HUMAN LIFE AND DEATH AT HIGH PRESSURES

Abstract

MEN are exposed to high pressures in a number of circumstances. They may be working in compressed air in a caisson or diving–bell, working under water in a diving dress, or attempting to escape from a sunken submarine. In the latter case it is obviously necessary that the air pressure inside a part of the ship should be equal to that of the water outside before a man emerges. This can be achieved either by flooding a small escape chamber holding only two men, or a whole compartment of the ship. Men have escaped by both these methods. They can rise through the water either holding their breath or breathing from a Davis submarine escape apparatus. The former method is not to be recommended, but it is not quite so hazardous as it sounds, for a lung–full of air at 5 atmospheres contains as much oxygen as a lung–full of oxygen at atmospheric pressure, and will allow a man to hold his breath for more than twice the normal time. The Davis submarine escape apparatus consists of a rubber bag and a soda–lime canister to absorb carbon dioxide. The bag is filled with oxygen from a small cylinder of the compressed gas. It has the advantage over air that it can be used almost to the last dreg. We shall come to its disadvantages later.