Directive 2005/55/EC of the European Parliament and of the Council (repealed)Dangos y teitl llawn

Appendix 4 MEASUREMENT AND SAMPLING PROCEDURES

1. INTRODUCTION U.K.

Gaseous components, particulates, and smoke emitted by the engine submitted for testing shall be measured by the methods described in Annex V. The respective sections of Annex V describe the recommended analytical systems for the gaseous emissions (Section 1), the recommended particulate dilution and sampling systems (Section 2), and the recommended opacimeters for smoke measurement (Section 3). U.K.

For the ESC, the gaseous components shall be determined in the raw exhaust gas. Optionally, they may be determined in the diluted exhaust gas, if a full flow dilution system is used for particulate determination. Particulates shall be determined with either a partial flow or a full flow dilution system.

For the ETC, only a full flow dilution system shall be used for determining gaseous and particulate emissions, and is considered the reference system. However, partial flow dilution systems may be approved by the Technical Service, if their equivalency according to Section 6.2 to Annex I is proven, and if a detailed description of the data evaluation and calculation procedures is submitted to the Technical Service.

2. DYNAMOMETER AND TEST CELL EQUIPMENT U.K.

The following equipment shall be used for emission tests of engines on engine dynamometers. U.K.

2.1. Engine dynamometer U.K.

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.

2.2. Other instruments U.K.

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	± 2 % of engine's maximum value
Air consumption	± 2 % of engine's maximum value
Temperatures ≤ 600 K (327 °C)	± 2 K absolute
Temperatures >600 K (327 °C)	± 1 % of reading
Atmospheric pressure	± 0,1 kPa absolute
Exhaust gas pressure	± 0,2 kPa absolute
Intake depression	± 0,05 kPa absolute
Other pressures	± 0,1 kPa absolute
Relative humidity	± 3 % absolute
Absolute humidity	± 5 % of reading

2.3. Exhaust gas flow U.K.

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:

G_EXHW = G_AIRW + G_FUEL (for wet exhaust mass)

The accuracy of exhaust flow determination shall be ± 2,5 % of reading or better.

2.4. Diluted exhaust gas flow U.K.

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 (G_TOTW) or the total mass of the diluted exhaust gas over the cycle (M_TOTW) 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. DETERMINATION OF THE GASEOUS COMPONENTS U.K.

3.1. General analyser specifications U.K.

The analysers shall have a measuring range appropriate for the accuracy required to measure the concentrations of the exhaust gas components (Section 3.1.1). It is recommended that the analysers be operated such that the measured concentration falls between 15 % and 100 % of full scale. U.K.

If read-out systems (computers, data loggers) can provide sufficient accuracy and resolution below 15 % of full scale, measurements below 15 % of full scale are also acceptable. In this case, additional calibrations of at least four non-zero nominally equally spaced points are to be made to ensure the accuracy of the calibration curves according to Annex III, Appendix 5, Section 1.5.5.2.

The electromagnetic compatibility (EMC) of the equipment shall be on a level as to minimise additional errors.

3.1.1. Measurement error U.K.

The total measurement error, including the cross sensitivity to other gases (see Annex III, Appendix 5, Section 1.9), shall not exceed ± 5 % of the reading or ± 3,5 % of full scale, whichever is smaller. For concentrations of less than 100 ppm the measurement error shall not exceed ± 4 ppm.

3.1.2. Repeatability U.K.

The repeatability, defined as 2,5 times the standard deviation of 10 repetitive responses to a given calibration or span gas, has to be not greater than ± 1 % of full scale concentration for each range used above 155 ppm (or ppmC) or ± 2 % of each range used below 155 ppm (or ppmC).

3.1.3. Noise U.K.

The analyser peak-to-peak response to zero and calibration or span gases over any 10 second period shall not exceed 2 % of full scale on all ranges used.

3.1.4. Zero drift U.K.

The zero drift during a one hour period shall be less than 2 % of full scale on the lowest range used. The zero response is defined as the mean response, including noise, to a zero gas during a 30 seconds time interval.

3.1.5. Span drift U.K.

The span drift during a one hour period shall be less than 2 % of full scale on the lowest range used. Span is defined as the difference between the span response and the zero response. The span response is defined as the mean response, including noise, to a span gas during a 30 seconds time interval.

3.2. Gas drying U.K.

The optional gas drying device must have a minimal effect on the concentration of the measured gases. Chemical dryers are not an acceptable method of removing water from the sample.

3.3. Analysers U.K.

Sections 3.3.1 to 3.3.4 describe the measurement principles to be used. A detailed description of the measurement systems is given in Annex V. The gases to be measured shall be analysed with the following instruments. For non-linear analysers, the use of linearising circuits is permitted. U.K.

3.3.1. Carbon monoxide (CO) analysis U.K.

The carbon monoxide analyser shall be of the Non-Dispersive InfraRed (NDIR) absorption type.

3.3.2. Carbon dioxide (CO₂) analysis U.K.

The carbon dioxide analyser shall be of the Non-Dispersive InfraRed (NDIR) absorption type.

3.3.3. Hydrocarbon (HC) analysis U.K.

For diesel and LPG fuelled gas engines, the hydrocarbon analyser shall be of the Heated Flame Ionisation Detector (HFID) type with detector, valves, pipework, etc. heated so as to maintain a gas temperature of 463K ± 10K (190 ± 10 °C). For NG fuelled gas engines, the hydrocarbon analyser may be of the non-heated Flame Ionisation Detector (FID) type depending upon the method used (see Annex V, Section 1.3).

3.3.4. Non-methane hydrocarbon (NMHC) analysis (NG fuelled gas engines only) U.K.

Non-methane hydrocarbons shall be determined by either of the following methods: U.K.

3.3.4.1. Gas chromatographic (GC) method U.K.

Non-methane hydrocarbons shall be determined by subtraction of the methane analysed with a Gas Chromatograph (GC) conditioned at 423 K (150 °C) from the hydrocarbons measured according to Section 3.3.3.

3.3.4.2. Non-methane cutter (NMC) method U.K.

The determination of the non-methane fraction shall be performed with a heated NMC operated in line with an FID as per Section 3.3.3 by subtraction of the methane from the hydrocarbons.

3.3.5. Oxides of nitrogen (NO_x) analysis U.K.

The oxides of nitrogen analyser shall be of the ChemiLuminescent Detector (CLD) or Heated ChemiLuminescent Detector (HCLD) type with a NO₂/NO converter, if measured on a dry basis. If measured on a wet basis, a HCLD with converter maintained above 328 K (55 °C) shall be used, provided the water quench check (see Annex III, Appendix 5, Section 1.9.2.2) is satisfied.

3.4. Sampling of gaseous emissions U.K.

3.4.1. Raw exhaust gas (ESC only) U.K.

The gaseous emissions sampling probes must be fitted at least 0,5 m or 3 times the diameter of the exhaust pipe whichever is the larger-upstream of the exit of the exhaust gas system as far as applicable and sufficiently close to the engine as to ensure an exhaust gas temperature of at least 343 K (70 °C) at the probe.

In the case of a multi-cylinder engine with a branched exhaust manifold, the inlet of the probe shall be located sufficiently far downstream so as to ensure that the sample is representative of the average exhaust emissions from all cylinders. In multi-cylinder engines having distinct groups of manifolds, such as in a ‘Vee’ engine configuration, it is permissible to acquire a sample from each group individually and calculate an average exhaust emission. Other methods which have been shown to correlate with the above methods may be used. For exhaust emission calculation the total exhaust mass flow must be used.

If the engine is equipped with an exhaust aftertreatment system, the exhaust sample shall be taken downstream of the exhaust aftertreatment system.

3.4.2. Diluted exhaust gas (mandatory for ETC, optional for ESC) U.K.

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 NO_x.

4. DETERMINATION OF THE PARTICULATES U.K.

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. U.K.

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.

4.1. Particulate sampling filters U.K.

4.1.1. Filter specification U.K.

Fluorocarbon coated glass fibre filters or fluorocarbon based membrane filters are required. All filter types shall have a 0,3 μm DOP (di-octylphthalate) collection efficiency of at least 95 % at a gas face velocity between 35 and 80 cm/s.

4.1.2. Filter size U.K.

Particulate filters must have a minimum diameter of 47 mm (37 mm stain diameter). Larger diameter filters are acceptable (Section 4.1.5).

4.1.3. Primary and back-up filters U.K.

The diluted exhaust shall be sampled by a pair of filters placed in series (one primary and one back-up filter) during the test sequence. The back-up filter shall be located no more than 100 mm downstream of, and shall not be in contact with the primary filter. The filters may be weighed separately or as a pair with the filters placed stain side to stain side.

4.1.4. Filter face velocity U.K.

A gas face velocity through the filter of 35 to 80 cm/s shall be achieved. The pressure drop increase between the beginning and the end of the test shall be no more than 25 kPa.

4.1.5. Filter loading U.K.

The recommended minimum filter loading shall be 0,5 mg/1 075 mm² stain area. For the most common filter sizes the values are shown in Table 9.

Table 9
Recommended filter loadings
Filter diameter	Recommended stain	Recommended minimum loading
(mm)	(mm)	(mg)
47	37	0,5
70	60	1,3
90	80	2,3
110	100	3,6

4.2. Weighing chamber and analytical balance specifications U.K.

4.2.1. Weighing chamber conditions U.K.

The temperature of the chamber (or room) in which the particulate filters are conditioned and weighed shall be maintained to within 295 K ± 3 K (22 °C ± 3 °C) during all filter conditioning and weighing. The humidity shall be maintained to a dewpoint of 282,5 K ± 3 K (9,5 °C ± 3 °C) and a relative humidity of 45 % ± 8 %.

4.2.2. Reference filter weighing U.K.

The chamber (or room) environment shall be free of any ambient contaminants (such as dust) that would settle on the particulate filters during their stabilisation. Disturbances to weighing room specifications as outlined in Section 4.2.1 will be allowed if the duration of the disturbances does not exceed 30 minutes. The weighing room should meet the required specifications prior to personal entrance into the weighing room. At least two unused reference filters or reference filter pairs shall be weighed within 4 hours of, but preferably at the same time as the sample filter (pair) weighings. They shall be the same size and material as the sample filters.

If the average weight of the reference filters (reference filter pairs) changes between sample filter weighings by more than ± 5 % (± 7,5 % for the filter pair respectively) of the recommended minimum filter loading (Section 4.1.5), then all sample filters shall be discarded and the emissions test repeated.

If the weighing room stability criteria outlined in Section 4.2.1 is not met, but the reference filter (pair) weighings meet the above criteria, the engine manufacturer has the option of accepting the sample filter weights or voiding the tests, fixing the weighing room control system and rerunning the test.

4.2.3. Analytical balance U.K.

The analytical balance used to determine the weights of all filters shall have a precision (standard deviation) of 20 μg and a resolution of 10 μg (1 digit = 10 μg). For filters less than 70 mm diameter, the precision and resolution shall be 2 μg and 1 μg, respectively.

4.3. Additional specifications for particulate measurement U.K.

All parts of the dilution system and the sampling system from the exhaust pipe up to the filter holder, which are in contact with raw and diluted exhaust gas, must be designed to minimise deposition or alteration of the particulates. All parts must be made of electrically conductive materials that do not react with exhaust gas components, and must be electrically grounded to prevent electrostatic effects.

5. DETERMINATION OF SMOKE U.K.

This section provides specifications for the required and optional test equipment to be used for the ELR test. The smoke shall be measured with an opacimeter having an opacity and a light absorption coefficient readout mode. The opacity readout mode shall only be used for calibration and checking of the opacimeter. The smoke values of the test cycle shall be measured in the light absorption coefficient readout mode. U.K.

5.1. General requirements U.K.

The ELR requires the use of a smoke measurement and data processing system which includes three functional units. These units may be integrated into a single component or provided as a system of interconnected components. The three functional units are:

• an opacimeter meeting the specifications of Annex V, Section 3,

• a data processing unit capable of performing the functions described in Annex III, Appendix 1, Section 6,

• a printer and/or electronic storage medium to record and output the required smoke values specified in Annex III, Appendix 1, Section 6.3.

5.2. Specific requirements U.K.

5.2.1. Linearity U.K.

The linearity shall be within ± 2 % opacity.

5.2.2. Zero drift U.K.

The zero drift during a one hour period shall not exceed ± 1 % opacity.

5.2.3. Opacimeter display and range U.K.

For display in opacity, the range shall be 0-100 % opacity, and the readability 0,1 % opacity. For display in light absorption coefficient, the range shall be 0-30 m^-1 light absorption coefficient, and the readability 0,01 m^-1 light absorption coefficient.

5.2.4. Instrument response time U.K.

The physical response time of the opacimeter shall not exceed 0,2 s. The physical response time is the difference between the times when the output of a rapid response receiver reaches 10 and 90 % of the full deviation when the opacity of the gas being measured is changed in less than 0,1 s.

The electrical response time of the opacimeter shall not exceed 0,05 s. The electrical response time is the difference between the times when the opacimeter output reaches 10 and 90 % of the full scale when the light source is interrupted or completely extinguished in less than 0,01 s.

5.2.5. Neutral density filters U.K.

Any neutral density filter used in conjunction with opacimeter calibration, linearity measurements, or setting span shall have its value known to within 1,0 % opacity. The filter's nominal value must be checked for accuracy at least yearly using a reference traceable to a national or international standard.

Neutral density filters are precision devices and can easily be damaged during use. Handling should be minimised and, when required, should be done with care to avoid scratching or soiling of the filter.