These requirements cover foam liquid concentrates@ proportioning equipment@ and discharging equipment for producing foam intended for fire extinguishment or control. For medium-expansion foam@ the expansion ratio is 20:1 to 200:1. For high-expansion foam@ the expansion ratio is 200:1 to approximately 1000:1. These requirements are based on the premise that a specific foam liquid concentrate shall be investigated for use with the intended foam equipment. Requirements for the design@ installation@ operation@ testing@ and maintenance of foam systems for fire protection are included in the Standard for Low-@ Medium-@ and High-Expansion Foam@ NFPA 11.