Last Updated: April 21, 2022
A scuba tank is one of the most important pieces of diving equipment a diver will ever need. Whether you are a professional or recreational diver, you must be aware of the basic functioning of a scuba tank.
Though the scuba tank lifespan depends on several factors, on average, it will last you for an hour.
Read on to discover what determines its lifespan and how much air is in a scuba tank.
Factors That Determine How Long a Scuba Tank Can Last
Typically, if an open water certified diver goes on a 40-foot dive, they will easily last for 45 minutes with an 80-cubic-foot aluminum tank. Let’s have a look at all the factors.
1. Volume of The Tank
The commonly used 80-cubic-foot recreational aluminum tank contains 80 cubic ft of compressed air, measuring 3000 lbs psi.
The market is flooded with scuba tanks of varying materials and sizes, depending upon their use. It goes without saying that a tank with greater volume will last longer.
Read: What is the Difference Between Bar and PSI?
Generally, expert divers who undertake lengthy and deep dives require cylinders that have a larger internal volume. Whereas, novice divers who do not go very far from the surface can do well with small and compact tanks.
2. Dive Depth
Water pressure exerted on a diver increases with the dive depth. The increased pressure at greater depths adds up to create a denser environment around the diver, making it difficult to breathe.
In other words, the tightly packed air found at deeper water depths will demand more effort to breathe. Consequently, you would require more air to fill your lungs with every breath, quickly depleting the air in your tank.
At a shallow depth, a tank will last you longer. For instance, at a depth of 33 ft or 10 m, that tank will easily last you an hour. Whereas at 40 meters, you will be able to use it only for some minutes.
Interestingly, with practice, professional divers are able to have a longer supply of air using the same tank by controlling their motion and regulating their breath. Beginners, on the other hand, find it harder to breathe underwater and thus consume more air.
3. Air Consumption Rate
Another related factor is a diver’s rate of consuming air or air consumption rate.
Also known as Respiratory Minute Volume (RMV) and Surface Air Consumption Rate (SAC), it determines the duration for which air will last in a diver’s tank compared to the time taken by an average diver.
You can make use of a scuba tank time calculator to assess your SAC.
If a diver has a large lung capacity, say large or tall people, they will need more air as compared to a short or petite person, who would have a smaller lung capacity. Apart from the volume of one’s lungs, several other factors affect a diver’s air consumption rate.
These include stress, practice or experience, energy consumed while diving, and buoyancy control.
If you are looking to reduce your air consumption rate and hence increase the lifespan of your tank, you should practice slow, relaxed, and deep breathing.
4. Diver’s Fitness Level
A healthy diver with optimum physical fitness levels will have naturally relaxed muscles. This will aid the breathing process and help avoid exertion.
This is one reason why many diving certification courses include beginner’s swimming classes before allowing to dive at deeper depths.
In essence, a good body shape significantly decreases your air consumption, allowing you to experience a longer dive with just the same level of oxygen in the scuba tank.
How Much Air Does a Tank Contain?
As stated previously, one standard-sized 6.5 lbs cylinder can hold about 80 cubic ft of compressed air under a pressure of 3000 psi. Make sure to check the markings on your tank to see how much air it contains.
Scuba cylinders get differentiated on the basis of their volume level (measured in liters). A standard scuba tank when filled properly contains 200 bars or 12 liters of air. The question that arises now is – how long does 200 bar of air last?
At the most, such a tank will last you for 60 minutes at a stretch.
Having said that, you can get one which suits your requirements. Whether you need a small air tank of 10 or 12 liters or a bigger one of 15 or 18 liters would depend on how much air you require to breathe underwater.
Also read: Can Scuba Tanks Float?
Tanks with greater capacities will be able to hold more air and will last you for longer. However, you must not buy a larger tank simply because it holds more air.
In case you find the tank too heavy to carry around, it will be of no help. This implies that a diver must take into consideration their body size and physical strength while selecting a tank.
Rather than overestimating your weightlifting abilities, make a fair judgment of the weight you can comfortably carry. We’d suggest that you test the weight of your tank while on the land itself before venturing down the waters.
For recreational divers and beginners, smaller scuba tanks are a good place to start, especially so because they will be limited to shallow dives at first. Later, when they go on for deeper dives, they can opt for a larger cylinders.
Also, there is always the option to take more than one air tank underwater and switch them up when needed. It is not a difficult procedure at all, just requires some practice.
How to Make Your Tank Last Longer
Is there a way through which you can make your tank last for a longer duration?
Well, yes! In fact, this is a common concern among divers who want to stay underwater for a little while longer.
Here, experience in handling the tank and optimizing your breathing pattern plays a key role in making it last longer. However, this can come only after months of practice.
Worry not, there are a number of useful tips that you can start following right away for consuming the air from your tank efficiently.
Following are the tips to reduce your air consumption and increase your tank lifespan:
- Try to maintain a calm and relaxed state of mind and body.
- Slow down your breathing rate.
- Avoid the use of arms while swimming.
- Make use of the optimum buoyancy level to kick only when needed.
- Slow down and limit your movements.
- Try breathing out for a longer period than breathing in.
- Find your breathing rhythm. This one too comes with experience and practice and is used by most of the advanced divers.
A scuba tank is a diver’s best friend and worst enemy, depending upon how much air it has left.
An average recreational tank containing 200 bars or 12 L of air should last you for 60 minutes. However, several factors come into play while determining the lifespan of a scuba air cylinder.
The amount of air that a diver needs depends on their air consumption rate, which in turn is based on their physical exertion level. Not only that, but your diving depth also affects the lifespan of your scuba tank.
Thus, you must assess your Air Consumption Rate, volume and size of the tank, depth of your dive, and fitness level before deciding on your preferred tank.
My unbounded love for the oceans and everything it has to offer motivated me to pursue my passion and become a professional scuba diving instructor.
I keep reading, exploring, and learning more about scuba diving and the underwater world all the time, so I’m excited to share my knowledge with fellow scuba enthusiasts and hopefully contribute a little to your development as a diver. I want people to fall in love with the oceans with as much passion as I have. Read more about me here.