The Non-Road Mobile Machinery (Emission of Gaseous and Particulate Pollutants) Regulations 1999

Sampling for gaseous emissions

1.4.4.  The gaseous emissions sampling probes must be fitted at least 0.5m or three times the diameter of the exhaust pipe—whichever is the larger—upstream of the exit of the exhaust gas system as far as applicable and sufficiently close to the engine as to ensure an exhaust gas temperature of at least 343 K (70°C) at the probe.

• In the case of a multicylinder engine with a branched exhaust manifold, the inlet of the probe shall be located sufficiently far downstream so as to ensure that the sample is representative of the average exhaust emissions from all cylinders. In multicylinder engines having distinct groups of manifolds, such as in a ‘V’-engine configuration, it is permissible to acquire a sample from each group individually and calculate an average exhaust emission. Other methods which have been shown to correlate with the above methods may be used. For exhaust emissions calculation the total exhaust mass flow of the engine must be used.

• If the composition of the exhaust gas is influenced by any exhaust after-treatment system, the exhaust sample must be taken upstream of this device in the tests of stage I and downstream of the device in the tests of stage II. When a full flow dilution system is used for the determination of the particulates, the gaseous emissions may also be determined in the diluted exhaust gas. The sampling probes shall be close to the particulate sampling probe in the dilution tunnel (Annex V, section 1.2.1.2, DT and section 1.2.2, PSP). CO and CO₂ may optionally be determined by sampling into a bag and subsequent measurement of the concentration in the sampling bag.