The explosives used as initiating explosives are the primary high explosives mentioned previously in this chapter. They are used in varying amounts in the different primers and detonators used by the Navy and may differ some insensitivity and in the amount of heat given off. The explosives discussed in this section are lead azide, lead, styphnate, and diazodinitrophenol (DDNP).

Lead Azide

Lead azide has a high-ignition temperature and is today the most commonly used primary explosive.

Lead azide is poisonous, slightly soluble in hot water and in alcohol, and highly soluble in a diluted solution of nitric or acetic acid in which a little sodium nitrate has been dissolved It reacts with copper, zinc, cadmium, or alloys containing such metals, forming an azide that is more sensitive than the original lead tide. Because lead azide does not react with aluminum, detonator capsules for lead azide are made of this metal. The hygroscopicity of lead azide is very low. Water does not reduce its impact sensitivity, as is the case with mercury fulminate. Ammonium acetate and sodium bichromate are used to destroy small quantities of lead azide. Lead tide may be used where detonation is caused by flame or heat. The velocity of detonation is approximately 17,500 feet per second (fps). Its color varies from white to buff. Lead azide is widely used as an initiating explosive in high-explosive detonator devices.

Lead azide, when protected from humidity, is completely stable in stowage.

Lead Styphnate

There are two forms of lead styphnate-the normal that appears as six-sided monohydrate crystals and the basic that appears as small, rectangular crystals. Lead styphnate is particularly sensitive to fire and the discharge of static electricity. When the styphnate is dry, it can readily ignite by static discharges from the human body. The longer and narrower the crystals, the more susceptible the material is to static electricity. Lead styphnate does not react with metals. It is less sensitive to shock and fiction than lead azide. Lead styphnate is slightly soluble in water and methyl alcohol and may be neutralized by a solution of sodium carbonate. The velocity of detonation is approximately 17,000 fps. The color of lead styphnate varies from yellow to brown. Lead styphnate is used as an initiating explosive in propellant primer and high-explosive detonator devices.

Diazodinitrophenol (DDNP)

DDNP is a yellowish brown powder. It is soluble in acetic acid, acetone, strong hydrochloric acid, and most of the solvents, but is insoluble in water. A cold sodium hydroxide solution may be used to destroy it. DDNP is desensitized by immersion in water and does not react with it at normal temperatures. It is less sensitive to impact but more powerful than lead tide. The sensitivity of DDNPto friction is approximately the same as that of lead tide.

DDNP is often used as an initiating explosive in propellant primer devices.