NFPA 11-1998 Standard for Low-Expansion Foam

NFPA 11-1998 Standard for Low-Expansion Foam. 1-4 Definitions. Air-Aspirating Discharge Devices. These devices are spe- cially designed to aspirate and mix air into the foam solution to generate foam. The foam then is discharged in a specific design pattern. Approved.* Acceptable to the authority having jurisdic- tion. Authority Having Jurisdiction.* The organization, office, or individual responsible for approving equipment, an installa- tion, or a procedure. Concentration. The percent of foam concentrate contained in a foam solution. The type of foam concentrate used deter- mines the percentage of concentration required. For exam- ple, a 3 percent foam concentrate is mixed in the ratio of 97 parts water to 3 parts foam concentrate to make foam solution. Discharge Device. A fixed, semifixed, or portable device that directs the flow of foam to the fire or flammable liquid surface. Eductor (Inductor).* A device that uses the venturi princi- ple to introduce a proportionate quantity of foam concentrate into a water stream. The pressure at the throat is below atmo- spheric pressure and will draw in liquid from atmospheric storage. Expansion. The ratio of final foam volume to original foam solution volume. Fixed Foam Discharge Outlet. A device permanently attached to a tank, dike, or other containment structure, designed to introduce foam. Fixed Monitor (Cannon). A device that delivers a large foam stream and is mounted on a stationary support that either is elevated or is at grade. The monitor can be fed solu- tion by permanent piping or hose. 2-3.2.4 Storage Conditions. In order to ensure the correct operation of any foam-producing system, the chemical and physical characteristics of the materials comprising the system shall be taken into consideration in design. Since such systems might or might not be operated for long periods after installa- tion, the choice of proper storage conditions and mainte- nance methods largely determines the reliability and the degree of excellence of system operation when they are put into service. 2-3.2.4.1* Foam concentrates are subject to freezing and to deterioration from prolonged storage at high temperatures and shall be stored within the listed temperature limitations. They might be stored in the containers in which they are trans- ported or might be transferred into large bulk storage tanks, depending on the requirements of the system. The location of stored containers requires special consideration to protect against exterior deterioration due to rusting or other causes. Bulk storage containers also require special...