Re: [new_distillers] Re: Copper Heater Tanks
- fizzynick wrote:
Subject: [new_distillers] Re: Copper Heater Tanks
I don't want to seem really dumb, but I have to ask the question so
What's a sacrificial anode ?
Not a dumb question at all ... just dumb of me assuming that everyone knew,
and there was no reason for me to think that.
A sacrificial anode is a lump of metal attached to the metal that you want
to protect, and this connection is electrically conducting. Metal corrosion
occurs when a tiny electrical circuit is set up between the metal and the
impurities embedded in it, with the liquid it is immersed in acting as a
current carrier, or electrolyte. It's just like a tiny battery, and the
metal is etched away from the positive pole by electrolysis (not to be
confused with chemical action of acids though, which is a different
process). If you clamp a suitable metal, say magnesium, to the surface of
the metal you want to protect, say copper, then the magnesium becomes the
preferential positive plate, or anode, and the magnesium is etched rather
than the copper ... hence the term "sacrificial anode". This is used in
ships to protect the steel of the hull by clamping magnesium or other
suitable metals/alloys to various parts of the hull. These corrode in time,
and have to be replaced, but the steel hull remains uncorroded. Some water
heaters have a small bar of magnesium alloy clamped to the inside of the
copper boiler to protect the copper. These bars slowly corrode over time,
introducing magnesium salts into the wash, but as salts are not vaporised
when you boil the wash, you may be assured that all of the magnesium is
retained in the boiler and never reaches the column ... or your product!
Sorry for the confusion.