We are remodeling our semiconductor cleanrooms and require a fire suppression system for our wet benches inside the cleanroom. What should I specify in issuing the request for quote? How do I qualify this system once installed?

There are two different types of fire suppression systems. The Integral-Factory (pre-engineered) design type is factory tested and certified by manufacturers such as Ansul, Fike, Kidde, Fenwal, and Pyro-Chem. These companies sell the equipment only to certified fire suppression operations (distributors) with cleanroom expertise for cleanroom installation. To become certified, one must meet several requirements including attending classes sponsored by these companies. Some manufacturers require re-certification of distributors at regularly scheduled intervals. The second type of fire suppression systems is a Retrofit-Field (engineered) installation. The components used in the retrofit are tested prior to installation at the factory and installed by a distributor with cleanroom expertise. In either of these cases, there must be a building permit in place and all installation is inspected by both the local building inspector and fire department inspector.

TYPES OF MEDIA AND SYSTEMS
There are different types of media used in fire suppression systems—dry chemical, liquid, and gas. The most commonly used media in cleanroom wet benches is CO₂. The piping, nozzles, and other apparatus used in cleanroom CO₂ fire suppression systems when solvents are used on the wet benches is stainless steel. However, if acid based products are used on the wet benches then the stainless steel piping is coated with Halar®. When CO₂ fire suppression systems are used to suppress the fire, one must use this type of high pressure piping. This piping is connected to several 75 -100 lb CO₂ cylinders which are located outside the cleanroom area.

The engineering design for cleanroom CO₂ fire suppression systems is performed and approved by both the customer and the authority having jurisdiction (AHJ). Cleanroom wet benches require unique location application designs which are designed to protect the four major areas of a wet bench. These areas are the work surface protected by “rate by volume”, the headcase, plenum and mini-environments protected by “Total Flood.”