P-385-63 Range Safety Pamphlet Download

through a #10 sieve). The sand cushion will not be less than that specified in table 15–1. Subsequent charges will not be placed where cratering from previous detonations has reduced the depth of sand. (b) Charges will be detonated on soil free from gravel, rock, metal or other possible missiles to a depth of at least 0. 15 m (6 in). Ground preparation will include loosening and raking the soil. A barricade constructed of sandbags or other suitable protective material at least 1 m above the surrounding level of ground will be provided between the location of the charge and personnel. Charges will be placed not less than 1 m or more than 2 m from the barricade. The detonation site will be maintained to prevent formation of clods or exposure of gravel or rock on or near the surface. It is helpful to place a layer of porous, water permeable matting (geo-textile fabric consisting of woven nylon, and polyester) between a rocky layer of soil and the upper layer of soil that must be free of gravel, rock, metal, or other potential missiles. This will help prevent contamination of the upper soil layer from the migration of gravel and rock and help reduce long-term maintenance costs. (3) During basic or familiarization demolition training, instructors will supervise not more than five students while they are priming individual charges. Not more than five students will prime charges at a time. The remainder of students and observers will withdraw to a safe position before priming occurs. (4) Single charges placed against steel, concrete, wood, or other solid material during training or demonstrations will be emplaced on the side nearest observers so that major fragments are propelled away from the observers. (5) Dual initiation systems are preferred over single initiation systems to increase reliability. Consult FM 3–34.214 and use the best combination of initiation systems to decrease the possibility of misfires. g. Explosives can propel lethal fragments and debris hazards great distances. (1) The distance explosion-propelled fragments or debris will travel in air depends mainly on the relationship between weight, shape, density, initial angle of projection, and initial velocity. Fragment and debris hazards from steel- cutting charges extend a greater distance under normal conditions than that from cratering, quarrying, or surface charges of bare explosives. (2) Fragment and debris hazard distances at which personnel in the open are relatively safe from missiles created by bare charges placed in or on the ground, regardless of type or condition of the soil, are as follows: (a) Charges more than 227 kg (500 lbs): Minimum 800 m fragment and debris hazard distance. (b) Charges from:12 kg (27 lbs) to 227 kg (500 lbs) charges, computed from the formula: Safe distance in meters=100 times the cube root of the pounds of explosive (D=100 x W 1/3 ). (c) Less than 12 kg (27 lbs): Minimum 300 m fragment and debris hazard distance. (d) See table 15–2 for computed safe distances for personnel near bare charges. (3) For 0.25-pound charges used to simulate enemy artillery fire and mortar fire that are detonated in specially constructed demolition pits constructed as described in paragraph 15–10e(8), the minimum distance may be reduced to not less than 3 m. h. Blast effects generate hazards. (1) Generally, the greatest danger to personnel is missiles thrown by an explosion. However, blast effect (such as an increase in air pressure) also generates hazards to personnel located within the SDZ. Special protective features used at detonation or demolition sites to eliminate or confine missiles may not reduce or mitigate overpressure and noise hazards. (2) Hearing protection is required for any exposure to noise greater than 140 dBP. Follow the hearing protection recommendations listing in the technical manuals for the explosive devices used. If the hearing protection recommenda- tions are not listed in the manuals, compute the 140 dBP contour from the formula: Distance to 140 dBP contour in meters=300 times the cube root of the weight of explosive in kg (D=300 x W 1/3 ). Table 15–3 contains the distances for various weights of explosives. i. The following methods are used for charges placed on steel and concrete (1) Charges placed on steel. (a) The preferred method of employing steel cutting charges is in a bunker designed for that purpose. Steel cutting charges (amount of explosives and placement) will be calculated based on appropriate formulas and tables in FM 3–34. 214. (b) If a steel-cutting bunker is not available, charges will be fired in an excavated pit that is at least 1 m deep. Steel- cutting charges fired outside of a steel-cutting bunker will not exceed 0.9 kg (2 lbs). (c) Personnel must be a minimum of 100 m from the charge at detonation in a missile-proof shelter, 300 m in defilade, or 1,000 m if in the open. (2) Charges placed on concrete. Charges placed on concrete will not exceed 18 kg (40 lbs) and should be placed on the side nearest observers. Observers must be at least 100 m away in a missile-proof shelter, 300 m away in defilade, or 900 m away in the open. An unoccupied distance of 900 m will be provided on the opposite side of the charge where most missile hazards will be thrown. (3) For the Army, all personnel will wear approved protective helmets, IBA, eye protection, and single hearing protection. For the Marine Corps, PPE Level 2. j. Explosive entry techniques are used in special missions where assault personnel require immediate access to the 184 DA PAM 385–63 • 16 April 2014