Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Fig. 21. Angle shot mortar.

A steel cylinder of 230 mm (9 in.) diameter and 2 m (~1/2 ft) in length with a right-angled groove is positioned in the gas chamber of a testing gallery against an impact steel plate at given distances and different impact angles, as shown in Fig. 21. Trains of several cartridges or of the full length of 2 m are placed in the groove of the angle and fired into the methane-air mixture.

3. Safety classes

The different mortar set-ups and other test arrangements can be varied to give a higher or lower probability of ignition; consequently, different safety grades for the explosives have been defined.

In France, there are three categories: explosifs roche, couche, and couche amelior´es´. They satisfy different requirements according to the borehole cannon test: short or long cannon, direct or inverse initiation, different thicknesses of stemming by means of steel plates.

In the United Kingdom, 5 groups are listed: group P1, the “classic” permitted explosives diluted with rock salt which must pass the least severe cannon test, direct initiation and stemmed; group P2, the now abandoned W Sheathed Explosives; group P3, the successor of Eq. S. (equivalent to sheathed) explosives; group P4, the class of highest safety, which meets the most severe break test conditions; and group P5, safe in cut-off conditions.

In Germany there are three classes: class I, the classic permissibles; class II, which are safe in the anglemortar test in position A, with charges of 40 cm in length in the groove; class III, the class of highest safety, which must give no ignition in the angle-mortar test in position B and with the groove filled over its full length with the explosive charge (2 m, 6 –1/2 ft).

As an example for possible authorised applications a diagram of the use of the German permitted explosives is given in Table 25.

Table 25. Areas of use and associated authorized application of German permitted explosives

adjacent rock in areas near coal faces, upcasts

Peroxides

Organic peroxides may be explosive. They are usually not manufactured for blasting purposes, but rather as catalysts for polymerization reactions. They are utilized in a safely phlegmatized condition. They will not be discussed in this book, except for two substances displaying properties of primary explosives: W Tricycloacetone Peroxide and W Hexamethylenetriperoxide Diamine.

PETN

pentaerythritol tetranitrate; Nitropenta; t´etranitrate de pentaerythrite; Pertitrit; corpent

colorless crystals

empirical formula: C5H8N4O12 molecular weight: 316.1

energy of formation: – 385.0 kcal/kg = –1610.7 kJ/kg enthalpy of formation: – 407.4 kcal/kg = –1704.7 kJ/kg oxygen balance: –10.1 %

nitrogen content: 17.72 %

volume of explosion gases: 780 l/kg heat of explosion

(H2O gas): 1398 kcal/kg = 5850 kJ/kg } calculated*) (H2O liq.): 1507 kcal/kg = 6306 kJ/kg

heat of detonation

(H2O liq.): 1510 kcal/kg = 6322 kJ/kg experimental**) specific energy: 123 mt/kg = 1205 kJ/kg

density: 1.76 g/cm3

melting point: 141.3 °C = 286.3 °F heat of fusion: 36.4 kcal/kg = 152 kJ/kg specific heat: 0.26 kcal/kg = 1.09 kJ/kg vapor pressure:

lead block test: 523 cm3/10 g detonation velocity, confined:

8400 m/s = 27 600 ft/s at r = 1.7 g/cm3 deflagration point: 202 °C = 396 F impact sensitivity: 0.3 kp m = 3 N m

* computed by the “ICT-Thermodynamic-Code”.

**value quoted from Brigitta M. Dobratz, Properties of Chemical Explosives and Explosive Simulants, University of California, Livermore.

friction sensitivity: 6 kp = 60 N pistil load critical diameter of steel sleeve test: 6 mm

PETN is very stable, insoluble in water, sparingly soluble in alcohol, ether, and benzene, and soluble in acetone and methyl acetate.

It is prepared by introducing pentaerythrol into concentrated nitric acid with efficient stirring and cooling.

The bulk of the tetranitrate thus formed crystallizes out of the acid. The solution is diluted to about 70 % HNO3 in order to precipitate the remainder of the product. The washed crude product is purified by reprecipitation from acetone.

PETN is one of the most powerful and most brisant explosives, its W Stability is satisfactory, and its W Sensitivity is not extreme. It is used in high-efficiency blasting-cap fillings and detonation cords. If phlegmatized with a small amount of wax and pressed, it may be used to produce boosters and fillings for smaller caliber projectiles. PETN can also be incorporated into gelatinous, industrial explosives (e.g., for seismic prospecting).

Petroleum Jelly

Vaseline

This substance is used as a gunpowder stabilizer. It is believed that the stabilizing effect is due to the presence of unsaturated hydrocarbons, which are capable of binding any decomposition products formed.

Phlegmatization

The impact sensitivity and friction sensitivity of highly sensitive crystalline explosives (e.g., W Cyclonite and W PETN) can be altered to a considerable extent by the addition of small amounts of a phlegmatizer, particularly wax. The added wax also serves as a desirable lubricant and as a binder. RDX, PETN, and W Octogen cannot be compacted by pressing, unless they contain phlegmatization additives.

Wax can also be added to pourable mixtures if they contain aluminum powder (W Torpex).

Picramic Acid

Dinitroaminophenol; acide picramique

empirical formula: C6H5N3O5 molecular weight: 199.1

energy of formation: – 279 kcal/kg = –1167 kJ/kg enthalpy of formation: – 298 kcal/kg = –1248 kJ/kg oxygen balance: – 76.3 %

nitrogen content: 21.11 %

volume of explosion gases: 847 l/kg heat of explosion

(H2O liq.): 639 kcal/kg = 2674 kJ/kg specific energy: 68.2 mt/kg = 669 kJ/kg melting point: 169.9 °C = 337.8 °F lead block test: 166 cm3/10 g deflagration point: 240 °C = 464 °F impact sensitivity: 3.5 pm m = 34 N m friction sensitivity: up to 36 kp = 353 N

pistil load no reaction

critical diameter of steel sleeve test: 2.5 mm

Diazotization of picramic acid yields W Diazodinitrophenol (DDNP). Lead picramate and DDNP are W Initiating Explosives.

Picratol

A 52 : 48 mixture of ammonium picrate and TNT was used as a bomb filling in the Second World War.

Picric Acid

2,4,6-trinitrophenol; Pikrinsäure; acide picrique; melinite;´ Ekrasit; lyddite; shimose; Granatfüllung 88

yellow crystals; (colorant) empirical formula: C6H3N3O7 molecular weight:: 229.1

energy of formation: – 242.5 kcal/kg = –1014.5 kJ/kg enthalpy of formation: – 259.3 kcal/kg = –1084.8 kJ/kg oxygen balance: – 45.4 %

nitrogen content: 18.34 %

volume of explosion gases: 826 l/kg heat of explosion

(H2O liq.): 822 kcal/kg = 3437 kJ/kg (H2O gas): 801 kcal/kg = 3350 kJ/kg specific energy: 101 mt/kg = 995 kJ/kg

density: 1.767 g/cm3

solidification point: 122.5 °C = 252.5 °F heat of fusion: 18.2 kcal/kg = 76.2 kJ/kg specific heat: 0.254 kcal/kg = 1.065 kJ/kg vapor pressure:

greenish, yellow-brown amorphous powder empirical formula of structural unit: C6HN3O6 molecular weight of structural unit: 211.1 mean molecular weight: 2350

oxygen value: – 49.3 % nitrogen content: 19.91 %

explosion heat (H2O liq.): 3200 kJ/kg = 764 kcal/kg density: 1.8 – 2.2 g/cm3

bulk density: 520 g/l

deflagration temperature: 280°– 304 °C impact sensitivity: 3 – 5 Nm = 0.2 – 0,5 kpm

sensitivity to friction: at 360 N = 37 kp pin load, reaction marginal diameter, stell case test: 6 mm

Polynitropolyphenylene is obtained from the reaction of a solution of 1,3-dichloro-2,4,6-trinitrobenzene in nitrobenzene at 150°–180 °C with copper powder (Ullmann reaction).

The raw product obtained in this manner is first separated from copper chloride and then cleaned in several stages from solvent residues and low molecular weight elements. The resulting compound is a noncrystalline explosive of extremely high thermal resistance. In the field of W LOVA technology, it is used as an W Active Binder in high ignition temperature propellants.

Polypropylene Glycol

Polypropylenglykol; polypropylene glycol; PPG

HO-[(CH2)3-O-]34H

viscous liquid

empirical formula: C10H20.2O3.4 molecular weight: 1992

energy of formation: – 853 kcal/kg = – 3571 kJ/kg enthalpy of formation: – 888 kcal/kg = – 3718 kJ/kg oxygen balance: – 218.4 %

density (20/4): 1.003 g/cm3

PPG serves as a prepolymer, which with diisocyanates as curing agents to form polyurethanes used as a binder in W Composite Propellants