Extinguishing and Suppression - Aerosol Overview16 July 2009Aerosol extinguishing technology has become a viable alternative to gaseous systems in a range of applications, says GianGuido Gianfilippi de Parenti. Here he explains how the technology works and the main considerations for its installation and use. The restrictions in the 1990s in the supply of Halon as a gaseous extinguishing agent, due to its ozone depleting characteristics, gave an added impetus to develop viable aerosol extinguishing systems. The technology has its origins in the Soyuz space programme and originally consisted of a solid aerosol forming compound made of Potassium salts and nitrocellulose, a boosting material used as an accelerator from the solid phase to aerosol phase. Nitrocellulose, however, is a pyrotechnical material and therefore can be unstable in increased temperatures and over time, its mechanical properties decay resulting in loss of efficiency. This led to manufacturers developing new aerosol forming compounds free of pyrotechnical materials, so providing stability in temperature rises and a lifespan of 15 years compared to five. As a result, today this technology is seen as one of the most efficient ‘Halon alternatives' available. Aerosol extinguishing systems employ a solid compound which is transformed into an aerosol that extinguishes fire by breaking the uncontrolled chemical chain reactions of combustion – without depleting oxygen. Their success can be partly attributed to their versatility which also allows for internal/local protection of areas where a fire might start e.g. electrical panels, cabinets etc. Some of the main benefits of the technology are:
Various national and international standards for condensed aerosol extinguishing systems have been developed (see below). Products and systems are tested for their extinguishing performance for different classes of fire, and for the mechanical functions of various components. Accreditation bodies can issue type approvals, performance reports and product certifications or listings when tested against the recognised standards. Consultants and specifiers in the UK should require that the manufacturer is certified to ISO 9001 and ISO 14001, the products are certified/listed by a UK accredited authority such as BSI or LPCB for land applications and by MCA for marine applications, and that the products carry the green label, thus ensuring that they are environment friendly. Additional certifications and listings issued by other accredited authorities will be an added advantage. Each extinguishing system model and size has to undergo all the tests mentioned in the standards in order to be certified, and all the models tested have to be listed in the certification issued. End users, specifiers and any inspection or enforcement authorities should expect to receive all information relevant to the certification including all the relevant technical information, data sheets, design calculations and operating manuals. Specifically, the certificate issued by an accredited body should mention:
Green credentials GianGuido Gianfilippi de Parenti is director of the technical division of FirePro Systems Ltd www.firepro.info
NATIONAL and INTERNATIONAL STANDARDS The following is a list of national and international bodies which have issued standards on condensed aerosol extinguishing systems:
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