Siebe Gorman Lungovox

Fire brigade & Mine Rescue Oxygen rebreather

THE “LUNGOVOX” SELF-CONTAINED OXYGEN BREATHING APPARATUS LUNG-GOVERNED TYPE

The “ Lungovox,” Self-contained Breathing Apparatus, carried wholly on the back, embodies a Reducing Valve and a Lung-governed device which control the supply of oxygen to the user according to his requirements when performing either moderate or heavy work. Instead of a constant supply of 2-litres of oxygen per minute through­ out the period of use, as given in some of the other types of apparatus de­ scribed herein, the“Lungovox” delivers a constant minimum sufficient for moder­ ate work, and responds automatically and immediately to the user’s need for more, as and when he requires it in the performance of harder work; thus the consumption of oxygen is economized. The “Lungovox” is made in two sizes:
(A) For Two Hours’ and
(B) for One Hour’s work.

With Oxygen Cylinders of light alloy steel, the total weight of (A) is 28 lbs., and of (B) 26 lbs. The apparatus, which is, of course, on the regenerative principle, uses the well-known absorbent “Protosorb” for the absorption of the carbon dioxide in the wearer’s exhaled air. An automatically-controlled relief valve prevents over-pressure (i.e., pressure over a pre-determined limit) in the breathing circuit, and thus ensures respiration with the minimum of resistance. The apparatus, which is housed in a metal protective case with hinged doors or removable cover, comprises two Refillable Canisters, containing ‘ Protosorb” CO₂ Absorbent; a Breathing Bag ; a Steel Cylinder containing Oxygen compressed to 120 atmospheres ; an Automatic Pressure Reducing Valve which delivers oxygen into the breathing bag at a fixed rate of 1,5 litres per minute, irrespective of the cylinder pressure.

An Automatic Oxygen Admission Valve—operated by a lever attached to the breathing bag—which admits additional oxygen when the wearer’s working effort demands it. When the breathing bag is emptied or nearly emptied by the wearer’s inhalation, the lever is pulled down, causing the oxygen admission valve to open. On inflation of the bag, the lever returns to the horizontal position, and the oxygen admission valve automatic­ ally closes. In addition a hand- operated by-pass, or emergency, valve is provided. This is operated by pressure of the thumb upon a button, oxygen being admitted when the button is pressed, and cut off when the pressure is released. The exhaled air passes from the mask, or mouthpiece, via a non­ return outlet valve through the CO₂ absorbent cartridge. From the latter it passes into the breathing bag, and thence by a non-return inlet valve, via a second tube, returns to the mask (or mouthpiece). An automatic relief valve is provided to permit the escape of any excess pressure of oxygen which may accumulate in the breathing bag when the wearer is standing still or doing light work. This valve, which is fitted to the breathing bag, is opened when the fully-inflated bag brings it into contact with a stop­ piece or bumper, and closes again automatically when the excess oxygen has been released and the bag resumes the correct degree of inflation. The contents of the oxygen cylinder are indicated by a pressure gauge which is carried in view of the wearer, a shut-off valve being provided for use in case the pressure gauge should become damaged.

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