What is the minimum overbottom pressure required from 61-130 FSW when diving the KM37?

The correct answer is 135 psi as the minimum overbottom pressure required for diving the KM37 at depths between 61 and 130 feet of seawater (FSW). When it comes to pressure requirements for diving systems, it is critical to consider the ambient pressure experienced at depth.

At 61 to 130 FSW, the ambient pressure significantly increases due to the weight of the water above the diver. Generally, the water pressure increases by approximately 0.445 psi for every foot of seawater. Therefore, at 130 FSW, the ambient pressure would be roughly 130 feet multiplied by 0.445 psi per foot, resulting in about 57.85 psi. Additionally, to ensure proper functioning of the surface supplied diving equipment and to keep the diver safe, it’s necessary to maintain a pressure that exceeds the ambient pressure.

The requirement of 135 psi as a minimum overbottom pressure ensures that there is a sufficient margin to support the diver's breathing apparatus and to provide adequate operational control of the diving system. This allows the diver to function safely and effectively under the increased pressure encountered at those depths.

Achieving a balance in pressure management is essential for the safety of the diver, ensuring that they are neither under