8.2.2.

Gas engines The parent engine of the family shall be selected using the primary criteria of the largest displacement. In the event that two or more engines share this primary criteria, the parent engine shall be selected using the secondary criteria in the following order: the highest fuel delivery per stroke at the speed of declared rated power; the most advanced spark timing; the lowest EGR rate; no air pump or lowest actual air flow pump. Under certain circumstances, the approval authority may conclude that the worst case emission rate of the family can best be characterised by testing a second engine. Thus, the approval authority may select an additional engine for test based upon features which indicate that it may have the highest emission level of the engines within that family.

9. 9.1.

PRODUCTION CONFORMITY Measures to ensure production conformity must be taken in accordance with the provisions of Article 10 of Directive 70/156/EEC. Production conformity is checked on the basis of the description in the typeapproval certificates set out in Annex VI to this Directive. Sections 2.4.2 and 2.4.3 of Annex X to Directive 70/156/EEC are applicable where the competent authorities are not satisfied with the auditing procedure of the manufacturer.

9.1.1.

If emissions of pollutants are to be measured and an engine type-approval has had one or several extensions, the tests will be carried out on the engine(s) described in the information package relating to the relevant extension. Conformity of the engine subjected to a pollutant test: After submission of the engine to the authorities, the manufacturer shall not carry out any adjustment to the engines selected.

9.1.1.1.

9.1.1.1.1.
Three engines are randomly taken in the series. Engines that are subject to testing only on the ESC and ELR tests or only on the ETC test for type approval to row A of the tables in Section 6.2.1 are subject to those applicable tests for the checking of production conformity. With the agreement of the authority, all other engines type approved to row A, B1 or B2, or C of the tables in Section 6.2.1 are subjected to testing either on the ESC and ELR cycles or on the ETC cycle for the checking of the production conformity. The limit values are given in Section 6.2.1 of this Annex.

9.1.1.1.2.

The tests are carried out according to Appendix 1 to this Annex, where the competent authority is satisfied with the production standard deviation given by the manufacturer, in accordance with Annex X to Directive 70/156/EEC, which applies to motor vehicles and their trailers. The tests are carried out according to Appendix 2 to this Annex, where the competent authority is not satisfied with the production standard deviation given by the manufacturer, in accordance with Annex X to Directive 70/156/EEC, which applies to motor vehicles and their trailers. At the manufacturer's request, the tests may be carried out in accordance with Appendix 3 to this Annex.

(1) ESC test. (2) ETC test only.
Engine performance Engine speeds (1)

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Low speed (nlo):. rpm High speed (nhi):. rpm for ESC and ELR cycles Idle:. rpm Speed A:. rpm Speed B:. rpm Speed C:. rpm for ETC cycle Reference speed:. rpm
Engine power (measured in accordance with the provisions of Directive 80/1269/EEC) in kW
Engine speed Idle Speed A (1) Speed B
P(m) Power measured test bed P(a) Power absorbed by auxiliaries to be fitted for test (Section 6.1) if fitted if not fitted P(b) Power absorbed by auxiliaries to be removed for test (Section 6.2) if fitted if not fitted P(n) Net engine power = P(m) P(a) + P(b)
Specify the tolerance; to be within 3 % of the values declared by the manufacturer.

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Dynamometer settings (kW) The dynamometer settings for the ESC and ELR tests and for the reference cycle of the ETC test shall be based upon the net engine power P(n) of Section 8.2. It is recommended to install the engine on the test bed in the net condition. In this case, P(m) and P(n) are identical. If it is impossible or inappropriate to operate the engine under net conditions, the dynamometer settings shall be corrected to net conditions using the above formula.

8.3.1.

ESC and ELR tests The dynamometer settings shall be calculated according to the formula in Annex III, Appendix 1, Section 1.2.
Engine speed Percent load Idle Speed A Speed B Speed C

8.3.2.

ETC test If the engine is not tested under net conditions, the correction formula for converting the measured power or measured cycle work, as determined according to Annex III, Appendix 2, Section 2, to net power or net cycle work shall be submitted by the engine manufacturer for the whole operating area of the cycle, and approved by the Technical Service.

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Appendix 2 ESSENTIAL CHARACTERISTICS OF THE ENGINE FAMILY 1. 1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 1.7. 1.8. 1.9. 1.10. Common parameters Combustion cycle:. Cooling medium:. Number of cylinders (1):. Individual cylinder displacement:. Method of air aspiration:. Combustion chamber type/design:. Valve and porting configuration, size and number:. Fuel system:. Ignition system (gas engines):. Miscellaneous features: charge cooling system (1):. exhaust gas recirculation (1):. water injection/emulsion (1):. air injection (1):. 1.11. Exhaust aftertreatment (1):. Proof of identical (or lowest for the parent engine) ratio: system capacity/fuel delivery per stroke, pursuant to diagram number(s):. 2. 2.1. 2.1.1. Engine family listing Name of diesel engine family:. Specification of engines within this family:.

1.3.3.

ETC test

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During a prescribed transient cycle of warmed-up engine operating conditions, which is based closely on road-type-specific driving patterns of heavy-duty engines installed in trucks and buses, the above pollutants shall be examined after diluting the total exhaust gas with conditioned ambient air. Using the engine torque and speed feedback signals of the engine dynamometer, the power shall be integrated with respect to time of the cycle resulting in the work produced by the engine over the cycle. The concentration of NOx and HC shall be determined over the cycle by integration of the analyser signal. The concentration of CO, CO2, and NMHC may be determined by integration of the analyser signal or by bag sampling. For particulates, a proportional sample shall be collected on suitable filters. The diluted exhaust gas flow rate shall be determined over the cycle to calculate the mass emission values of the pollutants. The mass emission values shall be related to the engine work to get the grams of each pollutant emitted per kilowatt hour, as described in Appendix 2 to this Annex. 2. 2.1. 2.1.1. TEST CONDITIONS Engine test conditions The absolute temperature (Ta) of the engine air at the inlet to the engine expressed in Kelvin, and the dry atmospheric pressure (ps), expressed in kPa shall be measured and the parameter F shall be determined according to the following provisions: (a) for diesel engines: Naturally aspirated and mechanically supercharged engines: F 99 Ta 0;ps
Turbocharged engines with or without cooling of the intake air: 0;Ta 1;5 ps 298
(b) for gas engines: 1;2 99 Ta 0;6 ps 298

2.1.2.

Test validity For a test to be recognised as valid, the parameter F shall be such that: 0,96 F 1,06
Engines with charge air cooling The charge air temperature shall be recorded and shall be, at the speed of the declared maximum power and full load, within 5 K of the maximum charge air temperature specified in Annex II, Appendix 1, Section 1.16.3. The temperature of the cooling medium shall be at least 293 K (20 C). If a test shop system or external blower is used, the charge air temperature shall be within 5 K of the maximum charge air temperature specified in Annex II, Appendix 1, Section 1.16.3 at the speed of the declared maximum power and full load. The setting of the charge air cooler for meeting the above conditions shall be used for the whole test cycle.

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idle A B B A A A B B C C C C

75 50

0,15 0,08 0,10 0,10 0,05 0,05 0,05 0,09 0,10 0,08 0,05 0,05 0,05
4 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes 2 minutes

2.7.2.

Test sequence The test sequence shall be started. The test shall be performed in the order of the mode numbers as set out in Section 2.7.1. The engine must be operated for the prescribed time in each mode, completing engine speed and load changes in the first 20 seconds. The specified speed shall be held to within 50 rpm and the specified torque shall be held to within 2 % of the maximum torque at the test speed. At the manufacturers request, the test sequence may be repeated a sufficient number of times for sampling more particulate mass on the filter. The manufacturer shall supply a detailed description of the data evaluation and calculation procedures. The gaseous emissions shall only be determined on the first cycle.

2.7.3.

Analyser response The output of the analysers shall be recorded on a strip chart recorder or measured with an equivalent data acquisition system with the exhaust gas flowing through the analysers throughout the test cycle.

2.7.4.

Particulate sampling One pair of filters (primary and back-up filters, see Annex III, Appendix 4) shall be used for the complete test procedure. The modal weighting factors specified in the test cycle procedure shall be taken into account by taking a sample proportional to the exhaust mass flow during each individual mode of the cycle. This can be achieved by adjusting sample flow rate, sampling time, and/or dilution ratio, accordingly, so that the criterion for the effective weighting factors in Section 5.6 is met. The sampling time per mode must be at least 4 seconds per 0,01 weighting factor. Sampling must be conducted as late as possible within each mode. Particulate sampling shall be completed no earlier than 5 seconds before the end of each mode.

2.7.5.

Engine conditions The engine speed and load, intake air temperature and depression, exhaust temperature and backpressure, fuel flow and air or exhaust flow, charge air temperature, fuel temperature and humidity shall be recorded during each mode, with the speed and load requirements (see Section 2.7.2) being met during the time of particulate sampling, but in any case during the last minute of each mode. Any additional data required for calculation shall be recorded (see Sections 4 and 5).

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2.7.6.
NOx check within the control area The NOx check within the control area shall be performed immediately upon completion of mode 13. The engine shall be conditioned at mode 13 for a period of three minutes before the start of the measurements. Three measurements shall be made at different locations within the control area, selected by the Technical Service. The time for each measurement shall be 2 minutes. The measurement procedure is identical to the NOx measurement on the 13-mode cycle, and shall be carried out in accordance with Sections 2.7.3, 2.7.5, and 4.1 of this Appendix, and Annex III, Appendix 4, Section 3. The calculation shall be carried out in accordance with Section 4.

Calculation of the emission mass flow rates The emission mass flow rates (g/h) for each mode shall be calculated as follows, assuming the exhaust gas density to be 1,293 kg/m3 at 273 K (0 C) and 101,3 kPa: (1) NOx mass = 0,001587 NOx conc KH,D GEXHW (2) COx mass = 0,000966 COconc GEXHW (3) HCmass = 0,000479 HCconc GEXHW where NOx conc, COconc, HCconc (1) are the average concentrations (ppm) in the raw exhaust gas, as determined in Section 4.1. If, optionally, the gaseous emissions are determined with a full flow dilution system, the following formulae shall be applied: (1) NOx mass = 0,001587 NOx conc KH,D GTOTW (2) COx mass = 0,000966 COconc GTOTW (3) HCmass = 0,000479 HCconc GTOTW where NOx conc, COconc, HCconc (1) are the average background corrected concentrations (ppm) of each mode in the diluted exhaust gas, as determined in Annex III, Appendix 2, Section 4.3.1.1.

Based on C1 equivalent.

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Calculation of the specific emissions The emissions (g/kWh) shall be calculated for all individual components in the following way: P NOx mass WFi NOx = P Pni WFi P COmass WFi CO = P Pni WFi P HCmass WFi HC = P Pni WFi The weighting factors (WF) used in the above calculation are according to Section 2.7.1.
Calculation of the area control values For the three control points selected according to Section 2.7.6, the NOx emission shall be measured and calculated according to Section 4.6.1 and also determined by interpolation from the modes of the test cycle closest to the respective control point according to Section 4.6.2. The measured values are then compared to the interpolated values according to Section 4.6.3.

4.6.1.

Calculation of the specific emission The NOx emission for each of the control points (Z) shall be calculated as follows: NOx mass,Z = 0,001587 NOx conc,Z KH,D GEXH W NOx;Z = NOx mass;Z PnZ

4.6.2.

Determination of the emission value from the test cycle The NOx emission for each of the control points shall be interpolated from the four closest modes of the test cycle that envelop the selected control point Z as shown in Figure 4. For these modes (R, S, T, U), the following definitions apply: Speed(R) Speed(S) Per cent load(R) Per cent load(T) = = = = Speed(T) = nRT Speed(U) = nSU Per cent load(S) Per cent load(U).

Speed Torque Power

Standard error of estimate (SE) of Y on X Slope of the regression line, m Coefficient of determination, r2 Y intercept of the regression line, b

Max 100 min1

Max 13 % (15 %) (*) of power map maximum engine torque 0,831,03 min 0,8800 (min 0,7500) (*) 20 Nm or 2 % ( 20 Nm or 3 %) (*) of max torque whichever is greater
Max 8 % (15 %) (*) of power map maximum engine power 0,891,03 (0,831,03) (*) min 0,9100 (min 0,7500) (*) 4 kW or 2 % ( 4 kW or 3 %) (*) of max power whichever is greater
0,95 to 1,03 min 0,9700 (min 0,9500) (*) 50 min-1
(*) Until 1 October 2005, the figures shown in brackets may be used for the type-approval testing of gas engines. The Commission shall report on the development of gas engine technology to confirm or modify the regression line tolerances applicable to gas engines given in this table.
Point deletions from the regression analyses are permitted where noted in Table 7.
Table 7 Permitted point deletions from regression analysis
Conditions Points to be deleted

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Full load and torque feedback < torque reference No load, not an idle point, and torque feedback > torque reference No load/closed throttle, idle point and speed > reference idle speed
Torque and/or power Torque and/or power Speed and/or power
CALCULATION OF THE GASEOUS EMISSIONS Determination of the diluted exhaust gas flow The total diluted exhaust gas flow over the cycle (kg/test) shall be calculated from the measurement values over the cycle and the corresponding calibration data of the flow measurement device (V 0 for PDP or KV for CFV, as determined in Annex III, Appendix 5, Section 2). The following formulae shall be applied, if the temperature of the diluted exhaust is kept constant over the cycle by using a heat exchanger ( 6 K for a PDP-CVS, 11 K for a CFV-CVS, see Annex V, Section 2.3). For the PDP-CVS system: MTOTW = 1,293 V0 Np (pB p1) 273 / (101,3 T) where: MTOTW = mass of the diluted exhaust gas on wet basis over the cycle, kg V0 NP pB p1 T = volume of gas pumped per revolution under test conditions, m3/rev = total revolutions of pump per test = atmospheric pressure in the test cell, kPa = pressure depression below atmospheric at pump inlet, kPa = average temperature of the diluted exhaust gas at pump inlet over the cycle, K
For the CFV-CVS system: MTOTW = 1,293 t Kv pA / T0,5 where: MTOTW = mass of the diluted exhaust gas on wet basis over the cycle, kg t Kv pA T = cycle time, s = calibration coefficient of the critical flow venturi for standard conditions = absolute pressure at venturi inlet, kPa = absolute temperature at venturi inlet, K
If a system with flow compensation is used (i.e. without heat exchanger), the instantaneous mass emissions shall be calculated and integrated over the cycle. In this case, the instantaneous mass of the diluted exhaust gas shall be calculated as follows: For the PDP-CVS system: MTOTW,i = 1,293 V0 Np,i (pB p1) 273 / (101,3 T) where: MTOTW,i = instantaneous mass of the diluted exhaust gas on wet basis, kg Np,i = total revolutions of pump per time interval

Engine dynamometer An engine dynamometer shall be used with adequate characteristics to perform the test cycles described in Appendices 1 and 2 to this Annex. The speed measuring system shall have an accuracy of 2 % of reading. The torque measuring system shall have an accuracy of 3 % of reading in the range > 20 % of full scale, and an accuracy of 0,6 % of full scale in the range 20 % of full scale.
Other instruments Measuring instruments for fuel consumption, air consumption, temperature of coolant and lubricant, exhaust gas pressure and intake manifold depression, exhaust gas temperature, air intake temperature, atmospheric pressure, humidity and fuel temperature shall be used, as required. These instruments shall satisfy the requirements given in Table 8: Table 8 Accuracy of measuring instruments
Measuring instrument Accuracy
Fuel consumption Air consumption Temperatures 600 K (327 C) Temperatures >600 K (327 C) Atmospheric pressure Exhaust gas pressure Intake depression Other pressures Relative humidity Absolute humidity
2 % of engine's maximum value 2 % of engine's maximum value 2 K absolute 1 % of reading 0,1 kPa absolute 0,2 kPa absolute 0,05 kPa absolute 0,1 kPa absolute 3 % absolute 5 % of reading

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Exhaust gas flow
For calculation of the emissions in the raw exhaust, it is necessary to know the exhaust gas flow (see Section 4.4 of Appendix 1). For the determination of the exhaust flow either of the following methods may be used: a) direct measurement of the exhaust flow by flow nozzle or equivalent metering system;
b) measurement of the air flow and the fuel flow by suitable metering systems and calculation of the exhaust flow by the following equation: GEXHW = GAIRW + GFUEL (for wet exhaust mass) The accuracy of exhaust flow determination shall be 2,5 % of reading or better.
Diluted exhaust gas flow For calculation of the emissions in the diluted exhaust using a full flow dilution system (mandatory for the ETC), it is necessary to know the diluted exhaust gas flow (see Section 4.3 of Appendix 2). The total mass flow rate of the diluted exhaust (GTOTW) or the total mass of the diluted exhaust gas over the cycle (MTOTW) shall be measured with a PDP or CFV (Annex V, Section 2.3.1). The accuracy shall be 2 % of reading or better, and shall be determined according to the provisions of Annex III, Appendix 5, Section 2.4.

3.4.2.

Diluted exhaust gas (mandatory for ETC, optional for ESC) The exhaust pipe between the engine and the full flow dilution system shall conform to the requirements of Annex V, Section 2.3.1, EP. The gaseous emissions sample probe(s) shall be installed in the dilution tunnel at a point where the dilution air and exhaust gas are well mixed, and in close proximity to the particulates sampling probe. For the ETC, sampling can generally be done in two ways: the pollutants are sampled into a sampling bag over the cycle and measured after completion of the test; the pollutants are sampled continuously and integrated over the cycle; this method is mandatory for HC and NOx.
DETERMINATION OF THE PARTICULATES The determination of the particulates requires a dilution system. Dilution may be accomplished by a partial flow dilution system (ESC only) or a full flow dilution system (mandatory for ETC). The flow capacity of the dilution system shall be large enough to completely eliminate water condensation in the dilution and sampling systems, and maintain the temperature of the diluted exhaust gas at or below 325K (52 C) immediately upstream of the filter holders. Dehumidifying the dilution air before entering the dilution system is permitted, and especially useful if dilution air humidity is high. The temperature of the dilution air shall be 298 K 5 K (25 C 5 C). If the ambient temperature is below 293 K (20 C), dilution air pre-heating above the upper temperature limit of 303K (30 C) is recommended. However, the dilution air temperature must not exceed 325 K (52 C) prior to the introduction of the exhaust in the dilution tunnel. The partial flow dilution system has to be designed to split the exhaust stream into two fractions, the smaller one being diluted with air and subsequently used for particulate measurement. For this it is essential that the dilution ratio be determined very accurately. Different splitting methods can be applied, whereby the type of splitting used dictates to a significant degree the sampling hardware and procedures to be used (Annex V, Section 2.2). The particulate sampling probe shall be installed in close proximity to the gaseous emissions sampling probe, and the installation shall comply with the provisions of Section 3.4.1. To determine the mass of the particulates, a particulate sampling system, particulate sampling filters, a microgram balance, and a temperature and humidity controlled weighing chamber, are required. For particulate sampling, the single filter method shall be applied which uses one pair of filters (see Section 4.1.3) for the whole test cycle. For the ESC, considerable attention must be paid to sampling times and flows during the sampling phase of the test.

1.8.2.

Hydrocarbon response factors The analyser shall be calibrated using propane in air and purified synthetic air, according to Section 1.5. Response factors shall be determined when introducing an analyser into service and after major service intervals. The response factor (Rf) for a particular hydrocarbon species is the ratio of the FID C1 reading to the gas concentration in the cylinder expressed by ppm C1. The concentration of the test gas must be at a level to give a response of approximately 80 % of full scale. The concentration must be known to an accuracy of 2 % in reference to a gravimetric standard expressed in volume. In addition, the gas cylinder must be preconditioned for 24 hours at a temperature of 298 K 5 K (25 C 5 C). The test gases to be used and the recommended relative response factor ranges are as follows: methane and purified synthetic air 1,00 Rf 1,15 propylene and purified synthetic air 0,90 Rf 1,10 toluene and purified synthetic air 0,90 Rf 1,10 These values are relative to the response factor (Rf) of 1,00 for propane and purified synthetic air.

1.8.3.

Oxygen interference check The oxygen interference check shall be determined when introducing an analyser into service and after major service intervals. The response factor is defined and shall be determined as described in Section 1.8.2. The test gas to be used and the recommended relative response factor range are as follows: propane and nitrogen 0,95 Rf 1,05 This value is relative to the response factor (Rf) of 1,00 for propane and purified synthetic air. The FID burner air oxygen concentration must be within 1 mole % of the oxygen concentration of the burner air used in the latest oxygen interference check. If the difference is greater, the oxygen interference must be checked and the analyser adjusted, if necessary.

1.8.4.

Efficiency of the non-methane cutter (NMC, for NG fuelled gas engines only) The NMC is used for the removal of the non-methane hydrocarbons from the sample gas by oxidising all hydrocarbons except methane. Ideally, the conversion for methane is 0 %, and for the other hydrocarbons represented by ethane is 100 %. For the accurate measurement of NMHC, the two efficiencies shall be determined and used for the calculation of the NMHC emission mass flow rate (see Annex III, Appendix 2, Section 4.3).

1.8.4.1.

Methane efficiency Methane calibration gas shall be flown through the FID with and without bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows:

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CEM = 1 concw =concw=o where, concw = HC concentration with CH4 flowing through the NMC HC concentration with CH4 bypassing the NMC

concw/o = 1.8.4.2.

Ethane efficiency Ethane calibration gas shall be flown through the FID with and without bypassing the NMC and the two concentrations recorded. The efficiency shall be determined as follows CEE = 1 concw concw=o

and TT is a constant fraction (split) of the exhaust gas flow. The split ratio is determined from the cross sectional areas of EP and ISP. The dilution air is sucked through DT by the suction blower SB, and the flow rate is measured with FM1 at the inlet to DT. The dilution ratio is calculated from the dilution air flow rate and the split ratio.

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Figure 13 Partial flow dilution system with CO2 or NOx concentration measurement and fractional sampling
Raw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the sampling probe SP and the transfer tube TT. The concentrations of a tracer gas (CO 2 or NOx) are measured in the raw and diluted exhaust gas as well as in the dilution air with the exhaust gas analyser(s) EGA. These signals are transmitted to the flow controller FC2 that controls either the pressure blower PB or the suction blower SB to maintain the desired exhaust split and dilution ratio in DT. The dilution ratio is calculated from the tracer gas concentrations in the raw exhaust gas, the diluted exhaust gas, and the dilution air.
Figure 14 Partial flow dilution system with CO2 concentration measurement, carbon balance and total sampling

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Raw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the sampling probe SP and the transfer tube TT. The CO2 concentrations are measured in the diluted exhaust gas and in the dilution air with the exhaust gas analyser(s) EGA. The CO2 and fuel flow GFUEL signals are transmitted either to the flow controller FC2, or to the flow controller FC3 of the particulate sampling system (see Figure 21). FC2 controls the pressure blower PB, FC3 the sampling pump P (see Figure 21), thereby adjusting the flows into and out of the system so as to maintain the desired exhaust split and dilution ratio in DT. The dilution ratio is calculated from the CO 2 concentrations and GFUEL using the carbon balance assumption.
Figure 15 Partial flow dilution system with single venturi, concentration measurement and fractional sampling
Raw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the sampling probe SP and the transfer tube TT due to the negative pressure created by the venturi VN in DT. The gas flow rate through TT depends on the momentum exchange at the venturi zone, and is therefore affected by the absolute temperature of the gas at the exit of TT. Consequently, the exhaust split for a given tunnel flow rate is not constant, and the dilution ratio at low load is slightly lower than at high load. The tracer gas concentrations (CO2 or NOx) are measured in the raw exhaust gas, the diluted exhaust gas, and the dilution air with the exhaust gas analyser(s) EGA, and the dilution ratio is calculated from the values so measured.

DC Damping chamber (Figure 17)
A damping chamber shall be installed at the exit of the multiple tube unit to minimise the pressure oscillations in the exhaust pipe EP.

VN Venturi (Figure 15)

A venturi is installed in the dilution tunnel DT to create a negative pressure in the region of the exit of the transfer tube TT. The gas flow rate through TT is determined by the momentum exchange at the venturi zone, and is basically proportional to the flow rate of the pressure blower PB leading to a constant dilution ratio. Since the momentum exchange is affected by the temperature at the exit of TT

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and the pressure difference between EP and DT, the actual dilution ratio is slightly lower at low load than at high load.
FC2 Flow controller (Figures 13, 14, 18, 19, optional)
A flow controller may be used to control the flow of the pressure blower PB and/or the suction blower SB. It may be connected to the exhaust, intake air, or fuel flow signals and/or to the CO 2 or NOx differential signals. When using a pressurised air supply (Figure 18), FC2 directly controls the air flow.
FM1 Flow measurement device (Figures 11, 12, 18, 19)
Gas meter or other flow instrumentation to measure the dilution air flow. FM1 is optional if the pressure blower PB is calibrated to measure the flow.
FM2 Flow measurement device (Figure 19)
Gas meter or other flow instrumentation to measure the diluted exhaust gas flow. FM2 is optional if the suction blower SB is calibrated to measure the flow.
PB Pressures blower (Figures 11, 12, 13, 14, 15, 16, 19)
To control the dilution air flow rate, PB may be connected to the flow controllers FC1 or FC2. PB is not required when using a butterfly valve. PB may be used to to measure the dilution air flow, if calibrated.
SB Suction blower (Figures 11, 12, 13, 16, 17, 19)
For fractional sampling systems only. SB may be used to measure the diluted exhaust gas flow, if calibrated.
DAF Dilution air filter (Figures 11 to 19)
It is recommended that the dilution air be filtered and charcoal scrubbed to eliminate background hydrocarbons. At the engine manufacturers request the dilution air shall be sampled according to good engineering practice to determine the background particulate levels, which can then be subtracted from the values measured in the diluted exhaust.

Figure 20 Full flow dilution system
The total amount of raw exhaust gas is mixed in the dilution tunnel DT with the dilution air. The diluted exhaust gas flow rate is measured either with a Positive Displacement Pump PDP or with a Critical Flow Venturi CFV. A heat exchanger HE or electronic flow compensation EFC may be used for proportional particulate sampling and for flow determination. Since particulate mass determination is based on the total diluted exhaust gas flow, the dilution ratio is not required to be calculated.

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Components of Figure 20
The exhaust pipe length from the exit of the engine exhaust manifold, turbocharger outlet or aftertreatment device to the dilution tunnel shall not exceed 10 m. If the exhaust pipe downstream of the engine exhaust manifold, turbocharger outlet or aftertreatment device exceeds 4 m in length, then all tubing in excess of 4 m shall be insulated, except for an in-line smokemeter, if used. The radial thickness of the insulation must be at least 25 mm. The thermal conductivity of the insulating material must have a value no greater than 0,1 W/mK measured at 673 K (400 C). To reduce the thermal inertia of the exhaust pipe a thickness to diameter ratio of 0,015 or less is recommended. The use of flexible sections shall be limited to a length to diameter ratio of 12 or less.
PDP Positive displacement pump
The PDP meters total diluted exhaust flow from the number of the pump revolutions and the pump displacement. The exhaust system backpressure must not be artificially lowered by the PDP or dilution air inlet system. Static exhaust backpressure measured with the PDP system operating shall remain within 1,5 kPa of the static pressure measured without connection to the PDP at identical engine speed and load. The gas mixture temperature immediately ahead of the PDP shall be within 6 K of the average operating temperature observed during the test, when no flow compensation is used. Flow compensation may only be used if the temperature at the inlet to the PDP does not exceed 323K (50 C).
CFV Critical Flow Venturi
CFV measures total diluted exhaust flow by maintaining the flow at choked conditions (critical flow). Static exhaust backpressure measured with the CFV system operating shall remain within 1,5 kPa of the static pressure measured without connection to the CFV at identical engine speed and load. The gas mixture temperature immediately ahead of the CFV shall be within 11 K of the average operating temperature observed during the test, when no flow compensation is used.

may be heated to no greater than 325 K (52 C) wall temperature by direct heating or by dilution air pre-heating, provided the air temperature does not exceed 325 K (52 C) prior to the introduction of the exhaust in the dilution tunnel;

may be insulated.

Particulate sampling system
The particulate sampling system is required for collecting the particulates on the particulate filter. In the case of total sampling partial flow dilution, which consists of passing the entire diluted exhaust sample through the filters, dilution (Section 2.2, Figures 14, 18) and sampling system usually form an integral unit. In the case of fractional sampling partial flow dilution or full flow dilution, which consists of passing through the filters only a portion of the diluted exhaust, the dilution (Section 2.2, Figures 11, 12, 13, 15, 16, 17, 19; Section 2.3, Figure 20) and sampling systems usually form different units.
In this Directive, the double dilution system (Figure 22) of a full flow dilution system is considered as a specific modification of a typical particulate sampling system as shown in Figure 21. The double dilution system includes all important parts of the particulate sampling system, like filter holders and sampling pump.
In order to avoid any impact on the control loops, it is recommended that the sample pump be running throughout the complete test procedure. For the single filter method, a bypass system shall be used for passing the sample through the sampling filters at the desired times. Interference of the switching procedure on the control loops must be minimised.

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Figure 21 Particulate sampling system
A sample of the diluted exhaust gas is taken from the dilution tunnel DT of a partial flow or full flow dilution system through the particulate sampling probe PSP and the particulate transfer tube PTT by means of the sampling pump P. The sample is passed through the filter holder(s) FH that contain the particulate sampling filters. The sample flow rate is controlled by the flow controller FC3. If electronic flow compensation EFC (see Figure 20) is used, the diluted exhaust gas flow is used as command signal for FC3.
Figure 22 Double dilution system (full flow system only)