Primary expls

As already mentioned (Section 1), the,prepn of most of the commonly used high expl compds involves one or more nitration reactions. Indeed, except for ammonium nitrate (AN), primary expls, and BkPdr, it is difficult to bring to mind any expl in common use (or even a laboratory curiosity) that was not prepared by nitration. In Table 1, we list the most important military and commercial high expl compds produced by nitration. We have grouped these compds by nitration type, ie C-nitration, O-nitration, and N-nitration. Note that either nitric acid or mixed acid are the nitrating agents principally employed in industry. This will be discussed further in the next section. The Table also gives Encyclopedia references for those compounds already described in previous Encyclopedia volumes... 

Oxalic Acid, Salts of, Bertholet (Ref 2) in 1883 noticed that some salts of oxalic add, eg mercuric or silver, have the properties of primary expls. According to Urbadski (Ref 14), although they have no practical application as initiators, it is interesting from a theoretical point of view, due chiefly to the fact that the general equation for the decompn of oxalates... 

CAHN RG ELECTROBALANCE/SEDIMENTATION ACCESSORY. This app produces a continuous, visible chart record of the sediment weight collected on the balance pan. It has been evaluated for measuring particle size distributions of the primary expls Lead Styphnate, Lead Azide, Tetracene by Hutchinson (Ref 41). 

It is difficult to obtain accurate particle size analyses of primary expls because (1) consideration and acceptance of necessary safety precautions make the usually tedious job of particle size analysis even more tedious, and (2) many primary expls used in production contain particles which are non-spherical in shape and are in the subsieve size range. Dry screening Lead Azide, for instance, is hazardous and must be done remotely. Furthermore, static charges... 

Some specialized uses of PETN are summarized below. Expendable cartridges for small arms are made by coating unglazed grains or single base smokeless powder with PETN, spraying with plasticized thermoplastic binder and compression molding to the desired shape (Ref 99). Tucker et al (Ref 85) describe a spark detonator without primary expls. Secondary... 

It is significant, however, that in most, and probably all, relative rankings of the impact sensitivities of solid expls (see Vol 7, I42-R), PETN ranks as the most sensitive secondary expl (primary expls, such as Lead Azides, Mercuric Fulminate, etc, are more sensitive)... 

C6H2(N02)30H (NH SaQs C02+HN03+HCN When mildly reduced, for example with Na sulfide or hydrosulfite or with ferrous sulfate, PA is converted into picramic acid, a very useful intermediate in the dyestuffs industry and a starting material for the preparation of Diazo-dinitrophenol, a primary expl (see Vol 2, B59-L). Stronger reduction may lead to the formation of triamino phenol... 

The pyrotechnic literature does not contain a critical evaluation of the ignition response time. of primary initiators in terms of their compn, temp tolerance and shock sensitivity. In general, primary expls such as Pb Azide or styphnate are selected whenever a brief (microsecond) response is desired, while, for instance, Pb thiocyanate-chlorate mixts are selected when high temps and high radiation environments are encountered, and presumably a longer ignition delay is the price which is paid for the extra margin of safety... 

Critical Mass of Explosive. The minimum quantity of an expi required for development of detonation it varies widely for different types, being only milligrams for sensitive primary expls and pounds or tons for non-detonating expls like colloided proplnts and AN Ref Dunkle s Syllabus (1957-58), 157-58... 

It is extremely small for primary expls (such as LA or MF), larger for secondary expls (such as TNT, Tetryl, PETN or RDX) and still larger for smokeless proplnts or BkPdr... 

Jones Jackson of Picatinny Arsenal (Ref 6) carried out experiments using the same procedure as that of Ubbelohde et al (Ref 4) except that a Cu rather than an Al sample holder was used. They performed two types of experiments a) measurements of the induction period as a function of temp for several common expls and b) examination of these expls to det which of them show the "memory effect . Jones Jackson reported that the memory effect is not found with all primary expls (eg Tetracene) and it is found with some HE s, but not all. Some of the props which might... 

Detonation High-, Low-, and Intermediate Order, Velocities of. It has been known since the end of the last century that some liquid expls (such as NG or NGc) and some gelatinous expls (such as Gelatin Dynamites) are capable of detonating at either low (1000-2000 m/sec) or high velocity (up to 8000 m/sec), depending on method of initiation. More recently it was found that the same phenomenon can occur, under certain conditions, with crystalline secondary, or even primary, expls... 

Stresau, PhysRev 87, 234(1952) CA 48, 8543(1954) (Low detonation velocity of certain primary expls) 9) R. Schall, ZAngewPhys 6, 470-75 (1954) ("Die Sta-bilitatlangsamer Detonationen ) The Engrg Index(1955), 362. Engl transin by Sgt A. Himsl, entitled "Stability of Detonations , Tech Transin No 20, Scientific and Technical Information Branch, FREL, PicArsn, Dover, NJ (1958) 10) T.C. Poulter, "A... 

PrRoySoc 246A, 189-96(1958) (Ignition of primary expls by electric discharges)... 

TrRoySoc 241 A, 280-86(1948) Research (London) 3, 207-12(1950) (The sensitiveness to initiation by mechanical action has been examined in relation to heat for LA, MF and, in some cases, for LSt, in order to see how far mechanical action could be equated with local heating. For primary expls, the process which "triggers energy release may involve thermal or tri-bochemical activation of the molecules)... 

Dunkle s Syllabus (1960-1961), pp 13c 17d (Spontaneous detonation of LA and other primary expls during crystal growth)... 

Such secondary explosives may be more susceptible than primary expls to combustion instability. Thus, the combustion temperatures for K Picrate and Tetryl at atmospheric pressure are 2800 and 2400°K, respectively, whereas the maximum comb... 

Thus primary expl have "a probably of the order of 0.1mm or less, expls commonly used as boosters have it probably equal to 1- 2mm, and insensitive HE s such as Amatols have it probably as high as 5mm... 

These primers can be used not only in small arms but also in some pyrotechnic devices and fuzes. All simple primers are small in size, 0.21 to 0.31 inch in diam and 0.12 to 0.23 inches long for rifle ammunition and slightly Smaller for carbines. They contain only one small charge of primary expl or a mixture which must have sufficient sensitivity to be initiated either by the crushing or stab action of a firing pin... 

When this method started to be investigated after WWII in USA, it was found that it had great possibilities. Not only could the electrical safety of detonators be improved but also the handling of sensitive primary expls could be eliminated... 

No single explosive has been used by itself in percussion primers because none has been found that meets both the input and output requirements. As can be seen from compns listed above, the usual ingredients are a primary expl, an oxidizer, a fuel, and, in some cases, an abrasive. Some mixts ate made of nonexplosive components, such as a fuel and oxidizer with or w/o abrasive... 

Davis (1943), 400-53 (Primary expls, detonators and primers) 453-54 (Friction primers) 454-58 (Percussion primers) 9a) D. Hart, "Compilation of Data on the Composition of Foreign Igniters and Tracers",... 

CA 58, 403(1963) [Main reasons for the difference between primary and secondary expls include 1) Primary expls are unstable in burning and convert rapidly into detonation. For example the burning of a 1-cm long cartridge of MF at 1-atm converts into deton, while similar cartridge of RDX or PETN continues to burn even at 10 and 100 atm 2) The gaseous products of a... 

The bridge wire ignites the styphnate, which in turn sets off the base chge (a mixt of B/KNOj pellets and granules) located in the same cavity. The basic elements of this system have been tested separately and proved to be satisfactory Ad 155) L.R. Rothstein et al, USP 3284255 (1966) 81 CA 66, 1989(1967) (An expl initiator contg a mixt of 1 part LA with 2 parts Ba styphnate as primary expl and PETN as a secondary expl. It is claimed that LA-BaSt mixts are no mote dangerous to handle than some secondary expls) Ad 156) G.W.C. Taylor S.E. Napier, USP 3291663(1966)... 

G.W.C. Taylor S.E. Napier, USP 3291664 (1966) CA 66, 5434(1967) [Primary expls, also suitable as fast-delay components, are prepd by pptg an expl (such Ba or Pb styphnate Pb 2,4- or 4,6-dinitroresorcinate LA and Ba trinitrophloroglucinate) from an aq Na carboxymethylcellulose soln contg a... 

Pb azide, Pb nitrophenols, Pb triethanol-ammonium perchlorate and PETN or RDX, with a sheath spun from filaments of a thermo plastic material or a ductile metal such as bronze) Ad 159) J.F. Kenney, USP 3293091(1966) CA 67, 7089(1967) [Primary expl mixts contg 46% of complex clathrate inclusion salts (as shown by X-ray diffraction data) of basic lead picrate, such as Pb(C5H2N3O7)2-Pb(OH)2-Pb(N03)2.-Pb(OAc)2, 50% Ba nitrate 4% Tetracene]... 

Ad 181) G.W.C. Taylor et al, BritP 1086861(1967) CA 68, 1422(1968)(Finely divided B is incorporated into primary expls to reduce their sensitivity to accidental ignition by electrostatic sparks. In some cases, this incorporation also increases the power percussion sensitivity of the expls) Ad 182) D.M. Welsh, CanP 770392(1967)... 

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