Inhibition of nonpremixed flames by phosphorus-containing compounds

Phosphorus-containing compounds (PCCs) are proposed as viable alternatives to current, ozone-destroying, flame-inhibiting agents. An opposed-jet burner apparatus was used to study the effectiveness of two low-vapor-pressure PCCs, dimethyl methylphosphonate (DMMP) and trimethyl phosphate (TMP), in extinguishing a nonpremixed methane–air flame. The global extinction strain rate was determined as a function of dopant loadings. Tests were also conducted using nitrogen as an inert additive for reference. Results demonstrate that these phosphorus-containing compounds are significant inhibitors of nonpremixed methane–air flames when introduced into the oxidizer stream, 40 times more effective than nitrogen on a molar basis. A novel technique for measuring the extinction strain rate while maintaining a constant dopant level in one gas stream was developed.