Scuba Tanks: What You Need To Know

A scuba tank is a gas cylinder used to store and move high pressure breathing gas needed by a diver. These cylindrical pressure vessels when combined with a valve are available in a whole range of pressures, dimensions, and capacities.

Cylinder valves have safety features designed to burst and release pressure if overfilled or expanded by heat. K-valves simply open to allow gas flow. And close to shut it off. Y and H valves have two outlets with their own valves which allows two regulators to be attached. So, you have a failsafe if one malfunctions.

Find out more about scuba tanks: what you need to know here…

Be Scuba Savvy

See answers to frequently asked questions:

How long does a scuba tank last?

The average divers air consumption in calm waters will run a tank to almost empty in about an hour at a depth of approximately 10 metres. As this directly depends on the dive depth the deeper you dive the faster you consume air from your tank.

Professional divers can double the time through breathing and buoyancy control. And with economy of movement.

What happens inside an empty tank when it is filled with air?

When you fill an empty tank with a mixture of nitrogen and oxygen the gases will be compressed. Putting gas molecules under pressure causes a heat reaction. The more pressure your tank is put under the hotter it will become.

Accurately calculating your dive means you should never have an empty tank. If the tank does become completely void, there’s no pressure left to keep out moisture. This can cause leakage which in turn leads to corrosion. Leaving a small amount of air in the tank will allow the tank valve to be opened enough to blow out any excess moisture.

How much does a scuba tank weigh?

Steel tanks normally weigh less than aluminium tanks. As a guide, a standard 80 cubic foot aluminium tank weighs about 15.87 kilograms. A similar capacity steel tank would weigh approximately 13.60 kilograms.

What are tanks made of?

The type of material needed for your tank will depend on your individual diving needs. See a brief summary of steel vs aluminium scuba tanks:

Steel tanks

• Are stronger and more durable
• Are usually smaller and lighter
• Are higher-pressured
• Last longer due to damage resistance
• Can be prone to corrosion
• Start off negatively buoyant and stay that way throughout the dive
• May cost more but support longer dives with increased air pressures

Aluminium tanks

• Generally, weigh heavier due to thicker walls
• Typically have a standard air pressure of 3000 psi
• Are economical and easy to maintain
• Are negatively buoyant when full and become positively buoyant as air is consumed
• Are less expensive

Scuba Tank Features

Scuba tank sizes and pressure ratings determine the capacity. Tanks from North America have capacities that range from 45 to 150 cubic feet main cylinders. And six to 40 cubic feet for reserves. This translates to six to 15 litres for main cylinders. And one to four litres for reserves.

Oxygen tank sizes don’t always relate to how much air the tank can hold when full. Volume is determined by the internal dimensions of the tank. And normally measured in cubic inches or litres of water. Tanks can actually hold less air than the size description.

The smallest scuba tank is 0.5 litres with an attached regulator and pressure gauge. And is marketed as a Mini-dive. There are safety considerations to be taken into account due to lack of security straps. And just three metres is the maximum depth limit for uncertified divers.

Scuba tank pressure varies depending on whether the tank is aluminium or steel. Aluminium tanks usually hold around 3,000 psi. And steel tanks can either have a low pressure of approximately 2400 psi. Or a high pressure of 3440 psi. Within the recreational pressure terms are defined as:

Low – 2400 to2600 psi
Standard – 3000 psi
High – 3300 to 3500 psi

Scuba Tank Maintenance

Following a few simple guidelines will ensure this vital piece of dive equipment stays in first-class condition:

• Treat your tank with care to avoid damage
• Never overfill your tank
• Give your tank a freshwater rinse after each use before putting it away
• Don’t keep full tanks for any longer than three months
• Store your tank in a vertical position
• Get a professional inspection at least once a year
• Have a hydrostatic test conducted at least once every five years

Air Tank Filling Stations

The Koox Scuba Tank Fill station in Tulum, Mexico will provide you with breathable air and gas mixtures to fill your scuba tanks. All types of air tank fills are available via the air compressor – from small stage to double tanks. And your tanks will be checked to ensure they’re in a good working condition. You’ll be able to refill your scuba cylinders with high-quality Nitrox 30 and 50. Or with 100% oxygen and helium for a longer and safe dive.