b. PETN (Pentaerythritol Tetranitrate). PETN is one of the strongest high explosives known. It is more sensitive to shock or friction than TNT or tetryl. In its pure form, PETN is a white crystalline powder; however, it may turn light gray from impurities. It will detonate under long, slow pressure. PETN in bulk must be stored wet. Its primary use is in booster and bursting charges in small-caliber ammunition; in upper detonators in some land mines and projectiles; and as the explosive core of primacord detonating fuze. It may be issued in sheet form. Suspended in TNT, with which it forms a pentolite explosive of high brisance.
c. RDX. RDX, cyclotrimethylenetrinitramine, one of the most powerful explosives, is commonly known as cyclonite; hexogen (German); T4 (Italian); and Tanoyaku (Japanese). It is a white crystalline solid having a melting point of +202°C. (+397°F.) and is very stable. It has slightly more power and brisance than PETN. It is more easily initiated by mercury fulminate than is tetryl. RDX has been used mainly in mixtures with other explosives, but can be used by itself as a subbooster, booster, and bursting charge. It is also combined with nitrohydrocarbons, which permit cast-loading, or with waxes or oils for press-loading. It has a high degree of stability in storage.
d. TNT (Trinitrotoluene). The 2, 4, 6-trinitrotoluene, commonly known as TNT, is a constituent of such explosives as amatol, pentolite, tetrytol, tritonal, picratol and composition B.
(1) Characteristics. TNT in a refined form is one of the most stable of high explosives. It is relatively insensitive to blows. or friction and can be stored for long periods of time. Confined TNT, when detonated, explodes with violence. When ignited by a flame, unconfined TNT burns slowly, does not explode, and emits a heavy, oily, black smoke; however, burning or rapid heating of large quantities, especially in closed vessels, may cause a violent detonation. TNT is nonhygroscopic and does not form sensitive compounds with metals. It is, however, readily acted upon by alkalies to form unstable compounds that are very sensitive to heat and impact. TNT usually resembles a light brown sugar; in the pure state, it is crystalline and nearly white. When melted and poured into a projectile or bomb, it forms a solid crystalline explosive charge. TNT is a very satisfactory military explosive. The melting point of standard grade 1 TNT is 80.2°C. (+176°F.). Ammunition loaded with TNT can be stored, handled, and shipped with comparative safety.
(2) Exudation. When stored in warm climates or during warm summer months, some ammunition loaded with TNT may exude an oily brown liquid. This exudate oozes out around the threads at the nose of the projectile and may form a pool on the floor. The exudate is flammable and may contain particles of TNT. Pools of exudate should be removed.
(3) Detonation. TNT in crystalline form can be detonated readily by a No. 6 blasting cap or, when highly compressed, by a No. 8 blasting cap. Cast TNT requires a booster charge of compressed tetryl or an explosive of similar brisance to assure complete detonation.
(a) Bursting charge. TNT is used as a bursting charge for high-explosive rounds and bombs, either alone or in a mixture, such as tritonal or composition B. TNT is also used in mines and for parts of certain rounds and bomb bursters. Flake TNT is used in fragmentation hand grenades.
(b) Demolition. TNT is used to demolish bridges, railroads, fortifications and other structures. For such purposes, it is used in the form of a large shaped charge or a small, highly compressed block inclosed in a waterproof fiber container. This protects the TNT from crumbling in handling. Triton blocks used by the Corps of Engineers are of pressed TNT inclosed in cardboard containers.
(c) Blasting. TNT is suitable for all types of blasting. It produces approximately the same effect as an equal weight of dynamite of 50 to 60 percent grade. TNT is also used as a surround in some amatol-loaded ammunition.
(1) General characteristics. Amatol, a mixture of ammonium nitrate and TNT in various percentages, has the same general characteristics as TNT. Amatol is crystalline, yellow or brownish, and insensitive to friction. However, it may be detonated by severe impact. It is less sensitive to detonation than TNT, but is readily detonated by mercury fulminate and other detonators. Amatol is hygroscopic and, in the presence of moisture, attacks copper, brass and bronze, forming dangerously sensitive compounds. Amatol 50/50 has approximately the same rate of detonation and brisance as TNT, while 80/20 amatol is slightly lower in velocity and brisance than TNT. Amatol 80/20 produces a white smoke on detonation, and amatol 50/50 produces a smoke less dark than straight TNT.
(2) Composition and form. Amatol 50/50 consists of 50 percent ammonium nitrate and 50 percent TNT by weight. When hot, amatol is sufficiently fluid to be poured or cast like TNT. Amatol 80/20 consists of 80 percent ammonium nitrate and 20 percent TNT. It resembles wet brown sugar. When hot, it becomes semiplastic (like putty) and can be pressed into rounds and bombs.
(3) Uses. Amatol is a substitute for TNT. Except for 80/20 amatol, amatols are obsolete. The primary use of 80/20 amatol is in bangalore torpedoes.
f. Picric Acid (Trinitrophenol).
(1) General. Picric acid, 2, 4, 6-trinitrophenol, a nitrated product of phenol under the name of melinite, was adopted as a military high explosive by the French in 1886. It has been used more extensively as a military explosive by foreign nations than by this country. The British designate it as lyddite.
(2) Characteristics. Picric acid is a lemon-yellow crystalline solid. It is stable but reacts with metals when moist, in some cases forming extremely sensitive compounds. Picric acid is more readily detonated by means of a detonator than TNT but has about the same sensitivity to shock. It is not so toxic as TNT. Although slightly soluble in water, picric acid is nonhygroscopic. Picric acid has a high melting point-approximately +122°C. (+251.6°F.).
g. Ammonium Picrate (Explosive D).
(1) Characteristics. Ammonium picrate is the least sensitive to shock and friction of all military explosives. This makes it well suited for use as a bursting charge in armor-piercing projectiles. A product of picric acid, it is slightly inferior in explosive strength to TNT. When heated, it does not melt but decomposes and explodes. It reacts slowly with metals; however, when wet, it may form sensitive and dangerous compounds with iron, copper and lead. It is difficult to detonate. When ignited in the open, it will burn readily like tar or resin.
(2) Special precautions.
(a) Ammonium picrate removed from a round is much more sensitive to shock or blow than fresh ammonium picrate. In contact with lead, iron or copper it forms sensitive compounds.
(b) Although less sensitive than TNT, ammonium picrate can be exploded by severe shock or friction. It is highly flammable and may detonate when heated to a high temperature.
(3) Uses. Explosive D is used as a bursting charge for armor-piercing rounds and in other types of projectiles that must withstand severe shock and stress before detonating.
h. Picratol. Picratol is a mixture of 52 percent explosive D and 48 percent TNT. It can be poured like straight TNT and has approximately the same resistance to shock as straight explosive D. The brisance of picratol is between that of explosive D and TNT. Picratol is nonhygroscopic. Picratol is a standard filler employed for all Army semi-armor-piercing bombs.
i. Pentolite. Pentolite, a 50/50 mixture of PETN and TNT also known as pentol (German) and pentritol, has largely been displaced by composition B. Pentolite should not be drilled to form booster cavities; forming tools should be used. It is superior to TNT in explosive strength and is less sensitive than PETN. Pentolite may be meltloaded and is satisfactory for the following uses:
(1) As a bursting charge in small-arms ammunition (e.g., 20-mm).
(2) In shaped-charge ammunition of many types (e.g., antitank, rifle grenades and bazookas).
(3) In some ammunition, as a booster or booster-surround.
(4) In rockets and shaped demolition charges.
j. Tetrytol. Tetrytol is a uniform mixture of 65 to 75 percent tetryl and the remainder TNT. Tetrytol has higher brisance than TNT and is more effective in cutting through steel and in demolition work. It is less sensitive to shock and friction than tetryl and only slightly more sensitive than TNT. Tetrytol is nonhygroscopic and is suitable for underwater demolition, since submergence for 24 hours does not appreciably affect its characteristics. Tetrytol is used in chain and individual demolition blocks and in certain destructors. Tetrytol is stable in storage but exudes at +65°C. (+149°F.).
k. Nitrostarch Explosives.
(1) Characteristics. Nitrostarch is nitrated starch. Obtained from corn, tapioca and similar starchy material, it is used to sensitize combustibles and oxidizing agents in much the same manner that nitroglycerin is used in dynamite. It is gray, highly flammable, can be ignited by the slightest spark, and burns with explosive violence. Nitrostarch is less sensitive than dry guncotton or nitroglycerin. As a demolition explosive, it is as insensitive to impact as explosive D and as sensitive to initiation as TNT. Nitrostarch explosives are readily detonated by a No. 6 blasting cap.
(2) Uses. A nitrostarch demolition explosive has been adopted as a substitute for TNT. It is available in 1-pound blocks, 1/2-pound blocks, and 1/4-pound units. Each 1/4-pound unit contains three 1/12-pound pellets (briquets) wrapped in paraffined paper, with markings to indicate the location of holes for the blasting caps. TNT formulas for computing small charges are directly applicable to the nitrostarch demolition explosive. It should be noted that fragmented blocks may cause detonation.
l. Dynamite. Commercial blasting explosives, with the exception of black powder, are referred to as dynamite. There are several types, each subdivided into a series of grades, all differing in one or more characteristics. Dynamite consists essentially of nitroglycerin absorbed in a porous material. Each composition generally is designated as straight, ammonia, gelatin or ammonia-gelatin dynamite. It is available in paraffin-coated, 1/2pound sticks or cartridges, rated according to the percent, by weight, of nitroglycerin content.
(1) Characteristics. Dynamite of from 50percent to 60-percent nitroglycerin content is equivalent (on an equal weight basis) to TNT in explosive strength. Dynamite of 40-percent nitroglycerin content is equivalent to TNT in the ratio of 11/4 pounds dynamite to 1 pound TNT. Straight dynamite is more sensitive to shock and friction than TNT and is capable of being detonated by a rifle bullet. Generally, the higher percentages of dynamite have very good water resistance. Explosion of the common types of dynamite produces poisonous fumes, which are dangerous in confined places. Dynamite, as well as other nitroglycerin explosives, is adversely affected by extreme cold. Nonfreezing dynamite (NG type) freezes at -30°C. (-22°F.); low-freezing dynamite freezes at 0°C. (+32°F.); and 60-percent NG dynamite freezes at +10°C. (+50°F.).
(2) Uses. Dynamite is used as a substitute for nitrostarch or TNT for training purposes. It is also employed by the Corps of Engineers for trench, harbor, dam, flood control, and mining demolitions. The following restrictions apply:
(a) Not to be issued or used for destruction of duds.
(b) Not to be supplied for training in use of demolition equipment.
(c) Not to be used in coastal defense submarine mines or mine batteries.
(d) Not to be carried in combat vehicles subject to extremes of temperature.
m. Tritonal. Tritonal is a generic term for explosives containing TNT and powdered aluminum, generally in the ratio of 80/20. Because of the aluminum powder, inclusion of moisture in the mixture must be avoided. Tritonal is used in light-case and general purpose bombs. It produces a greater blast effect than TNT or composition B.
n. HBX. HBX compositions (HBX-1, HBX-3, and H6) are aluminized (powdered aluminum) explosives used primarily as a replacement for the obsolete explosive, torpex. They are employed as bursting charges in mines, depth bombs, depth charges, and torpedoes. HBX-1 consists of 40 percent RDX, 38 percent TNT, 17 percent aluminum and 5 percent desensitizer. HBX-3 consists of 31 percent RDX, 29 percent TNT, 35 percent aluminum, and 5 percent desensitizer. H-6 consists of 45 percent RDX, 30 percent TNT, 20 percent aluminum, and 5 percent desensitizer. HBX-1 compares with torpex in brisance, but is less sensitive to impact and initiation. HBX-3 and H-6 have lower sensitivity to impact and much higher explosion test temperatures than torpex.
o. Composition A. Originally, composition A was a semiplastic mixture containing 91 percent RDX and 9 percent beeswax. When the beeswax was replaced by a wax derived from petroleum, and the method of adding the desensitizer changed, the designation was changed to composition A-2. Recently, the composition has been redesignated as composition A-3, because of changes in granulation of RDX and method of manufacture. Composition A-3 is granular in form, resembling tetryl in granulation. It is usually buff colored and is press-loaded in 20-mm, 37-mm and 40-mm cartridges. It is 30 percent stronger than TNT, its strength depending on the amount of wax binder. It is used as a filler for HEP rounds.
p. Composition B. Composition B (comp B) is a 60/39/1 mixture of RDX, TNT and desensitizer. Its color varies from dirty white to light yellow to brownish yellow. It is less sensitive than tetryl but more sensitive than TNT. It is intermediate between TNT and RDX with respect to sensitivity and initiation. It is only inferior to tritonal and torpex with respect to blast effect. Composition B is an authorized filler for Army-Navy (AN) standard aircraft bombs, mines, torpedoes, antitank artillery ammunition (76-mm and 105-mm), demolition charges and rockets. Composition B containing 60 percent RDX and 40 percent TNT, exclusive of wax, is known as composition B2, a nonstandard explosive. Because of its greater sensitivity to impact, composition B2 is less suitable than composition B for use in bombs. Composition B4, used as a burster in chemical projectiles, consists of a 60/39.5/0.5 mixture of RDX, TNT and calcium silicate.
q. Composition C (Series). (1) General. Composition C, sometimes referred to as PE, is a plastic explosive, an 88/12 mixture of RDX and a nonexplosive plasticizer composition. It is brown, plastic in form, and about the consistency of putty. It has a tendency to leach (sweat) out plasticizing oils, leaving pure RDX, which is too sensitive for use in the field.
(2) Composition C2. This putty-like composition is an 80/20 mixture of RDX and an explosive plasticizer composition. It is approximately 35 percent stronger than TNT, and was developed as a replacement for composition C as a demolition charge.
(3) Composition C3. This is a yellowish, putty-like mixture of 77 percent RDX and 23 percent of an explosive plasticizer. It is slightly inferior to composition B as an explosive for producing blast effect, and is considerably less sensitive than TNT. It may not always be detonated by a No. 8 blasting cap, but can be detonated by the special Corps of Engineers blasting cap. It was designed to replace Composition C2, and is used principally as a commando and demolition explosive or as a filler in some types of munitions. If its plasticity is lost by long storage at low temperatures, it may be restored to satisfactory plasticity by immersion in warm water and molding with the hands. It must not be exposed to open flame, as it catches fire easily and burns with an intense flame. If burned in large quantities, the heat generated may cause it to explode. Its explosion produces poisonous gases in such quantities that its use in closed spaces is dangerous. It is hygroscopic, volatile at elevated temperatures and hardens at temperatures below -29°C. (-20 F.).
(4) Composition C4. This is a 91/9 mixture of RDX and plastic nonexplosive composition. It is a semiplastic, putty-like material, dirty white to light brown in color, less sensitive, more stable, less volatile, and more brisant than composition C3. It is a nonhygroscopic material that has found application in demolition blocks and specialized uses. It hardens below -57°C. (-70°F.) and exudes when stored above +77°C. ( +170°F.).
r. HMX (Cyclotetramethylene tetranitramine) is almost as powerful as RDX, but is seldom used by itself in military explosive applications. It is usually mixed with a compound, such as TNT. Variations of such compositions, their properties and uses follows:
(4) Both octols and HTA-3 are used for HE filler in projectiles and bombs.
2-18. Initiating and Priming Explosives a. Lead Azide. Lead azide, one of the most stable initiators, is used to detonate high explosives. Because of its superior properties, it has replaced mercury fulminate. Lead azide flashes at much higher temperatures, stands up better in storage, and is less hazardous to manufacture. A smaller amount of lead azide is required than mercury fulminate to detonate an equal amount of TNT. Dextrinated lead azide (93%o lead azide, 4% lead hydroxide and 3 % dextrin and impurities), used for military purposes rather than crystalline (pure) lead azide, is a white-to-beige, powderlike material which can be compressed. Lead azide is used in primer mixtures, detonators and fuzes.
b. Lead Styphnate. This explosive, 2, 4, 6-trinitroresorcinate, is widely employed commercially and as an initiator for both foreign and domestic explosives. It is pale straw, deep yellow, orange-yellow or reddish-brown in color. Lead styphnate is slightly less sensitive to impact than mercury fulminate and has about the same strength and stability as lead azide. However, lead styphnate is more easily ignited by an electrical spark than is mercury fulminate, lead azide, or DDNP. As a primer, lead styphnate produces a very good flame. It should be stored under water in conductive rubber containers. In primer compositions, lead styphnate offers sensitivity, stability, and ample flame. It is incapable of initiating the detonation of any of the military high explosives except PETN.
c. Diazodinitrophenol (DDNP). Extensively employed in commercial blasting caps, this explosive serves in military priming compositions and detonators. It is nonhygroscopic and greenish yellow to brown in color. It is extremely sensitive to impact; however, its sensitivity to friction is about that of lead azide. If pressed into a blasting cap shell with a reinforcing cap, and a piece of black powder safety fuse is crimped in the shell, a charge of DDNP undergoes detonation when ignited. DDNP is a better initiator of the less sensitive high explosives (explosive D and cast TNT). For the more sensitive high explosives, DDNP is not superior to lead azide. It is used to some extent in loading fuze detonators and the manufacture of priming compositions.
Section V. CHEMICAL AGENTS
A military chemical agent is a substance that produces a toxic (casualty) or an irritating (harassing) effect, a
I screening smoke, an incendiary action, or a combination of these. For specific information on chemicals, see FM
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