Sunday, 15 March 2009

Galvanic corrosion of regulators

Knowing that South East Asia uses almost exclusively A-clamp (INT connector) we purchased two Scubapro's aluminium DIN to INT adapters (yeah, wanted to save some weight on air travel) for our Apex DS4/ATX-40 regulators.We knew that, as the 1st stage is made of admiralty brass and the adapter of aluminium, there might be some problems with galvanic corrosion between these two parts. And there were... Basically galvanic corrosion is an electrochemical process when in which one metal (e.g.. aluminium) corrodes preferentially when in contact with different metal (e.g. brass) and both metals are immersed in electrolyte (e.g.. salt water). This means that a metal that normally wouldn't corrode will when contacted with another one. But what does that mean for a mere mortal? Well, same as with a rusted screw that you cannot to unscrew, two metals can "rust" together. And this is what happened to Magda's reg and her yoke adapter. We tried everything, short of angle grinder and ultrasound bath, but the parts just won't budge:/

Fortunately the preventive measures I undertook (unscrewing the adapter from time to time and greasing the threading with silicon grease) turned out to be sufficient:D