# Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery, Division 9.3.1.1: Probe design and construction

Extent: E+W+S+N.I.

A probe is the first fitting in a sampling system. It protrudes into a raw or diluted exhaust gas stream to extract a sample, such that it's inside and outside surfaces are in contact with the exhaust gas. A sample is transported out of a probe into a transfer line.
Sample probes shall be made with inside surfaces of stainless steel or, for raw exhaust gas sampling, with any non-reactive material capable of withstanding raw exhaust gas temperatures. Sample probes shall be located where constituents are mixed to their mean sample concentration and where interference with other probes is minimised. It is recommended that all probes remain free from influences of boundary layers, wakes, and eddies — especially near the outlet of a raw-exhaust meter tailpipe where unintended dilution might occur. Purging or back-flushing of a probe shall not influence another probe during testing. A single probe to extract a sample of more than one constituent may be used as long as the probe meets all the specifications for each constituent.

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VI/division/9/division/9.3/division/9.3.1/division/9.3.1.1 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VI/division-9/division-9.3/division-9.3.1/division-9.3.1.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.