Posted on 02/03/2021 in Recycling 2021
Recycling fire-extinguishers to PIN FRs

Ammonium phosphate from end-of-life ABC dry-powder fire extinguishers is an effective PIN FR in polyethylene. Fire-extinguishers must be refilled or completely replaced after specified periods. The resulting spent mono ammonium phosphate (MAP) powder can be recycled as a fertiliser, but this requires purification, e.g. to remove silicones included to improve dispersion and prevent caking. This may not be feasible in some regions, because of logistics costs for transport to reprocessing sites. In this study, the spent MAP was tested directly as a PIN FR at 0 to 60% loading in polyethylene (Matrix Polymers). At 40% loading, the aircraft interior vertical fire test CS25.853 (group 1) was passed (1 mm sheets) but with some deterioration of mechanical properties.

pinfa note: MAP is not generally used as a flame retardant, with ammonium polyphosphate being preferred, because of the sensitivity to water of MAP.
“Mechanical and fire characterization of composite material made of polyethylene matrix and dry chemical powder obtained from end-of-life extinguishers”, Z. Ortega et al., Fire and Materials. 2020;1–10,

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