What is a long-term retardant?
A liquid fertilizer grade ammonium polyphosphate (11-37-0), combined with guar gum, color package and a corrosion inhibitor. It is shipped to the various tanker bases as a liquid concentrate and blended on demand into the airtanker. The mixing ratio of water to liquid concentrate retardant is generally 5.5:1
The active salt permits pyrolysis at a lower temperature and promotes the formation of water, carbon and char at the expense of flammable gases. Wood itself does not burn; rather, the gases that are produced through pyrolysis ignite when the” flash point” is reached and provide the additional heat required to produce additional flammable gases. In summary, long-term retardants inhibit flaming and glowing combustion and remain effective after the water portion is removed [i.e. evaporation]”.