Theemission composition is measured for a prototype burner while varyingthe equivalence ratio in discrete portions of the burner. Theburner is a three sector system, consisting of a separateigniter, pilot/stabilizer and main burner. The design allows for discretecontrol of equivalence ratio in each of the three sectors.The ignition sector, designated RPL (Rich-Pilot-Lean), operates from rich tolean equivalence values, and serves to ignite the pilot sector,which, in turn, stabilizes the main combustion sector. All threeburner sections are premixed. The burner is operated at atmosphericpressure with inlet flows heated to 650 K (±8 K).Tests were performed for three gases: methane, a model syngas(10% CH4, 22.5% CO, 67.5% H2), and dilute syngas. Thedilute gas includes sufficient nitrogen to lower the heating valueto 15 MJ/m3. The model syngas and diluted syngas arerepresentative of fuels produced by gasification process. The burner emissions,specifically, CO, CO2, O2 and NOx, are measured while holdingthe RPL equivalence value constant and varying the equivalence ratioof the pilot and main sectors. The equivalence ratios forpilot and main sectors are chosen such that the totalburner equivalence ratios remain constant during a test sequence. Thetarget total equivalence ratio for each gas is chosen suchthat all experiments should have the same flame temperature.