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Subchapter 7. General Industry Safety Orders
Group 18. Explosives and Pyrotechnics
Article 114. Storage of Explosives

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§5253. Quantity and Distance Table for Storage of Ammonium Nitrate and Blasting Agents.

(a) The quantity of ammonium nitrate or ammonium nitrate based blasting agents that may be stored in any magazine shall conform to Table EX-2, Table of Separation Distances, in Section 5252 which sets forth the minimum separation distances for ammonium nitrate and blasting agents from stores of high explosives or blasting agents. These distances apply to the separation of stores only. The American Table of Distances (See Table EX-1 in Section 5252) shall be used in determining separation distances from inhabited buildings.

(b) When the ammonium nitrate and/or blasting agent is not barricaded the distances shown in Table EX-2 in Section 5252 shall 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 storage is in bullet-resistant magazines recommended for explosives or where the storage is protected by a bullet-resistant wall, distances and barricade thicknesses in excess of those prescribed in Table EX-1 in Section 5252 and are not required. (See Section 5253.1 for bullet-resistant construction.)

(c) 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.

(d) When the ammonium nitrate must be counted in determining the distances to be maintained from inhabited buildings, it shall be counted at l/2 its actual weight because its blast effect is lower.

Note: Ammonium nitrate by itself is relatively insensitive and is widely used through the State as an agricultural fertilizer. When used for blasting purposes, it is customary to sensitize the ammonium nitrate by mixing it with carbonaceous materials such as coal dust, lamp black, carbon black, wood pulp, diesel fuel, stove oil, or other materials containing carbon. When mixed with carbonaceous materials, ammonium nitrate becomes much more sensitive to fire, friction, and shock, so it takes on characteristics resembling those of dynamite. For this reason, a mixture of ammonium nitrate and carbonaceous material must be stored in compliance with regulations governing storage of explosives. Burning ammonium nitrate produces oxides of nitrogen which are very dangerous to breathe.


Authority cited: Section 142.3, Labor Code. Reference: Section 142.3 Labor Code.


1. Repealer and new section filed 10-17-75; effective thirtieth day thereafter (Register 75, No. 42).

2. Amendments filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

3. Amendment of subsections (a) and (d) filed 9-18-80; effective thirtieth day thereafter (Register 80, No. 38).

4. Amendment of section, including transfer of section 5253 Table EX-2 to new section 5252 Table EX-2, filed 7-11-2003; operative 8-10-2003 (Register 2003, No. 28).

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