In many parts of the world, rental tanks available to SCUBA divers are made from aluminum. Lack of corrosion capabilities and lower initial investment are two main reasons dive shops and resorts choose to use aluminum tanks instead of steel tanks. Since dive shops and resorts occasionally have to do “hot fills” to keep up with demand or are filling in moist environments, there is a greater opportunity for moisture to enter a tank, which could create more issues in a steel tank.
However, if you are looking to purchase your own tank and know your dive center provides quality slow fills, here are a few reasons why you may want to consider a high pressure steel tank.
More Air in a Smaller Package
High pressure steel tanks typically hold roughly 3400 psi, while normal aluminum tanks max out at 3000 psi. Therefore, given exact same tank volume, you are actually getting an extra 400 psi. Also, high pressure steel tanks are typically a slightly larger diameter than aluminum tanks, but they are a shorter height. So if you’ve had issues trying to place large aluminum 80 cubic foot tanks where they don’t hit your head or the back of your legs, a high pressure steel tank may help to fix those problems.
Use Less Lead
Steel tanks weigh more than their aluminum counterparts, but since they stay negatively buoyant throughout the dive–aluminum tanks become more buoyant the less full they are–you can reduce the weight you carry on a weight belt or in your BCD.
Disadvantages to Steel
While most divers who move to high pressure steel tanks swear they’ll never go back, there are a few items to keep in mind when considering switching. First, high pressure steel tanks are more expensive than either aluminum or low pressure steel tanks of similar sizes. Second, you will need to convert your regulator to a DIN setup to take advantage of the full high pressure. Lastly, you may run into situations where dive shops either can’t or won’t fill to the full high pressure, sometimes simply due to unfamiliarity with high pressure tanks. Regardless of these hitches, many people who switch to high pressure steel tanks do their best to avoid anything else for the rest of their diving career, and happily claim the price is worth the benefits.
