nd its pressure of from 1,500 to 2,500 pounds per square inch. are worked by the low-pressure pneumatic system. With employment in non-gaseous mines are almost as potent. The combination regulator and automatic stop-valve this no electric power is required, the electro-magnet at A rather unique… … half-inch pipe from the. the pressure may be increased cabin. by immediate adjustment to In the operating pipes the 150 or 160 pounds. Not only pressure is 15 pounds per is the regulation of air be- square inch. When a switch tween the high-pressure and we a. or signal is not in use, its…
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