How much psi does the reserve on a SCUBA bottle typically hold back?

In the context of SCUBA diving, the reserve pressure in a SCUBA tank is designed to ensure diver safety, particularly during ascent and emergencies. Typically, a SCUBA tank is filled to a maximum pressure of around 3,000 psi, depending on the tank's specifications. The reserve is the amount of air left that cannot be used for normal diving but is crucial for safely reaching the surface.

A reserve of 500 psi is a common standard in the diving community, as this level provides enough air for a diver to safely ascend, manage any unexpected situations, and complete necessary safety stops if required. This pressure serves as a buffer zone, ensuring that divers do not deplete their tank entirely during their dive, which could lead to dangerous situations.

Having a reserve pressure allows divers additional time to react in case of unforeseen circumstances, such as equipment failure or the need to assist a buddy. The specified 500 psi reserve is therefore considered effective and aligned with safety protocols within the diving community.