When is a life preserver with a CO2 cartridge not authorized in diving?

A life preserver equipped with a CO2 cartridge is not authorized for use specifically when diving under obstacles. This is primarily due to the potential hazards associated with sudden inflation of the life preserver in confined or restricted spaces. When divers are navigating under obstacles, such as rock formations, wrecks, or other submerged structures, the use of a buoyant device that inflates rapidly could lead to entrapment or injury. The swift expansion of the life preserver could also hinder the diver's ability to maneuver effectively and could create additional hazards during an ascent or while attempting to free themselves from an obstacle.

In scenarios such as diving at night, diving in shallow water, or cold water diving, the primary concerns generally relate to visibility, depth, and thermal protection rather than the immediate risk of inflating a buoyant device. While all these factors require careful consideration in dive planning and execution, inflatable life preservers are typically not prohibited in those conditions and can offer safety benefits under those circumstances. Thus, the emphasis for avoiding CO2 life preservers centers on the challenges presented in navigating obstacles underwater.