Resource recovery systems —such an municipal waste shredding facilities with large hammermills — pose significant explosion threats. Not only do they process ordinary household materials (paper, wood, plastics and rubber products), but also volatile substances ranging from aerosol cans and paint to solvents and lacquers. So a dangerous explosion is only an ignition source away.

Often, the explosion involves both flammable dusts, generated by the shredding process as well as gases, vapors and liquids released during this process. Most explosions are started by the hammer impacting containers of flammable material creating sparks. Other explosions are initiated around the inlet conveyor or in the discharge area.

What's required to protect these complex and expensive shredders is a custom-designed system capable of detecting and suppressing explosions of varying composition that could occur in multiple hazard areas throughout the process. 

the solution

The Fenwal Explosion Protection System strategically locates sensitive pressure detectors where an explosion is likely to start... above and below the shredder rotor, infeed and dribble chute and in the discharge area. At the first indication of a pressure buildup, these detectors trigger the discharge of an agent that suppresses the fireball in milliseconds.

The first Fenwal System to protect a resource recovery operation was installed in 1970. Today, Fenwal is the standard of the industry as these reliable systems detect and suppress an average of ten explosions per year at sites throughout North America.

The Benefits 

How a Fenwal Explosion Protection System Works:

1. 1. Strategically-placed detectors sense changes in pressure caused by
2.      impending explosion
   2. In 3 to 5 milliseconds, high-rate-discharge (HRD) extinguishers begin
3.     to deliver an explosion suppressant to the protected area...suppressing
4.     the explosion's fireball and preventing flame from moving to upstream
5.     equipment
   3. Control unit provides both alarm outputs and process interlocks