The motion picture projectionist (Nov 1931-Jan 1933)

January, 1932 Motion Picture Projectionist 27 Reducing the Fire Hazard By Jerome J. Greilsheimer Nitro-cellulose film, as we all know, is highly combustible and its handling requires constant vigilance. To the enduring credit of the projectionist fraternity it may be said that it has to a man always recognized its responsibility in this respect. The marked absence of serious fire bears ■irrefutable testimony to the fact. In the following article the author describes a series of tests conducted by the Underwriters' Laboratories to determine the properties of a new type of film cabinet and its adaptability as an aid in the prevention of film fire. Mr. Greilsheimer is president of the Film-Safe Corporation. — The Editor. THE safe storage of motion picture film even in small quantities and for short periods of time has always presented a serious problem, but its terrifying possibilities can be fully appreciated only by the projectionist who has experienced a film fire of even limited size. Nitro-cellulose film, such as is now in universal use throughout the moving picture world, is usually stored either in sheet metal lockers with vents and sprinklers, or in the case of large quantities, in concrete vaults which are equipped with sprinkler systems or vented. Neither method has proved efficient in preventing film fires, because of the great mass of film concentrated at one location with no means of isolating fires to small quantities of film. Experience has shown that the gas given off from large quantities of film becomes ignited and explodes with terrific force. Problem of Storage It is obviously difficult or impossible to store and handle material as intrinsically hazardous as motion picture film without risk and the realization of this fact has led to the design of film vaults which furnish considerable protection. It is manifestly difficult, however^ to construct vaults at all locations where film is handled. In many places, such as motion picture theatres, the amount of film being used or in storage is not sufficient to justify the cost of a vault. In case where vault storage is provided, the loss of time incidental to obtaining film from and returning it to the vault encourages the accumulation of considerable quantities of film outside the vault with little or no protection. The solution must, therefore, be found in some form of cabinet which will permit the film to be stored in a position where it may be easily handled and which does not require a large initial expenditure, additional cabinets being obtained as needed. The requirements of such a cabinet Fig. 1. Sample Before Test may be roughly enumerated as follows: First — That film not exceeding 10 pounds be stored in individual insulated compartments, sealed tightly with automatically closing and latching doors, each compartment individually ventilated through an automatic pressure relief valve to a duct which leads to the outside air. Second — That burning reels in the compartments described will not communicate sufficient heat through the partition dividing it from its adjacent compartment to ignite nitro-cellulose film in that compartment, although reels of film may be burning on either side of it, Third — That only a minimum amount of gas escape around the joint of the self-closing doors and the quantity that does escape must offer no hazard to those near it, either from suffocation or from explosion. Fourth — That external fire similar in degree of temperature to that shown by a standard fire curve will not cause explosion or in other ways add to the force of such a fire. Fifth — That any quantity of film may be stored in the device, not to exceed 10 pounds to the compartment. Sixth — That when the device is submitted to the Standard Fire, as established by the National Board of Fire Underwriters, the film will not be ignited at one time and that there be an interval of one minute or more between the ignition of the individual reels of film. In this manner it is impossible for quantities of film to become ignited at once through external fire. Construction Details A film cabinet designed to meet these rigid requirements presents no inconsiderable task, but that the obstacles have been overcome is amply demonstrated by the fact that such a cabinet has been submitted to exhaustive tests, conducted by the Underwriters' Laboratories with highly gratifying results. A brief description of the nature of these tests as outlined in the Laboratories' Report will prove interesting, not only as an indication of the excellence of the equipment under test, but also as an indication of the painstaking thoroughness of the Laboratories' methods. Compartments Vented The film cabinet is of unit construction. It is made in two sizes: one style for the storage of 1,000-foot or approximately five-pound reels in each compartment, and the other for the storage of 2,00Q-foot or approximately ten-pound reels in each compartment. Fundamentally each cabinet consists of an insulated metal container divided into insulated compartments, each compartment designed to hold a single roll of film and individually vented to a common flue which opens into a hood. This hood is in turn connected with a smoke vent leading to the outer air. The films are suspended in a film carriage, which is automatically moved forward when the door of the compartment is opened. The door of each compartment closes and latches automatically. Sectional in Design The cabinets are designed to rest one on the other and provide storage for considerable quantities of film, provision being made for fastening the cabinets together somewhat like sectional bookcases. The manufacturer ordinarily provides the metal base designed to raise the cabinets off the floor and the hood for the top. The vent pipe is usually provided by the purchaser. Specifically, the cabinets are intended for the storage of nitro-cellulose moving picture film in motion picture booths and at other locations where it is necessary to have a limited amount of film on hand and the use of a vault is impossible or inconvenient. The investigation described in the following paragraphs was conducted by the Underwriters' Laboratories. It was planned to furnish data on which to base an opinion regarding