From The Chemistry of Explosives, Second Edition

EXPLOSIVE POWER AND POWER INDEX

In an explosive reaction, heat and gases are liberated. The volume of gas V and the heat of explosion Q can both be calculated independently but these values can be combined to give the value for the explosive power as shown in Equation 5.12.


The value for the explosive power is then compared with the explosive power of a standard explosive (picric acid) resulting in the power index, as shown in Equation 5.13, where data for Q (picric acid) and V (picric acid) are 3250 kJ kg ?1 and 0.831 dm 3 g ?1, respectively.


The power index values of some primary and secondary explosive substances are presented in Table 5.14.

Table 5.14: The power index of some primary and secondary explosive substances taking picric acid as the standard

Explosive substance

Q v/kJ g ?1

V/dm 3 g ?1

Q V 10 4

Power index/%

Primary explosives

Mercury fulminate

1755

0.215

37.7

14

Lead styphnate

1885

0.301

56.7

21

Lead azide

1610

0.218

35.1

13

Secondary explosives

Nitroglycerine

6194

0.740

458.4

170

EGDN

6658

0.737

490.7

182

PETN

5794

0.780

451.9

167

RDX

5036

0.908

457.3

169

HMX

5010

0.908

454.9

169

Nitroguanidine

2471

1.077

266.1

99

Picric acid

3249

0.831

270.0

100

Tetryl

4335

0.820

355.5

132

TATB

3496

0.781

273.0

101

HNS

3942

0.747

294.5

109

TNT

4247

0.740

314.3


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