LegalizeCommission 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
In continuous sampling, the constituent's concentration is measured continuously from raw or diluted exhaust gas. This concentration is multiplied by the continuous (raw or diluted) exhaust gas flow rate at the emission sampling location to determine the constituent's flow rate. The constituent's emission is continuously summed over the test interval. This sum is the total mass of the emitted constituent.
In batch sampling, a sample of raw or diluted exhaust gas is continuously extracted and stored for later measurement. The extracted sample shall be proportional to the raw or diluted exhaust gas flow rate. Examples of batch sampling are collecting diluted gaseous emissions in a bag and collecting PM on a filter. In principal the method of emission calculation is done as follows: the batch sampled concentrations are multiplied by the total mass or mass flow (raw or dilute) from which it was extracted during the test cycle. This product is the total mass or mass flow of the emitted constituent. To calculate the PM concentration, the PM deposited onto a filter from proportionally extracted exhaust gas shall be divided by the amount of filtered exhaust gas.
Any combination of continuous and batch sampling is permitted (e.g. PM with batch sampling and gaseous emissions with continuous sampling).
Figure 6.2 illustrates the two aspects of the test procedures for measuring emissions: the equipment with the sampling lines in raw and diluted exhaust gas and the operations requested to calculate the pollutant emissions in steady-state and transient test cycles.
Note on Figure 6.2: The term ‘Partial flow PM sampling’ includes the partial flow dilution to extract only raw exhaust gas with constant or varying dilution ratio.
The work shall be determined over the test cycle by synchronously multiplying speed and brake torque to calculate instantaneous values for engine brake power. Engine brake power shall be integrated over the test cycle to determine total work.
To achieve stable conditions, the sampling system and the engine shall be preconditioned before starting a test sequence as specified in this point.
The intent of engine preconditioning is to achieve the representativeness of emissions and emission controls over the duty cycle and to reduce bias in order to meet stable conditions for the following emission test.
Emissions may be measured during preconditioning cycles, as long as a predefined number of preconditioning cycles are performed and the measurement system has been started according to the requirements of point 7.3.1.4. The amount of preconditioning shall be identified by the engine manufacturer before starting to precondition. Preconditioning shall be performed as follows, noting that the specific cycles for preconditioning are the same ones that apply for emission testing.
Engines fitted with an after-treatment system may be operated prior to cycle-specific preconditioning set out in points 7.3.1.1.1 to 7.3.1.1.4, so that the after-treatment system is regenerated and, where applicable, the soot load in the particulate after-treatment system is re-established.
The engine shall be preconditioned by running at least one hot-start NRTC. Immediately after completing each preconditioning cycle, the engine shall be shut down and the engine-off hot-soak period shall be completed. Immediately after completing the last preconditioning cycle, the engine shall be shut down and the engine cool down described in point 7.3.1.2 shall be started.
This point describes the pre-conditioning that shall be applied when it is intended to sample emissions from the hot-start NRTC without running the cold-start run of the NRTC (‘cold-start NRTC’), or for the LSI-NRTC. The engine shall be preconditioned by running at least one hot-start NRTC or LSI-NRTC as applicable. Immediately after completing each preconditioning cycle, the engine shall be shut down, and then the next cycle shall be started as soon as practical. It is recommended that the next preconditioning cycle shall be started within 60 seconds after completing the last preconditioning cycle. Where applicable, following the last pre-conditioning cycle the appropriate hot-soak (hot-start NRTC) or cool-down (LSI-NRTC) period shall apply before the engine is started for the emissions test. Where no hot-soak or cool down period applies it is recommended that the emissions test shall be started within 60 seconds after completing the last pre-conditioning cycle.
For engine categories other than NRS and NRSh the engine shall be warmed-up and run until engine temperatures (cooling water and lube oil) have been stabilized on 50 % speed and 50 % torque for any discrete-mode NRSC test cycle other than type D2, E2, or G, or nominal engine speed and 50 % torque for any discrete-mode NRSC test cycle D2, E2 or G. The 50 % speed shall be calculated in accordance with point 5.2.5.1 in the case of an engine where MTS is used for the generation of test speeds, and calculated in accordance with point 7.7.1.3 in all other cases. 50 % torque is defined as 50 % of the maximum available torque at this speed. The emissions test shall be started without stopping the engine.
For engine categories NRS and NRSh the engine shall be warmed up according to the recommendation of the manufacturer and good engineering judgment. Before emission sampling can start, the engine shall be running on mode 1 of the appropriate test cycle until engine temperatures have been stabilized. The emissions test shall be started without stopping the engine.
The engine manufacturer shall select one of the following pre-conditioning sequences (a) or (b). The engine shall be pre-conditioned according to the chosen sequence.
(a) The engine shall be preconditioned by running at least the second half of the RMC, based on the number of test modes. The engine shall not be shut down between cycles. Immediately after completing each preconditioning cycle, the next cycle (including the emission test) shall be started as soon as practical. Where possible, it is recommended that the next cycle be started within 60 seconds after completing the last preconditioning cycle.
(b) The engine shall be warmed-up and run until engine temperatures (cooling water and lube oil) have been stabilized on 50 % speed and 50 % torque for any RMC test cycle other than type D2, E2, or G, or nominal engine speed and 50 % torque for any RMC test cycle D2, E2 or G. The 50 % speed shall be calculated in accordance with point 5.2.5.1 in the case of an engine where MTS is used for the generation of test speeds, and be calculated in accordance with point 7.7.1.3 in all other cases. 50 % torque is defined as 50 % of the maximum available torque at this speed.
A natural or forced cool-down procedure may be applied. For forced cool-down, good engineering judgment shall be used to set up systems to send cooling air across the engine, to send cool oil through the engine lubrication system, to remove heat from the coolant through the engine cooling system, and to remove heat from an exhaust after-treatment system. In the case of a forced after-treatment cool down, cooling air shall not be applied until the exhaust after-treatment system has cooled below its catalytic activation temperature. Any cooling procedure that results in unrepresentative emissions is not permitted.
If there is any presumption of an essential HC contamination of the exhaust gas measuring system, the contamination with HC may be checked with zero gas and the hang-up may then be corrected. If the amount of contamination of the measuring system and the background HC system has to be checked, it shall be conducted within 8 hours of starting each test-cycle. The values shall be recorded for later correction. Before this check, the leak check has to be performed and the FID analyzer has to be calibrated.
The following steps shall be taken before emission sampling begins:
(a) Leak checks shall be performed within 8 hours prior to emission sampling in accordance with point 8.1.8.7;
(b) For batch sampling, clean storage media shall be connected, such as evacuated bags or tare-weighed filters;
(c) All measurement instruments shall be started in accordance with the instrument manufacturer's instructions and good engineering judgment;
(d) Dilution systems, sample pumps, cooling fans, and the data-collection system shall be started;
(e) The sample flow rates shall be adjusted to desired levels, using bypass flow, if desired;
(f) Heat exchangers in the sampling system shall be pre-heated or pre-cooled to within their operating temperature ranges for a test;
(g) Heated or cooled components such as sample lines, filters, chillers, and pumps shall be allowed to stabilize at their operating temperatures;
(h) Exhaust gas dilution system flow shall be switched on at least 10 minutes before a test sequence;
(i) Calibration of gas analyzers and zeroing of continuous analyzers shall be carried out in accordance with the procedure of point 7.3.1.5;
(j) Any electronic integrating devices shall be zeroed or re-zeroed, before the start of any test interval.
Appropriate gas analyzer ranges shall be selected. Emission analyzers with automatic or manual range switching are allowed. During a test using transient (NRTC or LSI-NRTC) test cycles or RMC and during a sampling period of a gaseous emission at the end of each mode for discrete-mode NRSC testing, the range of the emission analyzers shall not be switched. Also the gains of an analyzer's analogue operational amplifier(s) shall not be switched during a test cycle.
All continuous analyzers shall be zeroed and spanned using internationally-traceable gases that meet the specifications of point 9.5.1. FID analyzers shall be spanned on a carbon number basis of one (C1).
The procedures for PM filter preconditioning and tare weighing shall be performed in accordance with point 8.2.3.
The following steps shall be taken after emission sampling is complete:
For any proportional batch sample, such as a bag sample or PM sample, it shall be verified that proportional sampling was maintained according to point 8.2.1. For the single filter method and the discrete steady-state test cycle, effective PM weighting factor shall be calculated. Any sample that does not fulfil the requirements of point 8.2.1 shall be voided.
Used PM sample filters shall be placed into covered or sealed containers or the filter holders shall be closed, in order to protect the sample filters against ambient contamination. Thus protected, the loaded filters have to be returned to the PM-filter conditioning chamber or room. Then the PM sample filters shall be conditioned and weighted accordingly to point 8.2.4 (PM filter post-conditioning and total weighing procedures).
As soon as practical, the following shall be performed:
(a) All batch gas analyzers shall be zeroed and spanned no later than 30 minutes after the test cycle is complete or during the soak period if practical to check if gaseous analyzers are still stable;
(b) Any conventional gaseous batch samples shall be analyzed no later than 30 minutes after the hot-start NRTC is complete or during the soak period;
(c) The background samples shall be analyzed no later than 60 minutes after the hot-start NRTC is complete.
After quantifying exhaust gas, drift shall be verified as follows:
(a) For batch and continuous gas analyzers, the mean analyzer value shall be recorded after stabilizing a zero gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response;
(b) The mean analyzer value shall be recorded after stabilizing the span gas to the analyzer. Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response;
(c) These data shall be used to validate and correct for drift as described in point 8.2.2.
The EU type-approval test shall be conducted using the appropriate NRSC and, where applicable, NRTC or LSI-NRTC, specified in Article 18 of Regulation (EU) 2016/1628 and Annex IV thereto. The technical specifications and characteristics of the NRSC, NRTC and LSI-NRTC are laid down in Annex XVII of this Regulation and the method for determination of the torque, power and speed settings for these test cycles set out in section 5.2.
Non-road steady-state test cycles (NRSC) are specified in Appendices 1 and 2 of Annex XVII as a list of discrete-modes NRSC (operating points), where each operating point has one value of speed and one value of torque. A NRSC shall be measured with a warmed up and running engine according to manufacturer's specification. At the choice of the manufacturer, a NRSC may be run as a discrete-mode NRSC or a RMC, as explained in points 7.4.1.1 and 7.4.1.2. It shall not be required to conduct an emission test according to both points 7.4.1.1 and 7.4.1.2.
The discrete-mode NRSC are hot running cycles where emissions shall be started to be measured after the engine is started, warmed up and running as specified in point 7.8.1.2. Each cycle consists of a number of speed and load modes (with the respective weighing factor for each mode) which cover the typical operating range of the specified engine category.
The RMC are hot running cycles where emissions shall be started to be measured after the engine is started, warmed up and running as specified in point 7.8.2.1. The engine shall be continuously controlled by the test bed control unit during the RMC. The gaseous and particulate emissions shall be measured and sampled continuously during the RMC in the same way as in a transient (NRTC or LSI-NRTC) test cycles.
An RMC is intended to provide a method for performing a steady-state test in a pseudo-transient manner. Each RMC consists of a series of steady state modes with a linear transition between them. The relative total time at each mode and its preceding transition match the weighting of the discrete-mode NRSC. The change in engine speed and load from one mode to the next one has to be linearly controlled in a time of 20 ± 1 seconds. The mode change time is part of the new mode (including the first mode). In some cases modes are not run in the same order as the discrete-mode NRSC or are split to prevent extreme changes in temperature.
The non-road transient cycle for engines of category NRE (NRTC) and the non-road transient cycle for large spark ignition engines of category NRS (LSI-NRTC) are each specified in Appendix 3 of Annex XVII as a second-by-second sequence of normalized speed and torque values. In order to perform the test in an engine test cell, the normalized values shall be converted to their equivalent reference values for the individual engine to be tested, based on specific speed and torque values identified in the engine-mapping curve. The conversion is referred to as denormalization, and the resulting test cycle is the reference NRTC or LSI-NRTC test cycle of the engine to be tested (see point 7.7.2).
A graphical display of the normalized NRTC dynamometer schedule is shown in Figure 6.3.
The NRTC shall be run twice after completion of pre-conditioning (see point 7.3.1.1.1) in accordance with the following procedure:
(a) the cold start run shall commence after either the engine and exhaust after-treatment systems have cooled down to room temperature after natural engine cool down, or after forced cool down, and the engine, coolant and oil temperatures, exhaust after-treatment systems and all engine control devices are stabilized between 293 K and 303 K (20 °C and 30 °C). The measurement of the emissions for this run shall be started with the start of the cold engine;
(b) the hot soak period shall commence immediately upon completion of the cold start phase. The engine shall be shut-down and conditioned for the hot-start run by soaking it for 20 minutes ± 1 minute;
(c) the hot-start run shall commence immediately after the soak period with the cranking of the engine. The gaseous analyzers shall be switched on at least 10 seconds before the end of the soak period to avoid switching signal peaks. The measurement of emissions for this run shall be started in parallel with the cranking of the engine.
Brake specific emissions expressed in (g/kWh), or number per kilowatt-hour (#/kWh) for PN, shall be determined by using the procedures set out in this section for both the cold start run and hot-start run of the test cycle. Composite weighted emissions shall be computed by weighting the cold-start run results by 10 % and the hot-start run results by 90 % as detailed in Annex VII.
The LSI-NRTC shall be run once as a hot-start run after completion of pre-conditioning (see point 7.3.1.1.2) in accordance with the following procedure:
(a) the engine shall be started and operated for the first 180 seconds of the duty cycle, then operated at idle without load for 30 seconds. Emissions shall not be measured during this warm-up sequence.
(b) At the end of the 30-second idling period, emissions measurement shall be started and the engine be operated over the entire duty cycle from the beginning (time 0 sec).
Brake specific emissions expressed in (g/kWh) shall be determined by using the procedures of Annex VII.
If the engine was already operating before the test, use good engineering judgment to let the engine cool down enough so measured emissions will accurately represent those from an engine starting at room temperature. For example, if an engine starting at room temperature warms up enough in three minutes to start closed-loop operation and achieve full catalyst activity, then minimal engine cooling is necessary before starting the next test.
With the prior agreement of the technical service, the engine warm-up procedure may include up to 15 minutes of operation over the duty cycle.
To measure engine emissions the following steps have to be performed:
(a) The engine test speeds and test loads have to be defined for the engine to be tested by measuring the max torque (for constant-speed engines) or max torque curve (for variable-speed engines) as function of the engine speed;
(b) Normalized test cycles have to be denormalized with the torque (for constant-speed engines) or speeds and torques (for variable-speed engines) found in the previous point 7.5(a);
(c) The engine, equipment, and measurement instruments shall be prepared for the following emission test or test series (cold-start run and hot-start run) in advance;
(d) Pre-test procedures shall be performed to verify proper operation of certain equipment and analyzers. All analysers have to be calibrated. All pre-test data shall be recorded;
(e) The engine shall be started (NRTC) or kept running (steady-state cycles and LSI-NRTC) at the beginning of the test cycle and the sampling systems shall be started at the same time;
(f) Emissions and other required parameters shall be measured or recorded during sampling time (for NRTC, LSI-NRTC and RMC throughout the whole test cycle);
(g) Post-test procedures shall be performed to verify proper operation of certain equipment and analyzers;
(h) PM filter(s) shall be pre-conditioned, weighed (empty weight), loaded, re-conditioned, again weighed (loaded weight) and then samples shall be evaluated in accordance with the pre-test (point 7.3.1.6) and post-test (point 7.3.2.2) procedures;
(i) Emission test results shall be evaluated.
Figure 6.4 gives an overview about the procedures needed to conduct NRMM test cycles with measuring exhaust engine emissions.
The engine shall be started:
(a) As recommended in the end-users' instructions using a production starter motor or air-start system and either an adequately charged battery, a suitable power supply or a suitable compressed air source; or
(b) By using the dynamometer to crank the engine until it starts. Typically operate the engine within ± 25 % of its typical in-use cranking speed or start the engine by linearly increasing the dynamometer speed from zero to 100 min– 1 below low idle speed but only until the engine starts.
Cranking shall be stopped within 1 s of starting the engine. If the engine does not start after 15 s of cranking, cranking shall be stopped and the reason for the failure to start determined, unless the end-users' instructions or the service-repair manual describes a longer cranking time as normal.
(a) If the engine stalls anywhere during the cold start run of the NRTC, the entire test shall be voided;
(b) If the engine stalls anywhere during the hot-start run of the NRTC, only this run shall be voided. The engine shall be soaked in accordance with point 7.8.3, and the hot-start run repeated. In this case, the cold-start run does not need to be repeated;
(c) If the engine stalls anywhere during the LSI-NRTC, the test shall be voided.
(d) If the engine stalls anywhere during the NRSC (discrete or ramped), the test shall be voided and be repeated beginning with the engine warm-up procedure. In the case of PM measurement utilizing the multi-filter method (one sampling filter for each operating mode), the test shall be continued by stabilizing the engine at the previous mode for engine temperature conditioning and then initiating measurement with the mode where the engine stalled.
The ‘operator’ may be a person (i.e., manual), or a governor (i.e., automatic) that mechanically or electronically signals an input that demands engine output. Input may be from an accelerator pedal or signal, a throttle-control lever or signal, a fuel lever or signal, a speed lever or signal, or a governor set point or signal.
Before starting the engine mapping, the engine shall be warmed up and towards the end of the warm up it shall be operated for at least 10 minutes at maximum power or according to the recommendation of the manufacturer and good engineering judgement in order to stabilize the engine coolant and lube oil temperatures. When the engine is stabilized, the engine mapping shall be performed.
Where the manufacturer intends to use the torque signal broadcast by the electronic control unit, of engines so equipped, during the conduct of in-service monitoring tests according to Delegated Regulation (EU) 2017/655 on monitoring of emissions of in-service engines, the verification set out in Appendix 3 shall additionally be performed during the engine mapping.
Except constant-speed engines, engine mapping shall be performed with fully open fuel lever or governor using discrete speeds in ascending order. The minimum and maximum mapping speeds are defined as follows:
Where:
n hiis the high speed, as defined in Article 1(12).
If the highest speed is unsafe or unrepresentative (e.g., for ungoverned engines), good engineering judgement shall be used to map up to the maximum safe speed or the maximum representative speed.
In the case of engine mapping for a variable-speed NRSC (only for engines which have not to run the NRTC or LSI-NRTC cycle), good engineering judgment shall be used to select a sufficient number of evenly spaced set-points. At each set-point, speed shall be stabilized and torque allowed to stabilize at least for 15 seconds. The mean speed and torque shall be recorded at each set-point. It is recommended that the mean speed and torque are calculated using the recorded data from the last 4 to 6 seconds. Linear interpolation shall be used to determine the NRSC test speeds and torques if needed. When engines are additionally required to run an NRTC or LSI-NRTC, the NRTC engine mapping curve shall be used to determine steady-state test speeds and torques.
At the choice of the manufacturer the engine mapping may alternatively be conducted according to the procedure in point 7.6.2.
The engine mapping shall be performed according to the following procedure:
(a) The engine shall be unloaded and operated at idle speed; (i) For engines with a low-speed governor, the operator demand shall be set to the minimum, the dynamometer or another loading device shall be used to target a torque of zero on the engine's primary output shaft and the engine shall be allowed to govern the speed. This warm idle speed shall be measured; (ii) For engines without a low-speed governor, the dynamometer shall be set to target a torque of zero on the engine's primary output shaft, and the operator demand shall be set to control the speed to the manufacturer-declared lowest engine speed possible with minimum load (also known as manufacturer-declared warm idle speed); (iii) The manufacturer declared idle torque may be used for all variable-speed engines (with or without a low-speed governor), if a nonzero idle torque is representative of in-use operation;
(b) Operator demand shall be set to maximum and engine speed shall be controlled to between warm idle and 95 % of its warm idle speed. For engines with reference duty cycles, which lowest speed is greater than warm idle speed, the mapping may be started at between the lowest reference speed and 95 % of the lowest reference speed;
(c) The engine speed shall be increased at an average rate of 8 ± 1 min– 1/s or the engine shall be mapped by using a continuous sweep of speed at a constant rate such that it takes 4 to 6 min to sweep from minimum to maximum mapping speed. The mapping speed range shall be started between warm idle and 95 % of warm idle and ended at the highest speed above maximum power at which less than 70 % of maximum power occurs. If this highest speed is unsafe or unrepresentative (e.g., for ungoverned engines), good engineering judgment shall be used to map up to the maximum safe speed or the maximum representative speed. Engine speed and torque points shall be recorded at a sample rate of at least 1 Hz;
(d) If a manufacturer believes that the above mapping techniques are unsafe or unrepresentative for any given engine, alternate mapping techniques may be used. These alternate techniques shall satisfy the intent of the specified mapping procedures to determine the maximum available torque at all engine speeds achieved during the test cycles. Deviations from the mapping techniques specified in this section for reasons of safety or representativeness shall be approved by the approval authority along with the justification for their use. In no case, however, the torque curve shall be run by descending engine speeds for governed or turbocharged engines;
(e) An engine need not be mapped before each and every test cycle. An engine shall be remapped if: (i) an unreasonable amount of time has transpired since the last map, as determined by good engineering judgment; or (ii) physical changes or recalibrations have been made to the engine which potentially affect engine performance; or (iii) the atmospheric pressure near the engine's air inlet is not within ± 5 kPa of the value recorded at the time of the last engine map.
The engine may be operated with a production constant-speed governor or a constant-speed governor maybe simulated by controlling engine speed with an operator demand control system. Either isochronous or speed-droop governor operation shall be used, as appropriate.
The following check shall be conducted:
(a) With the governor or simulated governor controlling speed using operator demand the engine shall be operated at the rated speed and the rated power for as long as required to achieve stable operation;
(b) The torque shall be increased until the engine is unable to maintain the governed speed. The power at this point shall be recorded. Before this check is performed the method to safely determine when this point has been reached shall be agreed between the manufacturer and the technical service conducting the check, depending upon the characteristics of the governor. The power recorded shall not exceed the rated power as defined in Article 3(27) of Regulation (EU) 2016/1628 by more than 12,5 %. If this value is exceeded the manufacturer shall revise the declared rated power.
If the specific engine being tested is unable to perform this check due to risk of damage to the engine or dynamometer the manufacturer shall present to the approval authority robust evidence that maximum power does not exceed the rated power by more than 12,5 %.
(a) With the governor or simulated governor controlling speed using operator demand, the engine shall be operated at no-load governed speed (at high speed, not low idle) for at least 15 seconds, unless the specific engine is unable to perform this task;
(b) The dynamometer shall be used to increase torque at a constant rate. The map shall be conducted such that it takes no less than 2 min to sweep from no-load governed speed to the torque corresponding to rated power for engines to be tested on cycle D2 or E2 or to maximum torque in the case of other constant-speed test cycles. During the engine mapping actual speed and torque shall be recorded with at least 1 Hz;
(c) In case of a constant-speed engine with a governor that can be reset to alternative speeds, the engine shall be tested at each applicable constant-speed.
For constant-speed engines good engineering judgment shall be used in agreement with the approval authority to apply other methods to record torque and power at the defined operating speed(s).
For engines tested on cycles other than D2 or E2, when both measured and declared values are available for the maximum torque, the declared value may be used instead of the measured value if it is between 95 and 100 % of the measured value.
This point shall be used to generate the engine speeds and loads over which the engine shall be operated during steady-state tests with discrete-mode NRSC or RMC.
For engines that are tested with either NRTC or LSI-NRTC in addition to a NRSC, the MTS specified in point 5.2.5.1 shall be used as the 100 % speed for both transient and steady state tests.
The MTS shall be used in place of rated speed when determining intermediate speed in accordance with point 5.2.5.4.
The idle speed shall be determined in accordance with point 5.2.5.5.
For engines that are not tested with a transient (NRTC or LSI-NRTC) test cycle, the rated speed specified in point 5.2.5.3 shall be used as the 100 % speed.
The rated speed shall be used to determine the intermediate speed in accordance with point 5.2.5.4. If the NRSC specifies additional speeds as a percentage they shall be calculated as a percentage of the rated speed.
The idle speed shall be determined in accordance with point 5.2.5.5.
With prior approval of the technical service, MTS may be used instead of rated speed for the generation of test speeds in this point.
The per cent load for each test mode of the chosen test cycle shall be taken from the appropriate NRSC Table of Appendix 1 or 2 of Annex XVII. Depending upon the test cycle, the per cent load in these Tables is expressed as either power or torque in accordance with point 5.2.6 and in the footnotes for each Table.
The 100 % value at a given test speed shall be the measured or declared value taken from the mapping curve generated in accordance with point 7.6.1, point 7.6.2 or point 7.6.3 respectively, expressed as power (kW).
The engine setting for each test mode shall be calculated by means of equation (6-14):
| (6-14) | |
|---|---|
Where:
S is the dynamometer setting in kW
P max is the maximum observed or declared power at the test speed under the test conditions (specified by the manufacturer) in kW
P AUX is the declared total power absorbed by auxiliaries as defined in equation (6-8) (see point 6.3.5) at the specified test speed in kW
L is per cent torque
A warm minimum torque that is representative of in-use operation may be declared and used for any load point that would otherwise fall below this value if the engine type will not normally operate below this minimum torque, for example because it will be connected to a non-road mobile machinery that does not operate below a certain minimum torque.
In the case of cycles E2 and D2 the manufacturer shall declare the rated power and these shall be used as 100 % power when generating the test cycle.
This point shall be used to generate the corresponding engine speeds and loads over which the engine shall be operated during NRTC or LSI-NRTC tests. Appendix 3 of Annex XVII defines applicable test cycles in a normalized format. A normalized test cycle consists of a sequence of paired values for speed and torque %.
Normalized values of speed and torque shall be transformed using the following conventions:
(a) The normalized speed shall be transformed into a sequence of reference speeds, n ref, in accordance with point 7.7.2.2;
(b) The normalized torque is expressed as a percentage of the mapped torque from the curve generated according to point 7.6.2 at the corresponding reference speed. These normalized values shall be transformed into a sequence of reference torques, T ref, according to point 7.7.2.3;
(c) The reference speed and reference torque values expressed in coherent units are multiplied to calculate the reference power values.
The engine speed shall be denormalized using by means of equation (6-15):
| (6-15) | |
|---|---|
Where:
n ref is the reference speed
MTS is the maximum test speed
n idle is the idle speed
%speed is the value of NRTC or LSI-NRTC normalized speed taken from Appendix 3 of Annex XVII.
The torque values in the engine dynamometer schedule of Appendix 3 of Annex XVII. are normalized to the maximum torque at the respective speed. The torque values of the reference cycle shall be denormalized, using the mapping curve determined according to point 7.6.2, by means of equation (6-16):
| (6-16) | |
|---|---|
for the respective reference speed as determined in point 7.7.2.2
Where:
T ref is the reference torque for the respective reference speed
max.torque is the maximum torque for the respective test speed taken from the engine mapping performed in accordance with point 7.6.2 adjusted where necessary in accordance with point 7.7.2.3(b)
%torque is the value of NRTC or LSI-NRTC normalized torque taken from Appendix 3 of Annex XVII
A minimum torque that is representative of in-use operation may be declared. For example, if the engine is typically connected to a non-road mobile machinery that does not operate below a certain minimum torque, this torque may be declared and used for any load point that would otherwise fall below this value.
Where auxiliaries are fitted in accordance with Appendix 2 there shall be no adjustment to the maximum torque for the respective test speed taken from the engine mapping performed according to point 7.6.2.
Where, according to points 6.3.2 or 6.3.3 necessary auxiliaries that should have been fitted for the test are not installed, or auxiliaries that should have been removed for the test are installed, the value of T max shall be adjusted by means of equation (6-17).
| T max = T map – T AUX | (6-17) |
|---|---|
with:
| TAUX = Tr – Tf | (6-18) |
|---|---|
where:
T map is the unadjusted maximum torque for the respective test speed taken from the engine mapping performed in accordance with point 7.6.2
T f is the torque required to drive auxiliaries that should have been fitted but were not installed for the test
Tr is the torque required to drive auxiliaries that should have been removed for the test but were installed for the test
As an example, the following test point shall be denormalized:
Given the following values:
results in
With the maximum torque of 700 Nm observed from the mapping curve at 1 288 min–1
Pre-test procedure according to point 7.3.1 shall be performed, including analyzer calibration. The engine shall be warmed-up using the pre-conditioning sequence in point 7.3.1.1.3. Immediately from this engine conditioning point, the test cycle measurement starts.
(a) The test shall be performed in ascending order of mode numbers as set out for the test cycle (see Appendix 1 of Annex XVII);
(b) Each mode has a mode length of at least 10 minutes. In each mode the engine shall be stabilised for at least 5 minutes. Gaseous emissions, and, where applicable, PN, shall be sampled for 1 to 3 minutes at the end of each mode and PM emissions shall be sampled in accordance with point (c); Notwithstanding the previous paragraph, when either testing spark ignition engines using cycles G1, G2 or G3 or when conducting measurements in accordance with Annex V of this Regulation each mode has a mode length of at least 3 minutes. In this case gaseous emissions, and, where applicable, PN, shall be sampled for at least the last 2 minutes of each mode and PM emissions shall be sampled in accordance with point (c). The mode length and sampling time may be extended to improve accuracy; The mode length shall be recorded and reported.
(c) For PM emissions, the PM sampling may be done either with the single filter method or with the multiple filter method. Since the results of the methods may differ slightly, the method used shall be declared with the results; For the single filter method the modal weighting factors specified in the test cycle procedure and the actual exhaust gas flow shall be taken into account during sampling by adjusting sample flow rate and/or sampling time, accordingly. It is required that the effective weighing factor of the PM sampling is within ± 0,005 of the weighing factor of the given mode; Sampling shall be conducted as late as possible within each mode. For the single filter method, the completion of PM sampling shall be coincident within ± 5 s with the completion of the gaseous emission measurement. The sampling time per mode shall be at least 20 s for the single filter method and at least 60 s for the multi-filter method. For systems without bypass capability, the sampling time per mode shall be at least 60 s for single and multiple filter methods;
(d) The engine speed and load, intake air temperature, fuel flow and where applicable air or exhaust gas flow shall be measured for each mode at the same time interval which is used for the measurement of the gaseous concentrations; Any additional data required for calculation shall be recorded.
(e) If the engine stalls or the emission sampling is interrupted at any time after emission sampling begins for a discrete-mode NRSC and the single filter method, the test shall be voided and be repeated beginning with the engine warm-up procedure. In the case of PM measurement utilizing the multi-filter method (one sampling filter for each operating mode), the test shall be continued by stabilizing the engine at the previous mode for engine temperature conditioning and then initiating measurement with the mode where the engine stalled;
(f) Post-test procedures according to point 7.3.2 shall be performed.
During each mode of the given steady-state test cycle after the initial transition period, the measured speed shall not deviate from the reference speed for more than ± 1 % of rated speed or ± 3 min– 1, whichever is greater except for idle which shall be within the tolerances declared by the manufacturer. The measured torque shall not deviate from the reference torque for more than ± 2 % of the maximum torque at the test speed.
Pre-test procedure according to point 7.3.1 shall be performed, including analyzer calibration. The engine shall be warmed-up using the pre-conditioning sequence in point 7.3.1.1.4. Immediately after this engine conditioning procedure, if the engine speed and torque are not already set for the first mode of the test they shall be changed in a linear ramp of 20 ± 1 s to the first mode of the test. In between 5 to 10 s after the end of the ramp, the test cycle measurement shall start.
The test shall be performed in the order of mode numbers as set out for the test cycle (see Appendix 2 of Annex XVII) Where there is no RMC available for the specified NRSC the discrete-mode NRSC procedure set out in point 7.8.1 shall be followed.
The engine shall be operated for the prescribed time in each mode. The transition from one mode to the next shall be done linearly in 20 s ± 1 s following the tolerances prescribed in point 7.8.2.4.
For RMC, reference speed and torque values shall be generated at a minimum frequency of 1 Hz and this sequence of points shall be used to run the cycle. During the transition between modes, the denormalized reference speed and torque values shall be linearly ramped between modes to generate reference points. The normalized reference torque values shall not be linearly ramped between modes and then denormalized. If the speed and torque ramp runs through a point above the engine's torque curve, it shall be continued to command the reference torques and it shall be allowed for the operator demand to go to maximum.
Over the whole RMC (during each mode and including the ramps between the modes), the concentration of each gaseous pollutant shall be measured and where there is an applicable limit the PM and PN be sampled. The gaseous pollutants may be measured raw or diluted and be recorded continuously; if diluted, they can also be sampled into a sampling bag. The particulate sample shall be diluted with conditioned and clean air. One sample over the complete test procedure shall be taken, and, in the case of PM collected on a single PM sampling filter.
For calculation of the brake specific emissions, the actual cycle work shall be calculated by integrating actual engine power over the complete cycle.
(a) Execution of the RMC, sampling exhaust gas, recording data, and integrating measured values shall be started simultaneously;
(b) Speed and torque shall be controlled to the first mode in the test cycle;
(c) If the engine stalls anywhere during the RMC execution, the test shall be voided. The engine shall be pre-conditioned and the test repeated;
(d) At the end of the RMC, sampling shall be continued, except for PM sampling, operating all systems to allow system response time to elapse. Then all sampling and recording shall be stopped, including the recording of background samples. Finally, any integrating devices shall be stopped and the end of the test cycle shall be indicated in the recorded data;
(e) Post-test procedures according to point 7.3.2 shall be performed.
RMC tests shall be validated using the regression analysis as described in points 7.8.3.3 and 7.8.3.5. The allowed RMC tolerances are given in the following Table 6.1. Note that the RMC tolerances are different from the NRTC tolerances of Table 6.2. When conducting testing of engines of reference power greater than 560 kW the regression line tolerances of Table 6.2 and the point deletion of Table 6.3 may be used.
| Speed | Torque | Power | |
|---|---|---|---|
| Standard error of estimate (SEE) of y on x | maximum 1 % of rated speed | maximum 2 % of maximum engine torque | maximum 2 % of maximum engine power |
| Slope of the regression line, a 1 | 0,99 to 1,01 | 0,98 - 1,02 | 0,98 - 1,02 |
| Coefficient of determination, r 2 | minimum 0,990 | minimum 0,950 | minimum 0,950 |
| y intercept of the regression line, a 0 | ± 1 % of rated speed | ± 20 Nm or 2 % of maximum torque whichever is greater | ± 4 kW or 2 % of maximum power whichever is greater |
In case of running the RMC test not on a transient test bed, where the second by second speed and torque values are not available, the following validation criteria shall be used.
At each mode the requirements for the speed and torque tolerances are given in point 7.8.1.3. For the 20 s linear speed and linear torque transitions between the RMC steady-state test modes (point 7.4.1.2) the following tolerances for speed and load shall be applied for the ramp:
(a) the speed shall be held linear within ± 2 % of rated speed,
(b) the torque shall be held linear within ± 5 % of the maximum torque at rated speed.
Reference speeds and torques commands shall be sequentially executed to perform the NRTC and LSI-NRTC. Speed and torque commands shall be issued at a frequency of at least 5 Hz. Because the reference test cycle is specified at 1 Hz, the in between speed and torque commands shall be linearly interpolated from the reference torque values generated from cycle generation.
Small denormalized speed values near warm idle speed may cause low-speed idle governors to activate and the engine torque to exceed the reference torque even though the operator demand is at a minimum. In such cases, it is recommended to control the dynamometer so it gives priority to follow the reference torque instead of the reference speed and let the engine govern the speed.
Under cold-start conditions engines may use an enhanced-idle device to quickly warm up the engine and the exhaust after-treatment system. Under these conditions, very low normalized speeds will generate reference speeds below this higher enhanced idle speed. In this case it is recommended controlling the dynamometer so it gives priority to follow the reference torque and let the engine govern the speed when the operator demand is at minimum.
During an emission test, reference speeds and torques and the feedback speeds and torques shall be recorded with a minimum frequency of 1 Hz, but preferably of 5 Hz or even 10 Hz. This larger recording frequency is important as it helps to minimize the biasing effect of the time lag between the reference and the measured feedback speed and torque values.
The reference and feedback speeds and torques maybe recorded at lower frequencies (as low as 1 Hz), if the average values over the time interval between recorded values are recorded. The average values shall be calculated based on feedback values updated at a frequency of at least 5 Hz. These recorded values shall be used to calculate cycle-validation statistics and total work.
Pre-test procedures according to point 7.3.1 shall be performed, including pre-conditioning, cool-down and analyzer calibration.
Testing shall be started as follows:
Post-test procedures according to point 7.3.2 shall be performed.
Pre-test procedures according to point 7.3.1 shall be performed, including pre-conditioning and analyzer calibration.
Testing shall be started as follows:
Post-test procedures according to point 7.3.2 shall be performed.
In order to check the validity of a test, the cycle-validation criteria in this point shall be applied to the reference and feedback values of speed, torque, power and overall work.
Before calculating the cycle work, any speed and torque values recorded during engine starting shall be omitted. Points with negative torque values have to be accounted for as zero work. The actual cycle work W act (kWh) shall be calculated based on engine feedback speed and torque values. The reference cycle work W ref (kWh) shall be calculated based on engine reference speed and torque values. The actual cycle work W act is used for comparison to the reference cycle work W ref and for calculating the brake specific emissions (see point 7.2).
W act shall be between 85 % and 105 % of W ref.
Linear regression between the reference and the feedback values shall be calculated for speed, torque and power.
To minimize the biasing effect of the time lag between the reference and feedback cycle values, the entire engine speed and torque feedback signal sequence may be advanced or delayed in time with respect to the reference speed and torque sequence. If the feedback signals are shifted, both speed and torque shall be shifted by the same amount in the same direction.
The method of least squares shall be used, with the best-fit equation having the form set out in equation (6-19):
| y = a 1 x + a 0 | (6-19) |
|---|---|
where:
y is the feedback value of speed (min– 1), torque (Nm), or power (kW)
a 1 is the slope of the regression line
x is the reference value of speed (min– 1), torque (Nm), or power (kW)
a 0 is the y intercept of the regression line.
The standard error of estimate (SEE) of y on x and the coefficient of determination (r 2) shall be calculated for each regression line in accordance with Appendix 3 of Annex VII.
It is recommended that this analysis be performed at 1 Hz. For a test to be considered valid, the criteria of Table 6.2 shall be met.
| Speed | Torque | Power | |
|---|---|---|---|
| Standard error of estimate (SEE) of y on x | ≤ 5,0 percent of maximum test speed | ≤ 10,0 % of maximum mapped torque | ≤ 10,0 % of maximum mapped power |
| Slope of the regression line, a 1 | 0,95 to 1,03 | 0,83 - 1,03 | 0,89 - 1,03 |
| Coefficient of determination, r 2 | minimum 0,970 | minimum 0,850 | minimum 0,910 |
| y intercept of the regression line, a 0 | ≤ 10 % of idle | ± 20 Nm or ± 2 % of maximum torque whichever is greater | ± 4 kW or ± 2 % of maximum power whichever is greater |
For regression purposes only, point deletions are permitted where noted in Table 6.3 before doing the regression calculation. However, those points shall not be deleted for the calculation of cycle work and emissions. An idle point is defined as a point having a normalized reference torque of 0 % and a normalized reference speed of 0 %. Point deletion may be applied to the whole or to any part of the cycle; points to which the point deletion is applied have to be specified.
| Event | Conditions (n = engine speed, T = torque) | Permitted point deletions |
|---|---|---|
| Minimum operator demand (idle point) | n ref = n idle and T ref = 0 % and T act > (T ref – 0,02 T maxmappedtorque) and T act < (T ref + 0,02 T maxmappedtorque) | speed and power |
| Minimum operator demand | n act ≤ 1,02 n ref and T act > T ref or n act > n ref and T act ≤ T ref' or n act > 1,02 n ref and T ref < T act ≤ (T ref + 0,02 T maxmappedtorque) | power and either torque or speed |
| Maximum operator demand | n act < n ref and T act ≥ T ref or n act ≥ 0,98 n ref and T act < T ref or n act < 0,98 n ref and T ref > T act ≥ (T ref – 0,02 T maxmappedtorque) | power and either torque or speed |
| Where: nref is the reference speed (see section 7.7.2.), nidle is the idle speed, nact is the actual (measured) speed, Tref is the reference torque (see section 7.7.2.), Tact is the actual (measured) torque, Tmaxmappedtorque is the highest value of torque on the full-load torque curve mapped in accordance with section 7.6. |
8. Measurement procedures
This point describes required calibrations and verifications of measurement systems. See point 9.4 for specifications that apply to individual instruments.
Calibrations or verifications shall be generally performed over the complete measurement chain.
If a calibration or verification for a portion of a measurement system is not specified, that portion of the system shall be calibrated and its performance verified at a frequency consistent with any recommendations from the measurement system manufacturer and consistent with good engineering judgment.
Internationally recognized-traceable standards shall be used to meet the tolerances specified for calibrations and verifications.
Table 6.4 summarizes the calibrations and verifications described in section 8 and indicates when these have to be performed.
| Type of calibration or verification | Minimum frequency () |
|---|---|
| 8.1.3: accuracy, repeatability and noise | Accuracy: Not required, but recommended for initial installation. Repeatability: Not required, but recommended for initial installation. Noise: Not required, but recommended for initial installation. |
| 8.1.4: linearity verification | Speed: Upon initial installation, within 370 days before testing and after major maintenance. Torque: Upon initial installation, within 370 days before testing and after major maintenance. Intake air, dilution air and diluted exhaust gas flows and batch sample flow rates: Upon initial installation, within 370 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance. Raw exhaust gas flow: Upon initial installation, within 185 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance. Gas dividers: Upon initial installation, within 370 days before testing and after major maintenance. Gas analyzers (unless otherwise noted): Upon initial installation, within 35 days before testing and after major maintenance. FTIR analyser: Upon installation, within 370 days before testing and after major maintenance. PM balance: Upon initial installation, within 370 days before testing and after major maintenance. Stand-alone pressure and temperature: Upon initial installation, within 370 days before testing and after major maintenance. |
| 8.1.5: Continuous gas analyzer system response and updating-recording verification — for gas analyzers not continuously compensated for other gas species | Upon initial installation or after system modification that would affect response. |
| 8.1.6: Continuous gas analyzer system response and updating-recording verification — for gas analyzers continuously compensated for other gas species | Upon initial installation or after system modification that would affect response. |
| 8.1.7.1: torque | Upon initial installation and after major maintenance. |
| 8.1.7.2: pressure, temperature, dew point | Upon initial installation and after major maintenance. |
| 8.1.8.1: fuel flow | Upon initial installation and after major maintenance. |
| 8.1.8.2: intake flow | Upon initial installation and after major maintenance. |
| 8.1.8.3: exhaust gas flow | Upon initial installation and after major maintenance. |
| 8.1.8.4: diluted exhaust gas flow (CVS and PFD) | Upon initial installation and after major maintenance. |
| 8.1.8.5: CVS/PFD and batch sampler verification () | Upon initial installation, within 35 days before testing, and after major maintenance. (Propane check) |
| 8.1.8.8: vacuum leak | Upon installation of the sampling system. Before each laboratory test according to point 7.1: within 8 hours before the start of the first test interval of each duty cycle sequence and after maintenance such as pre-filter changes. |
| 8.1.9.1: CO2 NDIR H2O interference | Upon initial installation and after major maintenance. |
| 8.1.9.2: CO NDIR CO2 and H2O interference | Upon initial installation and after major maintenance. |
| 8.1.10.1: FID calibration HC FID optimization and HC FID verification | Calibrate, optimize, and determine CH4 response: upon initial installation and after major maintenance. Verify CH4 response: upon initial installation, within 185 days before testing, and after major maintenance. |
| 8.1.10.2: raw exhaust gas FID O2 interference | For all FID analyzers: upon initial installation, and after major maintenance. For THC FID analyzers: upon initial installation, after major maintenance, and after FID optimization according to 8.1.10.1. |
| 8.1.11.1: CLD CO2 and H2O quench | Upon initial installation and after major maintenance. |
| 8.1.11.3: NDUV HC and H2O interference | Upon initial installation and after major maintenance. |
| 8.1.11.4: Sample dryer NO2 penetration (chiller) | Upon initial installation and after major maintenance. |
| 8.1.11.5: NO2-to-NO converter conversion | Upon initial installation, within 35 days before testing, and after major maintenance. |
| 8.1.12: Sample dryer verification | For thermal chillers: upon installation and after major maintenance. For osmotic membranes: upon installation, within 35 days of testing and after major maintenance. |
| 8.1.13.1: PM balance and weighing | Independent verification: upon initial installation, within 370 days before testing, and after major maintenance. Zero, span, and reference sample verifications: within 12 hours of weighing, and after major maintenance. |
| (1) Perform calibrations and verifications more frequently, according to measurement system manufacturer instructions and good engineering judgment. (2) The CVS verification is not required for systems that agree within ± 2 % based on a chemical balance of carbon or oxygen of the intake air, fuel, and diluted exhaust gas. |
The performance values for individual instruments specified in Table 6.8 are the basis for the determination of the accuracy, repeatability, and noise of an instrument.
It is not required to verify instrument accuracy, repeatability, or noise. However, it may be useful to consider these verifications to define a specification for a new instrument, to verify the performance of a new instrument upon delivery, or to troubleshoot an existing instrument.
A linearity verification shall be performed on each measurement system listed in Table 6.5 at least as frequently as indicated in the Table, consistent with measurement system manufacturer recommendations and good engineering judgment. The intent of a linearity verification is to determine that a measurement system responds proportionally over the measurement range of interest. A linearity verification shall consist of introducing a series of at least 10 reference values to a measurement system, unless otherwise specified. The measurement system quantifies each reference value. The measured values shall be collectively compared to the reference values by using a least squares linear regression and the linearity criteria specified in Table 6.5.
If a measurement system does not meet the applicable linearity criteria in Table 6.5, the deficiency shall be corrected by re-calibrating, servicing, or replacing components as needed. The linearity verification shall be repeated after correcting the deficiency to ensure that the measurement system meets the linearity criteria.
The following linearity verification protocol shall be used:
(a) A measurement system shall be operated at its specified temperatures, pressures, and flows;
(b) The instrument shall be zeroed as it would before an emission test by introducing a zero signal. For gas analyzers, a zero gas shall be used that meets the specifications of point 9.5.1 and it shall be introduced directly at the analyzer port;
(c) The instrument shall be spanned as it would before an emission test by introducing a span signal. For gas analyzers, a span gas shall be used that meets the specifications of point 9.5.1 and it shall be introduced directly at the analyzer port;
(d) After spanning the instrument, zero shall be checked with the same signal which has been used in paragraph (b) of this point. Based on the zero reading, good engineering judgment shall be used to determine whether or not to re-zero and or re-span the instrument before proceeding to the next step;
(e) For all measured quantities manufacturer recommendations and good engineering judgment shall be used to select the reference values, y ref i, that cover the full range of values that are expected during emission testing, thus avoiding the need of extrapolation beyond these values. A zero reference signal shall be selected as one of the reference values of the linearity verification. For stand-alone pressure and temperature linearity verifications, at least three reference values shall be selected. For all other linearity verifications, at least ten reference values shall be selected;
(f) Instrument manufacturer recommendations and good engineering judgment shall be used to select the order in which the series of reference values will be introduced;
(g) Reference quantities shall be generated and introduced as described in point 8.1.4.4. For gas analyzers, gas concentrations known to be within the specifications of point 9.5.1 shall be used and they shall be introduced directly at the analyzer port;
(h) Time for the instrument to stabilize while it measures the reference value shall be allowed;
(j) Steps in paragraphs (g) to (i) of this point shall be repeated until all reference quantities are measured;
(k) The arithmetic means
, and reference values, y ref i, shall be used to calculate least-squares linear regression parameters and statistical values to compare to the minimum performance criteria specified in Table 6.5. The calculations described in Appendix 3 of Annex VII shall be used.
This point describes recommended methods for generating reference values for the linearity-verification protocol in point 8.1.4.3. Reference values shall be used that simulate actual values, or an actual value shall be introduced and measured with a reference-measurement system. In the latter case, the reference value is the value reported by the reference-measurement system. Reference values and reference-measurement systems shall be internationally traceable.
For temperature measurement systems with sensors like thermocouples, RTDs, and thermistors, the linearity verification may be performed by removing the sensor from the system and using a simulator in its place. A simulator that is independently calibrated and cold junction compensated, as necessary shall be used. The internationally traceable simulator uncertainty scaled to temperature shall be less than 0,5 % of maximum operating temperature T max. If this option is used, it is necessary to use sensors that the supplier states are accurate to better than 0,5 % of T max compared to their standard calibration curve.
Table 6.5 indicates measurement systems that require linearity verifications. For this Table the following provisions shall apply:
(a) a linearity verification shall be performed more frequently if the instrument manufacturer recommends it or based on good engineering judgment;
(b) ‘min’ refers to the minimum reference value used during the linearity verification; Note that this value may be zero or a negative value depending on the signal;
(c) ‘max’ generally refers to the maximum reference value used during the linearity verification. For example for gas dividers, x max is the undivided, undiluted, span gas concentration. The following are special cases where ‘max’ refers to a different value: (i) For PM balance linearity verification, m max refers to the typical mass of a PM filter; (ii) For torque linearity verification, T max refers to the manufacturer's specified engine torque peak value of the highest torque engine to be tested;
(d) the specified ranges are inclusive. For example, a specified range of 0,98-1,02 for the slope a 1 means 0,98 ≤ a 1 ≤ 1,02;
(e) these linearity verifications are not required for systems that pass the flow-rate verification for diluted exhaust gas as described in point 8.1.8.5 for the propane check or for systems that agree within ± 2 % based on a chemical balance of carbon or oxygen of the intake air, fuel, and exhaust gas;
(f) a 1 criteria for these quantities shall be met only if the absolute value of the quantity is required, as opposed to a signal that is only linearly proportional to the actual value;
(g) stand-alone temperatures include engine temperatures and ambient conditions used to set or verify engine conditions; temperatures used to set or verify critical conditions in the test system; and temperatures used in emissions calculations: (i) these temperature linearity checks are required. Air intake; after-treatment bed(s) (for engines tested with exhaust after-treatment systems on cycles with cold start criteria); dilution air for PM sampling (CVS, double dilution, and partial flow systems); PM sample; and chiller sample (for gaseous sampling systems that use chillers to dry samples); (ii) these temperature linearity checks are only required if specified by the engine manufacturer. Fuel inlet; test cell charge air cooler air outlet (for engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler); test cell charge air cooler coolant inlet (for engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler); and oil in the sump/pan; coolant before the thermostat (for liquid cooled engines);
(h) stand-alone pressures include engine pressures and ambient conditions used to set or verify engine conditions; pressures used to set or verify critical conditions in the test system; and pressures used in emissions calculations: (i) required pressure linearity checks are: intake air pressure restriction; exhaust gas back-pressure; barometer; CVS inlet gage pressure (if measurement using CVS); chiller sample (for gaseous sampling systems that use chillers to dry samples); (ii) pressure linearity checks that are required only if specified by the engine manufacturer: test cell charge air cooler and interconnecting pipe pressure drop (for turbo-charged engines tested with a test cell heat exchanger simulating a non-road mobile machinery charge air cooler) fuel inlet; and fuel outlet.
| Measurement System | Quantity | Minimum verification frequency | Linearity Criteria | |||
|---|---|---|---|---|---|---|
| α | SEE | r 2 | ||||
| Engine speed | n | Within 370 days before testing | ≤ 0,05 % n max | 0,98-1,02 | ≤ 2 % n max | ≥ 0,990 |
| Engine torque | T | Within 370 days before testing | ≤ 1 % T max | 0,98-1,02 | ≤ 2 % T max | ≥ 0,990 |
| Fuel flow rate | qm | Within 370 days before testing | ≤ 1 % qm , max | 0,98-1,02 | ≤ 2 % qm , max | ≥ 0,990 |
| Intake-air flow rate (1) | qV | Within 370 days before testing | ≤ 1 % qV , max | 0,98-1,02 | ≤ 2 % qV , max | ≥ 0,990 |
| Dilution air flow rate (1) | qV | Within 370 days before testing | ≤ 1 % qV , max | 0,98-1,02 | ≤ 2 % qV , max | ≥ 0,990 |
| Diluted exhaust gas flow rate (1) | qV | Within 370 days before testing | ≤ 1 % qV , max | 0,98-1,02 | ≤ 2 % qV , max | ≥ 0,990 |
| Raw exhaust gas flow rate (1) | qV | Within 185 days before testing | ≤ 1 % qV , max | 0,98-1,02 | ≤ 2 % qV , max | ≥ 0,990 |
| Batch sampler flow rates (1) | qV | Within 370 days before testing | ≤ 1 % qV , max | 0,98-1,02 | ≤ 2 % qV , max | ≥ 0,990 |
| Gas dividers | x/x span | Within 370 days before testing | ≤ 0,5 % x max | 0,98-1,02 | ≤ 2 % x max | ≥ 0,990 |
| Gas analyzers | x | Within 35 days before testing | ≤ 0,5 % x max | 0,99-1,01 | ≤ 1 % x max | ≥ 0,998 |
| PM balance | m | Within 370 days before testing | ≤ 1 % m max | 0,99-1,01 | ≤ 1 % m max | ≥ 0,998 |
| Stand-alone pressures | p | Within 370 days before testing | ≤ 1 % p max | 0,99-1,01 | ≤ 1 % p max | ≥ 0,998 |
| Analog-to-digital conversion of stand-alone temperature signals | T | Within 370 days before testing | ≤ 1 % T max | 0,99-1,01 | ≤ 1 % T max | ≥ 0,998 |
| (1) Molar flow rate may be used instead of standard volumetric flow rate as the term representing ‘quantity’. In this case maximum molar flow rate may be used instead of the maximum standard volumetric flow rate in the corresponding linearity criteria. |
This section describes a general verification procedure for continuous gas analyzer system response and update recording. See point 8.1.6 for verification procedures for compensation type analysers.
This verification shall be performed after installing or replacing a gas analyzer that is used for continuous sampling. Also this verification shall be performed if the system is reconfigured in a way that would change system response. This verification is needed for continuous gas analysers used for transient (NRTC and LSI-NRTC) test cycles or RMC but is not needed for batch gas analyzer systems or for continuous gas analyzer systems used only for testing with a discrete-mode NRSC.
This test verifies that the updating and recording frequencies match the overall system response to a rapid change in the value of concentrations at the sample probe. Gas analyzer systems shall be optimized such that their overall response to a rapid change in concentration is updated and recorded at an appropriate frequency to prevent loss of information. This test also verifies that continuous gas analyzer systems meet a minimum response time.
The system settings for the response time evaluation shall be exactly the same as during measurement of the test run (i.e. pressure, flow rates, filter settings on the analyzers and all other response time influences). The response time determination shall be done with gas switching directly at the inlet of the sample probe. The devices for gas switching shall have a specification to perform the switching in less than 0,1 s. The gases used for the test shall cause a concentration change of at least 60 % full scale (FS).
The concentration trace of each single gas component shall be recorded.
(a) The system response time shall be ≤ 10 s with a rise time of ≤ 5 s for all measured components (CO, NOx, 2 and HC) and all ranges used. All data (concentration, fuel and air flows) have to be shifted by their measured response times before performing the emission calculations given in Annex VII.
(b) To demonstrate acceptable updating and recording with respect to the system's overall response, the system shall meet one of the following criteria: (i) The product of the mean rise time and the frequency at which the system records an updated concentration shall be at least 5. In any case the mean rise time shall be no more than 10 s; (ii) The frequency at which the system records the concentration shall be at least 2 Hz (see also Table 6.7).
The following procedure shall be used to verify the response of each continuous gas analyzer system:
(a) The analyzer system manufacturer's start-up and operating instructions for the instrument setup shall be followed. The measurement system shall be adjusted as needed to optimize performance. This verification shall be run with the analyzer operating in the same manner as used for emission testing. If the analyzer shares its sampling system with other analyzers, and if gas flow to the other analyzers will affect the system response time, then the other analyzers shall be started up and operated while running this verification test. This verification test may be run on multiple analyzers sharing the same sampling system at the same time. If analogue or real-time digital filters are used during emission testing, those filters shall be operated in the same manner during this verification;
(b) For equipment used to validate system response time, minimal gas transfer line lengths between all connections are recommended to be used, a zero-air source shall be connected to one inlet of a fast-acting 3-way valve (2 inlets, 1 outlet) in order to control the flow of zero and blended span gases to the sample system's probe inlet or a tee near the outlet of the probe. Normally the gas flow rate is higher than the probe sample flow rate and the excess is overflowed out the inlet of the probe. If the gas flow rate is lower than the probe flow rate, the gas concentrations shall be adjusted to account for the dilution from ambient air drawn into the probe. Binary or multi-gas span gases may be used. A gas blending or mixing device may be used to blend span gases. A gas blending or mixing device is recommended when blending span gases diluted in N2 with span gases diluted in air; Using a gas divider, an NO–CO–CO2–C3H8–CH4 (balance N2) span gas shall be equally blended with a span gas of NO2, balance purified synthetic air. Standard binary span gases may be also be used, where applicable, in place of blended NO-CO-CO2-C3H8-CH4, balance N2 span gas; in this case separate response tests shall be run for each analyzer. The gas divider outlet shall be connected to the other inlet of the 3-way valve. The valve outlet shall be connected to an overflow at the gas analyzer system's probe or to an overflow fitting between the probe and transfer line to all the analyzers being verified. A setup that avoids pressure pulsations due to stopping the flow through the gas blending device shall be used. Any of these gas constituents if they are not relevant to the analyzers for this verification shall be omitted. Alternatively the use of gas bottles with single gases and a separate measurement of response times is allowed;
(c) Data collection shall be done as follows: (i) The valve shall be switched to start the flow of zero gas; (ii) Stabilization shall be allowed for, accounting for transport delays and the slowest analyzer's full response; (iii) Data recording shall be started at the frequency used during emission testing. Each recorded value shall be a unique updated concentration measured by the analyzer; interpolation or filtering may not be used to alter recorded values; (iv) The valve shall be switched to allow the blended span gases to flow to the analyzers. This time shall be recorded as t 0; (v) Transport delays and the slowest analyzer's full response shall be allowed for; (vi) The flow shall be switched to allow zero gas to flow to the analyzer. This time shall be recorded as t 100; (vii) Transport delays and the slowest analyzer's full response shall be allowed for; (viii) The steps in paragraphs (c)(iv) to (vii) of this point shall be repeated to record seven full cycles, ending with zero gas flowing to the analyzers; (ix) Recording shall be stopped.
The data from point 8.1.5.4(c) shall be used to calculate the mean rise time for each of the analyzers.
(a) If it is chosen to demonstrate compliance with point 8.1.5.3(b)(i) the following procedure has to be applied: The rise times (in s) shall be multiplied by their respective recording frequencies in Hertz (1/s). The value for each result shall be at least 5. If the value is less than 5, the recording frequency shall be increased or the flows adjusted or the design of the sampling system shall be changed to increase the rise time as needed. Also digital filters may be configured to increase rise time;
(b) If it is chosen to demonstrate compliance with point 8.1.5.3(b)(ii), the demonstration of compliance with the requirements of point 8.1.5.3(b)(ii) is sufficient.
This verification shall be performed to determine a continuous gas analyzer's response, where one analyzer's response is compensated by another's to quantify a gaseous emission. For this check water vapour shall be considered to be a gaseous constituent. This verification is required for continuous gas analyzers used for transient (NRTC and LSI-NRTC) test cycles or RMC. This verification is not needed for batch gas analyzers or for continuous gas analyzers that are used only for testing with a discrete-mode NRSC. This verification does not apply to correction for water removed from the sample done in post-processing. This verification shall be performed after initial installation (i.e. test cell commissioning). After major maintenance, point 8.1.5 may be used to verify uniform response provided that any replaced components have gone through a humidified uniform response verification at some point.
This procedure verifies the time-alignment and uniform response of continuously combined gas measurements. For this procedure, it is necessary to ensure that all compensation algorithms and humidity corrections are turned on.
The general response time and rise time requirement set out in point 8.1.5.3(a) is also valid for compensation type analysers. Additionally, if the recording frequency is different than the update frequency of the continuously combined/compensated signal, the lower of these two frequencies shall be used for the verification required by point 8.1.5.3(b)(i).
All procedures set out in point 8.1.5.4(a) to (c) shall be used. Additionally also the response and rise time of water vapour has to be measured, if a compensation algorithm based on measured water vapour is used. In this case at least one of the used calibration gases (but not NO2) has to be humidified as follows:
If the system does not use a sample dryer to remove water from the sample gas, the span gas shall be humidified by flowing the gas mixture through a sealed vessel that humidifies the gas to the highest sample dew point that is estimated during emission sampling by bubbling it through distilled water. If the system uses a sample dryer during testing that has passed the sample dryer verification check, the humidified gas mixture may be introduced downstream of the sample dryer by bubbling it through distilled water in a sealed vessel at 298 ± 10 K (25 ± 10 °C), or a temperature greater than the dew point. In all cases, downstream of the vessel, the humidified gas shall be maintained at a temperature of at least 5 K (5 °C) above its local dew point in the line. Note that it is possible to omit any of these gas constituents if they are not relevant to the analyzers for this verification. If any of the gas constituents are not susceptible to water compensation, the response check for these analyzers may be performed without humidification.
Internal quality procedures traceable to recognised national or international standards shall be applied. Otherwise the following procedures apply.
All torque-measurement systems including dynamometer torque measurement transducers and systems shall be calibrated upon initial installation and after major maintenance using, among others, reference force or lever-arm length coupled with dead weight. Good engineering judgment shall be used to repeat the calibration. The torque transducer manufacturer's instructions shall be followed for linearizing the torque sensor's output. Other calibration methods are permitted.
This technique applies a known force by hanging known weights at a known distance along a lever arm. It shall be made sure that the weights' lever arm is perpendicular to gravity (i.e., horizontal) and perpendicular to the dynamometer's rotational axis. At least six calibration-weight combinations shall be applied for each applicable torque-measuring range, spacing the weight quantities about equally over the range. The dynamometer shall be oscillated or rotated during calibration to reduce frictional static hysteresis. Each weight's force shall be determined by multiplying its internationally-traceable mass by the local acceleration of Earth's gravity.
This technique applies force either by hanging weights on a lever arm (these weights and their lever arm length are not used as part of the reference torque determination) or by operating the dynamometer at different torques. At least six force combinations shall be applied for each applicable torque-measuring range, spacing the force quantities about equally over the range. The dynamometer shall be oscillated or rotated during calibration to reduce frictional static hysteresis. In this case, the reference torque is determined by multiplying the force output from the reference meter (such as a strain gage or proving ring) by its effective lever-arm length, which is measured from the point where the force measurement is made to the dynamometer's rotational axis. It shall be made sure that this length is measured perpendicular to the reference meter's measurement axis and perpendicular to the dynamometer's rotational axis.
Instruments shall be calibrated for measuring pressure, temperature, and dew point upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.
For temperature measurement systems with thermocouple, RTD, or thermistor sensors, the calibration of the system shall be performed as described in point 8.1.4.4 for linearity verification.
Fuel flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.
Intake air flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.
Exhaust flow meters shall be calibrated upon initial installation. The instrument manufacturer's instructions shall be followed and good engineering judgment shall be used to repeat the calibration.
(a) This section describes how to calibrate flow meters for diluted exhaust gas constant-volume sampling (CVS) systems;
(b) This calibration shall be performed while the flow meter is installed in its permanent position. This calibration shall be performed after any part of the flow configuration upstream or downstream of the flow meter has been changed that may affect the flow-meter calibration. This calibration shall be performed upon initial CVS installation and whenever corrective action does not resolve a failure to meet the diluted exhaust gas flow verification (i.e., propane check) in point 8.1.8.5;
(c) A CVS flow meter shall be calibrated using a reference flow meter such as a subsonic venturi flow meter, a long-radius flow nozzle, a smooth approach orifice, a laminar flow element, a set of critical flow venturis, or an ultrasonic flow meter. A reference flow meter shall be used that reports quantities that are internationally-traceable within ± 1 % uncertainty. This reference flow meter's response to flow shall be used as the reference value for CVS flow-meter calibration;
(d) An upstream screen or other pressure restriction that could affect the flow ahead of the reference flow meter may not be used, unless the flow meter has been calibrated with such a pressure restriction;
(e) The calibration sequence described under this point 8.1.8.4 refers to the molar based approach. For the corresponding sequence used in the mass based approach, see point 2.5 of Annex VII.
(f) CFV or SSV may alternatively be removed from its permanent position for calibration as long as the following requirements are met when installed in the CVS: (1) Upon installation of the CFV or SSV into the CVS, good engineering judgment shall be applied to verify that any leaks have not been introduced between the CVS inlet and the venturi. (2) After ex-situ venturi calibration, all venturi flow combinations must be verified for CFVs or at minimum of 10 flow points for an SSV using the propane check as described in point 8.1.8.5. The result of the propane check for each venturi flow point may not exceed the tolerance in point 8.1.8.5.6. (3) In order to verify the ex-situ calibration for a CVS with more than a single CFV, the following verification shall be conducted: (i) A constant flow device shall be used to deliver a constant flow of propane to the dilution tunnel. (ii) The hydrocarbon concentrations shall be measured at a minimum of 10 separate flow rates for an SSV flow meter, or at all possible flow combinations for a CFV flow meter, while keeping the flow of propane constant. (iii) The concentration of hydrocarbon background in the dilution air shall be measured at the beginning and end of this test. The average background concentration from each measurement at each flow point must be subtracted before performing the regression analysis in paragraph (iv). (iv) A power regression has to be performed using all the paired values of flow rate and corrected concentration to obtain a relationship in the form of y = a × xb, using the concentration as the independent variable and the flow rate as the dependent variable. For each data point, the calculation of the difference between the measured flow rate and the value represented by the curve fit is required. The difference at each point must be less than ± 1 % of the appropriate regression value. The value of b must be between – 1,005 and – 0,995. If the results do not meet these limits, corrective actions consistent with point 8.1.8.5.1(a) must be taken.
A positive-displacement pump (PDP) shall be calibrated to determine a flow-versus-PDP speed equation that accounts for flow leakage across sealing surfaces in the PDP as a function of PDP inlet pressure. Unique equation coefficients shall be determined for each speed at which the PDP is operated. A PDP flow meter shall be calibrated as follows:
(a) The system shall be connected as shown in Figure 6.5;
(b) Leaks between the calibration flow meter and the PDP shall be less than 0,3 % of the total flow at the lowest calibrated flow point; for example, at the highest pressure restriction and lowest PDP-speed point;
(c) While the PDP operates, a constant temperature at the PDP inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;
(d) The PDP speed is set to the first speed point at which it is intended to calibrate;
(e) The variable restrictor is set to its wide-open position;
(f) The PDP is operated for at least 3 minutes to stabilize the system. Then by continuously operating the PDP, the mean values of at least 30 s of sampled data of each of the following quantities are recorded:
(ii) The mean temperature at the PDP inlet, T in; (iii) The mean static absolute pressure at the PDP inlet, p in; (iv) The mean static absolute pressure at the PDP outlet, p out; (v) The mean PDP speed, n PDP;
(g) The restrictor valve shall be incrementally closed to decrease the absolute pressure at the inlet to the PDP, p in;
(h) The steps in paragraphs 8.1.8.4.2(f) and (g) shall be repeated to record data at a minimum of six restrictor positions reflecting the full range of possible in-use pressures at the PDP inlet;
(i) The PDP shall be calibrated by using the collected data and the equations set out in Annex VII;
(j) The steps in paragraphs (f) to (i) of this point shall be repeated for each speed at which the PDP is operated;
(k) The equations in section 3 of Annex VII (molar based approach) or section 2 of Annex VII (mass based approach) shall be used to determine the PDP flow equation for emission testing;
(l) The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.8.5;
(m) The PDP may not be used below the lowest inlet pressure tested during calibration.
A critical-flow venturi (CFV) shall be calibrated to verify its discharge coefficient, C d, at the lowest expected static differential pressure between the CFV inlet and outlet. A CFV flow meter shall be calibrated as follows:
(a) The system shall be connected as shown in Figure 6.5;
(b) The blower shall be started downstream of the CFV;
(c) While the CFV operates, a constant temperature at the CFV inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;
(d) Leaks between the calibration flow meter and the CFV shall be less than 0,3 % of the total flow at the highest pressure restriction;
(e) The variable restrictor shall be set to its wide-open position. In lieu of a variable restrictor the pressure downstream of the CFV may be varied by varying blower speed or by introducing a controlled leak. Note that some blowers have limitations on non-loaded conditions;
(f) The CFV shall be operated for at least 3 minutes to stabilize the system. The CFV shall continue operating and the mean values of at least 30 s of sampled data of each of the following quantities shall be recorded:
(ii) Optionally, the mean dew point of the calibration air, T dew. See Annex VII for permissible assumptions during emission measurements; (iii) The mean temperature at the venturi inlet, T in; (iv) The mean static absolute pressure at the venturi inlet, p in; (v) The mean static differential pressure between the CFV inlet and the CFV outlet, Δp CFV;
(g) The restrictor valve shall be incrementally closed to decrease the absolute pressure at the inlet to the CFV, p in;
(h) The steps in paragraphs (f) and (g) of this point shall be repeated to record mean data at a minimum of ten restrictor positions, such that the fullest practical range of Δp CFV expected during testing is tested. It is not required to remove calibration components or CVS components to calibrate at the lowest possible pressure restrictions;
(i) Cd and the highest allowable pressure ratio r shall be determined as described in Annex VII;
(j) Cd shall be used to determine CFV flow during an emission test. The CFV shall not be used above the highest allowed r, as determined in Annex VII;
(k) The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.z8.5;
(l) If the CVS is configured to operate more than one CFV at a time in parallel, the CVS shall be calibrated by one of the following: (i) Every combination of CFVs shall be calibrated according to this section and with Annex VII. See Annex VII for instructions on calculating flow rates for this option; (ii) Each CFV shall be calibrated according to this point and Annex VII. See Annex VII for instructions on calculating flow rates for this option.
A subsonic venturi (SSV) shall be calibrated to determine its calibration coefficient, C d, for the expected range of inlet pressures. An SSV flow meter shall be calibrated as follows:
(a) The system shall be connected as shown in Figure 6.5;
(b) The blower shall be started downstream of the SSV;
(c) Leaks between the calibration flow meter and the SSV shall be less than 0,3 % of the total flow at the highest pressure restriction;
(d) While the SSV operates, a constant temperature at the SSV inlet shall be maintained within ± 2 % of the mean absolute inlet temperature, T in;
(e) The variable restrictor or variable-speed blower shall be set to a flow rate greater than the greatest flow rate expected during testing. Flow rates may not be extrapolated beyond calibrated values, so it is recommended that it is made certain that a Reynolds number, Re, at the SSV throat at the greatest calibrated flow rate is greater than the maximum Re expected during testing;
(f) The SSV shall be operated for at least 3 min to stabilize the system. The SSV shall continue operating and the mean of at least 30 s of sampled data of each of the following quantities shall be recorded:
(ii) Optionally, the mean dew point of the calibration air, T dew. See Annex VII for permissible assumptions; (iii) The mean temperature at the venturi inlet, T in; (iv) The mean static absolute pressure at the venturi inlet, p in; (v) Static differential pressure between the static pressure at the venturi inlet and the static pressure at the venturi throat, Δp SSV;
(g) The restrictor valve shall be incrementally closed or the blower speed decreased to decrease the flow rate;
(h) The steps in paragraphs (f) and (g) of this point shall be repeated to record data at a minimum of ten flow rates;
(i) A functional form of C d versus Re shall be determined by using the collected data and the equations in Annex VII;
(j) The calibration shall be verified by performing a CVS verification (i.e., propane check) as described in point 8.1.8.5 using the new C d versus Re equation;
(k) The SSV shall be used only between the minimum and maximum calibrated flow rates;
(l) The equations in section 3 of Annex VII (molar based approach) or section 2 of Annex VII (mass based approach) shall be used to determine SSV flow during a test.
(a) A propane check serves as a CVS verification to determine if there is a discrepancy in measured values of diluted exhaust gas flow. A propane check also serves as a batch-sampler verification to determine if there is a discrepancy in a batch sampling system that extracts a sample from a CVS, as described in paragraph (f) of this point. Using good engineering judgment and safe practices, this check may be performed using a gas other than propane, such as CO2 or CO. A failed propane check might indicate one or more problems that may require corrective action, as follows: (i) Incorrect analyzer calibration. The FID analyzer shall be re-calibrated, repaired, or replaced; (ii) Leak checks shall be performed on CVS tunnel, connections, fasteners, and HC sampling system according to point 8.1.8.7; (iii) The verification for poor mixing shall be performed in accordance with point 9.2.2; (iv) The hydrocarbon contamination verification in the sample system shall be performed as described in point 7.3.1.3; (v) Change in CVS calibration. An in-situ calibration of the CVS flow meter shall be performed as described in point 8.1.8.4; (vi) Other problems with the CVS or sampling verification hardware or software. The CVS system, CVS verification hardware, and software shall be inspected for discrepancies;
(b) A propane check uses either a reference mass or a reference flow rate of C3H8 as a tracer gas in a CVS. If a reference flow rate is used, any non-ideal gas behaviour of C3H8 in the reference flow meter shall be accounted for. See section 2 of Annex VII (mass based approach) or section 3 of Annex VII (molar based approach), which describe how to calibrate and use certain flow meters. No ideal gas assumption may be used in point 8.1.8.5 and Annex VII. The propane check compares the calculated mass of injected C3H8 using HC measurements and CVS flow rate measurements with the reference value.
The total accuracy of the CVS sampling system and analytical system shall be determined by introducing a known mass of a pollutant gas into the system while it is being operated in the normal manner. The pollutant is analyzed, and the mass calculated in accordance with Annex VII. Either of the following two techniques shall be used:
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