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
De-humidifying the dilution air before entering the dilution system is permitted. The partial flow dilution system has to be designed to extract a proportional raw exhaust gas sample from the engine exhaust gas stream, thus responding to excursions in the exhaust gas stream flow rate, and introduce dilution air to this sample to achieve a temperature at the test filter as prescribed by point 9.3.3.4.3. For this it is essential that the dilution ratio be determined such that the accuracy requirements of point 8.1.8.6.1 are fulfilled.
To ensure that a flow is measured that corresponds to a measured concentration, either aqueous condensation shall be prevented between the sample probe location and the flow meter inlet in the dilution tunnel or aqueous condensation shall be allowed to occur and humidity at the flow meter inlet measured. The PFD system may be heated or insulated to prevent aqueous condensation. Aqueous condensation shall be prevented throughout the dilution tunnel.
The minimum dilution ratio shall be within the range of 5:1 to 7:1 based on the maximum engine exhaust gas flow rate during the test cycle or test interval.
The residence time in the system shall be between 0,5 and 5 s, as measured from the point of diluent introduction to the filter holder(s).
To determine the mass of the particulates, a particulate sampling system, a particulate sampling filter, a gravimetric balance, and a temperature and humidity controlled weighing chamber, are required.
PFD may be used to extract a proportional raw exhaust gas sample for any batch or continuous PM and gaseous emission sampling over any transient (NRTC and LSI-NRTC) duty cycle, any discrete-mode NRSC or any RMC duty cycle.
The system may be used also for a previously diluted exhaust gas where, via a constant dilution-ratio, an already proportional flow is diluted (see Figure 6.7). This is the way of performing secondary dilution from a CVS tunnel to achieve the necessary overall dilution ratio for PM sampling.
The calibration of the PFD to extract a proportional raw exhaust gas sample is considered in point 8.1.8.6.
A probe is the first fitting in a sampling system. It protrudes into a raw or diluted exhaust gas stream to extract a sample, such that it's inside and outside surfaces are in contact with the exhaust gas. A sample is transported out of a probe into a transfer line.
Sample probes shall be made with inside surfaces of stainless steel or, for raw exhaust gas sampling, with any non-reactive material capable of withstanding raw exhaust gas temperatures. Sample probes shall be located where constituents are mixed to their mean sample concentration and where interference with other probes is minimised. It is recommended that all probes remain free from influences of boundary layers, wakes, and eddies — especially near the outlet of a raw-exhaust meter tailpipe where unintended dilution might occur. Purging or back-flushing of a probe shall not influence another probe during testing. A single probe to extract a sample of more than one constituent may be used as long as the probe meets all the specifications for each constituent.
Where permitted by the manufacturer, a mixing chamber may be used when testing engines of category NRSh. The mixing chamber is an optional component of a raw gas sampling system and is located in the exhaust system between the silencer and the sample probe. The shape and dimensions of the mixing chamber and tubing before and after shall be such that it provides a well-mixed, homogenous sample at the sample probe location and so that strong pulsations or resonances of the chamber influencing the emissions results are avoided.
Transfer lines that transport an extracted sample from a probe to an analyzer, storage medium, or dilution system shall be minimized in length by locating analyzers, storage media, and dilution systems as close to the probes as practical. The number of bends in transfer lines shall be minimized and that the radius of any unavoidable bend shall be maximized.
For continuous and batch sampling, introduced in point 7.2, the following conditions apply:
(a) When extracting from a constant flow rate, the sample shall also be carried out at a constant flow rate;
(b) When extracting from a varying flow rate, the sample flow rate shall be varied in proportion to the varying flow rate;
(c) Proportional sampling shall be validated as described in point 8.2.1.
Either single-port or multi-port probes are used for sampling gaseous emissions. The probes may be oriented in any direction relative to the raw or diluted exhaust gas flow. For some probes, the sample temperatures shall be controlled, as follows:
(a) For probes that extract NOx from diluted exhaust gas, the probe's wall temperature shall be controlled to prevent aqueous condensation;
(b) For probes that extract hydrocarbons from the diluted exhaust gas, a probe wall temperature is recommended to be controlled approximately 191 °C to minimise contamination.
When used in accordance with point 9.3.1.1.1, the internal volume of the mixing chamber shall not be less than ten times the individual cylinder swept volume of the engine under test. The mixing chamber shall be coupled as closely as possible to the engine silencer and shall have a minimum inner surface temperature of 452 K (179 °C). The manufacturer may specify the design of the mixing chamber.
Transfer lines with inside surfaces of stainless steel, PTFE, VitonTM, or any other material that has better properties for emission sampling shall be used. A non-reactive material capable of withstanding exhaust gas temperatures shall be used. In-line filters may be used if the filter and its housing meet the same temperature requirements as the transfer lines, as follows:
(a) For NOx transfer lines upstream of either an NO2-to-NO converter that meets the specifications set out in point 8.1.11.5 or a chiller that meets the specifications set out in point 8.1.11.4 a sample temperature that prevents aqueous condensation shall be maintained;
(b) For THC transfer lines a wall temperature tolerance throughout the entire line of (464 ± 11) K [(191 ± 11) °C] shall be maintained. If sampled from raw exhaust gas, an unheated, insulated transfer line may be connected directly to a probe. The length and insulation of the transfer line shall be designed to cool the highest expected raw exhaust gas temperature to no lower than 191 °C, as measured at the transfer line outlet. For dilute sampling a transition zone between the probe and transfer line of up to 0,92 m in length is allowed to transition the wall temperature to (464 ± 11) K [(191 ± 11) °C].
Sample dryers may be used for removing moisture from the sample in order to decrease the effect of water on gaseous emissions measurement. Sample dryers shall meet the requirements set out in point 9.3.2.3.1.1 and in point 9.3.2.3.1.2. The moisture content 0,8 volume % is used in equation (7-13).
For the highest expected water vapour concentration Hm, the water removal technique shall maintain humidity at ≤ 5 g water/kg dry air (or about 0,8 volume % H2O), which is 100 % relative humidity at 277,1 K (3,9 °C) and 101,3 kPa. This humidity specification is equivalent to about 25 % relative humidity at 298 K (25 °C) and 101,3 kPa. This may be demonstrated by either:
(a) measuring the temperature at the outlet of the sample dryer; or
(b) measuring humidity at a point just upstream of the CLD; or
(c) performing the verification procedure in point 8.1.12.
Either type of sample dryer described in this point may be used.
(a) If an osmotic-membrane dryer upstream of any gaseous analyzer or storage medium is used, it shall meet the temperature specifications set out in point 9.3.2.2. The dew point, T dew, and absolute pressure, p total, downstream of an osmotic-membrane dryer shall be monitored. The amount of water shall be calculated as specified in Annex VII by using continuously recorded values of T dew and p total or their peak values observed during a test or their alarm set points. Lacking a direct measurement, the nominal p total is given by the dryer's lowest absolute pressure expected during testing.
(b) A thermal chiller upstream of a THC measurement system for compression-ignition engines may not be used. If a thermal chiller upstream of an NO2-to-NO converter or in a sampling system without an NO2-to-NO converter is used, the chiller shall meet the NO2 loss-performance check specified in point 8.1.11.4. The dew point, T dew, and absolute pressure, p total, downstream of a thermal chiller shall be monitored. The amount of water shall be calculated as specified in Annex VII by using continuously recorded values of T dew and p total or their peak values observed during a test or their alarm set points. Lacking a direct measurement, the nominal p total is given by the thermal chiller's lowest absolute pressure expected during testing. If it is valid to assume the degree of saturation in the thermal chiller, T dew based on the known chiller efficiency and continuous monitoring of chiller temperature, T chiller may be calculated. If values of T chiller are not continuously recorded, its peak value observed during a test, or its alarm set point, may be used as a constant value to determine a constant amount of water in accordance with Annex VII. If it is valid to assume that T chiller is equal to T dew, T chiller may be used in lieu of T dew in accordance with Annex VII. If it is valid to assume a constant temperature offset between T chiller and T dew, due to a known and fixed amount of sample reheat between the chiller outlet and the temperature measurement location, this assumed temperature offset value may be factored in into emission calculations. The validity of any assumptions allowed by this point shall be shown by engineering analysis or by data.
Sample pumps upstream of an analyzer or storage medium for any gas shall be used. Sample pumps with inside surfaces of stainless steel, PTFE, or any other material having better properties for emission sampling shall be used. For some sample pumps, temperatures shall be controlled, as follows:
(a) If a NOx sample pump upstream of either an NO2-to-NO converter that meets the requirements set out in point 8.1.11.5 or a chiller that meets the requirements set out in point 8.1.11.4 is used, it shall be heated to prevent aqueous condensation;
(b) If a THC sample pump upstream of a THC analyzer or storage medium is used, its inner surfaces shall be heated to a tolerance of 464 ± 11 K (191 ± 11) °C.
Ammonia scrubbers may be used for any or all gaseous sampling systems to prevent NH3 interference, poisoning of NO2-to-NO converter, and deposits in the sampling system or analysers. Installation of the ammonia scrubber shall follow the manufacturer's recommendations.
In the case of bag sampling, gas volumes shall be stored in sufficiently clean containers that minimally off-gas or allow permeation of gases. Good engineering judgment shall be used to determine acceptable thresholds of storage media cleanliness and permeation. To clean a container, it may be repeatedly purged and evacuated and may be heated. A flexible container (such as a bag) within a temperature-controlled environment, or a temperature controlled rigid container that is initially evacuated or has a volume that can be displaced, such as a piston and cylinder arrangement, shall be used. Containers meeting the specifications in the following Table 6.6 shall be used.
| CO, CO2, O2, CH4, C2H6, C3H8, NO, NO2 (1) | polyvinyl fluoride (PVF) (2) for example TedlarTM, polyvinylidene fluoride (2) for example KynarTM, polytetrafluoroethylene (3) for example TeflonTM, or stainless steel (3) |
|---|---|
| HC | polytetrafluoroethylene (4) or stainless steel (4) |
| (1) As long as aqueous condensation in storage container is prevented. (2) Up to 313 K (40 °C). (3) Up to 475 K (202 °C). (4) At 464 ± 11 K (191 ± 11 °C). |
PM probes with a single opening at the end shall be used. PM probes shall be oriented to face directly upstream.
The PM probe may be shielded with a hat that conforms with the requirements in Figure 6.8. In this case the pre-classifier described in point 9.3.3.3 shall not be used.
Insulated or heated transfer lines or a heated enclosure are recommended to minimize temperature differences between transfer lines and exhaust gas constituents. Transfer lines that are inert with respect to PM and are electrically conductive on the inside surfaces shall be used. It is recommended using PM transfer lines made of stainless steel; any material other than stainless steel will be required to meet the same sampling performance as stainless steel. The inside surface of PM transfer lines shall be electrically grounded.
The use of a PM pre-classifier to remove large-diameter particles is permitted that is installed in the dilution system directly before the filter holder. Only one pre-classifier is permitted. If a hat shaped probe is used (see Figure 6.8), the use of a pre-classifier is prohibited.
The PM pre-classifier may be either an inertial impactor or a cyclonic separator. It shall be constructed of stainless steel. The pre-classifier shall be rated to remove at least 50 % of PM at an aerodynamic diameter of 10 μm and no more than 1 % of PM at an aerodynamic diameter of 1 μm over the range of flow rates for which it is used. The pre-classifier outlet shall be configured with a means of bypassing any PM sample filter so that the pre-classifier flow can be stabilized before starting a test. PM sample filter shall be located within 75 cm downstream of the pre-classifier's exit.
The diluted exhaust gas shall be sampled by a filter that meets the requirements set out in points 9.3.3.4.1 to 9.3.3.4.4 during the test sequence.
All filter types shall have a collection efficiency of at least 99,7 %. The sample filter manufacturer's measurements reflected in their product ratings may be used to show this requirement. The filter material shall be either:
(a) Fluorocarbon (PTFE) coated glass fibre; or
(b) Fluorocarbon (PTFE) membrane.
If the expected net PM mass on the filter exceeds 400 μg, a filter with a minimum initial collection efficiency of 98 % may be used.
The nominal filter size shall be 46,50 mm ± 0,6 mm diameter (at least 37 mm stain diameter). Larger diameter filters may be used with prior agreement of the approval authority. Proportionality between filter and stain area is recommended.
PM samples shall be diluted at least once upstream of transfer lines in case of a CVS system and downstream in case of PFD system (see point 9.3.3.2 relating to transfer lines). Sample temperature shall be controlled to a 320 ± 5 K (47 ± 5 °C) tolerance, as measured anywhere within 200 mm upstream or 200 mm downstream of the PM filter media. The PM sample is intended to be heated or cooled primarily by dilution conditions as specified in point 9.2.1(a).
A filter face velocity shall be between 0,90 and 1,00 m/s with less than 5 % of the recorded flow values exceeding this range. If the total PM mass exceeds 400 μg, the filter face velocity may be reduced. The face velocity shall be measured as the volumetric flow rate of the sample at the pressure upstream of the filter and temperature of the filter face, divided by the filter's exposed area. The exhaust system stack or CVS tunnel pressure shall be used for the upstream pressure if the pressure drop through the PM sampler up to the filter is less than 2 kPa.
To minimize turbulent deposition and to deposit PM evenly on a filter, a 12,5° (from centre) divergent cone angle to transition from the transfer-line inside diameter to the exposed diameter of the filter face shall be used. Stainless steel for this transition shall be used.
This section describes the two environments required to stabilize and weigh PM for gravimetric analysis: the PM stabilization environment, where filters are stored before weighing; and the weighing environment, where the balance is located. The two environments may share a common space.
Both the stabilization and the weighing environments shall be kept free of ambient contaminants, such as dust, aerosols, or semi-volatile material that could contaminate PM samples.
The cleanliness of the PM-stabilization environment using reference filters shall be verified, as described in point 8.1.12.1.4.
The temperature of the chamber (or room) in which the particulate filters are conditioned and weighed shall be maintained to within 295 ± 1 K (22 °C ± 1 °C) during all filter conditioning and weighing. The humidity shall be maintained to a dew point of 282,5 ± 1 K (9,5 °C ± 1 °C) and a relative humidity of 45 % ± 8 %. If the stabilization and weighing environments are separate, the stabilization environment shall be maintained at a tolerance of 295 ± 3 K (22 °C ± 3 °C).
When using measurement instruments that meet the specifications in point 9.4 the following ambient conditions shall be verified:
(a) Dew point and ambient temperature shall be recorded. These values shall be used to determine if the stabilization and weighing environments have remained within the tolerances specified in point 9.3.4.3 for at least 60 min before weighing filters;
(b) Atmospheric pressure shall be continuously recorded within the weighing environment. An acceptable alternative is to use a barometer that measures atmospheric pressure outside the weighing environment, as long as it can be ensured that the atmospheric pressure at the balance is always at the balance within ± 100 Pa of the shared atmospheric pressure. A means to record the most recent atmospheric pressure shall be provided when each PM sample is weighed. This value shall be used to calculate the PM sample filter buoyancy correction in point 8.1.13.2.
The balance shall be installed as follows:
(a) Installed on a vibration-isolation platform to isolate it from external noise and vibration;
(b) Shielded from convective airflow with a static-dissipating draft shield that is electrically grounded.
Static electric charge shall be minimized in the balance environment, as follows:
(a) The balance is electrically grounded;
(b) Stainless steel tweezers shall be used if PM samples shall be handled manually;
(c) Tweezers shall be grounded with a grounding strap, or a grounding strap shall be provided for the operator such that the grounding strap shares a common ground with the balance;
(d) A static-electricity neutralizer shall be provided that is electrically grounded in common with the balance to remove static charge from PM samples.
This point specifies measurement instruments and associated system requirements related to emission testing. This includes laboratory instruments for measuring engine parameters, ambient conditions, flow-related parameters, and emission concentrations (raw or diluted).
Any instrument mentioned in this Regulation shall be used as described in the Regulation itself (see Table 6.5 for measurement quantities provided by these instruments). Whenever an instrument mentioned in this Regulation is used in a way that is not specified, or another instrument is used in its place, the requirements for equivalency provisions shall apply as specified in point 5.1.1. Where more than one instrument for a particular measurement is specified, one of them will be identified by the approval authority upon application as the reference for showing that an alternative procedure is equivalent to the specified procedure.
Data from multiple instruments to calculate test results for a single test may be used for all measurement instruments described in this point, with prior approval of the approval authority. Results from all measurements shall be recorded and the raw data shall be retained. This requirement applies whether or not the measurements are actually used in the calculations.
The test system shall be able to update data, record data and control systems related to operator demand, the dynamometer, sampling equipment, and measurement instruments. Data acquisition and control systems shall be used that can record at the specified minimum frequencies, as shown in Table 6.7 (this Table does not apply to discrete-mode NRSC testing).
| Applicable Test Protocol Section | Measured Values | Minimum Command and Control Frequency | Minimum Recording Frequency |
|---|---|---|---|
| 7.6 | Speed and torque during an engine step-map | 1 Hz | 1 mean value per step |
| 7.6 | Speed and torque during an engine sweep-map | 5 Hz | 1 Hz means |
| 7.8.3 | Transient (NRTC and LSI-NRTC) duty cycle reference and feedback speeds and torques | 5 Hz | 1 Hz means |
| 7.8.2 | Discrete-mode NRSC and RMC duty cycle reference and feedback speeds and torques | 1 Hz | 1 Hz |
| 7.3 | Continuous concentrations of raw analyzers | N/A | 1 Hz |
| 7.3 | Continuous concentrations of dilute analyzers | N/A | 1 Hz |
| 7.3 | Batch concentrations of raw or dilute analyzers | N/A | 1 mean value per test interval |
| 7.6 8.2.1 | Diluted exhaust gas flow rate from a CVS with a heat exchanger upstream of the flow measurement | N/A | 1 Hz |
| 7.6 8.2.1 | Diluted exhaust gas flow rate from a CVS without a heat exchanger upstream of the flow measurement | 5 Hz | 1 Hz means |
| 7.6 8.2.1 | Intake-air or exhaust gas flow rate (for raw transient measurement) | N/A | 1 Hz means |
| 7.6 8.2.1 | Dilution air if actively controlled | 5 Hz | 1 Hz means |
| 7.6 8.2.1 | Sample flow from a CVS with a heat exchanger | 1 Hz | 1 Hz |
| 7.6 8.2.1 | Sample flow from a CVS without a heat exchanger | 5 Hz | 1 Hz mean |
The test system as a whole shall meet all the applicable calibrations, verifications, and test-validation criteria specified in point 8.1, including the requirements of the linearity check of points 8.1.4 and 8.2. Instruments shall meet the specifications in Table 6.7 for all ranges to be used for testing. Furthermore, any documentation received from instrument manufacturers showing that instruments meet the specifications in Table 6.7 shall be kept.
Table 6.8 shows the specifications of transducers of torque, speed, and pressure, sensors of temperature and dew point, and other instruments. The overall system for measuring the given physical and/or chemical quantity shall meet the linearity verification in point 8.1.4. For gaseous emissions measurements, analyzers may be used, that have compensation algorithms that are functions of other measured gaseous components, and of the fuel properties for the specific engine test. Any compensation algorithm shall only provide offset compensation without affecting any gain (that is no bias).
| Measurement Instrument | Measured quantity symbol | Complete System Rise time | Recording update frequency | Accuracy () | Repeatability () |
|---|---|---|---|---|---|
| Engine speed transducer | n | 1 s | 1 Hz means | 2,0 % of pt. or 0,5 % of max | 1,0 % of pt. or 0,25 % of max |
| Engine torque transducer | T | 1 s | 1 Hz means | 2,0 % of pt. or 1,0 % of max | 1,0 % of pt. or 0,5 % of max |
| Fuel flow meter (Fuel totalizer) | 5 s (N/A) | 1 Hz (N/A) | 2,0 % of pt. or 1,5 % of max | 1,0 % of pt. or 0,75 % of max | |
| Total diluted exhaust gas meter (CVS) (With heat exchanger before meter) | 1 s (5 s) | 1 Hz means (1 Hz) | 2,0 % of pt. or 1,5 % of max | 1,0 % of pt. or 0,75 % of max | |
| Dilution air, inlet air, exhaust gas, and sample flow meters | 1 s | 1 Hz means of 5 Hz samples | 2,5 % of pt. or 1,5 % of max | 1,25 % of pt. or 0,75 % of max | |
| Continuous gas analyzer raw | x | 5 s | 2 Hz | 2,0 % of pt. or 2,0 % of meas. | 1,0 % of pt. or 1,0 % of meas. |
| Continuous gas analyzer dilute | x | 5 s | 1 Hz | 2,0 % of pt. or 2,0 % of meas. | 1,0 % of pt. or 1,0 % of meas. |
| Continuous gas analyzer | x | 5 s | 1 Hz | 2,0 % of pt. or 2,0 % of meas. | 1,0 % of pt. or 1,0 % of meas. |
| Batch gas analyzer | x | N/A | N/A | 2,0 % of pt. or 2,0 % of meas. | 1,0 % of pt. or 1,0 % of meas. |
| Gravimetric PM balance | m PM | N/A | N/A | See 9.4.11 | 0,5 μg |
| Inertial PM balance | m PM | 5 s | 1 Hz | 2,0 % of pt. or 2,0 % of meas. | 1,0 % of pt. or 1,0 % of meas. |
| (1) Accuracy and repeatability are all determined with the same collected data, as described in point 9.4.3, and based on absolute values. ‘pt.’ refers to the overall mean value expected at the emission limit; ‘max.’ refers to the peak value expected at the emission limit over the duty cycle, not the maximum of the instrument's range; ‘meas.’ refers to the actual mean measured over the duty cycle. |
Measurement instruments for work inputs and outputs during engine operation shall meet the specifications in this point. Sensors, transducers, and meters meeting the specifications in Table 6.8 are recommended. Overall systems for measuring work inputs and outputs shall meet the linearity verifications in point 8.1.4.
Work and power shall be calculated from outputs of speed and torque transducers according to point 9.4.4.1. Overall systems for measuring speed and torque shall meet the calibration and verifications in points 8.1.7 and 8.1.4.
Torque induced by the inertia of accelerating and decelerating components connected to the flywheel, such as the drive shaft and dynamometer rotor, shall be compensated for as needed, based on good engineering judgment.
Overall systems for measuring pressure, temperature, and dew point shall meet the calibration in point 8.1.7.
Pressure transducers shall be located in a temperature-controlled environment, or they shall compensate for temperature changes over their expected operating range. Transducer materials shall be compatible with the fluid being measured.
For any type of flow meter (of fuel, intake-air, raw exhaust gas, diluted exhaust gas, sample), the flow shall be conditioned as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. For some meters, this may be accomplished by using a sufficient length of straight tubing (such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, straightening fins, orifice plates (or pneumatic pulsation dampeners for the fuel flow meter) to establish a steady and predictable velocity profile upstream of the meter.
Overall system for measuring fuel flow shall meet the calibration in point 8.1.8.1. In any fuel flow measurement it shall be accounted for any fuel that bypasses the engine or returns from the engine to the fuel storage tank.
Overall system for measuring intake-air flow shall meet the calibration in point 8.1.8.2.
The overall system for measuring raw exhaust gas flow shall meet the linearity requirements in point 8.1.4. Any raw-exhaust meter shall be designed to appropriately compensate for changes in the raw exhaust gas' thermodynamic, fluid, and compositional states.
For the purpose of controlling of a partial flow dilution system to extract a proportional raw exhaust gas sample, a flow meter response time faster than indicated in Table 6.8 is required. For partial flow dilution systems with online control, the flow meter response time shall meet the specifications of point 8.2.1.2.
This point does not apply to cooling of the exhaust gas due to the design of the engine, including, but not limited to, water-cooled exhaust manifolds or turbochargers.
Exhaust gas cooling upstream of the flow meter is permitted with the following restrictions:
(a) PM shall not be sampled downstream of the cooling;
(b) If cooling causes exhaust gas temperatures above 475 K (202 °C) to decrease to below 453 K (180 °C), HC shall not be sampled downstream of the cooling;
(c) If cooling causes aqueous condensation, NOx shall not be sampled downstream of the cooling unless the cooler meets the performance verification in point 8.1.11.4;
(d) If cooling causes aqueous condensation before the flow reaches a flow meter, dew point T dew and pressure p total shall be measured at the flow meter inlet. These values shall be used in emission calculations in accordance with Annex VII.
Instantaneous diluted exhaust gas flow rates or total diluted exhaust gas flow over a test interval shall be determined by using a diluted exhaust flow meter. Raw exhaust gas flow rates or total raw exhaust gas flow over a test interval may be calculated from the difference between a diluted exhaust flow meter and a dilution air meter.
The overall system for measuring diluted exhaust gas flow shall meet the calibration and verifications in points 8.1.8.4 and 8.1.8.5. The following meters may be used:
(a) For constant-volume sampling (CVS) of the total flow of diluted exhaust gas, a critical-flow venturi (CFV) or multiple critical-flow venturis arranged in parallel, a positive-displacement pump (PDP), a subsonic venturi (SSV), or an ultrasonic flow meter (UFM) may be used. Combined with an upstream heat exchanger, either a CFV or a PDP will also function as a passive flow controller by keeping the diluted exhaust gas temperature constant in a CVS system;
(b) For the Partial Flow Dilution (PFD) system the combination of any flow meter with any active flow control system to maintain proportional sampling of exhaust gas constituents may be used. The total flow of diluted exhaust gas, or one or more sample flows, or a combination of these flow controls may be controlled to maintain proportional sampling.
For any other dilution system, a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a critical-flow venturi or multiple critical-flow venturis arranged in parallel, a positive-displacement meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer may be used.
Diluted exhaust gas upstream of a dilute flow meter may be cooled, as long as all the following provisions are observed:
(a) PM shall not be sampled downstream of the cooling;
(b) If cooling causes exhaust gas temperatures above 475 K (202 °C) to decrease to below 453 K (180 °C), HC shall not be sampled downstream of the cooling;
(c) If cooling causes aqueous condensation, NOx shall not be sampled downstream of the cooling unless the cooler meets the performance verification in point 8.1.11.4;
(d) If cooling causes aqueous condensation before the flow reaches a flow meter, dew point, T dew and pressure p total shall be measured at the flow meter inlet. These values shall be used in emission calculations in accordance with Annex VII.
A sample flow meter shall be used to determine sample flow rates or total flow sampled into a batch sampling system over a test interval. The difference between two flow meters may be used to calculate sample flow into a dilution tunnel e.g. for partial flow dilution PM measurement and secondary dilution flow PM measurement. Specifications for differential flow measurement to extract a proportional raw exhaust gas sample is set out in point 8.1.8.6.1 and the calibration of differential flow measurement is given in point 8.1.8.6.2.
Overall system for the sample flow meter shall meet the calibration requirements set out in point 8.1.8.
A gas divider may be used to blend calibration gases.
A gas divider shall be used that blends gases to the specifications of point 9.5.1 and to the concentrations expected during testing. Critical-flow gas dividers, capillary-tube gas dividers, or thermal-mass-meter gas dividers may be used. Viscosity corrections shall be applied as necessary (if not done by gas divider internal software) to appropriately ensure correct gas division. The gas-divider system shall meet the linearity verification set out in point 8.1.4.5. Optionally, the blending device may be checked with an instrument which by nature is linear, e.g. using NO gas with a CLD. The span value of the instrument shall be adjusted with the span gas directly connected to the instrument. The gas divider shall be checked at the settings used and the nominal value shall be compared to the measured concentration of the instrument.
A Non-dispersive infrared (NDIR) analyzer shall be used to measure CO and CO2 concentrations in raw or diluted exhaust gas for either batch or continuous sampling.
The NDIR-based system shall meet the calibration and verifications set out in point 8.1.9.1 or 8.1.9.2, as applicable.
A heated flame-ionization detector (HFID) analyzer shall be used to measure hydrocarbon concentrations in raw or diluted exhaust gas for either batch or continuous sampling. Hydrocarbon concentrations shall be determined on a carbon number basis of one, C1. Heated FID analyzers shall maintain all surfaces that are exposed to emissions at a temperature of 464 ± 11 K (191 ± 11 °C). Optionally, for NG and LPG fuelled and SI engines, the hydrocarbon analyzer may be of the non-heated flame ionization detector (FID) type.
The FID-based system for measuring THC shall meet all of the verifications for hydrocarbon measurement in point 8.1.10.
FID fuel and burner air shall meet the specifications of point 9.5.1. The FID fuel and burner air shall not mix before entering the FID analyzer to ensure that the FID analyzer operates with a diffusion flame and not a premixed flame.
Two measurement instruments are specified for NOx measurement and either instrument may be used provided it meets the criteria specified in point 9.4.8.1 or 9.4.8.2, respectively. The chemiluminescent detector shall be used as the reference procedure for comparison with any proposed alternate measurement procedure under point 5.1.1.
A chemiluminescent detector (CLD) coupled with an NO2-to-NO converter is used to measure NOx concentration in raw or diluted exhaust gas for batch or continuous sampling.
The CLD-based system shall meet the quench verification set out in point 8.1.11.1. A heated or unheated CLD may be used, and a CLD that operates at atmospheric pressure or under a vacuum may be used.
An internal or external NO2-to-NO converter that meets the verification in point 8.1.11.5 shall be placed upstream of the CLD, while the converter shall be configured with a bypass to facilitate this verification.
All CLD temperatures shall be maintained to prevent aqueous condensation. To remove humidity from a sample upstream of a CLD, one of the following configurations shall be used:
(a) A CLD connected downstream of any dryer or chiller that is downstream of an NO2-to-NO converter that meets the verification set out in point 8.1.11.5;
(b) A CLD connected downstream of any dryer or thermal chiller that meets the verification set out in point 8.1.11.4.
A heated CLD may be used to improve CLD response time.
A non-dispersive ultraviolet (NDUV) analyzer is used to measure NOx concentration in raw or diluted exhaust gas for batch or continuous sampling.
The NDUV-based system shall meet the verifications set out in point 8.1.11.3.
If the NDUV analyzer measures only NO, an internal or external NO2-to-NO converter that meets the verification set out in point 8.1.11.5 shall be placed upstream of the NDUV analyzer. The converter shall be configured with a bypass to facilitate this verification.
The NDUV temperature shall be maintained to prevent aqueous condensation, unless one of the following configurations is used:
(a) An NDUV shall be connected downstream of any dryer or chiller that is downstream of an NO2-to-NO converter that meets the verification in point 8.1.11.5;
(b) An NDUV shall be connected downstream of any dryer or thermal chiller that meets the verification in point 8.1.11.4.
A paramagnetic detection (PMD) or magneto pneumatic detection (MPD) analyzer shall be used to measure O2 concentration in raw or diluted exhaust gas for batch or continuous sampling.
A Zirconia (ZrO2) analyser may be used to measure air-to-fuel ratio in raw exhaust gas for continuous sampling. O2 measurements with intake air or fuel flow measurements may be used to calculate exhaust gas flow rate in accordance with Annex VII.
A balance shall be used to weigh net PM collected on sample filter media.
The minimum requirement on the balance resolution shall be equal or lower than the repeatability of 0,5 microgram recommended in Table 6.8. If the balance uses internal calibration weights for routine spanning and linearity verifications, the calibration weights shall meet the specifications in point 9.5.2.
The balance shall be configured for optimum settling time and stability at its location.
A FTIR (Fourier transform infrared) analyser, NDUV or laser infrared analyser may be used in accordance with Appendix 4.
Analytical gases shall meet the accuracy and purity specifications of this section.
The following gas specifications shall be considered:
(a) Purified gases shall be used to blend with calibration gases and to adjust measurement instruments so as to obtain a zero response to a zero calibration standard. Gases with contamination no higher than the highest of the following values in the gas cylinder or at the outlet of a zero-gas generator shall be used: (i) 2 % contamination, measured relative to the mean concentration expected at the emission limit value. For example, if a CO concentration of 100,0 μmol/mol is expected, then it would be allowed to use a zero gas with CO contamination less than or equal to 2 000 μmol/mol; (ii) Contamination as specified in Table 6.9, applicable for raw or dilute measurements; (iii) Contamination as specified in Table 6.10, applicable for raw measurements. Table 6.9 Contamination limits, applicable for raw or dilute measurements [μmol/mol = ppm] Constituent Purified Synthetic Air () Purified N2 () THC (C1 equivalent) ≤ 0,05 μmol/mol ≤ 0,05 μmol/mol CO ≤ 1 μmol/mol ≤ 1 μmol/mol
CO2 ≤ 10 μmol/mol ≤ 10 μmol/mol
O2 0,205 to 0,215 mol/mol ≤ 2 μmol/mol NOx ≤ 0,02 μmol/mol ≤ 0,02 μmol/mol (1) It is not required that these levels of purity are internationally and/or nationally recognized standards traceable. Table 6.10 Contamination limits applicable for raw measurements [μmol/mol = ppm] Constituent Purified Synthetic Air () Purified N2 () THC (C1 equivalent) ≤ 1 μmol/mol ≤ 1 μmol/mol CO ≤ 1 μmol/mol ≤ 1 μmol/mol CO2 ≤ 400 μmol/mol ≤ 400 μmol/mol O2 0,18 to 0,21 mol/mol — NOx ≤ 0,1 μmol/mol ≤ 0,1 μmol/mol (1) It is not required that these levels of purity are internationally and/or nationally recognized standards traceable.
(b) The following gases shall be used with a FID analyzer: (i) FID fuel shall be used with an H2 concentration of (0,39 to 0,41) mol/mol, balance He or N2. The mixture shall not contain more than 0,05 μmol/mol THC; (ii) FID burner air shall be used that meets the specifications of purified air in paragraph (a) of this point; (iii) FID zero gas. Flame-ionization detectors shall be zeroed with purified gas that meets the specifications in paragraph (a) of this point, except that the purified gas O2 concentration may be any value; (iv) FID propane span gas. The THC FID shall be spanned and calibrated with span concentrations of propane, C3H8. It shall be calibrated on a carbon number basis of one (C1); (v) Reserved;
(c) The following gas mixtures shall be used, with gases traceable within ±1,0 % of the international and/or national recognized standards true value or of other gas standards that are approved: (i) CH4, balance purified synthetic air and/or N2 (as applicable); (ii) Reserved; (iii) C3H8, balance purified synthetic air and/or N2 (as applicable); (iv) CO, balance purified N2; (v) CO2, balance purified N2; (vi) NO, balance purified N2; (vii) NO2, balance purified synthetic air; (viii) O2, balance purified N2; (ix) C3H8, CO, CO2, NO, balance purified N2; (x) C3H8, CH4, CO, CO2, NO, balance purified N2.
(d) Gases for species other than those listed in paragraph (c) of this point may be used (such as methanol in air, which may be used to determine response factors), as long as they are traceable to within ± 3,0 % of the international and/or national recognized standards true value, and meet the stability requirements of point 9.5.1.2;
(e) Own calibration gases may be generated using a precision blending device, such as a gas divider, to dilute gases with purified N2 or purified synthetic air. If the gas dividers meet the specifications in point 9.4.5.6, and the gases being blended meet the requirements of paragraphs (a) and (c) of this point, the resulting blends are considered to meet the requirements of this point 9.5.1.1.
The concentration of any calibration gas standard and its expiration date specified by the gas supplier shall be recorded.
(a) No calibration gas standard may be used after its expiration date, except as allowed by paragraph (b) of this point.
(b) Calibration gases may be relabelled and used after their expiration date if it is approved in advance by approval authority.
Gases shall be transferred from their source to analyzers using components that are dedicated to controlling and transferring only those gases.
PM balance calibration weights that are certified as international and/or national recognized standards-traceable within 0,1 % uncertainty shall be used. Calibration weights may be certified by any calibration lab that maintains international and/or national recognized standards-traceability. It shall be made sure that the lowest calibration weight has no greater than ten times the mass of an unused PM-sample medium. The calibration report shall also state the density of the weights.
Appendix 1
Particle number emissions measurement equipment
Measurement test procedure
Particle number emissions shall be measured by continuous sampling from either a partial flow dilution system, as described in point 9.2.3 of this Annex or a full flow dilution system as described in point 9.2.2 of this Annex.
Diluent used for both the primary and, where applicable, secondary dilution of the exhaust gas in the dilution system shall be passed through filters meeting the High-Efficiency Particulate Air (HEPA) filter requirements defined in Article 1(19). The diluent may optionally be charcoal scrubbed before being passed to the HEPA filter to reduce and stabilize the hydrocarbon concentrations in the diluent. It is recommended that an additional coarse particle filter is situated before the HEPA filter and after the charcoal scrubber, if used.
To compensate for the mass flow extracted from the dilution system for particle number sampling the extracted mass flow (filtered) shall be returned to the dilution system. Alternatively, the total mass flow in the dilution system may be mathematically corrected for the particle number sample flow extracted. Where the total mass flow extracted from the dilution system for the sum of particle number sampling and particulate mass sampling is less than 0,5 % of the total diluted exhaust gas flow in the dilution tunnel (med) this correction, or flow return, may be neglected.
1.3.1. For partial flow dilution systems the mass flow extracted from the dilution system for particle number sampling shall be accounted for in controlling the proportionality of sampling. This shall be achieved either by feeding the particle number sample flow back into the dilution system upstream of the flow measuring device or by mathematical correction as outlined in point 1.3.2. In the case of total sampling type partial flow dilution systems, the mass flow extracted for particle number sampling shall also be corrected for in the particulate mass calculation as outlined in point 1.3.3.
| 1.3.2. | The instantaneous exhaust gas flow rate into the dilution system (qmp), used for controlling the proportionality of sampling, shall be corrected according to one of the following methods: (a) In the case where the extracted particle number sample flow is discarded, equation (6-20) in point 8.1.8.6.1 of this Annex shall be replaced by equation (6-29): qmp = qmdew – qmdw + qex (6-29) Where: qmdew is the diluted exhaust gas mass flow rate, kg/s, qmdw is the dilution air mass flow rate, kg/s, qex is the particle number sample mass flow rate, kg/s. The qex signal sent to the partial flow system controller shall be accurate to within ± 0,1 % of qmdew at all times and should be sent with frequency of at least 1 Hz. (b) In the case where the extracted particle number sample flow is fully or partially discarded, but an equivalent flow is fed back to the dilution system upstream of the flow measurement device, equation (6-20) in point 8.1.8.6.1 of this Annex shall be replaced by equation (6-30): qmp = qmdew – qmdw + qex – qsw (6-30) Where: qmdew is the diluted exhaust gas mass flow rate, kg/s, qmdw is the dilution air mass flow rate, kg/s, qex is the particle number sample mass flow rate, kg/s, qsw is the mass flow rate fed back into dilution tunnel to compensate for particle number sample extraction, kg/s. The difference between qex and qsw sent to the partial flow system controller shall be accurate to within ± 0,1 % of qmdew at all times. The signal (or signals) should be sent with frequency of at least 1 Hz. |
|---|---|
| qmp = qmdew – qmdw + qex | (6-29) |
| qmdew | is the diluted exhaust gas mass flow rate, kg/s, |
| qmdw | is the dilution air mass flow rate, kg/s, |
| qex | is the particle number sample mass flow rate, kg/s. |
| qmp = qmdew – qmdw + qex – qsw | (6-30) |
| qmdew | is the diluted exhaust gas mass flow rate, kg/s, |
| qmdw | is the dilution air mass flow rate, kg/s, |
| qex | is the particle number sample mass flow rate, kg/s, |
| qsw | is the mass flow rate fed back into dilution tunnel to compensate for particle number sample extraction, kg/s. |
| 1.3.3. | Correction of PM measurementWhen a particle number sample flow is extracted from a total sampling partial flow dilution system, the mass of particulates (mPM) calculated in point 2.3.1.1 of Annex VII shall be corrected as follows to account for the flow extracted. This correction is required even where filtered extracted flow is fed back into the partial flow dilution systems, as set out in equation (6-31): (6-31) Where: mPM is the mass of particulates determined in accordance with point 2.3.1.1 of Annex VII, g/test, msed is the total mass of diluted exhaust gas passing through the dilution tunnel, kg, mex is the total mass of diluted exhaust gas extracted from the dilution tunnel for particle number sampling, kg. |
| --- | --- |
| (6-31) | |
| mPM | is the mass of particulates determined in accordance with point 2.3.1.1 of Annex VII, g/test, |
| msed | is the total mass of diluted exhaust gas passing through the dilution tunnel, kg, |
| mex | is the total mass of diluted exhaust gas extracted from the dilution tunnel for particle number sampling, kg. |
1.3.4. For particle number measurement, exhaust gas mass flow rate, determined according to any of the methods described in points 2.1.6.1 to 2.1.6.4 of Annex VII, is used for controlling the partial flow dilution system to take a sample proportional to the exhaust gas mass flow rate. The quality of proportionality shall be checked by applying a regression analysis between sample and exhaust gas flow in accordance with point 8.2.1.2 of this Annex.
1.3.5. Determination and calculation of PN are laid down in Appendix 5 of Annex VII.
Measurement equipment
2.1.1.1. The particle sampling system shall consist of a probe or sampling point extracting a sample from a homogenously mixed flow in a dilution system as described in point 9.2.2 or 9.2.3 of this Annex, a volatile particle remover (VPR) upstream of a particle number counter (PNC) and suitable transfer tubing.
2.1.1.2. It is recommended that a particle size pre-classifier (e.g. cyclone, impactor, etc.) be located prior to the inlet of the VPR. However, a sample probe acting as an appropriate size-classification device, such as shown in Figure 6.8, is an acceptable alternative to the use of a particle size pre-classifier. In the case of partial flow dilution systems it is acceptable to use the same pre-classifier for particulate mass and particle number sampling, extracting the particle number sample from the dilution system downstream of the pre-classifier. Alternatively separate pre-classifiers may be used, extracting the particle number sample from the dilution system upstream of the particulate mass pre-classifier.
2.1.2.1. The particle sampling point shall be located within a dilution system. The sampling probe tip or particle sampling point and particle transfer tube (PTT) together comprise the particle transfer system (PTS). The PTS conducts the sample from the dilution tunnel to the entrance of the VPR. The PTS shall meet the following conditions: In the case of full flow dilution systems and partial flow dilution systems of the fractional sampling type (as described in point 9.2.3 of this Annex) the sampling probe shall be installed near the tunnel centre line, 10 to 20 tunnel diameters downstream of the gas inlet, facing upstream into the tunnel gas flow with its axis at the tip parallel to that of the dilution tunnel. The sampling probe shall be positioned within the dilution tract so that the sample is taken from a homogeneous diluent/exhaust gas mixture. In the case of partial flow dilution systems of the total sampling type (as described in point 9.2.3.of this Annex) the particle sampling point or sampling probe shall be located in the particulate transfer tube, upstream of the particulate filter holder, flow measurement device and any sample/bypass bifurcation point. The sampling point or sampling probe shall be positioned so that the sample is taken from a homogeneous diluent/exhaust gas mixture. The dimensions of the particle sampling probe should be sized not to interfere with the operation of the partial flow dilution system. Sample gas drawn through the PTS shall meet the following conditions:
2.1.2.2. The VPR shall include devices for sample dilution and for volatile particle removal.
2.1.2.3. All parts of the dilution system and the sampling system from the exhaust pipe up to the PNC, which are in contact with raw and diluted exhaust gas, shall be designed to minimize deposition of the particles. All parts shall be made of electrically conductive materials that do not react with exhaust gas components, and shall be electrically grounded to prevent electrostatic effects.
2.1.2.4. The particle sampling system shall incorporate good aerosol sampling practice that includes the avoidance of sharp bends and abrupt changes in cross-section, the use of smooth internal surfaces and the minimisation of the length of the sampling line. Gradual changes in the cross-section are permissible.
2.1.3.1. The particle sample shall not pass through a pump before passing through the PNC.
2.1.3.2. A sample pre-classifier is recommended.
2.1.3.3. The sample preconditioning unit shall:
2.1.3.4. The PNC shall:
2.1.3.5. Where they are not held at a known constant level at the point at which PNC flow rate is controlled, the pressure and/or temperature at inlet to the PNC shall be measured and reported for the purposes of correcting particle concentration measurements to standard conditions.
2.1.3.6. The sum of the residence time of the PTS, VPR and OT plus the response time of the PNC shall be no greater than 20 s.
2.1.3.7. The transformation time of the entire particle number sampling system (PTS, VPR, OT and PNC) shall be determined by aerosol switching directly at the inlet of the PTS. The aerosol switching shall be done in less than 0,1 s. The aerosol used for the test shall cause a concentration change of at least 60 % full scale (FS). The concentration trace shall be recorded. For time alignment of the particle number concentration and exhaust gas flow signals, the transformation time is defined as the time from the change (t0) until the response is 50 % of the final reading (t50).
This point contains the recommended practice for measurement of particle number. However, any system meeting the performance specifications in points 2.1.2 and 2.1.3 is acceptable.
Figures 6.9 and 6.10 are schematic drawings of the recommended particle sampling system configures for partial and full flow dilution systems respectively.
The particle sampling system shall consist of a sampling probe tip or particle sampling point in the dilution system, a particle transfer tube (PTT), a particle pre-classifier (PCF) and a volatile particle remover (VPR) upstream of the particle number concentration measurement (PNC) unit. The VPR shall include devices for sample dilution (particle number diluters: PND1 and PND2) and particle evaporation (Evaporation tube, ET). The sampling probe or sampling point for the test gas flow shall be so arranged within the dilution tract that a representative sample gas flow is taken from a homogeneous diluent/exhaust gas mixture. The sum of the residence time of the system plus the response time of the PNC shall be no greater than 20 s.
The sampling probe tip or particle sampling point and Particle Transfer Tube (PTT) together comprise the Particle Transfer System (PTS). The PTS conducts the sample from the dilution tunnel to the entrance to the first particle number diluter. The PTS shall meet the following conditions:
Sample gas drawn through the PTS shall meet the following conditions:
Any other sampling configuration for the PTS for which equivalent particle penetration for particles of 30 nm electrical mobility diameter can be demonstrated will be considered acceptable.
The outlet tube (OT) conducting the diluted sample from the VPR to the inlet of the PNC shall have the following properties:
Any other sampling configuration for the OT for which equivalent particle penetration for particles of 30 nm electrical mobility diameter can be demonstrated will be considered acceptable.
The recommended particle pre-classifier shall be located upstream of the VPR. The pre-classifier 50 % cut point particle diameter shall be between 2,5 μm and 10 μm at the volumetric flow rate selected for sampling particle number emissions. The pre-classifier shall allow at least 99 % of the mass concentration of 1 μm particles entering the pre-classifier to pass through the exit of the pre-classifier at the volumetric flow rate selected for sampling particle number emissions. In the case of partial flow dilution systems, it is acceptable to use the same pre-classifier for particulate mass and particle number sampling, extracting the particle number sample from the dilution system downstream of the pre-classifier. Alternatively separate pre-classifiers may be used, extracting the particle number sample from the dilution system upstream of the particulate mass pre-classifier.
The VPR shall comprise one particle number diluter (PND1), an evaporation tube and a second diluter (PND2) in series. This dilution function is to reduce the number concentration of the sample entering the particle concentration measurement unit to less than the upper threshold of the single particle count mode of the PNC and to suppress nucleation within the sample. The VPR shall provide an indication of whether or not PND1 and the evaporation tube are at their correct operating temperatures.
The VPR shall achieve > 99,0 % vaporisation of 30 nm tetracontane (CH3(CH2)38CH3) particles, with an inlet concentration of ≥ 10 000 cm– 3, by means of heating and reduction of partial pressures of the tetracontane. It shall also achieve a particle concentration reduction factor (fr) for particles of 30 nm and 50 nm electrical mobility diameters, that is no more than 30 % and 20 % respectively higher, and no more than 5 % lower than that for particles of 100 nm electrical mobility diameter for the VPR as a whole.
The first particle number dilution device shall be specifically designed to dilute particle number concentration and operate at a (wall) temperature of 423 K to 673 K (150 °C to 400 °C). The wall temperature set point should be held at a constant nominal operating temperature, within this range, to a tolerance of ± 10 °C and not exceed the wall temperature of the ET (point 2.1.4.4.2). The diluter should be supplied with HEPA filtered dilution air and be capable of a dilution factor of 10 to 200 times.
The entire length of the ET shall be controlled to a wall temperature greater than or equal to that of the first particle number dilution device and the wall temperature held at a fixed nominal operating temperature between 300 °C and 400 °C, to a tolerance of ± 10 °C.
PND2 shall be specifically designed to dilute particle number concentration. The diluter shall be supplied with HEPA filtered dilution air and be capable of maintaining a single dilution factor within a range of 10 to 30 times. The dilution factor of PND2 shall be selected in the range between 10 and 15 such that particle number concentration downstream of the second diluter is less than the upper threshold of the single particle count mode of the PNC and the gas temperature prior to entry to the PNC is < 35 °C.
The PNC shall meet the requirements of point 2.1.3.4.
2.2.1.1 The Technical Service shall ensure the existence of a calibration certificate for the PNC demonstrating compliance with a traceable standard within a 12-month period prior to the emissions test.
2.2.1.2. The PNC shall also be recalibrated and a new calibration certificate issued following any major maintenance.
2.2.1.3. Calibration shall be traceable to a standard calibration method: In the electrometer case, calibration shall be undertaken using at least six standard concentrations spaced as uniformly as possible across the PNC's measurement range. These points will include a nominal zero concentration point produced by attaching HEPA filters of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of each instrument. With no calibration factor applied to the PNC under calibration, measured concentrations shall be within ± 10 % of the standard concentration for each concentration used, with the exception of the zero point, otherwise the PNC under calibration shall be rejected. The gradient from a linear regression of the two data sets shall be calculated and recorded. A calibration factor equal to the reciprocal of the gradient shall be applied to the PNC under calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R2) of the two data sets and shall be equal to or greater than 0,97. In calculating both the gradient and R2 the linear regression shall be forced through the origin (zero concentration on both instruments). In the reference PNC case, calibration shall be undertaken using at least six standard concentrations across the PNC's measurement range. At least 3 points shall be at concentrations below 1 000 cm– 3, the remaining concentrations shall be linearly spaced between 1 000 cm– 3 and the maximum of the PNC's range in single particle count mode. These points will include a nominal zero concentration point produced by attaching HEPA filters of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of each instrument. With no calibration factor applied to the PNC under calibration, measured concentrations shall be within ± 10 % of the standard concentration for each concentration, with the exception of the zero point, otherwise the PNC under calibration shall be rejected. The gradient from a linear regression of the two data sets shall be calculated and recorded. A calibration factor equal to the reciprocal of the gradient shall be applied to the PNC under calibration. Linearity of response is calculated as the square of the Pearson product moment correlation coefficient (R2) of the two data sets and shall be equal to or greater than 0,97. In calculating both the gradient and R2 the linear regression shall be forced through the origin (zero concentration on both instruments).
2.2.1.4. Calibration shall also include a check, against the requirements in point 2.1.3.4.8, on the PNC's detection efficiency with particles of 23 nm electrical mobility diameter. A check of the counting efficiency with 41 nm particles is not required.
2.2.2.1. Calibration of the VPR's particle concentration reduction factors across its full range of dilution settings, at the instrument's fixed nominal operating temperatures, shall be required when the unit is new and following any major maintenance. The periodic validation requirement for the VPR's particle concentration reduction factor is limited to a check at a single setting, typical of that used for measurement on diesel particulate filter equipped non-road mobile machinery. The Technical Service shall ensure the existence of a calibration or validation certificate for the volatile particle remover within a 6-month period prior to the emissions test. If the volatile particle remover incorporates temperature monitoring alarms a 12 month validation interval shall be permissible. The VPR shall be characterised for particle concentration reduction factor with solid particles of 30 nm, 50 nm and 100 nm electrical mobility diameter. Particle concentration reduction factors (ƒr(d)) for particles of 30 nm and 50 nm electrical mobility diameters shall be no more than 30 % and 20 % higher respectively, and no more than 5 % lower than that for particles of 100 nm electrical mobility diameter. For the purposes of validation, the mean particle concentration reduction factor shall be within ± 10 % of the mean particle concentration reduction factor (
) determined during the primary calibration of the VPR.
| 2.2.2.2. | The test aerosol for these measurements shall be solid particles of 30, 50 and 100 nm electrical mobility diameter and a minimum concentration of 5 000 particles cm– 3 at the VPR inlet. Particle concentrations shall be measured upstream and downstream of the components. The particle concentration reduction factor at each particle size (ƒr(di)) shall be calculated by means of equation (6-32): (6-32) Where: Nin(di) is the upstream particle number concentration for particles of diameter di Nout(di) is the downstream particle number concentration for particles of diameter di di is the particle electrical mobility diameter (30, 50 or 100 nm) Nin(di) and Nout(di) shall be corrected to the same conditions.The mean particle concentration reduction () at a given dilution setting shall be calculated by means of equation (6-33): (6-33) It is recommended that the VPR is calibrated and validated as a complete unit. |
| --- | --- | | | (6-32) | | Nin(di) | is the upstream particle number concentration for particles of diameter di | | Nout(di) | is the downstream particle number concentration for particles of diameter di | | di | is the particle electrical mobility diameter (30, 50 or 100 nm) | | | (6-33) |
2.2.2.3. The Technical Service shall ensure the existence of a validation certificate for the VPR demonstrating effective volatile particle removal efficiency within a 6 month period prior to the emissions test. If the volatile particle remover incorporates temperature monitoring alarms a 12 month validation interval shall be permissible. The VPR shall demonstrate greater than 99,0 % removal of tetracontane (CH3(CH2)38CH3) particles of at least 30 nm electrical mobility diameter with an inlet concentration of ≥ 10 000 cm– 3 when operated at its minimum dilution setting and manufacturers recommended operating temperature.
2.2.3.1. Prior to each test, the particle counter shall report a measured concentration of less than 0,5 particles cm– 3 when a HEPA filter of at least class H13 of EN 1822:2008, or equivalent performance, is attached to the inlet of the entire particle sampling system (VPR and PNC).
2.2.3.2. On a monthly basis, the flow into the particle counter shall report a measured value within 5 % of the particle counter nominal flow rate when checked with a calibrated flow meter.
2.2.3.3. Each day, following the application of a HEPA filter of at least class H13 of EN 1822:2008, or equivalent performance, to the inlet of the particle counter, the particle counter shall report a concentration of ≤ 0,2 cm– 3. Upon removal of this filter, the particle counter shall show an increase in measured concentration to at least 100 particles cm– 3 when challenged with ambient air and a return to ≤ 0,2 cm– 3 on replacement of the HEPA filter.
2.2.3.4. Prior to the start of each test it shall be confirmed that the measurement system indicates that the evaporation tube, where featured in the system, has reached its correct operating temperature.
2.2.3.5. Prior to the start of each test it shall be confirmed that the measurement system indicates that the diluter PND1 has reached its correct operating temperature.
Appendix 2
Installation requirements for equipment and auxiliaries
| Number | Equipment and auxiliaries | Fitted for emission test |
|---|---|---|
| 1 | Inlet system | |
| Inlet manifold | Yes | |
| Crankcase emission control system | Yes | |
| Air flow meter | Yes | |
| Air filter | Yes ((i) (ii)) | |
| Inlet silencer | Yes ((i) (ii)) | |
| 2 | Exhaust system | |
| Exhaust after-treatment system | Yes | |
| Exhaust manifold | Yes | |
| Connecting pipes | Yes ((i) (ii)) | |
| Silencer | Yes ((i) (ii)) | |
| Tail pipe | Yes ((i) (ii)) | |
| Exhaust brake | No () | |
| Pressure charging device | Yes | |
| 3 | Fuel supply pump | Yes () |
| 4 | Fuel injection equipment | |
| Prefilter | Yes | |
| Filter | Yes | |
| Pump | Yes | |
| 5 | High-pressure pipe | Yes |
| Injector | Yes | |
| Electronic control unit, sensors, etc. | Yes | |
| Governor/control system | Yes | |
| Automatic full-load stop for the control rack depending on atmospheric conditions | Yes | |
| 6 | Liquid-cooling equipment | |
| Radiator | No | |
| Fan | No | |
| Fan cowl | No | |
| Water pump | Yes () | |
| Thermostat | Yes () | |
| 7 | Air cooling | |
| Cowl | No () | |
| Fan or Blower | No () | |
| Temperature-regulating device | No | |
| 8 | Pressure charging equipment | |
| Compressor driven either directly by the engine and/or by the exhaust system | Yes | |
| Charge air cooler | Yes () () | |
| Coolant pump or fan (engine-driven) | No () | |
| Coolant flow control device | Yes | |
| 9 | Auxiliary test-bed fan | Yes, if necessary |
| 10 | Anti-pollution device | Yes |
| 11 | Starting equipment | Yes or test bed equipment () |
| 12 | Lubricating oil pump | Yes |
| 13 | Certain auxiliaries whose definition is linked with the operation of the non-road mobile machinery and which may be mounted on the engine shall be removed for the test. The following non-exhaustive list is given as an example: (i) air compressor for brakes (ii) power steering compressor (iii) suspension compressor (iv) air-conditioning system. | No |
| (1) The complete inlet system shall be fitted as provided for the intended application: (i) where there is a risk of an appreciable effect on the engine power; (ii) when the manufacturer requests that this should be done. In other cases, an equivalent system may be used and a check should be made to ascertain that the intake pressure does not differ by more than 100 Pa from the upper limit specified by the manufacturer for a clean air filter. (2) The complete exhaust system shall be fitted as provided for the intended application: (i) where there is a risk of an appreciable effect on the engine power; (ii) when the manufacturer requests that this should be done. In other cases, an equivalent system may be installed provided the pressure measured does not differ by more than 1 000 Pa from the upper limit specified by the manufacturer. (3) If an exhaust system brake is incorporated in the engine, the throttle valve shall be fixed in the fully open position. (4) The fuel feed pressure may be adjusted, if necessary, to reproduce the pressure existing in the particular engine application (particularly when a ‘fuel return’ system is used). (5) The cooling-liquid circulation shall be operated by the engine water pump only. Cooling of the liquid may be produced by an external circuit, such that the pressure loss of this circuit and the pressure at the pump inlet remain substantially the same as those of the engine cooling system. (6) The thermostat may be fixed in the fully open position. (7) When the cooling fan or blower is fitted for the test, the power absorbed shall be added to the results, except for cooling fans of air cooled engines directly fitted on the crankshaft. The fan or blower power shall be determined at the speeds used for the test either by calculation from standard characteristics or by practical tests. (8) Charge air-cooled engines shall be tested with charge air cooling, whether liquid — or air-cooled, but if the manufacturer prefers, a test bench system may replace the air cooler. In either case, the measurement of power at each speed shall be made with the maximum pressure drop and the minimum temperature drop of the engine air across the charge air cooler on the test bench system as those specified by the manufacturer. (9) The power for electrical or other starting systems shall be provided from the test bed. |
Appendix 3
Verification of torque signal broadcast by electronic control unit
Introduction
The purpose of this Appendix is to set out the requirements for verification in the case that the manufacturer intends to use the torque signal broadcast by the electronic control unit (ECU), of engines so equipped, during the conduct of in-service monitoring tests according to Delegated Regulation (EU) 2017/655.
The basis for the net torque shall be uncorrected net torque delivered by the engine inclusive of the equipment and auxiliaries to be included for an emissions test according to Appendix 2.
ECU torque signal
With the engine installed on the test bench for conducting the mapping procedure, means shall be provided to read the torque signal broadcast by the ECU according to the requirements of Appendix 6 of Annex I to Delegated Regulation (EU) 2017/655.
Verification procedure
When conducting the mapping procedure according to section 7.6.2 of this Annex readings of the torque measured by the dynamometer and torque broadcast by the ECU shall be taken simultaneously at a minimum of three points on the torque curve. At least one of the readings shall be taken at a point on the curve where the torque is no less than 98 % of the maximum value.
The torque broadcast by the ECU shall be accepted without correction if, at each point where measurements were taken, the factor calculated from dividing the torque value from the dynamometer by the torque value from the ECU is not less than 0,93 (i.e. a maximum difference of 7 %). In this case it shall be recorded in the type approval certificate that the torque broadcast by the ECU has been verified without correction. Where the factor at one or more test points is less than 0,93 the average correction factor shall be determined from all the points where readings were taken and recorded in the type approval certificate. Where a factor is recorded in the type approval certificate it shall be applied to the torque broadcast by the ECU when conducting in-service monitoring tests according to Delegated Regulation (EU) 2017/655.
Appendix 4
Procedure for the measurement of ammonia
This appendix describes the procedure for measurement of ammonia (NH3). For non-linear analysers, the use of linearising circuits shall be permitted.
2. Three measurement principles are specified for NH3 measurement and either principle may be used provided it meets the criteria specified in points 2.1, 2.2 or 2.3, respectively. Gas dryers shall not be permitted for NH3 measurement.
2.1. Fourier Transform Infrared (hereinafter ‘FTIR’) analyser 2.1.1. Measurement principle The FTIR employs the broad waveband infrared spectroscopy principle. It allows simultaneous measurement of exhaust gas components whose standardized spectra are available in the instrument. The absorption spectrum (intensity/wavelength) is calculated from the measured interferogram (intensity/time) by means of the Fourier transform method. 2.1.2. Installation and sampling The FTIR shall be installed in accordance with the instrument manufacturer's instructions. The NH3 wavelength shall be selected for evaluation. The sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C) in order to minimize NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible. 2.1.3. Cross interference The spectral resolution of the NH3 wavelength shall be within 0,5 cm– 1 in order to minimize cross interference from other gases present in the exhaust gas. 2.2. Non Dispersive Ultra Violet Resonance Absorption analyser (hereinafter ‘NDUV’) 2.2.1. Measurement Principle The NDUV is based on a purely physical principle, no auxiliary gases or equipment is necessary. The main element of the photometer is an electrode-less discharge lamp. It produces a sharply structured radiation in the ultraviolet range, enabling the measurement of several components such as NH3. The photometric system has a dual beam in time design set up to produce a measuring and a reference beam by filter correlation technique. In order to achieve a high stability of the measuring signal the dual beam in time design is combined with a dual beam in space design. The detector signals processing fosters an almost negligible amount of zero point drift rate. In the calibration mode of the analyser a sealed-off quartz cell is tilted into the beam path to obtain an exact calibration value, since any reflection and absorption losses of the cell windows are compensated. Since the gas filling of the cell is very stable, this calibration method leads to a very high long term stability of the photometer. 2.2.2. Installation The analyser shall be installed within an analyser cabinet using extractive sampling in accordance with the instrument manufacturer's instructions. The analyzer location shall be capable of supporting the weight specified by the manufacturer. The sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C). In addition, the sampling line shall be as short as possible. Influence from exhaust gas temperature and pressure, installation environment and vibrations on the measurement shall be minimized. The gas analyzer shall be protected from cold, heat, temperature variations, and strong air currents, accumulation of dust, corrosive atmosphere and vibrations. Adequate air circulation shall be provided to avoid heat build-up. The complete surface shall be used to dissipate the heat losses. 2.2.3. Cross Sensitivity An appropriate spectral range shall be chosen in order to minimize cross interferences of accompanying gases. Typical components causing cross sensitivities on the NH3 measurement are SO2, NO2 and NO. Additionally, further methods can be applied to reduce the cross sensitivities. 2.3. Laser Infrared analyser 2.3.1. Measurement principle An infrared laser such as a tunable diode laser (TDL) or a quantum cascade laser (QCL) can emit coherent light in the near-infrared region or in mid-infrared region respectively where nitrogen compounds including NH3 have strong absorption. This laser optics can give a pulsed-mode high resolution narrow band near-infrared or mid-infrared spectrum. Therefore, laser infrared analyzers can reduce interference caused by the spectral overlap of co-existing components in engine exhaust gas. 2.3.2. Installation The analyser shall be installed either directly in the exhaust pipe (in-situ) or within an analyser cabinet using extractive sampling in accordance with the instrument manufacturer's instructions. If installed in an analyser cabinet, the sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to set points between 383 K (110 °C) and 464 K (191 °C) in order to minimize NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible. Influence from exhaust gas temperature and pressure, installation environment and vibrations on the measurement shall be minimized, or compensation techniques be used. If applicable, sheath air used in conjunction with in-situ measurement for protection of the instrument, shall not affect the concentration of any exhaust gas component measured downstream of the device, or sampling of other exhaust gas components shall be made upstream of the device. 2.3.3. Interference verification for NH3 laser infrared analyzers (cross interference) 2.3.3.1. Scope and frequency If NH3 is measured using laser infrared analyser, the amount of interference shall be verified after initial analyser installation and after major maintenance. 2.3.3.2. Measurement principles for interference verification Interference gasses can positively interfere with certain laser infrared analyzer by causing a response similar to NH3. If the analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, these other measurements shall be simultaneously conducted to test the compensation algorithms during the analyzer interference verification. Good engineering judgment shall be used to determine interference gases for laser infrared analyzer. Note that interference species, with the exception of H2O, are dependent on the NH3 infrared absorption band chosen by the instrument manufacturer. For each analyzer the NH3 infrared absorption band shall be determined. For each NH3 infrared absorption band, good engineering judgment shall be used to determine interference gases to use in the verification.
4. 4.1. Linearity requirements
The analyser shall comply with the linearity requirements specified in Table 6.5 of this Annex. The linearity verification in accordance with point 8.1.4 of this Annex shall be performed at least at the minimum frequency set out in Table 6.4 of this Annex. With the prior approval of the approval authority, less than 10 reference points are permitted, if an equivalent accuracy can be demonstrated. For the linearity verification, a NH3 gas that meets the specifications set out in point 4.2.7 shall be used. The use of reference cells that contain NH3 span gas shall be permitted. Instruments, whose signals are used for compensation algorithms, shall meet the linearity requirements specified in Table 6.5 of this Annex. Linearity verification shall be done as required by internal audit procedures, by the instrument manufacturer or in accordance with ISO 9000 requirements. 4.2. Analyser specifications The analyser shall have a measuring range and response time appropriate for the accuracy required to measure the concentration of NH3 under transient and steady state conditions. 4.2.1. Minimum detection limit The analyser shall have a minimum detection limit of < 2 ppm under all conditions of testing. 4.2.2. Accuracy The accuracy, defined as the deviation of the analyser reading from the reference value, shall not exceed ± 3 % of the reading or ± 2 ppm, whichever is larger. 4.2.3. Zero drift The drift of the zero response and the related time interval shall be specified by the instrument manufacturer. 4.2.4. Span drift The drift of the span response and the related time interval shall be specified by the instrument manufacturer. 4.2.5. System response time The system response time shall be ≤ 20 s. 4.2.6. Rise time The rise time of the analyser shall be ≤ 5 s. 4.2.7. NH3 calibration gas A gas mixture with the following chemical composition shall be available. NH3 and purified nitrogen. The true concentration of the calibration gas shall be within ± 3 % of the nominal value. The concentration of NH3 shall be given on a volume basis (volume per cent or volume ppm). The expiration date of the calibration gases shall be recorded. 4.2.8. Interference verification procedure The interference verification shall be performed as follows:
5. Other systems or analysers may be approved by the approval authority, if it is found that they yield equivalent results in accordance with point 5.1.1 of this Annex. In this case, ‘Results’ in that point shall refer to mean NH3 concentration calculated for the applicable cycle.
Appendix 5
Description of system responses
This appendix describes the times used to express the response of analytical systems and other measurement systems to an input signal.
The following times apply, as shown in figure 6-11:
Figure 6-11 Illustration of system responses
ANNEX VII
Method for data evaluation and calculation
1. General requirements
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