Why we need a pressurized tank (Boyle’s Law)

By: Miranda, Aliny & Vanessa

What is Boyle’s Law? Boyle’s law indicates that pressure is inversely proportional to volume. As pressure increases, volume decreases, and vice versa.

Boyle’s Law:

P₁V₁=P₂V₂

The diagram on the left demonstrates that as pressure is exerted, gas is being compressed into a smaller area to fit more of it into the given space.

Robert Boyle

- As all of you may know, scuba divers require an immense amount of air in order to descend further into an area where air is unavailable.

- Scuba tanks are carried by divers since it can store and provide air for the them. Scuba tanks are usually produced by aluminum or steel and can altogether hold 200 to 300 atmospheres of pressurized air.

- Those scuba tanks need to be pressurized in order to:

• Provide enough air for the diver

• Prevent the tank from collapsing

Pressurized tanks provide enough air for scuba divers

As the tank is being pressurized, the volume decreases in order to fit additional air into the smaller space. This benefits the scuba diver because with the additional amount of air, the diver can go deeper in depth and can also stay under water for a long period of time. Moreover, the continuous air supply from the pressurized tank can help our lungs inflate and deflate regularly, allowing us to breathe properly.

Referring to the diagram above, high pressure causes low volume, allowing additional air to fit into the tank, whereas low pressure does not have much room for air to fit into the tank.

Pressurized tanks prevents itself from collapsing

The further you descend, the more pressure will be gained by the tank. If the tank was not pressurized, it would not be able to handle the increased pressure and will eventually collapse because the pressure inside the tank is not the same as the pressure of the surrounding water. When you breathe from a pressurized scuba tank, you breathe air at the same pressure as the surrounding water. Without the pressurized tank, the diver would have difficulties breathing because the air he is inhaling is pushing out at a different pressure as the air around him.

When you push against a wall, the wall does not react because the wall is exerting the same force as your hands, similar to the idea of inhaling and exhaling air at the same pressure as the surrounding water.

How does Boyle’s law apply to scuba diving?

Boyle’s law affects scuba diving in many ways. It explains the role of pressure in the aquatic environment. As divers descend, the water pressure surrounding them increases, causing air in their body and equipment to have a smaller volume. As divers ascend, water pressure decreases, causing their body and equipment to expand to acquire a greater volume. Furthermore, it is crucial that a scuba diver never attempts to hold their breath when immersed in water. According to Boyle’s Law, if a diver attempts this when they ascend to a body of water of less pressure, then the air that is trapped in their lungs will over-expand and rupture. This is known as Pulmonary Barotrauma.

It is important for scuba divers to exhale as they ascend because the external pressure changes.