How long can you stay underwater with a scuba tank?
Scuba diving is a popular underwater activity during the summer months, but it can be limited by the amount of air that you have in your scuba tank. Knowing how long you have underwater is imperative to your enjoyment and your safety, but how much time do you have?
How long can you stay underwater with a scuba tank?
A standard aluminum 80-cubic-foot tank used during a 40-foot dive allows a scuba diver to stay underwater for about 45 minutes, giving them enough time to resurface with enough air.
Although about 45 minutes is the average for most scuba tanks, there are a few factors that could affect your air consumption while you are scuba diving. Read on to find out more about the factors that could change your length of time underwater, along with safety factors that you should be aware of before even attempting your first dive.
Volume
Most scuba tanks used in recreational diving are the aluminum 80-cubic-foot tank. These tanks hold 80 cubic feet of air, which is compressed at 3000 pounds per square inch. This means that there are about 12 liters of air within a scuba tank.
Many tank sizes can be found in many different materials, even though that size is the most common. Depending on what you are doing, you could find a scuba tank with more pressurized air for a longer dive, or if you are a smaller diver, you can get a smaller tank for your own comfort.
Some divers also take two tanks—usually with about 8 liters of air each. These usually weigh about the same
Water Pressure
Because scuba diving allows swimmers to reach deeper waters than free-swimming or snorkeling, divers need to be aware of the water pressure. Because the air in the tank is already pressurized, the water pressure does not affect the air, but it does compress the air in your hoses as you try to breathe.
Being aware of this means that the deeper you go, the less air you have in the scuba tank to breathe, so understanding water pressure and your time limit is key before you head into the depths.
Need a new scuba regulator? Here are the 7 most reliable you can buy.
Air Consumption
Along with water pressure affecting your breathing time, your own personal air consumption can change how long you have under the water. While scuba divers are taught not to hold their breath, every person is different, and their air consumption could vary from person to person. When you are learning to scuba dive, make sure you understand your limits before you head out underwater.
Knowing not to hold your breath may seem counterproductive and could extend your time underwater, but it could cause severe medical problems. If you hold your breath, you seal your lungs, and when you ascend, the water pressure will cause the air pressure in your lungs to expand, and then it has no place to escape. If you hold your breath, your lungs could be damaged by the pressure alone.
Holding your breath could also affect your buoyancy. Because when you breathe, you increase your buoyancy, holding your breath can negatively affect how you move and swim.
Holding your breath also builds up carbon dioxide in your lungs, and when you breathe again, it could increase your air consumption and cut down on your time underwater.
Depending on your physical fitness, your strength and endurance could also affect your air consumption. The better you are at swimming and handling yourself underwater, the less likely you are to take in too much air and the longer you can stay under.
Nitrogen Absorption
When you descend deeper underwater, it isn’t just the water pressure that affects your air as you try to breathe. As you descend, the oxygen and nitrogen in your air supply is absorbed into your body’s tissues—while oxygen is used, nitrogen is simply stored. Your body can only handle so much nitrogen, therefore you must be aware of decompression sickness.
Also called “the bends,” it happens when dissolved gasses come out of your tissue as bubbles during decompression or depressurization, causing such symptoms as joint pain to rashes. If it happens while you are still underwater, it can cause death. This is why it is important to both understand how much air you have left and how the water pressure affects you.
Because of this potential sickness, it changes how deep you can dive and how long you can stay at that depth. Most scuba classes and educators will teach you the time limits before you head out.
Water Temperature
As you get deeper, the water gets colder, and that is another factor in your length of time spent underwater. While a wetsuit helps you trap body heat, you can still get too cold the deeper you go, which affects the way you breathe. Because your body loses heat to water much faster than you do in air, you can become very cold very quickly.
While there are several factors that affect a scuba diver’s air supply, the average is usually about 45 minutes underwater. Before you head out on your scuba diving adventure, make sure to take the appropriate classes or brush up on your skills so you know exactly how long that you personally can handle in the depths, for your own safety and your enjoyment!
RELATED QUESTIONS
How long can you keep air in a scuba tank?
Because scuba tanks are properly filtered, air should never go bad inside a scuba tank. That being said, there are several reasons the air could go bad, and it is advised not to store air in a tank for a long period of time.
What is inside a scuba tank?
Scuba tanks usually have about 20 percent oxygen, as using pure oxygen can kill you, no matter what depth you dive. Most scuba tanks use a mixture of nitrogen and oxygen, helium and oxygen, or a mix of all three. Mixing these gasses is dangerous and should only be done by a trained professional.
Please note: This blog post is for educational purposes only and does not constitute legal or medical advice. Please consult a legal expert or medical professional to address your specific needs.