Bradley granted patent – Archiviews, March 25, 1940

Bradley Granted Patent. John G. Bradley, Chief of the Division of Motion Pictures and Sound Recordings, the National Archives, has just received Letters Patent No. 2,190,229 from the Commissioner of Patents covering what appears to be a unique storage cabinet for motion-picture films. The cabinet is so designed that a fire in any one compartment (a remote possibility, according to Mr. Bradley) or from any other source will operate a water sprinkler located in the top of the flue at hte rear of the cabinet. In such case the sprinkler automatically throws a spray of water simultaneously into each compartment of hte cabinet, thus affoding instant protection to all the films stored both from a spread of fire and from excessive heat. The water thus sprayed into the compartment falls on showerproff containers holding the films, and completely encases hte containers in a thin sheet of water. In a few seconds, according to the claims, the water fills up in the bottom of each compartment and forms a "water seal" at the juncture of two overlapping baffles in the rear so that the heat from the flue or from adjacent compartments is effectively kept out of unaffected compartments. One of the principal features in this patent is the provision that keeps the water constantly moving or cascading from each compartment to the one next below it, thus the water never gets overheated and effectively carries off the heat units resulting from combustion. Mr. Bradley points out that the cabinet, although primarily designed for the storage of motion-picture films, is adaptable to the storage of any type of inflammable material--still films, documents, papers, etc. Prior to the filing of claims of this design, a total of 66 burning tests were made in which both internal fires (fires inside the cabinet) and external fires were deliberately started as a means of measuring the effectiveness of the cabinet. In the last test the cabinet was placed inside of a specially designed cubicle where approximately 1400 pounds of combustible material was piled around the cabinet and ignited. This represents a rather high concentration of combustibles and approximates the condition one would find in a burning building. The combustibles were ignited and the fire burned actively for 3 1/2 hours, after which it was allowed to diminish. The test was terminated at the end of 24 hours. The maximum temperature reached on the outside of the cabinet was approximately 1500 F; the maximum temperature reached on the inside of the cabinet, however, was only 148 degrees--a temperature considerably below the flash point of film. None of the film was damaged.

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