Dust Explosions,

Explosion Isolation

Isolating an explosion can restrict the amount of damage caused in several ways. Primarily it stops the explosion from reaching other areas of the plant through the process ducts or pipes, but also it stops the possibility of flame jets that can occur at the end of long pipes and stops the pressure from the primary explosion making secondary explosions in further vessels even more violent.

Isolation can be achieved in two different ways, either passive (activated by the explosion itself) or active (requiring tripping by a sensor for activation). Passive systems are favoured as they are simpler and more reliable, as long as they function as intended. Usually these systems will, upon triggering, spray the dust ahead of the flame front with extinguishing agent stopping further propagation, alternatively they may simply close a valve ahead of the flame front (although this can cause pressure problems).

There are a number of plant items that will avoid the propagation of flame throughout the system. These include choked screw conveyers, rotary airlocks, and special bursting disk systems that involve flow reversal.