What is the required air supply for surface supplied diving?

For surface supplied diving, the required air supply is typically established to ensure that the diver has sufficient breathing gas available for safe operations underwater. The correct choice of 1.4 acfm (actual cubic feet per minute) is derived from industry standards and practices, which take into account the physiological needs of the diver as well as safety margins for various diving conditions.

When determining air supply requirements, factors such as the depth of the dive, the diver's workload, and the duration of the dive play critical roles. At greater depths, the pressure increases, which can lead to increased breathing rates; hence, a higher air supply is necessary to maintain safety and comfort.

1.4 acfm is recognized as a suitable baseline for most applications, considering divers may experience varying levels of physical activity. This rate offers a balance that supports activities without risking hypoxia or running out of air prematurely.

In contrast, the other values, while they could appear plausible, generally do not meet the consensus safety standards for the conditions that surface supplied diving often involves. Therefore, 1.4 acfm not only meets the minimum physiological requirements but also provides an adequate buffer to accommodate different diving scenarios.