International projectionist (Jan-Dec 1950)

but the real danger lies in the presence of nitrogen dioxide and its polymer. The maximum safe concentration is stated in Van Nostrand's Scientific Encyclopedia to be 0.04% in air by volume for carbon monoxide, and 0.003% for nitrogen dioxide (tetroxide). Nitric oxide is not involved in film fires, since the air immediately oxidizes it to nitrogen dioxide. Innumerable cases are on record of projectionists being burned to death, asphyxiated, and fatally poisoned by exposing themselves to burning film and to the fumes thereby produced. The poisonous action of nitrogen dioxide is especially insidious in that the immediate effects may not indicate to the injured person that he is in grave danger. Several hours may elapse before the onset of the acute symptoms (extreme shortness of breath and weakness caused by the presence of nitric acid in the lungs and nitrates in the blood). Suggested Course of Action Alert projectionists have been known to prevent bad film fires by snatching the burning film from the upper fire valve before the flame can spread to the reel of film in the magazine; and occasionally we hear of some intrepid, but foolhardy, soul who is lucky enough to succeed in putting out a small film fire by squirting a carbon-dioxide extinguisher on the nascent conflagration. Such attempts are permissible if — and only if — the projectionist actually sees the start of the blaze and allows himself no more than five seconds to extinguish the fire. If the fire is not out at the end of five seconds, not even the most heroic efforts will be of avail. In practically every case of film fire, however, the projectionist is strongly urged not to attempt fighting the blaze. It is not his duty to do so; and enlightened fire officials recognize this fact by prohibiting fire extinguishers in projection rooms. In the event of fire the projectionist should: 1. Switch on the HOUSE LIGHTS. 2. Drop the PORT SHUTTERS. 3. GET OUT of the projection room. Other emergency steps, such as closing the douser, shutting off the arc light, or stopping the projector motor, are comparatively unimportant. The projectionist's first duty in the event of fire is to protect his own person. Acetate Film No Hazard Acetate film (high-acetyl safety film) poses no fire hazard whatsoever. Safety film will burn in a feeble manner if the combustion is assisted by gently fanning the film; but as a rule a burning roll of safety film cannot be kept burning without the continuous application of heat from an external source. Your Red Cross Needs Help — Give Generously High-acetyl safety film contains no nitrogen, and it produces no poisonous nitrogen oxide when it burns. Without emulsion it burns about as paper does; but the emulsion-coated acetate film burns much less readily than paper. When nitrate films are completely replaced by prints on safety film, and the use of nitrate prints outlawed, there will be no reason in the world why any special fire precautions should be observed in the projection room. During the period of transition from nitrate to acetate, however, projectionists and exchange workers must be on their guard against carelessness. All prints should be suspect unless known posi tively to be acetate film throughout their entire length. To quote a publication of Eastman Kodak Company:6 Identification of Film "The manufacturers print their company name together with the words 'Safety Film' between the perforations and one edge of the film. This is not visible until the film is developed. Then it shows up in sharp black letters. "Inexperienced people are often misled, however, because of the fact that in motion picture work images are transferred from one film to another. Thus the lettering that appeared on the negative film in black would appear on the positive in white. This makes it possible for the words 'Safety Film' actually to be printed on nitrate film. "The one sure test is the burning test . . . "A single frame should be cut from the roll. This piece of film should be taken to another room where there is no fire hazard. It should then be ignited with a match. "Anyone familiar with the way nitrate film burns can immediately tell whether it is nitrate or acetate. Nitrate film burns fiercely; while acetate film burns quietly, and may even go out of itself. A glowing cigarette can burn a hole in acetate film without igniting it, while nitrate is almost always ignited." [To be Continued] 0 "Questions and Answers on Safety Film"; IP for September 1949, p. 14. How Many? Was this copy dog-eared when it came to you? How many men read it ahead of you? You would receive a clean, fresh copy if you had a personal subscription — and you wouldn't have to wait — you would be first to read it. Use coupon below. INTERNATIONAL PROJECTIONIST. 19 West 44 St., New York 18, N. Y. □ 1 year— 12 issues— $2.50 □ 2 years — 24 issues — $4.00 Foreign and Canada: Add 50c per year. Enter my subscription for Name Address City State 34 INTERNATIONAL PROJECTIONIST • February 1950