5.

Section 4.5 is replaced by the following: ‘4.5. Emissions test run The following flow chart outlines the test sequence: One or more practice cycles may be run as necessary to check engine, test cell and emissions systems before the measurement cycle. 4.5.1. Preparation of the sampling filters At least one hour before the test, each filter shall be placed in a petri dish, which is protected against dust contamination and allows air exchange, and placed in a weighing chamber for stabilisation. At the end of the stabilisation period, each filter shall be weighed and the weight shall be recorded. The filter shall then be stored in a closed petri dish or sealed filter holder until needed for testing. The filter shall be used within eight hours of its removal from the weighing chamber. The tare weight shall be recorded. 4.5.2. Installation of the measuring equipment The instrumentation and sample probes shall be installed as required. The tailpipe shall be connected to the full-flow dilution system, if used. 4.5.3. Starting the dilution system The dilution system shall be started. The total diluted exhaust gas flow of a full-flow dilution system or the diluted exhaust gas flow through a partial flow dilution system shall be set to eliminate water condensation in the system, and to obtain a filter face temperature between 315 K (42 °C) and 325 K (52 °C). 4.5.4. Starting the particulate sampling system The particulate sampling system shall be started and run on by-pass. The particulate background level of the dilution air may be determined by sampling the dilution air prior to entrance of the exhaust into the dilution tunnel. It is preferred that background particulate sample be collected during the transient cycle if another PM sampling system is available. Otherwise, the PM sampling system used to collect transient cycle PM can be used. If filtered dilution air is used, one measurement may be done prior to or after the test. If the dilution air is not filtered, measurements should be carried out prior to the beginning and after the end of the cycle and the values averaged. 4.5.5. Checking the analysers The emission analysers shall be set at zero and spanned. If sample bags are used, they shall be evacuated. 4.5.6. Cool-down requirements A natural or forced cool-down procedure may be applied. For forced cool-down, good engineering judgement 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 after-treatment system has cooled below its catalytic activation temperature. Any cooling procedure that results in unrepresentative emissions is not permitted. The cold start cycle exhaust emission test may begin after a cool-down only when the engine oil, coolant and after-treatment temperatures are stabilised between 20 °C and 30 °C for a minimum of 15 minutes. 4.5.7. Cycle run 4.5.7.1. Cold start cycle The test sequence shall commence with the cold start cycle at the completion of the cool-down when all the requirements specified in section 4.5.6 are met. The engine shall be started according to the starting procedure recommended by the manufacturer in the owner's manual, using either a production starter motor or the dynamometer. As soon as it is determined that the engine is started, start a “free idle” timer. Allow the engine to idle freely with no-load for 23 ± 1 s. Begin the transient engine cycle such that the first non-idle record of the cycle occurs at 23 ± 1 s. The free idle time is included in the 23 ± 1 s. The test shall be performed according to the reference cycle as set out in Annex III, Appendix 4. Engine speed and torque command set points shall be issued at 5 Hz (10 Hz recommended) or greater. The set points shall be calculated by linear interpolation between the 1 Hz set points of the reference cycle. Feedback engine speed and torque shall be recorded at least once every second during the test cycle, and the signals may be electronically filtered. 4.5.7.2. Analyser response At the start of the engine the measuring equipment shall be started, simultaneously: — start collecting or analysing dilution air, if a full flow dilution system is used, — start collecting or analysing raw or diluted exhaust gas, depending on the method used, — start measuring the amount of diluted exhaust gas and the required temperatures and pressures, — start recording the exhaust gas mass flow rate, if raw exhaust gas analysis is used, — start recording the feedback data of speed and torque of the dynamometer. If raw exhaust measurement is used, the emission concentrations (HC, CO and NOx) and the exhaust gas mass flow rate shall be measured continuously and stored with at least 2 Hz on a computer system. All other data may be recorded with a sample rate of at least 1 Hz. For analogue analysers the response shall be recorded, and the calibration data may be applied online or offline during the data evaluation. If a full flow dilution system is used, HC and NOx shall be measured continuously in the dilution tunnel with a frequency of at least 2 Hz. The average concentrations shall be determined by integrating the analyser signals over the test cycle. The system response time shall be no greater than 20 s, and shall be coordinated with CVS flow fluctuations and sampling time/test cycle offsets, if necessary. CO and CO2 shall be determined by integration or by analysing the concentrations in the sample bag collected over the cycle. The concentrations of the gaseous pollutants in the dilution air shall be determined by integration or by collection in the background bag. All other parameters that need to be measured shall be recorded with a minimum of one measurement per second (1 Hz). 4.5.7.3. Particulate sampling At the start of the engine the particulate sampling system shall be switched from by-pass to collecting particulates. If a partial flow dilution system is used, the sample pump(s) shall be adjusted so that the flow rate through the particulate sample probe or transfer tube is maintained proportional to the exhaust mass flow rate. If a full flow dilution system is used, the sample pump(s) shall be adjusted so that the flow rate through the particulate sample probe or transfer tube is maintained at a value within ± 5 % of the set flow rate. If flow compensation (i.e. proportional control of sample flow) is used, it must be demonstrated that the ratio of main tunnel flow to particulate sample flow does not change by more than ± 5 % of its set value (except for the first 10 seconds of sampling). NOTE: For double dilution operation, sample flow is the net difference between the flow rate through the sample filters and the secondary dilution airflow rate. The average temperature and pressure at the gas meter(s) or flow instrumentation inlet shall be recorded. If the set flow rate cannot be maintained over the complete cycle (within ± 5 %) because of high particulate loading on the filter, the test shall be voided. The test shall be rerun using a lower flow rate and/or a larger diameter filter. 4.5.7.4. Engine stalling during the cold start test cycle If the engine stalls anywhere during the cold start test cycle, the engine shall be preconditioned, then the cool-down procedure repeated; finally the engine shall be restarted, and the test repeated. If a malfunction occurs in any of the required test equipment during the test cycle, the test shall be voided. 4.5.7.5. Operations after cold start cycle At the completion of the cold start cycle of the test, the measurement of the exhaust gas mass flow rate, the diluted exhaust gas volume, the gas flow into the collecting bags and the particulate sample pump shall be stopped. For an integrating analyser system, sampling shall continue until system response times have elapsed. The concentrations of the collecting bags, if used, shall be analysed as soon as possible and in any case not later than 20 minutes after the end of the test cycle. After the emission test, a zero gas and the same span gas shall be used for re-checking the analysers. The test will be considered acceptable if the difference between the pre-test and post-test results is less than 2 % of the span gas value. The particulate filters shall be returned to the weighing chamber no later than one hour after completion of the test. They shall be conditioned in a petri dish, which is protected against dust contamination and allows air exchange, for at least one hour, and then weighed. The gross weight of the filters shall be recorded. 4.5.7.6. Hot soak Immediately after the engine is turned off, the engine cooling fan(s) shall be turned off if used, as well as the CVS blower (or disconnect the exhaust system from the CVS), if used. Allow the engine to soak for 20 ± 1 minutes. Prepare the engine and dynamometer for the hot start test. Connect evacuated sample collection bags to the dilute exhaust and dilution air sample collection systems. Start the CVS (if used or not already on) or connect the exhaust system to the CVS (if disconnected). Start the sample pumps (except the particulate sample pump(s), the engine cooling fan(s) and the data collection system. The heat exchanger of the constant volume sampler (if used) and the heated components of any continuous sampling system(s) (if applicable) shall be preheated to their designated operating temperatures before the test begins. Adjust the sample flow rates to the desired flow rate and set the CVS gas flow measuring devices to zero. Carefully install a clean particulate filter in each of the filter holders and install assembled filter holders in the sample flow line. 4.5.7.7. Hot start cycle As soon as it is determined that the engine is started, start a “free idle” timer. Allow the engine to idle freely with no-load for 23 ± 1 s. Begin the transient engine cycle such that the first non-idle record of the cycle occurs at 23 ± 1 s. The free idle time is included in the 23 ± 1 s. The test shall be performed according to the reference cycle as set out in Appendix 4 to Annex III. Engine speed and torque command set points shall be issued at 5 Hz (10 Hz recommended) or greater. The set points shall be calculated by linear interpolation between the 1 Hz set points of the reference cycle. Feedback engine speed and torque shall be recorded at least once every second during the test cycle, and the signals may be electronically filtered. The procedure described in previous sections 4.5.7.2 and 4.5.7.3 shall then be repeated. 4.5.7.8. Engine stalling during the hot start cycle If the engine stalls anywhere during the hot start cycle, the engine may be shut off and re-soaked for 20 minutes. The hot start cycle may then be rerun. Only one hot re-soak and hot start cycle restart is permitted. 4.5.7.9. Operations after hot start cycle At the completion of the hot start cycle, the measurement of the exhaust gas mass flow rate, the diluted exhaust gas volume, the gas flow into the collecting bags and the particulate sample pump shall be stopped. For an integrating analyser system, sampling shall continue until system response times have elapsed. The concentrations of the collecting bags, if used, shall be analysed as soon as possible and in any case not later than 20 minutes after the end of the test cycle. After the emission test, a zero gas and the same span gas shall be used for re-checking the analysers. The test will be considered acceptable if the difference between the pre-test and post-test results is less than 2 % of the span gas value. The particulate filters shall be returned to the weighing chamber no later than one hour after completion of the test. They shall be conditioned in a petri dish, which is protected against dust contamination and allows air exchange, for at least one hour, and then weighed. The gross weight of the filters shall be recorded.’