Facts About Scuba Tanks

There are many facts about scuba dive tanks that should be taken into consideration when researching which one is best for you:

1. Tanks are comprised of the same type of air mixture that we breathe on land, which is about 21% oxygen and 79% nitrogen. Pure oxygen can be lethal, particularly at shallow depths. This compressed air mixture will not become perilous until you have surpassed 200 feet.
2. The average recreational scuba dive tank is aluminum and contains 80 cubic feet of air and is generally filled with approximately 2500 psi of air pressure. They are regulated by US and foreign agencies to maintain the utmost safety standard for the diver. They must frequently undergo inspection and pressure tests to make sure they are safe to use.
3. Always fill your tank at a reputable dive shop and make sure their intake pipe is in its proper location. Air will expand in hot conditions so never leave a filled tank inside of a vehicle on a warm day.
4. The transportation of a scuba tank is vital to the way it propels. Be sure the tank valve is facing the passengers and they keep a close watch on it at all times while the car is in motion. Damage to the valve could cause it to mobilize in the wrong direction.
5. Always check the gauges to be certain plenty of air pressure is present. Write the psi down for easy recollection and then there should be plenty of air remaining when the dive ends.

High Pressure vs. Low Pressure

Most scuba tanks range from 2640 psi to 3500 psi. The tanks on the lower end of the pressure spectrum tend to be favored by Nitrox and technical divers. They use partial pressure and mix gases. The higher pressure tanks are ideal for the recreational diver as these tanks are more compact. For overall dependability, high pressure tanks have more strain on the regulator and valve pieces thus causing a greater likelihood of failure. Also, the when water seeps into the interior of the tank, it will cause it to erode at a faster rate at high pressures compared to low pressures

The concept of overfilling a tank is common in the professional diving community with low pressure tanks but this occurs rarely with high pressure tanks. The benefit to this is an increase of volume in 2640 to 3000 psi tanks. Most tanks are unable to obtain much more than 3500 psi and there is not a volume increase. Also, it is nearly impossible to overfill high pressure tanks because of the heat caused by the significant amount of gas.

The best scenario would seem to be high pressure tank to be under filled to around 2800 psi. This is enough gas for most dives, it will not put a strain on the equipment, and if more gas is needed there will not be a problem with capacity.

How To Choose the Perfect Tank

There are many things that must be taken into consideration when choosing the dive tank that is best for you:

1. Size of the tank - This is very important to consider for the utmost comfort while diving. The diameter is rarely an issue. The length is what causes the most grief. You should be able to carry it without dragging it across the dock. If you cannot do this, more than likely the tank is too heavy. Also, you do not want a tank valve that continuously hits your head and or bounces off of your rear end at the same time. Be sure the tank of your choosing is fitted properly to your body, otherwise each trip you make underwater may be extremely unpleasant!
2. Air capacity should also be considered when choosing the best tank. This is based mainly on body size and the dive objective. A larger tank of around 100 cubic feet may be necessary for those who wish to stay under water for long periods of time. They are also ideal for a larger body type. A smaller 50 cubic foot tank would be best for a more petite framed diver who desires a shorter dive.
3. Lastly the cost of the tank and what your personal budget will permit should be analyzed. For those with less wiggle room in their bank account, an aluminum dive tank may be your best option. If you can afford to part with a little more money, steel tanks might be the way to go. You can find a good tank on almost any budget but the important thing to remember is to take proper care of the tank so that repairs and maintenance will be infrequent.

Steel Tanks

Steel dive tanks have historically been much heavier than aluminum. Steel is much more durable and less prone to rupture or puncture. The threads on its neck are such that you will be less likely have to utilize the regulator kit for part replacement.

Aluminum creates aluminum oxide in the same way that steel rusts into the form of iron oxide. This occurs when any water or humidity infiltrates the interior of the tank. It is not dangerous to your health but must be maintained frequently to eliminate contaminants. 

Steel tanks do not have the positive buoyancy issues that aluminum has but they operate at higher pressures. Sometimes they cannot be filled in certain dive operations.

Lastly, the steel tank is more costly than the aluminum, up to twice or three times the amount of aluminum tanks. Sure, they are more durable but the pros and cons of each type of tank are about equal. As with any purchasing decision, it is important to look at your unique needs as it pertains to scuba diving. All tanks can have a reasonable shelf life as long as they are taken care of and not abused on diving missions.

Taking Care of Your Tank

There are a few do's and dont's to ensure the life of your dive tank:

1. Wash the interior and exterior with some fresh water. Sand and saltwater can accumulate on the valve knob and the o-rings can deteriorate and crack. It is important to rinse everything out after each dive so that buildup will not cause degradation of the tank.
2. Do not leave your tank (or any of your scuba gear for that matter) lying in the sun. This has a drying effect and will diminish your tanks capacity. They should be stored in an upright position, in a cool dry place at full working pressure so that no moisture compromises the cylinder.
3. Have your tank hydrostatically tested every five years to be sure tank walls are intact. Inspect air cylinders on a regular basis and open valve after each use to release moisture build up.

The Aluminum Tank

The aluminum dive tank is one of the most common types of tanks used on scuba diving expeditions. They are very light compared to other types of tanks. The drawback to this is that more effort must be placed in switching them between each dive. Their buoyancy tends to be positive which must be compensated for by including weights.

Aluminum tanks are less expensive than most and are widely available in most dive shops. They do need to be taken care of every so often in order to clean out any contaminants that may have accumulated. The nature of aluminum is that is can deteriorate and create aluminum oxide. It does not pose any health risks yet it is important to maintain the life of your tank for as long as possible. 

The majority of aluminum tanks hold approximately 80 cubic feet of compressed air. There are other sizes ranging from 50 to 100 cubic feet depending on the physical size of the diver as well as how long the dive is, timewise. 

Always remember that any dive, tank regardless of what material it is made of, can be useful for many many years of diving. All it takes is proper care and maintenance, and keep in mind that a tank must be chosen to suit your specific, individual dive needs.

What To Look For When Renting A Tank On Vacation

Some people simply don't want to buy all the equipment necessary for scuba diving because they do not partake that often. In fact, it is really most wise to rent equipment if you dive less than once or twice a month. The most common of course is the Aluminum 80 tank but depending on where you are on vacation, you may have more options at your disposal. There are a few things that must be checked before renting any tank for your dive expedition:

1. Check the O-ring- Look for cracks and listen for leaks. You can even bring your own as a just in case because they are inexpensive.
2. Submerge the tank in water to check valve to tank seal. If you see bubbles, there is a leak so be sure to ask for another tank and test it the same way.
3. Check to see if the valve action is easy to turn. If not or it is slippery or sticky it likely needs to be repaired but if there is not a leak, there should not be a problem.
4. Check the overall appearance of the tank. It may look a little dingy or like it has lots of wear and tear but there is nothing to worry about unless there is a deep gash.