<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2008) (Learn how and when to remove this template message) </Td> </Tr> <P> Monoammonium phosphate, ABC Dry Chemical, ABE Powder, tri-class, or multi-purpose dry chemical is a dry chemical extinguishing agent used on class A, class B, and class C fires . It uses a specially fluidized and siliconized monoammonium phosphate powder . ABC dry chemical is usually a mix of monoammonium phosphate and ammonium sulfate, the former being the active one . The mix between the two agents is usually 40--60%, 60 - 40%, or 90 - 10% depending on local standards worldwide . The USGS uses a similar mixture, called Phos Chek G75F . </P> <P> It insulates Class A fires by melting at approximately 350--400 degrees F. Class "A" fires are caused by the burning of common combustible materials, such as wood, paper, or most plastics . </P> <P> The powder breaks the chain reaction of liquid and gas fires by coating the surface to which it is applied . These fires (Class B in the American system; Classes B and C in the European and Australian systems) include the burning of gasoline, oil, propane, and natural gas . </P>

What does an abc fire extinguisher work for