of the cartridges or case. No loose cartridges or detonators should be left lying around; they should be kept in a closed container. Explosives should be stored apart from all other material, especially detonators, electric detonators, carbide, and flammable materials. Accidental ignition of detonators might detonate explosives; and tools and materials other than explosives should be kept out of magazines to minimize the need for access to magazines by more persons than necessary as well as to permit proper explosives storage without the complications and probable occurrence of accidents by handling tools within magazines. FUSE Safety fuse, detonating fuse, or blasting supplies may be stored with either explosives or detonators. Fuse should be stored in a dry, cool place; the ideal storage temperature is between 45° and 70° F. Fuse stored in a damp place is likely to absorb enough moisture to delay its burning speed or even to prevent its burning. If the fuse is dried out before using, the normal burning speed may be slowed and, worst of all, become irregular; irregularity obviously tends to increase the chances of misfires and of the spoiling of rounds due to charges exploding out of the intended order. This latter condition may result in cutting off the drill holes, leaving unexploded dynamite in the bottoms of the holes and possibly in the muck pile. If fuse is stored in a hot place, the waterproofing may become soft and sticky and may penetrate the powder train, thereby slowing the burning speed and making the fuse irregular or even damaging the powder so that it will not burn at all. On the other hand, too much heat may dry the waterproofing so that it will crack and render the fuse useless for damp or wet work. Cracked fuse may also result in side-flashing as the fuse burns, causing misfires or premature shots through ignition of the dynamite. The arrangement of stored fuse should facilitate the use of old stocks ahead of new stocks, thus avoiding accumulations of extremely old fuse, as the waterproofing coats tend to lose their elasticity and become brittle with age. Such conditions are almost certain to have an adverse effect on the efficiency of the fuse when used. If fuse is allowed to come into contact with oils, paints, kerosine, gasoline, distillates, or similar solvents, these substances may penetrate the powder train and cause it to fail completely or to burn with irregular speed. CONSTRUCTION OF MAGAZINES In the administration of the Federal Explosives Act, the Bureau of Mines has approved certain types of storage magazines and has recommended standards of construction, location, and operation of magazines that fulfil the requirements of the act affecting safety. The recommendations thus made respecting storage are: PERMANENT MAGAZINES FOR EXPLOSIVES All high explosives in amounts exceeding 125 pounds should be stored in permanent magazines which are theft-resistant, fire-resistant and bullet-resistant. A 9 Federal Explosives Act of December 26, 1941 (55 Stat. 863) as amended. pamphlet containing the act, the regulations issued thereunder and certain recommendations for storing, handling, and transporting explosives may be obtained from the United States Bureau of Mines, Washington 25, D. C., or from regional offices of the Bureau. 1. Construction of permanent magazines. Permanent magazines should be of a building type, an igloo or army type, a portable type, or a tunnel or dugout type, whether located on or exposed to the surface or underground. Walls of building-type magazines should be substantially constructed of theft- and bulletresistant materials and should meet the following standards or be constructed of other materials in a manner which will make them at least FIGURE 2.-Surface storage magazine, brick construction. equally theft- and bullet-resistant: a. Solid construction, not less than 6 inches in thickness of materials such as concrete, masonry, medium-soft brick (fig. 2), or wood; or b. Filled construction, such as concrete blocks with the cells filled with screened sand, weak concrete, cement mortar, or other effective bullet-resistant filler; or exterior and interior wooden walls not less than 6 inches apart with the space between filled with screened sand, weak concrete, cement mortar, or other effective bullet-resistant filler, and the exterior walls covered with sheet iron not lighter than No. 26 gage, or other fire-resistant material; or c. Lined construction, such as steel not lighter than No. 14 gage, lined with weak concrete, cement mortar, brick, or screened sand not less than 6 inches in thickness, or with hardwood not less than 2 inches in thickness or with softwood not less than 3 inches in thickness. The same standards should govern the construction of any artificial enclosing wall for tunnel- or dugout-type magazines on or exposed to the surface of the ground. Any artificial enclosing wall for permanent underground magazines should be substantially constructed of wood not less than 2 inches in thickness or of other material of equivalent or greater strength. Foundations of building-type magazines should be substantially constructed, and any space between the floor and the ground should be enclosed in such a manner as to prevent the entrance of persons, animals, sparks, and firebrands. Roofs of building-type magazines should be fire-resistant and substantially constructed to resist theft, as for example, by 3/4-inch sheathing covered with sheet iron or slate. Roofs not constructed of fireproof material should be covered with sheet iron not lighter than No. 26 gage or other fire-resistant material. The roofs of magazines so located that it is possible to fire bullets directly through the roof into the explosives should be made bullet-resistant by material of construction or by a ceiling that forms a tray containing not less than a 4-inch thickness of sand or other equally effective bulletresistant filler erected in the interior of the magazine, or by other methods. Doors of magazines on or exposed to the surface of the ground should be constructed of 3/8-inch steel plate lined with a 2-inch thickness of wood; or of a thinner steel plate with a greater thickness of wood, at the rate of 1 additional inch of wood for each 1/8-inch decrease in the thickness of the steel plate; or of wooden walls at least 4 inches apart and filled with screened sand or other effective bulletresistant filler, the exterior being covered with sheet iron not lighter than No. 26 gage, or other fire-resistant material; or of wood not less than 6 inches in thickness; or of reinforced concrete not less than 4 inches in thickness. Doors of magazines located underground should be substantially constructed of wood not less than 2 inches in thickness or of other material of equivalent or greater strength. Doors of permanent magazines should be equipped with mortise locks; or with padlocks fastened in strong hasps and staples; or with a three-point lock. Padlocks and mortise locks should be the equivalent of five-tumbler jarproof locks. Doors should be provided with strong hinges, hasps, and staples attached by welds, by rivets, or by bolts fitted with lock washers and nuts on the inside of the magazine and installed in such a manner that the fastening cannot be removed when the magazine is locked. Magazines should have no openings, except for entrance and ventilation. Foundation vents should be of an offset-type construction, and all vents should be effectively protected with metal screening or otherwise constructed to prevent the entrance of persons, animals, sparks, or firebrands, or the direct penetration of bullets that can detonate the explosives. 2. Marking of premises. The premises on which a permanent magazine is located should be conspicuously marked by signs containing the words "ExplosivesKeep Off. No signs should be placed on surface of magazines or be so located that a bullet passing directly through the face of a sign will strike the magazine. BOX-TYPE MAGAZINES FOR EXPLOSIVES High explosives in amounts of 125 pounds or less should be stored in permanent magazines or in box-type magazines that are theftresistant. 1. Construction of box-type magazines. Box-type magazines should be strongly constructed of 2-inch hardwood or of 3-inch softwood or other equally theft-resistant material. Any metal magazine should be lined with a nonsparking material. Doors or lids should be provided with strong hinges, hasps, and staples attached by welds, rivets, or bolts fitted with lock washers and nuts on the interior of the magazine and installed in such a manner that the fastening cannot be removed when the magazine is locked. Boxtype magazines should be equipped with a lock equivalent to a fivetumbler jarproof lock. 2. Marking of magazines. Box-type magazines should be painted a distinctive color and clearly and conspicuously marked "Explosives." DETONATOR MAGAZINES 1. All detonators in numbers of 1,000,000 or more should be stored in permanent magazines complying with the standards given. 2. All detonators in numbers of more than 5,000 but less than 1,000,000 should be stored in permanent magazines complying with the standards set forth, except that magazines need not be bullet-resistant. Any metal magazine should be lined with a nonsparking material. FIGURE 3.-Underground detonator magazine. 3. All detonators in numbers of 5,000 or less may be stored in permanent magazines; if not so stored, such detonators should be stored in box-type magazines complying with the standards for this type of magazine. 4. No detonators should be stored in any magazine containing high or low explosives or blasting-device heaters. An underground magazine for storing detonators is shown in figure 3. LOCATION SURFACE MAGAZINES Accessibility in the location of a magazine is desirable for the transfer of explosives to the place where they are used, but it is more important that a magazine be located far enough away from other buildings or valuable structures so that the least possible damage will be done to buildings or to persons in the surrounding area if an explosion occurs within the magazine. Damage from a magazine explosion is caused by the resulting air blast, by shock waves in the air and in the ground, and by flying missiles.10 Direct effects of the moving air blasts are severe at the point of the blast but fade rapidly with distance. The shock waves create a sharp pressure push away from the explosion, immediately followed by a slower, but equally strong, pressure push or suction wave in the opposite direction. These pressure waves cause no appreciable movement of the air itself but move objects and cause windows, walls, and roofs to collapse or shatter. Flying and burning fragments thrown from the exploded magazine may do severe damage at great distances. Explosions of magazines containing approximately 10 tons of high explosives have caused serious damage at distances of 1,500 to 2,000 feet; explosions of amounts in the neighborhood of 100 tons have caused severe damage as much as a mile away. The areas in which minor damage from missiles and broken windows result are much more extended. Some States and cities have laws or regulations specifying the locations of magazines; where such laws do not contain more particular specifications, it is recommended that surface magazines be located in conformity with the American Table of Distances when practicable (table 6). This table specifies the distances that magazines containing explosives should be located from inhabited buildings, highways, and railroads. In the administration of the Federal Explosives Act, it was recommended that surface magazines be located detached from other buildings, in conformity with the distances given in table 6, and that they be not nearer than 200 feet from any power plant, mill, or other vital structure, or from the surface opening of any mine. The topography or other physical conditions may prevent the location of a proposed magazine at the distances recommended in the table, in which event it may be possible to construct the magazine behind natural or builtup barricades or divide the necessary maximum amount stored between two magazines located at a safe distance from each other (figs. 4, 5, and 6). Permanent magazines should be at least 200 feet from any other magazine, except a detonator magazine; and magazines where quantities of explosives over 25,000 pounds are stored should have an increase over 200 feet of 2-2/3 feet for each 1,000 pounds of explosives in excess of 25,000 pounds stored therein, provided that these distances may be disregarded where the total quantity stored in said magazines, considered as a whole, complies with the amended American Table of Distances; under no circumstances should a detonator magazine be less than 100 feet, not barricaded, or 50 feet, barricaded, from a magazine containing explosives. The distance between 10 Robinson, C. S., Explosions, Their Anatomy and Destructiveness: McGraw-Hill Book Co., New York, 1944, pp. 45-78. |