Dating to 1968, “The Care and Use of a Permissible Flame Safety Lamp” was one of a series of training films produced by the Bureau of Mines. A safety lamp is any of several types of lamp that provides illumination in coal mines, and can also be used to detect the presence of dangerous gas and/or the deficiency of oxygen. The permissible gas safety lamp is specially designed to operate in air that may contain coal dust or gases, both of which are potentially flammable or explosive. These lamps were developed to enclose a flame without extinguishing it, thus preventing it from igniting the surrounding atmosphere. In modern times, flame safety lamps have been replaced sealed, explosion-proof electric lights.

According to this film, flame safety lamps were occasionally the cause of coal mine fires in the 195-60s. A chart shown at (2:50) indicates taht over a 13-year period, there were 13 ignitions caused by safety lamps — a small number when compared to the 66 caused by electrical arcing, but still a concern. These incidents were apparently entirely preventable, and were linked to defective or poorly maintained lamps. At (3:10) lamps are tested for defects, with the defective lamp causing a small gas explosion that knocks the top off the testing device. At (3:50) a wire mesh screen sheet is shown being used above a Bunsen burner. At (4:05) the history of the permissible flame safety lamp is discussed. At (4:16), two miners who are smoking cigarettes in a coal mine, are killed by a gas explosion. At (5:13) a book is shown with a portrait of Sir Humphry Davy, one of the inventors of the flame safety lamp. Also credited is George Stephenson, and Dr. William Reid Clanny. At (5:35) a gas safety lamp is used to detect the presence of methane in a mine. At (5:40) a variety of antique lamps are shown. At (5:53) the interior of a coal mine is shown, with lamps being used to detect any deficiency of oxygen. At (6:20) a fine wire mesh screen is shown being used over a bare flame. The screen provides protection in that the flame cannot penetrate the mesh, unless it gets overheated. At (6:37) an early type of flame lamp is shown in use in a re-enactment of an early 1900s type mine. At (6:50) research by the Bureau of Mines with lamps is shown in a laboratory. At (7:37) one of eight rigid tests is shown, which each lamp has to pass in order to be certified. At (9:06) a drop test is performed. At (10:36) kerosene or a similar fuel is put into a lamp, to demonstrate that it can burn for sufficient time. A bonnet deformation test follows. At (11:17) permissible gas safety lamps are subject to maintenance, with a special focus on the condition of the all important wire mesh (14:00). At (16:24), serviced lamps are tested for flame leaks or other issues that could result in an explosion or fire. At (17:13) a broken gasket is discovered in a lamp. At (17:42) methods of proper operation are demonstrated, including how to use the lamp properly to discover the presence of methane in a mine. At (21:36), one of the lamps is dropped in a mine. The narrator points out that it must be relocated outside the mine to be relit. At (22:10) changes in the flame in a lamp are shown, which demonstrate a lack of oxygen. At (23:05) an older methane gas detector is shown, as well as a more modern detector. At (24:00) a mining machine is shown in operation, with a methane detector in place to continuously monitor the presence of gas. At (24:50) an African American employee of the Bureau of Mines is shown demonstrating a smaller, experimental detector. The film ends with a recap of the information presented, including proper use and maintenance of the permissible flame safety lamp.

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