27 C.F.R. § 555.220   Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting agents.


Title 27 - Alcohol, Tobacco Products and Firearms


Title 27: Alcohol, Tobacco and Firearms
PART 555—COMMERCE IN EXPLOSIVES
Subpart K—Storage

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§ 555.220   Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting agents.

Table: Department of Defense Ammunition and Explosives Standards, Table 5–4.1 Extract; 4145.27 M, March 1969

 ------------------------------------------------------------------------    Donor weight (pounds)     Minimum separation distance----------------------------- of acceptor from donor when     Minimum                                    barricaded (ft.)        thickness of                             -----------------------------   artificial     Over         Not over       Ammonium      Blasting      barricades                                 nitrate         agent         (in.)------------------------------------------------------------------------                     100             3             11            12      100            300             4             14            12      300            600             5             18            12      600          1,000             6             22            12    1,000          1,600             7             25            12    1,600          2,000             8             29            12    2,000          3,000             9             32            15    3,000          4,000            10             36            15    4,000          6,000            11             40            15    6,000          8,000            12             43            20    8,000         10,000            13             47            20   10,000         12,000            14             50            20   12,000         16,000            15             54            25   16,000         20,000            16             58            25   20,000         25,000            18             65            25   25,000         30,000            19             68            30   30,000         35,000            20             72            30   35,000         40,000            21             76            30   40,000         45,000            22             79            35   45,000         50,000            23             83            35   50,000         55,000            24             86            35   55,000         60,000            25             90            35   60,000         70,000            26             94            40   70,000         80,000            28            101            40   80,000         90,000            30            108            40   90,000        100,000            32            115            40  100,000        120,000            34            122            50  120,000        140,000            37            133            50  140,000        160,000            40            144            50  160,000        180,000            44            158            50  180,000        200,000            48            173            50  200,000        220,000            52            187            60  220,000        250,000            56            202            60  250,000        275,000            60            216            60  275,000        300,000            64            230            60------------------------------------------------------------------------

Table: National Fire Protection Association (NFPA) Official Standard No. 492, 1968

Notes of Table of Separation Distances of Ammonium Nitrate and Blasting Agents From Explosives or Blasting Agents

(1) This table specifies separation distances to prevent explosion of ammonium nitrate and ammonium nitrate-based blasting agents by propagation from nearby stores of high explosives or blasting agents referred to in the table as the “donor.” Ammonium nitrate, by itself, is not considered to be a donor when applying this table. Ammonium nitrate, ammonium nitrate-fuel oil or combinations thereof are acceptors. If stores of ammonium nitrate are located within the sympathetic detonation distance of explosives or blasting agents, one-half the mass of the ammonium nitrate is to be included in the mass of the donor.

(2) When the ammonium nitrate and/or blasting agent is not barricaded, the distances shown in the table must be multiplied by six. These distances allow for the possibility of high velocity metal fragments from mixers, hoppers, truck bodies, sheet metal structures, metal containers, and the like which may enclose the “donor.” Where explosives storage is in bullet-resistant magazines or where the storage is protected by a bullet-resistant wall, distances and barricade thicknesses in excess of those prescribed in the table in §555.218 are not required.

(3) These distances apply to ammonium nitrate that passes the insensitivity test prescribed in the definition of ammonium nitrate fertilizer issued by the Fertilizer Institute.1 Ammonium nitrate failing to pass the test must be stored at separation distances in accordance with the table in §555.218.

1 Definition and Test Procedures for Ammonium Nitrate Fertilizer, Fertilizer Institute 1015–18th St. N.W. Washington, DC 20036.

(4) These distances apply to blasting agents which pass the insensitivity test prescribed in regulations of the U.S. Department of Transportation (49 CFR part 173).

(5) Earth or sand dikes, or enclosures filled with the prescribed minimum thickness of earth or sand are acceptable artificial barricades. Natural barricades, such as hills or timber of sufficient density that the surrounding exposures which require protection cannot be seen from the “donor” when the trees are bare of leaves, are also acceptable.

(6) For determining the distances to be maintained from inhabited buildings, passenger railways, and public highways, use the table in §555.218.

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