What is the purpose of the "dump valve" on a lift bag?

The purpose of the "dump valve" on a lift bag is fundamentally to allow air to be vented during ascent. This functionality is critical during the ascent phase of a dive, as it helps to control the buoyancy of the lift bag. By releasing air through the dump valve, divers can make precise adjustments to the buoyancy and ascent rate of the lift bag, ensuring a controlled and safe ascent to the surface.

When a lift bag is deployed, it can become over-inflated due to the expanding air as a diver ascends. The dump valve provides a means to let excess air escape, preventing rapid, uncontrolled ascents that could compromise safety. This controlled ventilation is essential for managing the lift bag's buoyancy and enhancing overall safety during underwater operations.

The other options, while related to lift bags, do not accurately describe the primary function of the dump valve. While the quick inflation of a lift bag is important, it is achieved through other means, such as inflating valves. Similarly, monitoring pressure and attaching the lift bag to objects involve different components and functions unrelated to the specific role of the dump valve.