Another category, called “specialized systems,” includes those systems that are designed to protect special or unique hazards and that have been tested and approved under these specific conditions.
There are no NFPA design and installation standards for local application clean agent systems.
Total flooding systems protect enclosed, or at least partially enclosed, hazards. A sufficient quantity of extinguishing agent is discharged into the enclosure to provide a uniform fire- extinguishing concentration of agent throughout the entire enclosure.
Examples of total flooding systems using halogenated agents are found in computer rooms, electrical switchgear rooms, magnetic tape storage vaults, and electronic control rooms; storage areas for artwork, books, and stamps; aerosol filling rooms; machinery spaces in ships; cargo areas in large transport aircraft; processing and storage areas for paints, solvents, and other flammable liquids; and so on.
Total flooding systems may be further distinguished by their method of design or installation.
An engineered system is custom-designed for a particular hazard, using components that are approved or listed only for their broad performance characteristics. Components may be arranged into an almost unlimited variety of configurations.
In preengineered systems, the number of components and configurations are determined in advance and included in the description of the system’s approval or listing. Although the degree of preengineering can differ from one system to another, the following limits of components and configurations must be considered:
1. Maximum number of cylinders per manifold
2. Maximum and minimum size and length of piping
3. Maximum and minimum size and number of elbows, tees, and discharge nozzles
4. Container volume, fill density, and level of nitrogen superpressurization
Modular systems consist of single containers connected to discharge nozzles with minimal piping. A group of container nozzle assemblies may be distributed throughout the protected area and interconnected electrically. Modular systems permit a more attractive and less expensive initial installation but often result in higher maintenance costs.