to insulate connections in water systems between piping of different metals, such as iron or galvanized connected to copper or to high-copper content brass. No current will be produced if two pieces of the same metal were immersed in an electrolyte and connected together, but if two different metals are used, a current will flow in circuit
through the electrolyte and any metallic connection outside the electrolyte (water). The dielectric bushing interrupts the metallic circuit and the electric current. If the electric circuit is complete, as in metal-to-metal contact of the different pipes, the current through the water-electrolyte produces ions at the water-to-metal interfaces that are destructive of one or both metals. In the connection of copper to iron or galvanized, destruction or corrosion of the iron occurs with a heavy buildup of rust (iron-oxide) inside the pipe. The pipe wall may become corroded entirely through, and the inside passage will become severely restricted. If the outside of the copper-iron pipe connection becomes wet due to condensation, or if the joint is immersed in water, corrosion of the iron will also occur on the outside. The mineral content and acidity of the water supply affect the rate of corrosion, and both the mineral and acidity vary in domestic water supplies. Hot water is much more active than cold water, and many times a hot water pipe may be choked to a trickle of water, yet the cold water pipe next to it may be only moderately corroded. The corrosion typically occurs in pipes within only 3 or 4 inches of the joint in pipes of 3/4 size or smaller. If copper tubing is connected directly to a galvanized hot water tank, the entire inside of the tank is likely to corrode, with the zinc galvanizing disappearing first, then corrosion proceeding into the iron. Any pinholes or bare spots in a "glass-lined" tank will corrode rapidly if copper tubing is connected directly to the tank. Since the current developed in this corrosion process has a potential of only about 1-1/4 volts, any insulating interruption of the circuit will atop this corrosion. Aqua Technic Nylon is a tough material and in the formulation used in bushings is resistant to water and the minerals formed in domestic water supplies with intermittent use up to 1800 F. If your application approaches 1800F we recommend individual testing of the bushing for your application. As the water temperature is increased above 1800 F., long-term deterioration occurs, with higher temperatures accelerating the deterioration. Even a few months of exposure to 2500 F. water will seriously deteriorate the nylon. ELECTRICAL GROUND CONNECTIONS for telephone and house wiring systems are commonly made by straps or clamps to water pipes. The electrical codes specify that these connections be made between the water service entrance and the first shutoff valve in the building. Since the code specification is sometimes disregarded and grounding connections are made to some other point in the plumbing system, installation of dielectric bushings may interrupt the electrical ground. A quick check should be made of the electrical ground connections whenever a portion of a pipe system is insulated with dielectric bushings. Water softening and treating equipment produces greater chemical activity in the nearby systems. Even small differences in steel alloys used for tanks and piping can cause electrolytic corrosion in these areas. Protection with dielectric connections is desirable in all connections to the equipment.
