Fuses, detonating

Concerned mainly with the security of explosives and restncted substances. Applicable to the acquisition, keeping, handling and control of explosives, e.g. blasting explosives, detonators, fuses, ammunitions, propellants, pyrotechnics and fireworks. 

Spreng-wirkung, /. explosive effect, explosive action, -wolke, /. cloud from an explosion, bmst smoke, -zunder, m. detonating fuse. Sprenkel, m. speckle, spot, sprenkeln, v.t. sprinkle speckle, mottle, spot. Sprenkler, m. sprinkler, sparger, sprenkllg, a. speckled, spotted. 

For routine use by unskilled personnel, the best method of measuring velocities of detonation is one due to Dautriche. The principle is illustrated in Fig. 6.5. The two ends of a length of detonating fuse are inserted in the explosive under test at a known distance apart. The mid point of the piece Mark will appear here... 

From about 1930 onwards a new type of detonating fuse appeared on the market. This consisted of a core of PETN with textile and plastic coatings. Compared with Cordeau, this detonating fuse has several advantages in being more flexible, more easily jointed, lighter in weight and cheaper to manufacture. Under such names as Cordtex and Primacord it has completely replaced Cordeau in normal use. 

Detonating fuse is made by either a dry process or a wet process. The former is generally more popular because of its lower costs for ordinary types of fuse. The latter is, however, used particularly in North America. 

The tensile strength of the fuse is of some importance, as it is common practice to lower charges down a large hole by means of the detonating fuse. A strength of 35 kg is adequate, but higher strengths can be achieved when necessary by the addition of further amounts of textile. 

Further properties which a detonating fuse should have are the ability to initiate blasting explosives (tested with suitable relatively insensitive mixtures usually of TNT and ammonium nitrate) resistance to low temperatures without cracking on flexing and to hot storage without desensitisation and toughness to prevent damage from stones, etc. The fuse must always be waterproof and must often withstand diesel oil, which can separate from ANFO. 

The first type to be introduced consisted of PETN or RDX in a metal sheath drawn down to a small diameter. More recently, cord made by the wet process, covered with plastic instead of metal, has been introduced in North America and is available in charges down to 0-6 g m. The methods of manufacture of these cords are believed to be similar to that of Cordeau and the wet detonating fuse process described above. 

For some purposes, particularly in fireworks, instantaneous or almost instantaneous transmission of flame is required without detonation such as is characteristic of detonating fuse. Instantaneous fuse is used for this purpose, deliberate use being made of one of the possible faults in safety fuse, namely, the rapid speeding up which can occur if the core of the safety fuse is porous. 

Cordtex. British trade name for detonating fuse. 

Detonating fuse. A fuse with a core of detonating explosive. 

L.E.D.C. Low Energy Detonating Cord. A detonating fuse with a core charge too low to enable it to be used reliably for initiating high explosives (see p. 124). 

With a sharp knife cut around the detonator just below the lowest or second crimp mark where it is attached to the fuse assembly. This is most easily done by holding the knife firmly on the metal and slowly rolling the detonator-fuse assembly on a flat surface. See Figure 22. The soft metal of the detonator case cuts easily, allowing the detonator to be pulled off the nipple of the fuse assembly. 

Pyrolants deflagration detonation gas generators, igniters, fireworks, squibs, safety fuses detonators, primers, initiators, detonating fuses... 

In order to answer the question of efficiency more or less quantitatively, Deffet and Fosse (Ref 7) conducted, in Belgium, tests by initiating by various methods AN-Fuel Oil (as well as RDX, AN/TNT/Al, etc) explosive cylindrical charges enclosed in Perspex containers. The method was similar to that used by Hershkowitz Dalrymple (Ref 6) at Picatinny Arsenal, Dover, New Jersey. For axial initiation, the detonating fuse extended thru whole length of the charge, as shown in Fig 1... 

Determination of Heat Liberated on Explosion with Calorimeter (99-104) Lead Block Expansion Test (Trauzl Test) (104-06) Compression Tests with Small Lead Blocks (106-08) Testing of Detonators, which include Sand Test and Nail Test (108-14) Water Resistance of Electric Detonators (114-15) Testing Burning (Safety) Fuse (115-18) Testing Detonating Fuse (118-19)... 

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