A 60 percent oxygen supply for medical use.

A supply of 60% oxygen with 40% nitrogen should be acceptable for most clinical purposes, since usually only low dosages of oxygen are required. The gas may be provided by means of an oxygen concentrator (Rimer-Birlec), which is a compact, transportable, electrically operated apparatus capable of providing 28 l./min. (1 cu. ft./min.) of 60% oxygen from a source of compressed air. The biological effect of the gas from the device is the same as that of 60% oxygen from a conventional source. Measurements of inspired oxygen concentration show that the 60% oxygen may be used with present-day oxygen masks to provide inspired oxygen concentrations in the range 25 to 40%; for higher inspired concentrations alternative equipment is likely to be required. The concentrator appears to be a practical source of oxygen for expeditions and out-of-the-way places. It may provide an economical supply for a ward block, and with further development should be a convenient source of 30% oxygen for domiciliary use.