{
  "url": "https://openlegislation.uk/eu-directive-2004-26/annex-II",
  "json_url": "https://openlegislation.uk/eu-directive-2004-26/annex-II.json",
  "legislation": "eudr/2004/26",
  "legislation_title": "Directive 2004/26/EC of the European Parliament and of the Council of 21 April 2004 amending Directive 97/68/EC on the approximation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery (Text with EEA relevance)",
  "legislation_url": "https://openlegislation.uk/eu-directive-2004-26",
  "path": "annex/II",
  "kind": "annex",
  "number": "II",
  "heading": null,
  "text": "\"Annex VI\nANALYTICAL AND SAMPLING SYSTEM\n1.\nGASEOUS AND PARTICULATE SAMPLING SYSTEMS\nFigure Number\nDescription\n2\nExhaust gas analysis system for raw exhaust\n3\nExhaust gas analysis system for dilute exhaust\n4\nPartial flow, isokinetic flow, suction blower control, fractional sampling\n5\nPartial flow, isokinetic flow, pressure blower control, fractional sampling\n6\nPartial flow, CO2 or NOx control, fractional sampling\n7\nPartial flow, CO2 or carbon balance, total sampling\n8\nPartial flow, single venturi and concentration measurement, fractional sampling\n9\nPartial flow, twin venturi or orifice and concentration measurement, fractional sampling\n10\nPartial flow, multiple tube splitting and concentration measurement, fractional sampling\n11\nPartial flow, flow control, total sampling\n12\nPartial flow, flow control, fractional sampling\n13\nFull flow, positive displacement pump or critical flow venturi, fractional sampling\n14\nParticulate sampling system\n15\nDilution system for full flow system\n1.1.\nDetermination of the gaseous emissions\nSection 1.1.1 and Figures 2 and 3 contain detailed descriptions of the recommended sampling and analysing systems. Since various configurations can produce equivalent results, exact conformance with these figures is not required. Additional components such as instruments, valves, solenoids, pumps and switches may be used to provide additional information and coordinate the functions of the component systems. Other components which are not needed to maintain the accuracy on some systems, may be excluded if their exclusion is based upon good engineering judgement.\n1.1.1.\nGaseous exhaust components CO, CO2, HC, NOx\nAn analytical system for the determination of the gaseous emissions in the raw or diluted exhaust gas is described based on the use of:\nHFID analyser for the measurement of hydrocarbons,\nNDIR analysers for the measurement of carbon monoxide and carbon dioxide,\nHCLD or equivalent analyser for the measurement of nitrogen oxide.\nFor the raw exhaust gas (Figure 2), the sample for all components may be taken with one sampling probe or with two sampling probes located in close proximity and internally split to the different analysers. Care must be taken that no condensation of exhaust components (including water and sulphuric acid) occurs at any point of the analytical system.\nFor the diluted exhaust gas (Figure 3), the sample for the hydrocarbons shall be taken with another sampling probe than the sample for the other components. Care must be taken that no condensation of exhaust components (including water and sulphuric acid) occurs at any point of the analytical system.\nFigure 2\nFlow diagram of exhaust gas analysis system for CO, NOx and HC\nFigure 3\nFlow diagram of dilute exhaust gas analysis system for CO, CO2, NOx and HC\nDescriptions – Figures 2 and 3\nGeneral statement:\nAll components in the sampling gas path must be maintained at the temperature specified for the respective systems.\nSP1 raw exhaust gas sampling probe (Figure 2 only)\nA stainless steel straight closed and multihole probe is recommended. The inside diameter shall not be greater than the inside diameter of the sampling line. The wall thickness of the probe shall not be greater than 1 mm. There shall be a minimum of three holes in three different radial planes sized to sample approximately the same flow. The probe must extend across at least 80% of the diameter of the exhaust pipe.\nSP2 dilute exhaust gas HC sampling probe (Figure 3 only)\nThe probe shall:\nbe defined as the first 254 mm to 762 mm of the hydrocarbon sampling line (HSL3),\nhave a 5 mm minimum inside diameter,\nbe installed in the dilution tunnel DT (section 1.2.1.2) at a point where the dilution air and exhaust gas are well mixed (i.e. approximately 10 tunnel diameters downstream of the point where the exhaust enters the dilution tunnel),\nbe sufficiently distant (radially) from other probes and the tunnel wall so as to be free from the influence of any wakes or eddies,\nbe heated so as to increase the gas stream temperature to 463 K (190oC) ± 10 K at the exit of the probe.\nSP3 dilute exhaust gas CO, CO2, NOx sampling probe (Figure 3 only)\nThe probe shall:\nbe in the same plane as SP2,\nbe sufficiently distant (radially) from other probes and the tunnel wall so as to be free from the influence of any wakes or eddies,\nbe heated and insulated over its entire length to a minimum temperature of 328 K (55oC) to prevent water condensation.\nHSL1 heated sampling line\nThe sampling line provides gas sampling from a single probe to the split point(s) and the HC analyser.\nThe sampling line shall:\nhave a 5 mm minimum and a 13,5 mm maximum inside diameter,\nbe made of stainless steel or PTFE,\nmaintain a wall temperature of 463 (190oC) ± 10 K as measured at every separately controlled heated section, if the temperature of the exhaust gas at the sampling probe is equal or below 463 K (190oC),\nmaintain a wall temperature greater than 453 K (180oC) if the temperature of the exhaust gas at the sampling probe is above 463 K (190oC),\nmaintain a gas temperature of 463 K (190oC) ± 10 K immediately before the heated filter (F2) and the HFID.\nHSL2 heated NOx sampling line\nThe sampling line shall:\nmaintain a wall temperature of 328 to 473 K (55 to 200oC) up to the converter when using a cooling bath, and up to the analyser when a cooling bath is not used,\nbe made of stainless steel or PTFE.\nSince the sampling line need only be heated to prevent condensation of water and sulphuric acid, the samplingline temperature will depend on the sulphur content of the fuel.\nSL sampling line for CO (CO2)\nThe line shall be made of PTFE or stainless steel. It may be heated or unheated.\nBK background bag (optional; Figure 3 only)\nFor the measurement of the background concentrations.\nBG sample bag (optional; Figure 3 CO and CO2 only)\nFor the measurement of the sample concentrations.\nF1 heated pre-filter (optional)\nThe temperature shall be the same as HSL1.\nF2 heated filter\nThe filter shall extract any solid particles from the gas sample prior to the analyser. The temperature shall be the same as HSL1. The filter shall be changed as needed.\nP heated sampling pump\nThe pump shall be heated to the temperature of HSL1.\nHC\nHeated flame ionization detector (HFID) for the determination of the hydrocarbons. The temperature shall be kept at 453 to 473 K (180 to 200oC).\nCO, CO2\nNDIR analysers for the determination of carbon monoxide and carbon dioxide.\nNO2\n(H)CLD analyser for the determination of the oxides of nitrogen. If a HCLD is used it shall be kept at a temperature of 328 to 473 K (55 to 200oC).\nC converter\nA converter shall be used for the catalytic reduction of NO2 to NO prior to analysis in the CLD or HCLD.\nB cooling bath\nTo cool and condense water from the exhaust sample. The bath shall be maintained at a temperature of 273 to 277 K (0 to 4oC) by ice or refrigeration. It is optional if the analyser is free from water vapour interference as determined in Annex III, Appendix 2, sections 1.9.1 and 1.9.2.\nChemical dryers are not allowed for removing water from the sample.\nT1, T2, T3 temperature sensor\nTo monitor the temperature of the gas stream.\nT4 temperature sensor Temperature of the NO2-NO converter.\nT5 temperature sensor\nTo monitor the temperature of the cooling bath.\nG1, G2, G3 pressure gauge\nTo measure the pressure in the sampling lines.\nR1, R2 pressure regulator\nTo control the pressure of the air and the fuel, respectively, for the HFID.\nR3, R4, R5 pressure regulator\nTo control the pressure in the sampling lines and the flow to the analysers.\nFL1, FL2, FL3 flow meter\nTo monitor the sample bypass flow.\nFL4 to FL7 flow meter (optional)\nTo monitor the flow rate through the analysers.\nV1 to V6 selector valve\nSuitable valving for selecting sample, span gas or zero gas flow to the analyser.\nV7, V8 solenoid valve\nTo bypass the NO2-NO converter.\nV9 needle valve\nTo balance the flow through the NO2-NO converter and the bypass.\nV10, V11 needle valve\nTo regulate the flows to the analysers.\nV12, V13 toggle valve\nTo drain the condensate from the bath B.\nV14 selector valve\nSelecting the sample or background bag.\n1.2.\nDetermination of the particulates\nSections 1.2.1 and 1.2.2 and Figures 4 to 15 contain detailed descriptions of the recommended dilution and sampling systems. Since various configurations can produce equivalent results, exact conformance with these figures is not required. Additional components such as instruments, valve, solenoids, pumps and switches may be used to provide additional information and coordinate the functions of the component systems. Other components which are not needed to maintain the accuracy on some systems, may be excluded if their exclusion is based on good engineering judgement.\n1.2.1.\nDilution system\n1.2.1.1.\nPartial flow dilution system (Figures 4 to 12)\nA dilution system is described based on the dilution of a part of the exhaust stream. Splitting of the exhaust stream and the following dilution process may be done by different dilution system types. For subsequent collection of the particulates, the entire dilute exhaust gas or only a portion of the dilute exhaust gas may be passed to the particulate sampling system (section 1.2.2, Figure 14). The first method is referred to as total sampling type, the second method as fractional sampling type.\nThe calculation of the dilution ratio depends on the type of system used.\nThe following types are recommended:\nisokinetic systems (Figures 4 and 5)\nWith these systems, the flow into the transfer tube is matched to the bulk exhaust flow in terms of gas velocity and/or pressure, thus requiring an undisturbed and uniform exhaust flow at the sampling probe. This is usually achieved by using a resonator and a straight approach tube upstream of the sampling point. The split ratio is then calculated from easily measurable values like tube diameters. It should be noted that isokinesis is only used for matching the flow conditions and not for matching the size distribution. The latter is typically not necessary, as the particles are sufficiently small as to follow the fluid streamlines,\nflow controlled systems with concentration measurement (Figures 6 to 10)\nWith these systems, a sample is taken from the bulk exhaust stream by adjusting the dilution air flow and the total dilution exhaust flow. The dilution ratio is determined from the concentrations of tracer gases, such as CO2 or NOx, naturally occurring in the engine exhaust. The concentrations in the dilution exhaust gas and in the dilution air are measured, whereas the concentration in the raw exhaust gas can be either measured directly or determined from fuel flow and the carbon balance equation, if the fuel composition is known. The systems may be controlled by the calculated dilution ratio (Figures 6 and 7) or by the flow into the transfer tube (Figures 8, 9 and 10),\nflow controlled systems with flow measurement (Figures 11 and 12)\nWith these systems, a sample is taken from the bulk exhaust stream by setting the dilution air flow and the total dilution exhaust flow. The dilution ratio is determined from the difference of the two flow rates. Accurate calibration of the flow meters relative to one another is required, since the relative magnitude of the two flow rates can lead to significant errors at higher dilution ratios. Flow control is very straightforward by keeping the dilute exhaust flow rate constant and varying the dilution air flow rate, if needed.\nIn order to realise the advantages of the partial flow dilution systems, attention must be paid to avoiding the potential problems of loss of particulates in the transfer tube, ensuring that a representative sample is taken from the engine exhaust, and determination of the split ratio.\nThe systems described pay attention to these critical areas.\nFigure 4\nPartial flow dilution system with isokinetic probe and fractional sampling (SB control)\nRaw exhaust gas is transferred from the exhaust pipe to EP to the dilution tunnel DT through the transfer tube TT by the isokinetic sampling probe ISP. The differential pressure of the exhaust gas between exhaust pipe and inlet to the probe is measured with the pressure transducer DPT. This signal is transmitted to the flow controller FC1 that controls the suction blower SB to maintain a differential pressure of zero at the tip of the probe. Under these conditions, exhaust gas velocities in EP and ISP are identical, and the flow through ISP 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 flow rate is measured with the flow measurement device FM1. The dilution ratio is calculated from the dilution air flow rate and the split ratio.\nFigure 5\nPartial flow dilution system with isokinetic probe and fractional sampling (PB control)\nRaw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the transfer tube TT by the isokinetic sampling probe ISP. The differential pressure of the exhaust gas between exhaust pipe and inlet to the probe is measured with the pressure transducer DPT. This signal is transmitted to the flow controller FC1 that controls the pressure blower PB to maintain a differential pressure of zero at the tip of the probe. This is done by taking a small fraction of the dilution air whose flow rate has already been measured with the flow measurement device FM1, and feeding it to TT by means of a pneumatic orifice. Under these conditions, exhaust gas velocities in EP and ISP are identical, and the flow through ISP 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.\nFigure 6\nPartial flow dilution system with CO2 or NOx concentration measurement and fractional sampling\nRaw 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 (CO2 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.\nFigure 7\nPartial flow dilution system with CO2 concentration measurement, carbon balance and total sampling\nRaw 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 (Figure 14). FC2 controls the pressure blower PB, while FC3 controls the particulate sampling system (Figure 14), 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 CO2 concentrations and GFUEL using the carbon balance assumption.\nFigure 8\nPartial flow dilution system with single venturi, concentration measurement and fractional sampling\nRaw 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.\nFigure 9\nPartial flow dilution system twin venturi or twin orifice, concentration measurement and fractional sampling\nRaw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the sampling probe SP and the transfer tube TT by a flow divider that contains a set of orifices or venturis. The first one (FD1) is located in EP, the second one (FD2) in TT. Additionally, two pressure control valves (PCV1 and PCV2) are necessary to maintain a constant exhaust split by controlling the backpressure in EP and the pressure in DT. PC VI is located downstream of SP in EP, PCV2 between the pressure blower PB and DT. 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. They are necessary for checking the exhaust split, and may be used to adjust PCV1 and PCV2 for precise split control. The dilution ratio is calculated from the tracer gas concentrations.\nFigure 10\nPartial flow dilution system with multiple tube splitting, concentration measurement and fractional sampling\nRaw exhaust gas is transferred from the exhaust pipe EP to the dilution tunnel DT through the transfer tube TT by the flow divider FD3 that consists of a number of tubes of the same dimensions (same diameter, length and bed radius) installed in EP. The exhaust gas through one of these tubes is lead to DT, and the exhaust gas through the rest of the tubes is passed through the damping chamber DC. Thus, the exhaust split is determined by the total number of tubes. A constant split control requires a differential pressure of zero between DC and the outlet of TT, which is measured with the differential pressure transducer DPT. A differential pressure of zero is achieved by injecting fresh air into DT at the outlet of TT. 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. They are necessary for checking the exhaust split and may be used to control the injection air flow rate for precise split control. The dilution ratio is calculated from the tracer gas concentrations.\nFigure 11\nPartial flow dilution system with flow control and total sampling\nRaw 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 total flow through the tunnel is adjusted with the flow controller FC3 and the sampling pump P of the particulate sampling system (Figure 16).\nThe dilution air flow is controlled by the flow controller FC2, which may use GEXH, GAIR or GFUEL as command signals, for the desired exhaust split. The sample flow into DT is the difference of the total flow and the dilution air flow. The dilution air flow rate is measured with flow measurement device FM1, the total flow rate with the flow measurement device FM3 of the particulate sampling system (Figure 14). The dilution ratio is calculated from these two flow rates.\nFigure 12\nPartial flow dilution system with flow control and fractional sampling\nRaw 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 exhaust split and the flow into DT is controlled by the flow controller FC2 that adjusts the flows (or speeds) of the pressure blower PB and the suction blower SB, accordingly. This is possible since the sample taken with the particulate sampling system is returned into DT. GEXH, GAIR or GFUEL may be used as command signals for FC2. The dilution air flow rate is measured with the flow measurement device FM1, the total flow with the flow measurement device FM2. The dilution ratio is calculated from these two flow rates.\nDescription - Figures 4 to 12\nEP exhaust pipe\nThe exhaust pipe may be insulated. 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. Bends will be minimised to reduce inertial deposition. If the system includes a test bed silencer, the silencer may also be insulated.\nFor an isokinetic system, the exhaust pipe must be free of elbows, bends and sudden diameter changes for at least six pipe diameters upstream and three pipe diameters downstream of the tip of the probe. The gas velocity at the sampling zone must be higher than 10 m/s except at idle mode. Pressure oscillations of the exhaust gas must not exceed ± 500 Pa on the average. Any steps to reduce pressure oscillations beyond using a chassis-type exhaust system (including silencer and after-treatment device) must not alter engine performance nor cause the deposition of particulates.\nFor systems without isokinetic probes, it is recommended to have a straight pipe of six pipe diameters upstream and three pipe diameters downstream of the tip of the probe.\nSP sampling probe (Figures 6 to 12)\nThe minimum inside diameter shall be 4 mm. The minimum diameter ratio between exhaust pipe and probe shall be four. The probe shall be an open tube facing upstream on the exhaust pipe centre-line, or a multiple hole probe as described under SP1 in section 1.1.1.\nISP isokinetic sampling probe (Figures 4 and 5)\nThe isokinetic sampling probe must be installed facing upstream on the exhaust pipe centre-line where the flow conditions in section EP are met, and designed to provide a proportional sample of the raw exhaust gas. The minimum inside diameter shall be 12 mm.\nA control system is necessary for isokinetic exhaust splitting by maintaining a differential pressure of zero between EP and ISP. Under these conditions exhaust gas velocities in EP and ISP are identical and the mass flow through ISP is a constant fraction of the exhaust gas flow. The ISP has to be connected to a differential pressure transducer. The control to provide a differential pressure of zero between EP and ISP is done with blower speed or flow controller.\nFD1, FD2 flow divider (Figure 9)\nA set of venturis or orifices is installed in the exhaust pipe EP and in the transfer tube TT, respectively, to provide a proportional sample of the raw exhaust gas. A control system consisting of two pressure control valves PCV1 and PCV2 is necessary for proportional splitting by controlling the pressures in EP and DT.\nFD3 flow divider (Figure 10)\nA set of tubes (multiple tube unit) is installed in the exhaust pipe EP to provide a proportional sample of the raw exhaust gas. One of the tubes feeds exhaust gas to the dilution tunnel DT, whereas the other tubes exit exhaust gas to a damping chamber DC. The tubes must have the same dimensions (same diameter, length, bend radius), so that the exhaust split depends on the total number of tubes. A control system is necessary for proportional splitting by maintaining a differential pressure of zero between the exit of the multiple tube unit into DC and the exit of TT. Under these conditions, exhaust gas velocities in EP and FD3 are proportional, and the flow TT is a constant fraction of the exhaust gas flow. The two points have to be connected to a differential pressure transducer DPT. The control to provide a differential pressure of zero is done with the flow controller FC1.\nEGA exhaust gas analyser (Figures 6 to 10)\nCO2 or NOx analysers may be used (with carbon balance method CO2 only). The analysers shall be calibrated like the analysers for the measurement of the gaseous emissions. One or several analysers may be used to determine the concentration differences.\nThe accuracy of the measuring systems has to be such that the accuracy of GEDFW,i is within ± 4%.\nTT transfer tube (Figures 4 to 12)\nThe particulate sample transfer tube shall be:\nas short as possible, but not more than 5 m in length,\nequal to or greater than the probe diameter, but not more than 25 mm in diameter,\nexiting on the centre-line of the dilution tunnel and pointing down-stream.\nIf the tube is 1 metre or less in length, it is to be insulated with material with a maximum thermal conductivity of 0,05 W/(m · K) with a radial insulation thickness corresponding to the diameter of the probe. If the tube is longer than 1 metre, it must be insulated and heated to a minimum wall temperature of 523 K (250oC).\nAlternatively, the transfer tube wall temperatures required may be determined through standard heat transfer calculations.\nDPT differential pressure transducer (Figures 4, 5 and 10)\nThe differential pressure transducer shall have a range of ± 500 Pa or less.\nFC1 flow controller (Figures 4, 5 and 10)\nFor the isokinetic systems (Figures 4 and 5) a flow controller is necessary to maintain a differential pressure of zero between EP and ISP. The adjustment can be done by:\n(a) controlling the speed or flow of the suction blower (SB) and keeping the speed of the pressure blower (PB) constant during each mode (Figure 4);\nor\n(b) adjusting the suction blower (SB) to a constant mass flow of the diluted exhaust and controlling the flow of the pressure blower PB, and therefore the exhaust sample flow in a region at the end of the transfer tube (TT) (Figure 5).\nIn the case of a pressure controlled system the remaining error in the control loop must not exceed ± 3 Pa. The pressure oscillations in the dilution tunnel must not exceed ± 250 Pa on average.\nFor a multi-tube system (Figure 10) a flow controller is necessary for proportional exhaust splitting to maintain a differential pressure of zero between the outlet of the multi-tube unit and the exit of TT. The adjustment can be done by controlling the injection air flow rate into DT at the exit of TT.\nPCV1, PCV2 pressure control valve (Figure 9)\nTwo pressure control valves are necessary for the twin venturi/twin orifice system for proportional flow splitting by controlling the backpressure of EP and the pressure in DT. The valves shall be located downstream of SP in EP and between PB and DT.\nDC damping chamber (Figure 10)\nA damping chamber shall be installed at the exit of the multiple tube unit to minimize the pressure oscillations in the exhaust pipe EP.\nVN venturi (Figure 8)\nA 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 and the pressure difference between EP and DT, the actual dilution ratio is slightly lower at low load than at high load.\nFC2 flow controller (Figures 6, 7, 11 and 12; optional)\nA 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 flow or fuel flow signal and/or to the CO2 or NOx differential signal.\nWhen using a pressurized air supply (Figure 11) FC2 directly controls the air flow.\nFM1 flow measurement device (Figures 6, 7, 11 and 12)\nGas meter or other flow instrumentation to measure the dilution air flow. FM1 is optional if PB is calibrated to measure the flow.\nFM2 flow measurement device (Figure 12)\nGas 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.\nPB pressure blower (Figures 4, 5, 6, 7, 8, 9 and 12)\nTo 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 measure the dilution air flow, if calibrated.\nSB suction blower (Figures 4, 5, 6, 9, 10 and 12)\nFor fractional sampling systems only. SB may be used to measure the dilute exhaust gas flow, if calibrated.\nDAF dilution air filter (Figures 4 to 12)\nIt is recommended that the dilution air be filtered and charcoal scrubbed to eliminate background hydrocarbons. The dilution air shall have a temperature of 298 K (25oC) ± 5 K.\nAt the manufacturer's 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.\nPSP particulate sampling probe (Figures 4, 5, 6, 8, 9, 10 and 12)\nThe probe is the leading section of PTT and\nshall be installed facing upstream at a point where the dilution air and exhaust gas are well mixed, i.e. on the dilution tunnel DT centre-line of the dilution systems approximately 10 tunnel diameters downstream of the point where the exhaust enters the dilution tunnel,\nshall be 12 mm in minimum inside diameter,\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel,\nmay be insulated.\nDT dilution tunnel (Figures 4 to 12)\nThe dilution tunnel:\nshall be of a sufficient length to cause complete mixing of the exhaust and dilution air under turbulent flow conditions,\nshall be constructed of stainless steel with:\na thickness to diameter ratio of 0,025 or less for dilution tunnels of greater than 75 mm inside diameter,\na nominal wall thickness of not less than 1,5 mm for dilution tunnels of equal to or less than 75 mm inside diameter,\nshall be at least 75 mm in diameter for the fractional sampling type,\nis recommended to be at least 25 mm in diameter for the total sampling type.\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel.\nmay be insulated.\nThe engine exhaust shall be thoroughly mixed with the dilution air. For fractional sampling systems, the mixing quality shall be checked after introduction into service by means of a CO2 profile of the tunnel with the engine running (at least four equally spaced measuring points). If necessary, a mixing orifice may be used.\nNOTE: If the ambient temperature in the vicinity of the dilution tunnel (DT) is below 293 K (20oC), precautions should be taken to avoid particle losses onto the cool walls of the dilution tunnel. Therefore, heating and/or insulating the tunnel within the limits given above is recommended.\nAt high engine loads, the tunnel may be cooled by a non-aggressive means such as a circulating fan, as long as the temperature of the cooling medium is not below 293 K (20oC).\nHE heat exchanger (Figures 9 and 10)\nThe heat exchanger shall be of sufficient capacity to maintain the temperature at the inlet to the suction blower SB within ± 11 K of the average operating temperature observed during the test.\n1.2.1.2.\nFull flow dilution system (Figure 13)\nA dilution system is described based upon the dilution of the total exhaust using the constant volume sampling (CVS) concept. The total volume of the mixture of exhaust and dilution air must be measured. Either a PDP or a CFV or a SSV system may be used.\nFor subsequent collection of the particulates, a sample of the dilute exhaust gas is passed to the particulate sampling system (section 1.2.2, Figures 14 and 15). If this is done directly, it is referred to as single dilution. If the sample is diluted once more in the secondary dilution tunnel, it is referred to as double dilution. This is useful, if the filter face temperature requirement cannot be met with single dilution. Although partly a dilution system, the double dilution system is described as a modification of a particulate sampling system in section 1.2.2, (Figure 15), since it shares most of the parts with a typical particulate sampling system.\nThe gaseous emissions may also be determined in the dilution tunnel of a full flow dilution system. Therefore, the sampling probes for the gaseous components are shown in Figure 13 but do not appear in the description list. The respective requirements are described in section 1.1.1.\nDescriptions (Figure 13)\nEP exhaust pipe\nThe exhaust pipe length from the exit of the engine exhaust manifold, turbocharger outlet or after-treatment device to the dilution tunnel is required to be not more than 10 m. If the system exceeds 4 m in length, then all tubing in excess of 4 m shall be insulated, except for an in-line smoke-meter, 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/(m · K) measured at 673 K (400oC). 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.\nFigure 13\nFull flow dilution system\nThe 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 or with a sub-sonic venturi SSV. A heat exchanger FIE 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.\nPDP positive displacement pump\nThe PDP meters total diluted exhaust flow from the number of the pump revolutions and the pump displacement. The exhaust system back pressure must not be artificially lowered by the PDP or dilution air inlet system. Static exhaust back pressure measured with the CVS system operating shall remain within ± 1,5 kPa of the static pressure measured without connection to the CVS at identical engine speed and load.\nThe 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.\nFlow compensation can only be used if the temperature at the inlet of the PDP does not exceed 50oC (323 K).\nCFV critical flow venturi\nCFV 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.\nSSV sub-sonic venturi\nSSV measures total diluted exhaust flow as a function of inlet pressure, inlet temperature, pressure drop between the SSV inlet and throat. Static exhaust backpressure measured with the SSV system operating shall remain within ± 1,5 kPa of the static pressure measured without connection to the SSV at identical engine speed and load. The gas mixture temperature immediately ahead of the SSV shall be within ± 11 K of the average operating temperature observed during the test, when no flow compensation is used.\nHE heat exchanger (optional if EFC is used)\nThe heat exchanger shall be of sufficient capacity to maintain the temperature within the limits required above.\nEFC electronic flow compensation (optional if HE is used)\nIf the temperature at the inlet to either the PDP or CFV or SSV is not kept within the limits stated above, a flow compensation system is required for continuous measurement of the flow rate and control of the proportional sampling in the particulate system. To that purpose, the continuously measured flow rate signals are used to correct the sample flow rate through the particulate filters of the particulate sampling system (Figures 14 and 15), accordingly.\nDT dilution tunnel\nThe dilution tunnel:\nshall be small enough in diameter to cause turbulent flow (Reynolds number greater than 4000) of sufficient length to cause complete mixing of the exhaust and dilution air. A mixing orifice may be used,\nshall be at least 75 mm in diameter,\nmay be insulated.\nThe engine exhaust shall be directed downstream at the point where it is introduced into the dilution tunnel, and thoroughly mixed.\nWhen using single dilution, a sample from the dilution tunnel is transferred to the particulate sampling system (section 1.2.2, Figure 14). The flow capacity of the PDP or CFV or SSV must be sufficient to maintain the diluted exhaust at a temperature of less than or equal to 325 K (52oC) immediately before the primary particulate filter.\nWhen using double dilution, a sample from the dilution tunnel is transferred to the secondary dilution tunnel where it is further diluted, and then passed through the sampling filters (section 1.2.2, Figure 15). The flow capacity of the PDP or CFV or SSV must be sufficient to maintain the diluted exhaust stream in the DT at a temperature of less than or equal to 464 K (191oC) at the sampling zone. The secondary dilution system must provide sufficient secondary dilution air to maintain the doubly-diluted exhaust stream at a temperature of less than or equal to 325 K (52oC) immediately before the primary particulate filter.\nDAF dilution air filter\nIt is recommended that the dilution air be filtered and charcoal scrubbed to eliminate background hydrocarbons. The dilution air shall have a temperature of 298 K (25oC) ± 5 K. At the manufacturer's 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.\nPSP particulate sampling probe\nThe probe is the leading section of PTT and\nshall be installed facing upstream at a point where the dilution air and exhaust gas are well mixed, i.e. on the dilution tunnel DT centre-line of the dilution systems approximately 10 tunnel diameters downstream of the point where the exhaust enters the dilution tunnel,\nshall be 12 mm in minimum inside diameter,\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel,\nmay be insulated.\n1.2.2.\nParticulate sampling system (Figures 14 and 15)\nThe 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 dilute exhaust sample through the filters, dilution (section 1.2.1.1, Figures 7 and 11) 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 1.2.1.1, Figures 4, 5, 6, 8, 9, 10 and 12 and section 1.2.1.2, Figure 13) and sampling systems usually form different units.\nIn this Directive, the double dilution system DDS (Figure 15) of a full flow dilution system is considered as a specific modification of a typical particulate sampling system as shown in Figure 14. The double dilution system includes all important parts of the particulate sampling system, like filter holders and sampling pump, and additionally some dilution features, like a dilution air supply and a secondary dilution tunnel.\nIn 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 minimized.\nDescriptions - Figures 14 and 15\nPSP particulate sampling probe (Figures 14 and 15)\nThe particulate sampling probe shown in the figures is the leading section of the particulate transfer tube PTT. The probe:\nshall be installed facing upstream at a point where the dilution air and exhaust gas are well mixed, i.e. on the dilution tunnel DT centre-line of the dilution systems (section 1.2.1), approximately 10 tunnel diameters downstream of the point where the exhaust enters the dilution tunnel),\nshall be 12 mm in minimum inside diameter,\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air pre-heating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel,\nmay be insulated.\nFigure 14\nParticulate sampling system\nA 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 holders(s) FH that contain the particulate sampling filters. The sample flow rate is controlled by the flow controller FC3. If electronic flow compensation EFC (Figure 13) is used, the diluted exhaust gas flow is used as command signal for FC3.\nFigure 15\nDilution system (full flow system only)\nA sample of the diluted exhaust gas is transferred from the dilution tunnel DT of a full flow dilution system through the particulate sampling probe PSP and the particulate transfer tube PTT to the secondary dilution tunnel SDT, where it is diluted once more. The sample is then passed through the filter holder(s) FH that contain the particulate sampling filters. The dilution air flow rate is usually constant whereas the sample flow rate is controlled by the flow controller FC3. If electronic flow compensation EFC (Figure 13) is used, the total diluted exhaust gas flow is used as command signal for FC3.\nPTT particulate transfer tube (Figures 14 and 15)\nThe particulate transfer tube must not exceed 1 020 mm in length, and must be minimised in length whenever possible.\nThe dimensions are valid for:\nthe partial flow dilution fractional sampling type and the full flow single dilution system from the probe tip to the filter holder,\nthe partial flow dilution total sampling type from the end of the dilution tunnel to the filter holder,\nthe full flow double dilution system from the probe tip to the secondary dilution tunnel.\nThe transfer tube:\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel,\nmay be insulated.\nSDT secondary dilution tunnel (Figure 15)\nThe secondary dilution tunnel should have a minimum diameter of 75 mm and should be sufficient length so as to provide a residence time of at least 0,25 seconds for the doubly-diluted sample. The primary filter holder, FH, shall be located within 300 mm of the exit of the SDT. The secondary dilution tunnel:\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC) prior to the introduction of the exhaust in the dilution tunnel,\nmay be insulated.\nFH filter holder(s) (Figures 14 and 15)\nFor primary and back-up filters one filter housing or separate filter housings may be used. The requirements of Annex III, Appendix 1, section 1.5.1.3 have to be met.\nThe filter holder(s):\nmay be heated to no greater than 325 K (52oC) wall temperature by direct heating or by dilution air preheating, provided the air temperature does not exceed 325 K (52oC),\nmay be insulated.\nP sampling pump (Figures 14 and 15)\nThe particulate sampling pump shall be located sufficiently distant from the tunnel so that the inlet gas temperature is maintained constant (± 3 K), if flow correction by FC3 is not used.\nDP dilution air pump (Figure 15) (full flow double dilution only)\nThe dilution air pump shall be located so that the secondary dilution air is supplied at a temperature of 298 K (25oC) ± 5 K.\nFC3 flow controller (Figures 14 and 15)\nA flow controller shall be used to compensate the particulate sample flow rate for temperature and backpressure variations in the sample path, if no other means are available. The flow controller is required if electronic flow compensation EFC (Figure 13) is used.\nFM3 flow measurement device (Figures 14 and 15) (particulate sample flow)\nThe gas meter or flow instrumentation shall be located sufficiently distant from the sample pump so that the inlet gas temperature remains constant (± 3 K), if flow correction by FC3 is not used.\nFM4 flow measurement device (Figure 15) (dilution air, full flow double dilution only)\nThe gas meter or flow instrumentation shall be located so that the inlet gas temperature remains at 298 K (25 oC) ± 5K.\nBV ball valve (optional)\nThe ball valve shall have a diameter not less than the inside diameter of the sampling tube and a switching time of less than 0,5 seconds.\nNOTE: If the ambient temperature in the vicinity of PSP, PTT, SDT, and FH is below 239 K (20oC), precautions should be taken to avoid particle losses onto the cool wall of these parts. Therefore, heating and/or insulating these parts within the limits given in the respective descriptions is recommended. It is also recommended that the filter face temperature during sampling be not below 293 K (20oC).\nAt high engine loads, the above parts may be cooled by a non-aggressive means such as a circulating fan, as long as the temperature of the cooling medium is not below 293 K (20oC).",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "Figures 4 to 12 show many types of partial flow dilution systems, which normally can be used for the steady-state test (NRSC). But, because of very severe constraints of the transient tests, only those partial flow dilution systems (Figures 4 to 12) able to fulfill all the requirements quoted in the section \"Partial flow dilution system specifications\" of Annex III, Appendix 1, Section 2.4, are accepted for the transient test (NRTC)."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudr/2004/26/annex/II",
    "retrieved_at": "2026-11-01T15:22:49.839825+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}