Basic Tank Values for SCUBA from By The Shore SCUBA instruction

Scuba Tank Valve Types

    • Different types of air tank valves have been employed in the scuba industry over the years.

Thanks to a chap named Jacques Cousteau, the advent of the self-contained underwater breathing apparatus, or scuba as it’s commonly known, helped create a boom in the recreational diving industry. Arguably one of the most important components of the new scuba setup was the air tank, which delivered air to the diver via a valve that released air. A few types of valves have since been incorporated into air tank systems over the years.

  1. K Valve
    k-valueUnder the auspices of the U.S. Department of Transportation (and other such foreign agencies), scuba air tank valves are made from chrome plated brass, a material that’s highly resistant to corrosive environments (like the salty sea). The K valve, a rather simplistic on-off valve system, attaches to the regulator first-stage via an A-clamp type fitting. This yoke system features a outer rubber ring that acts as an external sealant to prevent air leakage. Although still in use, especially across the Caribbean and related U.S. island territories, the K is becoming a rarity. Considered a bit outdated, most K valves have since been replaced with the more stable DIN system.Din-valueDIN The Deutsches Institut Fur Normung, or DIN for short, is the German counterpart to the USDOT. The development of the DIN regulated DIN system created a much more stable link between the air tank and the first-stage. Another simplified yoke-type assembly, DIN systems allow the first-stage to screw directly into the top of the air tank. An internalized rubber O-ring helps create a tighter seal and prevent leakage. Because of the effectiveness of the DIN assembly, this type of valve rates higher at being able to handle ambient (underwater) pressures, thus is popular among divers who enjoy diving at greater depths.

J Valve

  • J-valueLess common than the DIN system but still widely popular, the J valve operates differently than the other two types of valve assemblies. A spring-operated valve automatically shuts off when pressure inside the air tank drops to about 20 to 40 Bar, or 300 to 500 psi. When pressure drops to that point, the internal pressure isn’t sufficient enough to hold the auto shutoff open, thus increasing resistance and making breathing slightly more laborious. This signals the diver that her air supply is running dangerously low. The J valve was immensely popular throughout most of the 1960s and early ’70s, since replaced with the use of the submersible pressure gauge (SPG), a unit that attaches to the first stage and allows the diver to monitor air

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