This European Standard specifies the requirements and describes the methods for design, installation, testing and maintenance of low, medium, and high expansion foam fire extinguishing systems. This European Standard provides guidance for the design of various foam systems available to persons with knowledge and experience in determining the selection of foam fire extinguishing systems which will be effective in protecting specific hazard configurations. The requirement for foam systems derives from risk assessment by those competent to carry out such assessments which are outside the scope of this European Standard. This European Standard does not cover a risk analysis carried out by a competent person. Nothing in this European Standard is intended to restrict new technologies or alternative arrangements, provided that the level of safety prescribed in this standard is not lowered, and supported by documented evidence/test reports. All foam systems are generally unsuitable for the following: chemicals, such as cellulose nitrate, that release sufficient oxygen or other oxidising agents which can sustain combustion; energized unenclosed electrical equipment; metals such as sodium, potassium and sodium-potassium alloys which are reactive to water; hazardous, water reactive materials such as triethyl-aluminium and phosphorous pentoxide; combustible metals such as aluminium and magnesium.