Section 162.161-3 - Materials(a) All system components must meet the requirements of NFPA 2001 (incorporated by reference, see § 162.161-2 ) and be made of metal, except for bushings, o-rings, and gaskets. Aluminum or aluminum alloys may not be used.(b) Metal components must: (1) Have a solidus melting point of at least 1700 °F;(2) Be corrosion resistant; and(3) Be galvanically compatible with each adjoining metal component, or if galvanically incompatible, be separated by a bushing, o-ring, gasket, or similar device.(c) Each extinguishing agent must be: (1) Listed as an acceptable total flooding agent for occupied areas on the Environmental Protection Agency's Significant New Alternative Products (SNAP) list, 40 CFR part 82, subpart G, Appendix A; and(2) Identified as an extinguishing agent in NFPA 2001 (incorporated by reference, see § 162.161-2 ).(d) The extinguishing concentration of extinguishing agent required for each system must be determined by the cup burner method, described in NFPA 2001 (incorporated by reference, see § 162.161-2 ), for the specific fuel requiring the highest extinguishing concentration.(e) The design concentration of the agent required for each protected space must be calculated using a safety factor of 1.3 times the extinguishing concentration. The quantity must be calculated at the minimum expected ambient temperature using the design concentration based on either:(1) Gross volume, including the casing, bilge, and free air contained in air receivers; or(2) Net volume, calculated as shown in NFPA 2001 (incorporated by reference, see § 162.161-2 ), including the casing, bilge, and free air contained in air receivers, if one of the following is satisfactorily performed:(i) Full discharge test; or(ii) Enclosure integrity procedure in accordance with Annex C of NFPA 2001; for discharge or enclosure integrity tests, the minimum concentration hold time must be 15 minutes, and the extinguishing agent concentration at the end of the hold time must be at least 85 percent of the design concentration.(f) If fuel can drain from the compartment being protected to an adjacent compartment or if the compartments are not entirely separate, the quantity must be sufficient for both compartments.