The plungers are 31⁄2 inches diameter and 51⁄2 inches stroke. The pump and motor are mounted upon a rigid box girder frame: this unit is self-contained and occupies a relatively small floor space.
Electric Drive for Fire Pumps. The importance of instantly operating fire extinguishing apparatus can scarcely be exaggerated. The largest conflagrations are but little flames at the beginning, and if caught at the critical moment they make no record of destruction; for such service the electric current is the ideal agent. A notable installation of electric-driven pumps for fire service is in the Marshall Field store, Chicago, a building occupying an entire city block. The outfit consists of a Laidlaw-Dunn-Gordon duplex Underwriter pump connected by single reduction gearing to a waterproof electric motor.
Fig. 242.
The pump cylinders, 8 × 12 inches, have a computed capacity of 700 gallons per minute at 140 pounds water pressure. The pump, besides its other special features, is claimed to be rust proof throughout so that it will not get out of ready running condition.
Fig. 243.