Storage Compatibility Groups

GROUP J - Ammunition in this group contains both explosives and flammable liquids or gels. This ammunition contains flammable liquids or gels other than those that are spontaneously flammable when exposed to water or to the atmosphere. Examples of these items are liquid- or gel-filled incendiary ammunition, fuel air explosive (FAE) devices, flammable-fueled missiles and torpedoes. 
GROUPK- Ammunition in group K contains both explosives and toxic chemical agents. Ammunition in this group contains chemicals specifically designed for incapacitating effects that are more severe than lachrymation. Examples of these items are artillery or mortar ammunition (fused or un-fused), grenades, and rockets or bombs filled with a lethal or incapacitating chemical agent.
GROUP L - Ammunition in-group L is not included in other compatibility groups. Ammunition in this group has characteristics that don't permit storage with other types of ammunition, explosives, or dissimilar ammunition within this group. Examples of these items are water-activated devices, prepackaged hypergolic liquid-fueled rocket engines, certain fuel-air-explosive (FAE) devices, TPA (thickened TEA), and damaged or suspect ammunition of any other group. Types of ammunition having similar hazards can be stored together but cannot be mixed with other groups. 
GROUP S - Ammunition in this group presents no significant hazard. It is designed or packed so all the accidental functioning hazards are confined within the package, unless the package has been degraded by fire. In this case, all blast or projection effects are limited to the extent they will not significantly hinder fire-fighting operations. Examples of these items are thermal batteries, explosive switches or valves, and other ammunition items that are packaged to meet the criteria established for this group. Ammunition and explosives are assigned to compatibility groups. When stored within their assigned group, ammunition and explosives can be stored together without significantly increasing either the probability of an accident or, for a given quantity, the magnitude of the effects of such an accident. The mixing of storage compatibility groups is permitted by NAVSEASYSCOM, as shown below. The mixing of storage compatibility groups other than those shown below must be approved by NAVSEASYSCOM. 

Storage Compatibility Groups

Examples of these items are explosive switches or valves, and other ammunition items packaged to meet the criteria established for this group.
GROUP E - Group E items are ammunition that contains HE without its own means of initiation with a propulsive charge (other than one containing a flammable or hypergolic liquid). Examples of these items are artillery ammunition, rockets, and guided missiles. 
GROUP F - Group F items are articles containing a secondary detonating explosive substance with its means of initiation, with a propelling charge (other than one containing flammable liquid or hypergolic liquid) or without a propelling charge. Examples are items initiated by means of a button-firing device, grenades, sounding devices, and similar items that have an in-line explosive train in the initiator.
GROUP G - Group G items is fireworks, and illuminating, incendiary, smoke (including HC) or tear-producing munitions other than those munitions that are water activated or contain white phosphorus,  flammable liquid or gel. This group includes ammunition that, upon functioning, results in an incendiary, illumination, lachrymatory, smoke, or sound effect. Examples of these items are flares, signals, incendiary or illuminating ammunition, and other smoke or tear-producing devices. 
GROUP H - Group H items contains explosives and white phosphorus or other pyrophoric material. Ammunition in this group contains filler, which is spontaneously flammable when exposed to the atmosphere. Examples of these items are white phosphorus (WP), white phosphorus plasticized (PWP), or other ammunition containing pyrophoric material.

Storage Compatibility Groups

GROUP A - Group A items are initiating explosives. These are bulk initiating explosives that have the necessary sensitivity to heat, friction, or percussion to make them suitable for use as initiating elements in an explosive train. Wet lead oxide, wet mercury fulminate, dry RDX, and dry PETN are examples of initiating explosives. 
GROUP B - Group B items are detonators and similar initiating devices. These are items containing explosives that are designed to initiate or continue the functioning of an explosive train. Detonators, blasting caps, small arms primers, and fuses without two or more safety features are examples of Group B items.
GROUP C - Group C items are bulk solid propellants, propelling charges, devices containing propellant with or without a means of ignition, and items that will deflagrate, explode or detonate upon initiation. Examples of Group C items are single-, double-, and triple-base propellants, composite propellants, rocket motors (solid propellant), and ammunition with inert projectiles.
GROUP D - Group D items are secondary detonating explosive substances or black powder or articles containing a secondary detonating explosive substance, in each case without means of initiation and without a propelling charge, or articles containing a primary explosive substance and containing two or more effective protective features. Examples of these items are explosive switches or valves, and other ammunition items packaged to meet the criteria established for this group.

Explosive Safety Quantity-Distance (ESQD) Requirements

Explosive Safety Quantity Distance (ESQD) requirements apply to the concentration of ammunition, explosives, and other hazardous materials at Naval Shore Establishments for development; manufacturing; test and maintenance; storage, loading and off-loading of vehicles, railcars and aircraft; disposal; and all related handling incidents. Explosive Safety Quantity Distance (ESQD) requirements are based on records of actual fires and explosions involving ammunition and explosives. ESQD requirements safeguard personnel against possible serious injury or equipment destruction from possible fires or explosions. These requirements also protect the inhabitants of nearby communities, private and public property, and the Naval Shore Establishment personnel. These requirements keep the loss of valuable ammunition stores (including inert ordnance items) to a minimum if there were a fire or explosion. The Department of Defense (DOD) ESQD hazard classification system is based on a system recommended for international use by the United Nations Organization (UNO). The UNO system has nine classes of hazardous material; but, DOD only uses three of the nine classes�Class 1, explosives; Class 2, Division 3, poison A; and Class 6, poisonous (toxic) and infectious substances. The table identifies each of the nine classes. In reviewing the table, you can see that some items are placed in classes other than Class 1. Since DOD uses only Class 1 items for explosives, Class 1 assignments have been made. However, to maintain identity, DOD places these items in Class 1 for storage only until DOD implements other classes. As an AO, you are involved with the storage of Class 1 material; therefore, the information contained in this section only deal with Class 1 classifications. DOD Hazard Class 1 is subdivided into divisions 1 through 5, based on the character and predominance of the associated hazards and the potential for causing personnel casualties or property damage. These subdivision are not based upon compatibility groups or intended use.

Evolution of Heat

The generation of heat in large quantities accompanies most explosive chemical reaction. The exceptions are called entropic explosives and include organic peroxides such as acetone peroxide. It is the rapid liberation of heat that causes the gaseous products of most explosive reactions to expand and generate high pressures. This rapid generation of high pressures of the released gas constitutes the explosion. The liberation of heat with insufficient rapidity will not cause an explosion. For example, although a pound of coal yields five times as much heat as a pound of nitroglycerin, the coal cannot be used as an explosive because the rate at which it yields this heat is quite slow. In fact, a substance which burns less rapidly (i.e. slow combustion) may actually evolve more total heat than an explosive which detonates rapidly (i.e. fast combustion). In the former, slow combustion converts more of the internal energy (i.e. chemical potential) of the burning substance into heat released to the surroundings, while in the latter, fast combustion (i.e. detonation) instead converts more internal energy into work on the surroundings (i.e. less internal energy converted into heat); c.f. heat and work (thermodynamics) are equivalent forms of energy. See Heat of Combustion for a more thorough treatment of this topic.
When a chemical compound is formed from its constituents, heat may either be absorbed or released. The quantity of heat absorbed or given off during transformation is called the heat of formation. Heats of formations for solids and gases found in explosive reactions have been determined for a temperature of 15 °C and atmospheric pressure, and are normally given in units of kilocalories per gram-molecule. A negative value indicates that heat is absorbed during the formation of the compound from its elements; such a reaction is called an endothermic reaction. In explosive technology only materials that are exothermic—that have a net liberation of heat—are of interest. Reaction heat is measured under conditions either of constant pressure or constant volume. It is this heat of reaction that may be properly expressed as the "heat of explosion."E

Sensitivity of explosive material

Sensitivity of an explosive refers to the ease with which an explosive can be ignited or detonated, i.e., the amount and intensity of shock, friction, or heat that is required. When the term sensitivity is used, care must be taken to clarify what kind of sensitivity is under discussion. The relative sensitivity of a given explosive to impact may vary greatly from its sensitivity to friction or heat. Some of the test methods used to determine sensitivity relate to:

• Impact — Sensitivity is expressed in terms of the distance through which a standard weight must be dropped onto the material to cause it to explode.
• Friction — Sensitivity is expressed in terms of what occurs when a weighted pendulum scrapes across the material (it may snap, crackle, ignite, and/or explode).
• Heat — Sensitivity is expressed in terms of the temperature at which flashing or explosion of the material occurs.

Sensitivity is an important consideration in selecting an explosive for a particular purpose. The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired. The explosive lenses around nuclear charges are also designed to be highly insensitive, to minimize the risk of accidental detonation.

Causes of Explosion: Industrial

The most common artificial explosives are chemical explosives, usually involving a rapid and violent oxidation reaction that produces large amounts of hot gas. Gunpowder was the first explosive to be discovered and put to use. Other notable early developments in chemical explosive technology were Frederick Augustus Abel's development of nitrocellulose in 1865 and Alfred Nobel's invention of dynamite in 1866. Chemical explosions ( both intentional and accidental) are often initiated by an electric spark or flame. Accidental explosions may occur in fuel tanks, rocket engines, etc.


A high current electrical fault can create an electrical explosion by forming a high energy electrical arc which rapidly vaporizes metal and insulation material. This arc flash hazard is a danger to persons working on energized switchgear. Also, excessive magnetic pressure within an ultra-strong electromagnet can cause a magnetic explosion.


Strictly a physical process, as opposed to chemical or nuclear, e.g., the bursting of a sealed or partially sealed container under internal pressure is often referred to as a 'mechanical explosion'. Examples include an overheated boiler or a simple tin can of beans tossed into a fire.


Boiling liquid expanding vapor explosions are one type of mechanical explosion that can occur when a vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates. Note that the contents of the container may cause a subsequent chemical explosion, the effects of which can be dramatically more serious, such as a propane tank in the midst of a fire. In such a case, to the effects of the mechanical explosion when the tank fails are added the effects from the explosion resulting from the released (initially liquid and then almost instantaneously gaseous) propane in the presence of an ignition source. For this reason, emergency workers often differentiate between the two events.



In addition to stellar (star) nuclear explosions, a man-made nuclear weapon is a type of explosive weapon that derives its destructive force from nuclear fission or from a combination of fission and fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives available, with a single weapon capable of completely destroying an entire city.