Re: Dielectric couplings
Posted by Bud...Suncoast Plumbing on May 14, 1998 at 07:14:30:
In response to Re: Dielectric couplings
John: Di-electric unions are designed to prevent physical contact of dissimilar metals within a piping system. The junction of two dissimilar metals in the presence of an electrolyte will produce a small (milli-volt) electrical energy source much like a car battery. It is this unwanted electrical energy that fuels the corrosion process that results in pipe and fitting failures. The use of di-electric union is a step in the right direction, but does not guarantee that the corrosion process has been defeated.
The water supply to our homes , from private wells or municipal sources has the ability to conduct electrical energy(an electrolyte), and it has little difficulty jumping across the di-electric barrier installed in the plumping system.
A more effective means of dealing with the nagging problem of internal corrosion that leads to pipe and fitting failures, is to include a "Sacrificial Anode" in the system. This concept has been around for at least a century, and is extremely effective, the anode is in essence a scape goat and is destroyed by the forces that would otherwise be dining on your piping.
When the anode is depleted, it is simply unscrewed like a light bulb and replaced with a new one. (average life of the anode 5-10 years)

Your water heater is protected from failure due to electrolytic corrosion by a sacrificial anode inside the tank. This anode will also provide some protection for the hotwater piping connected to that heater. This is why most pipe failures occur on the cold water piping.

There are other forms of corrosion associated with hot water lines due to erosion of the pipe walls from the frictional scouring of recirculating pump action. This too can be controlled by the deposition of a Magnesium Oxide film on the interior surface of the piping.

You may wish to check the web site below for additional information on the problem of pin hole leaks and other signs of corrosive activity with in your plumbing system.........Bud




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