Page:Popular Science Monthly Volume 90.djvu/846

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Protecting Mine Rescue Workers from Gas

��A new type of breathing apparatus sup- plies oxygen in just the right quantities

��IN January, 1914, the director of the Bureau of Mines commissioned Mr. WilHam E. Gibbs, a mechanical engineer of New York City, to design a new type of apparatus for use in mine disasters.

The new apparatus has many points of superiority over those which have been used formerly. By means of a special device, oxygen is supplied to the wearer at the rate it is used. While sufficient is available when the wearer is working, none is wasted when he is resting. The harder a man works the more oxygen is necessary for him.

The flow of oxygen may be regulated by means of a valve which is very easy to operate. When this reducing valve is attached to a cylinder of gas, it is possible to admit oxy- gen to the breathing bag in the exact quantity re- quired by the user.

The new breathing ap- . paratus is constructed of x.'^^^j^" metal, with the excep- tion of a rubber gasket. All parts of the apparatus are mounted on a frame of steel tubing which is carried on the back. When in use, the entire apparatus is protected by an alum- inum cover. The oxygen is carried in a cylinder or bottle at the bottom of the ap- paratus. This cylinder has a stop valve connected with the reducing valve, from which the gas passes by way of a tube past the safety valve within the breathing bag. The safety valve has a whistle in its outlet. This whistle gives warn- ing of leakage at the reducing valve. When the wearer breathes, air from the breathing bag lifts the inhalation valve and passes through a flexible tube and mouthpiece to the

���lungs. The exhaled breath passes to the exhalation valve down a flue to the ab- sorber where it is converted, then up through the cooling can, where it loses its heat, and then into the breath- ing bag. When the supply of oxygen in the bag gets low, the flap opens the admission valve and a fresh supply enters.

The absorbing can contains twenty vertically arranged sheets of fine iron-wire gauze, held parallel to each other one-fifth of an inch apart. Before being inclosed in the can this bundle of gauze sheets is dipped into molten caustic soda con- taining twenty per cent of water. The mixture solidifies on the

��itKing

��._j5afety valve

��Reducing vaVvfe

.Carbon- dioxide absofbeK

��A mine rescue worker wearing the new breathing apparatus. The aluminum cover is broken away to show interior

���The reducing valve automatically regu- lates the flow of oxygen from the tank

��on gauze when cool, forming reinforced plates about one- sixteenth of an inch thick. This makes an absorber of carbon dioxide. The plates maintain a uniform sur- face from which the con- densed and chemically produced moisture con- stantly drains away, car- rying with it the newly formed sodium carbonate. The capacity of this absorber is practically constant, until the active material is all used.

The apparatus is completed by a pressure gage (finimeter) which is read by touch instead of by sight, because, in the dark- ness of a mine disaster, it would be im- practicable to depend on sight. This gage sounds an alarm when the oxygen in the cylin- der has been reduced beyond the point of safety.

Instead of a helmet a simple mouthpiece and nose clip are used with the apparatus.

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