gas tank valves, CW or CCW

Is there a rule about tank valves for gas (not gasoline) about which way to turn to open and close?
The valve in question was a cheap valve for auto AC freon. (Although later I saw on tv a more expensive valve for a Hydrogen tank.)
The freon valve was supposed to pierce the top of the can by turning clockwise (CW), then one opened the little 10 oz. tank by turning CCW.
Nothing came out. My neighbor who said he fixes cars for a living but whose valves were at work told me that I was turning the wrong direction, even though I wasn't. He told me the same thing when I did it a bit later, and that's part of the reason I stoppped working on it. He told me it was the expansion valve or something.
Later when he wasn't there, I tried again, and found the tank probably had been pierced but in order to open the valve I had to unscrew it, CCW, more than 5 full turns. I had thought only a couple turns would be enough. (and originally I hadn't tighted the valve nearly as much, only 1 to 3 turns past the resistance when the needle tip met the metal top it was supposed to puncture.)
Then a couple nights ago, in a program about the burning of the Hindenberg, they showed someone turning the valve clockwise and the pressure on the gauge increasing. So maybe full size tanks with quality valves turn the opposite direction???
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As to the freon tanks, you have to turn them CW, until it won't turn any more. This is typically three or four complete turns past where you feel the pointer hit the metal.
Then, CCW, several complete turns to release the refrigerant.
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Short answer: Yes, depends on the Gas in the cylinder. There is some industry standard on compressed gases in a cylinder and which way the valve opens. I cannot find the link.
Phil
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