Springall Roberts rules

A variation to Kistiakowsky Wilson and modified Kistiakowsky-Wilson rules is provided by the Springall Roberts rules. 

The Springall Roberts rules take the unmodified Kistiakowsky-Wilson rules and add on two more conditions as shown in Table 5.9. 

Using the Springall Roberts rules the products for the decomposition reaction of TNT (C7H5N306) are presented in Table 5.10. 

The three different rules for determining the decomposition products will only provide an insight to the decomposition products they do not give any information as to the energy released on decomposition, but 

2 If any oxygen remains then hydrogen is then oxidized to water 

3 If any oxygen still remains then carbon monoxide is oxidized to 

---

Table 5.10 Decomposition products of TNT using the Springall Roberts rules...

The thermochemistry of explosive compositions has been discussed in detail in Chapter 5. The Kistiakowsky-Wilson and the Springall Roberts rules both give an approximate estimate for the products of decomposition, which is independent of the temperature of explosion. The formulae and calculations for determining the heat of explosion also assume that the explosive reactions go to total completion. However, in practice the reactions do not go to completion and an equilibrium is set up between the reactants and the products. This equilibrium is also dependent upon the temperature of the explosion Te. 

In order to determine the products of decomposition for equilibrium reactions the Kistiakowsky-Wilson or the Springall Roberts rules can be applied as a starting point. From the products of decomposition the heat and temperature of explosion can then be calculated. The temperature of explosion can then be used to calculate the products of decomposition. In practice, this process is repeated many times until there is agreement between the answers obtained. Equilibria of complex reactions and of multi-component systems are today obtained by computer however, the ability to use tabulated data is useful in predicting the direction and extent of the reaction. 

As an example, in Table 4.2, the Springall-Roberts-Rules have been applied to work out the detonation products of TNT. 

The liberated volume of detonation gases (V0, usually back-calculated for standard conditions of 273 I< and 1 bar) is also an important parameter when assessing the performance of an explosive. V0 can easily be calculated using the reaction equation derived from the Springall-Roberts rules and applying the ideal gas law and it is usually given in 1 kg 1. 

Table 9.5 Springall Roberts Rules for Determining the Gaseous Products of Explosives...

Secondary explosive Single-base powder Spontaneous ignition temperature Springall Roberts rules Stoichiometric ratio Triple-base powder Upper flammability limit (UFL)... 

Springall Roberts rules One of several sets of rules used to approximate the mixture of products produced in an explosion. 

---