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As a person breathes, the body consumes oxygen and produces carbon dioxide. Base metabolism requires about 0.25 L/min of oxygen from a breathing rate of about 6 L/min, and a fit person working hard may ventilate at a rate of 95 L/min but will only metabolise about 4 L/min of oxygen [10] The oxygen metabolised is generally about 4% to 5% of the inspired volume at normal atmospheric pressure, or ...
Semi-closed circuit rebreather, also known as a gas extender: A semi-closed circuit rebreather either dumps some loop gas nearly constantly or constantly adds gas to the loop, and consequently needs an inflow of both diluent and oxygen to make up the volume. Changes in ambient pressure also require changes in the number (mass) of gas in the ...
The Lambertsen Amphibious Respiratory Unit (LARU) is an early model of closed circuit oxygen rebreather used by military frogmen. Christian J. Lambertsen designed a series of them in the US in 1940 (patent filing date: 16 Dec 1940) and in 1944 (issue date: 2 May 1944).
A rebreather is a closed circuit or semi-closed circuit breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the recycling of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the user.
The apparatus can be open-circuit (supplementary) or closed-circuit; the 1953 British Mount Everest expedition used both types. Although there is considerable similarity in the basic conditions in which aviation and mountaineering breathing apparatus is used, there are differences sufficient to make directly transferable use of equipment ...
The breathing circuit may be open, closed, or semi-closed, depending on whether breathing gas is recycled. A closed or semi-closed circuit will include components which remove carbon dioxide from the exhaled gas and add oxygen before it is delivered for inhalation, so that the mixture remains stable and suitable for supporting life.
The bailout valve (BOV) can switch to an open circuit demand valve fitted to the mouthpiece of a rebreather with a manually operated mechanism to switch from closed circuit to open circuit. The position selecting the open circuit demand valve may substitute for the closed state of a dive-surface valve (DSV) as the breathing loop is effectively ...
The word SCUBA was coined in 1952 by Major Christian Lambertsen who served in the U.S. Army Medical Corps from 1944 to 1946 as a physician. [1] Lambertsen first called the closed-circuit rebreather apparatus he had invented "Laru", an (acronym for Lambertsen Amphibious Respiratory Unit) but, in 1952, rejected the term "Laru" for "SCUBA" ("Self-Contained Underwater Breathing Apparatus"). [2]