vixtor
Contributor
Hello,
Yesterday I was washing my tank (it had to stay one day unwashed after the dive). I have rinsed the valve (DIN) with warm water and then purged some air from the tank to dry it. At that moment I have noticed that some black stain was forming on the flat bottom of the DIN valve. The tank is new (I think it was filled ~8 times). I wiped out the dirt with a paper napkin and purged again. The stain formed again. It looked as either a very fine black (100% black, not rust or something else) powder sticking to the still wet inner surface of the valve or it could have even been liquid already (hard to tell).
Anyway, after a few air purges it ceased to apear again. I had the tank visually inspected - everything is shiny inside. The valve has no sign of corrosion. The regulator is also clean inside.
Any ideas what this could have been?
Yesterday I was washing my tank (it had to stay one day unwashed after the dive). I have rinsed the valve (DIN) with warm water and then purged some air from the tank to dry it. At that moment I have noticed that some black stain was forming on the flat bottom of the DIN valve. The tank is new (I think it was filled ~8 times). I wiped out the dirt with a paper napkin and purged again. The stain formed again. It looked as either a very fine black (100% black, not rust or something else) powder sticking to the still wet inner surface of the valve or it could have even been liquid already (hard to tell).
Anyway, after a few air purges it ceased to apear again. I had the tank visually inspected - everything is shiny inside. The valve has no sign of corrosion. The regulator is also clean inside.
Any ideas what this could have been?