Final Answer:
Scuba tanks should always have pressure in them to ensure a diver's safety underwater. The pressure in the tank allows the diver to breathe by delivering air to the regulator consistently. Without pressure, the regulator cannot supply air, jeopardizing the diver's ability to breathe and navigate safely underwater.
Step-by-step explanation:
The fundamental reason scuba tanks must maintain pressure lies in the mechanics of the diving process. A typical scuba tank contains compressed air, with an average pressure of around 3000 psi (pounds per square inch). This high-pressure air gets regulated through the scuba diving regulator, which reduces the pressure to a breathable level as the diver inhales. A diver's inhalation draws air from the tank, and the pressure difference between the tank and the regulator allows a continuous flow of air.
Consider Boyle's law, which states that the pressure of a gas is inversely proportional to its volume at a constant temperature. As a diver descends underwater, the surrounding pressure increases. The scuba tank must maintain pressure to counteract this external pressure and ensure a steady flow of air to the regulator. Without sufficient pressure, the regulator cannot deliver air to the diver effectively. Thus, an empty or low-pressure tank compromises the diver's ability to breathe and function safely underwater.
Moreover, calculating the remaining air in a tank becomes critical for dive planning. Divers estimate their air consumption rate to gauge the duration of a dive. An empty tank prematurely ends a dive, potentially causing dangerous situations. Therefore, the necessity for pressure in scuba tanks isn't merely about breathing but also crucial for determining dive durations and ensuring a safe return to the surface.