Activity of Secondary Reactions

For cases where the secondary reaction plays a role (class 5), or if the gas release rate must be checked (classes 2 or 4), the heat release rate can be calculated from the thermal stability tests (DSC or Calvet calorimeter). Secondary reactions are often characterized using the concept of Time to Maximum Rate under adiabatic conditions (TMRad). A long time to maximum rate means that the time available to take risk-reducing measures is sufficient. However, a short time means that the 

Note that in this case, the equation is solved for q, an algebraic solution, whereas solving for T (as required for the determination of TD24) results in a transcendental equation, since the heat release rate is an exponential function of temperature. This would require an iterative procedure. This heat release rate may serve as a reference for the extrapolation  

---

The situation is similar to class 1, except that the MTT is above Tm4. This means that under heat accumulation conditions, the activity of secondary reactions cannot be neglected, leading to a slow but significant pressure increase, or gas or vapor release. Nevertheless, the situation may become critical only if the reaction mass is left for a longer time at the level MTT. The assessment can be made using the same procedure as for criticality class 1, represented in Figure 10.8. The gas or vapor flow rate is an important parameter for the design of the required protection measures such as condenser, scrubber, or other treatment units. 

By adjusting reaction conditions to minimize activity of secondary reactions. 

---