A non-methane cutter is a heated catalyst that removes non-methane hydrocarbons from the exhaust stream before the FID analyser measures the remaining hydrocarbon concentration. An ideal non-methane cutter would have a methane conversion efficiency ECH4 [-] of 0 (that is, a methane penetration fraction, PFCH4, of 1,000), and the conversion efficiency for all other hydrocarbons would be 1,000, as represented by an ethane conversion efficiency EC2H6 [-] of 1 (that is, an ethane penetration fraction PFC2H6 [-] of 0).
