A high-volume miniature air blower was developed to overcome the usual disadvantages of low ratio of flow-rate to battery drain, high initial cost, frequent shop maintenance, and pulsating flow. It consists of a two-stage blower with backward-curved impellers powered by a commercially available 1/100-hp, dc, permanent-magnet motor;at 15,000 rpm and 27-1/2 V dc, the motor draws 0.6 A. The air mover is 2-1/2 in. diam by 3-3/4 in. long and weighs about 13 oz. The entire unit can be made with low-cost, light-weight, uniform parts that are easily assembled. Brass adapters for inlet and exit ports can be made to accommodate a variety of applications.nTests of free air-flow rate and static pressure as functions of voltage from 6 to 24 V indicate the efficiency of the system and also suggest a considerable degree of versatility for different applica¬tions. Flow-rate is also shown as a function of pressure drop across the cartridge in the same voltage range for five typical respirator cartridges as principal source of system resistance. The blower is now in use as the air mover for a portable air-sampler and as a source of pressurized, filtered air for a full-face mask respirator. Its low cost, efficiency, compactness, and toughness should permit a wide range of applications.
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