Green Valve Knobs.

[a4lod]

I have Thermo valves and am considering about changing the knobs (they aren't hard plastic, but they are not rubbery like the Sherwood knobs). On Abysmal's website they have black knobs for $10 each and green knobs for $2. Given the price difference, I am leaning towards the the green ones. Question is, what are the green one's for? I was thinking nitrox, but am unsure. Does the color matter? Comments? Thanks.

 

[Waterborne]

The color green on gas cylinders in the US is usually associated with pure O2. Sometimes people use green valve knobs and/or other markings for a higher percentage of O2 in a gas like nitrox. If I were me, and I am, I would opt for the black valve knobs. Less confusion, not necessarily on your part, between dive shops, charter boats and potential buddies. I say confusion because (key part here) some people might mistake the tanks for dedicated O2 or nitrox service. They may have issues with what you want to put in it. Not necessarily going to happen put possible. I'd just avoid the potential hassle and go with black knobs.