Explosion ignition sensitivity

Index of explosibility = ignition sensitivity x explosion severity... 

Relative explosion Ignition sensitivity Explosion severity Index of explosivity... 

Type of Explosion Ignition Sensitivity Explosion Severity Explosibility Index... 

Therefore, the initial choice for an oxidizer is one with an exothermic heat of decomposition such as potassium chlorate (KCIO 3). However, mixtures of both chlorate and perchlorate salts with active metal fuels are too ignition-sensitive for commercial use, and the less-reactive - but safer - nitrate compormds are usually selected. Potassium perchlorate is used with aluminum and magnesium in some "photoflash" mixtures these are extremely reactive compositions, with velocities in the explosive range. 

Test No 3 If the explosive withstands the Fuse Test, it is subjected to the Red Hot Iron Test described under Ignition Sensitiveness Tests Test No 4 Wood Fire Test In some cases, larger quantities, ie a pound or two, are burned in a wood fire to ascertain the degree of danger the explosive may offer in case of fire. Tne observations should be made under precautions at a safe distance. (Compare with Iron Box Test, described under Ignition Sensitiveness)... 

Tests made on explosives for "sensitivity by impact or friction, although in reality only ignition tests, should correlate well with the hazard of detonating the material. On the other hand, the same tests on a cohesive solid propellant would indicate only its ignitability under that particular stimulus and would not correlate prior experience in the explosives industry. 

This represents the ease with which an explosive can be set off by a blow friction and is expressed in terms of what occurs when a pendulum of known weight scrapes across an explosive (ignites or explodes or snaps or crackles). Sensitivity to friction is less well-defined than the sensitivity to impact and is expressed only by figures compared with a standard. Some explosives can be arranged as follows in terms of decreasing sensitivity. 

Substance Sensitiveness to impact Maximum height of drop (cm) not causing explosion Ignition temperature °C Stability... 

The BurMines criteria for racing the potential explosion hazard of dust by the standard electric spark is defined by the ignition sensitivity, explosion severity and the overall explosibility indices or the correlative adjectives, weak, moderate, strong and severe (Ref 10)... 

L. Schmitz, Chem Ing Tech 21, 386-89 (1949) CA44, 1259 (1950) (Measurement of electrostatic charge and ignition sensitivity of various primary and initiating explosives) 7) R.F. Wilkerson "Research and Development in the Field... 

Methyl, ethyl, and propyl perchlorates are highly explosive oils sensitive to shock, heat, and friction all organic perchlorates are self-contained explosives mixtures of inorganic perchlorates with combustible materials are readily ignited mixtures with finely divided combustibles frequently react explosively.2-6... 

The sensitivity of explosives to inflammation varies widely. Black powder can be exploded by a spark from a spark-producing tool smokeless powders are exploded by the brief flame jet produced by striking a percussion cap. On the other hand, the combustion of an ion-ex-changed -> Permitted Explosive, ignited by a gas flame, is extinguished as soon as the flame source is removed. 

Lead styphnate (Figure 3.17) is a primary explosive (very sensitive) widely used as the ignition element in many hot-wire detonators. In that application it is often mixed with lead azide, another primary explosive. It is also used as one of the major ingredients in modem noncorrosive percussion primers. It is pre-... 

The related curves are given in Vol. Hi, pp. 250, 251,262 and reproduced now in Fig. I. Both curves (T -sensitivity to elevated temperature, Af-sensitivity to impact) are clearly composed of two parts and II. (Curve T was established by determining the temperature of ignition of the samples of 5 g in test tubes placed in wood alloy at 150 C by increasing the temperature of the alloy at the rate of lO C/min. The sensitivity to impact is expressed in ordinates as the work in kg/cm produces 50% of explosion). The sensitivity to impact is manifest by a shape where fraction I of the curve M indicates the increase of the sensitivity of compound A by adding a less sensitive compound B, This is rationalized in terms of the friction between two foreign solid particles. 

Nitroethylene polymer is a white amorphous solid which does tun melt. According to [6 it decomposed slowly at 75 C. After 2 hours of maintaining this temperature it ignited. Wlien heated to I00 ( it deflagrated with a sooty smoke in 23 min. On a hot plate of 200°C it decomposed without explosion. Tlie sensitivity to impact is of the order of TNT. The strength (in ballistic mortar) constitutes only 29% of that of TNT. Hungarian authors (I5 reported the data for polynitrocthylenc as follows ... 

Calculating the ignition sensitivity and explosion severity as defined below ... 

Most of the published explosion hazard data were obtained under standard conditions. If the actual process conditions are different from the standard conditions, the published data may not represent the actual gas explosion hazards, and the ignition sensitivity, flammability, and explosion severity/violence of the combustible gases should be measured under the actual process conditions with adequate test methods. 

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