Definitions
Article 1
The following definitions shall apply: (1) ‘wobbe index’ or ‘W’ means the ratio of the corresponding calorific value of a gas per unit volume and the square root of its relative density under the same reference conditions: (2) ‘λ-shift factor’ or ‘S λ ’ means an expression that describes the required flexibility of the engine management system regarding a change of the excess-air ratio λ if the engine is fuelled with a gas composition different from pure methane; (3) ‘liquid-fuel mode’ means the normal operating mode of a dual-fuel engine during which the engine does not use any gaseous fuel for any engine operating condition; (4) ‘dual-fuel mode’ means the normal operating mode of a dual-fuel engine during which the engine simultaneously uses liquid fuel and a gaseous fuel at some engine operating conditions; (5) ‘particulate after-treatment system’ means an exhaust after-treatment system designed to reduce emissions of particulate pollutants through a mechanical, aerodynamic, diffusional or inertial separation; (6) ‘governor’ means a device or control strategy that automatically controls engine speed or load, other than an over-speed limiter as installed in an engine of category NRSh limiting the maximum engine speed for the sole purpose of preventing the engine operating at speeds in excess of a certain limit; (7) ‘ambient temperature’ means, in relation to a laboratory environment (e.g. filter weighing room or chamber), the temperature within the specified laboratory environment; (8) ‘base emission control strategy’ or ‘BECS’ means an emission control strategy that is active throughout the range of torque and speed over which the engine operates, unless an auxiliary emission control strategy (AECS) is activated; (9) ‘reagent’ means any consumable or non-recoverable medium required and used for the effective operation of the exhaust after-treatment system; (10) ‘auxiliary emission control strategy’ or ‘AECS’ means an emission control strategy that is activated and temporarily modifies a base emission control strategy (BECS) for a specific purpose and in response to a specific set of ambient and/or operating conditions and only remains in operation as long as those conditions exist; (11) ‘good engineering judgment’ means judgments consistent with generally accepted scientific and engineering principles and available relevant information; (12) ‘high speed’ or ‘n hi ’ means the highest engine speed where 70 % of the maximum power occurs; (13) ‘low speed’ or ‘n lo ’ means the lowest engine speed where 50 % of the maximum power occurs; (14) ‘maximum power’ or ‘P max ’ means the maximum power in kW as designed by the manufacturer; (15) ‘partial flow dilution’ means the method of analysing the exhaust gas whereby a part of the total exhaust gas flow is separated, then mixed with an appropriate amount of dilution air prior to reaching the particulate sampling filter; (16) ‘drift’ means the difference between a zero or calibration signal and the respective value reported by a measurement instrument immediately after it was used in an emission test; (17) ‘to span’ means to adjust an instrument so that it gives a proper response to a calibration standard that represents between 75 % and 100 % of the maximum value in the instrument range or expected range of use; (18) ‘span gas’ means a purified gas mixture used to span gas analysers; (19) ‘HEPA filter’ means high-efficiency particulate air filters that are rated to achieve a minimum initial particle-removal efficiency of 99,97 % using ASTM F 1471–93; (20) ‘calibration’ means the process of setting a measurement system's response to an input signal so that its output agrees with a range of reference signals; (21) ‘specific emissions’ means the mass emissions expressed in g/kWh; (22) ‘operator demand’ means an engine operator's input to control engine output; (23) ‘maximum torque speed’ means the engine speed at which the maximum torque is obtained from the engine, as designed by the manufacturer; (24) ‘engine governed speed’ means the engine operating speed when it is controlled by the installed governor; (25) ‘open crankcase emissions’ means any flow from an engine's crankcase that is emitted directly into the environment; (26) ‘probe’ means the first section of the transfer line which transfers the sample to the next component in the sampling system; (27) ‘test interval’ means a duration of time over which brake-specific emissions are determined; (28) ‘zero gas’ means a gas that yields the value zero as response to its input in an analyser; (29) ‘zeroed’ means that an instrument was adjusted in a manner that it gives a zero response to a zero calibration standard, such as purified nitrogen or purified air; (30) ‘variable-speed non-road steady-state test cycle'’ (hereinafter ‘variable-speed NRSC’) means a non-road steady-state test cycle that is not a constant-speed NRSC; (31) ‘constant-speed non-road steady-state test cycle’ (hereinafter ‘constant-speed NRSC’) means any of the following non-road steady-state test cycles defined in Annex IV to Regulation (EU) 2016/1628: D2, E2, G1, G2 or G3; (32) ‘updating-recording’ means the frequency at which the analyser provides new, current, values; (33) ‘calibration gas’ means a purified mixture of gases used to calibrate gas analysers; (34) ‘stoichiometric’ means relating to the particular ratio of air and fuel such that if the fuel were fully oxidised, there would be no remaining fuel or oxygen; (35) ‘storage medium’ means a particulate filter, sample bag, or any other storage device used for batch sampling; (36) ‘full flow dilution’ means the method of mixing the exhaust gas flow with dilution air prior to separating a fraction of the diluted exhaust gas flow for analysis; (37) ‘tolerance’ means the interval in which 95 % of a set of recorded values of a certain quantity shall lie, with the remaining 5 % of the recorded values deviating from the tolerance interval; (38) ‘service mode’ means a special mode of a dual-fuel engine that is activated for the purpose of repairing, or of moving the non-road mobile machinery to a safe location when operation in the dual-fuel mode is not possible;