The cutter oxidises all hydrocarbons except CH4 to CO2 and H2O, so that by passing the sample through the NMC only CH4 is detected by the FID. If bag sampling is used, a flow diverter system shall be installed at SL (see Section 1.2, Figure 8) with which the flow can be alternatively passed through or around the cutter according to the upper part of Figure 10.
