During the past ten years, a handful of semiconductor companies have suffered crippling fires. A fire would start in a process tool, such as a wet bench, and then be drawn into the fume exhaust system. The fume exhaust system was typically made of combustible material and devoid of internal automatic sprinkler protection. As a result, the fire would spread rapidly throughout the ductwork system all the way to the scrubbers.

In new fume exhaust ductwork installations, the preferred material is one which meets FM Approval Standard for Fume Exhaust Ducts or Fume and Smoke Exhaust Ducts (Class 4922). Even when subjected to a severe fire, FM4922-Approved ductwork will not collapse, will not propagate fire, and will release only minimal amounts of smoke.

Increasingly, new and retrofitted cleanrooms are installing FM4922-Approved ductwork. However, a considerable amount of combustible ductwork with no automatic sprinkler protection remains in many facilities. Installing either FM4922 products or proper sprinkler protection in these cleanrooms is highly recommended. Replacing combustible ductwork with FM4922-Approved ductwork in existing operating semiconductor cleanrooms is not as daunting a challenge as it may appear.

From: “Cleanroom Fire Prevention”