6.4 - Direct Measurement and Monitoring method
22.214.171.124 The following Direct Measurement and Monitoring procedure may be applied for onboard verification at renewal, annual and intermediate surveys.
126.96.36.199 Due attention is to be given to the safety implications related to the handling and proximity of exhaust gases, the measurement equipment and the storage and use of cylindered pure and calibration gases. Sampling positions and access staging shall be such that this monitoring may be performed safely and will not interfere with the engine.
6.4.2 Emission species measurement
188.8.131.52 Onboard NOx monitoring includes, as an absolute minimum, the measurement of gaseous emission concentrations of NOx (as NO + NO2).
184.108.40.206 If exhaust gas mass flow is to be determined in accordance with the carbon balance method in accordance with appendix 6 of this Code, then CO2 shall also be measured. Additionally CO, HC and O2 may be measured.
6.4.3 Engine performance measurements
220.127.116.11 Table 7 lists the engine performance parameters that shall be measured, or calculated, and recorded at each mode point during onboard NOx monitoring.
Engine parameters to be measured and recorded
|Engine speed |
|Charge air pressure at receiver|
|Brake power (as specified below)|
|Auxiliary power (if relevant)|
|Charge air temperature at receiver (if applicable)|
|Charge air cooler, coolant inlet temperature (if applicable)|
|Charge air cooler, coolant outlet temperature (if applicable) |
|Seawater temperature (if applicable)|
|Fuel oil flow (as specified below)|
18.104.22.168 Other engine settings necessary to define engine-operating conditions, e.g., waste-gate, charge air bypass, turbocharger status, shall be determined and recorded.
22.214.171.124 The settings and operating conditions of any NOx reducing devices shall be determined and recorded.
126.96.36.199 If it is difficult to measure power directly, uncorrected brake power may be estimated by any other means as approved by the Administration. Possible methods to determine brake power include, but are not limited to:
- indirect measurement in accordance with 6.3.3; or
- by estimation from nomographs.
188.8.131.52 The fuel oil flow (actual consumption rate) shall be determined by:
- direct measurement; or
- test-bed data in accordance with 184.108.40.206
6.4.4 Ambient condition measurements
220.127.116.11 Table 8 lists the ambient condition parameters that shall be measured, or calculated, and recorded at each mode point during onboard NOx monitoring.
Ambient condition parameters to be measured and recorded
|Ha||absolute humidity (mass of engine intake air water content related to mass of dry air)|
|pb||total barometric pressure (in ISO 3046-1, 1995: px=Px=site ambient total pressure) |
|Ta||temperature at air inlet (in ISO 3046-1, 1995: Tx=TTx=site ambient thermodynamic air temperature)|
6.4.5 Engine performance and ambient condition monitoring equipment
18.104.22.168 The engine performance and ambient condition monitoring equipment shall be installed and maintained in accordance with manufacturers’ recommendations such that requirements of section 1.3 and tables 3 and 4 of appendix 4 of this Code are met in respect of the permissible deviations.
6.4.6 Test cycles
22.214.171.124 Engine operation on board under a specified test cycle may not always be possible, but the test procedure, as approved by the Administration, shall be as close as possible to the procedure defined in 3.2. Therefore, values measured in this case may not be directly comparable with test-bed results because measured values are very much dependant on the test cycle.
126.96.36.199 In the case of the E3 test cycle, if the actual propeller curve differs from the E3 curve, the load point used shall be set using the engine speed, or the corresponding mean effective pressure (MEP) or mean indicated pressure (MIP), given for the relevant mode of that cycle.
188.8.131.52 Where the number of measuring points on board is different from those on the test bed, the number of measurement points and the associated revised weighting factors shall be approved by the Administration.
184.108.40.206 Further to 220.127.116.11 where the E2, E3 or D2 test cycles are applied, a minimum of load points shall be used of which the combined nominal weighting factor, as given in 3.2, is greater than 0.50.
18.104.22.168 Further to 22.214.171.124 where the C1 test cycle is applied, a minimum of one load point shall be used from each of the rated, intermediate and idle speed sections. If the number of measuring points on board is different from those on the test bed, the nominal weighting factors at each load point shall be increased proportionally in order to sum to unity (1.0).
126.96.36.199 With regard to the application of 188.8.131.52 guidance in respect of the selection of load points and revised weighting factors is given in section 6 of appendix 8 of this Code.
184.108.40.206 The actual load points used to demonstrate compliance shall be within ± 5% of the rated power at the modal point except in the case of 100% load where the range shall be +0 to –10%. For example, at the 75% load point the acceptable range shall be 70% – 80% of rated power.
220.127.116.11 At each selected load point, except idle, and after the initial transition period (if applicable), the engine power shall be maintained at the load set point within a 5% coefficient of variance (%C.O.V.) over a 10-minute interval. A worked example of the coefficient of variance calculation is given in section 7 of appendix 8 of this Code.
18.104.22.168 Regarding the C1 test cycle, the idle speed tolerance shall be declared, subject to the approval of the Administration.
6.4.7 Test condition parameter
22.214.171.124 The test condition parameter specified in 5.2.1, shall not apply to onboard NOx monitoring. Data under any prevailing ambient condition shall be acceptable.
6.4.8 Analyser in-service performance
126.96.36.199 Analysing equipment shall be operated in accordance with manufacturer’s
188.8.131.52 Prior to measurement, zero and span values shall be checked and the analysers shall be adjusted as necessary.
184.108.40.206 After measurement, analyser zero and span values shall be verified as being within that permitted by 5.9.9.
6.4.9 Data for emission calculation
220.127.116.11 The output of the analysers shall be recorded both during the test and during all response checks (zero and span). This data shall be recorded on a strip chart recorder or other types of data recording devices. Data recording precision shall be in accordance with 18.104.22.168.
22.214.171.124 For the evaluation of the gaseous emissions, a 1-Hertz minimum chart reading of a stable 10-minute sampling interval of each load point shall be averaged. The average concentrations of NOx, and if required CO2, and optionally CO, HC and O2, shall be determined from the averaged chart readings and the corresponding calibration data.
126.96.36.199 As a minimum, emission concentrations, engine performance and ambient condition data shall be recorded over the aforementioned 10-minute period.
6.4.10 Exhaust gas flow rate
188.8.131.52 Exhaust gas flow rate shall be determined:
- in accordance with 5.5.2 or 5.5.3; or
- in accordance with 5.5.4 and appendix 6 of this Code, with not measured species set to zero and cCO2d set to 0.03%.
6.4.11 Fuel oil composition
184.108.40.206 Fuel oil composition, to calculate gas mass flow wet, qmf, shall be provided by one of the following:
- fuel oil composition, carbon, hydrogen, nitrogen and oxygen, by analysis (default oxygen value may be adopted); or
- default values as given in table 9.
Default fuel oil parameters
|Distillate fuel oil|
(ISO 8217 DM grade)
|Residual fuel oil|
(ISO 8217 RM grade)
6.4.12 Dry/wet correction
220.127.116.11 If not already measured on a wet basis, the gaseous emissions concentrations shall be converted to a wet basis according to:
direct measurement of the water component; or
dry/wet correction calculated in accordance with 5.12.3.
6.4.13 NOx correction for humidity and temperature
18.104.22.168 NOx correction for humidity and temperature shall be in accordance with 5.12.4. The reference charge air temperature (TSCRef) shall be stated and approved by the Administration. The TSCRef values are to be referenced to 25°C seawater temperature and in the application of the TSCRef value due allowance shall be made for the actual seawater temperature.
6.4.14 Calculation of emission flow rates and specific emissions
22.214.171.124 The calculation of emission flow rates and specific emissions shall be in accordance with 5.12.5 and 5.12.6.
6.4.15 Limit value and allowances
126.96.36.199 In the case of the application of 188.8.131.52 the emission value obtained shall, subject to the approval of the Administration, be corrected as follows:
Corrected gasx = gasx · 0.9 (21)
184.108.40.206 The emission value, gasx or corrected gasx as appropriate, shall be compared to the applicable NOx emission limit value as given in regulation 13 together with the allowance values as given in 220.127.116.11, 18.104.22.168 and 22.214.171.124 in order to verify that an engine continues to comply with the requirements of regulation 13.
6.4.16 Data for demonstrating compliance
126.96.36.199 Compliance is required to be demonstrated at renewal, annual and intermediate surveys or following a substantial modification as per 1.3.2. In accordance with 2.4.5, data is required to be current; that is within 30 days. Data is required to be current; that is within 30 days. Data is required to be retained on board for at least three months. These time periods shall be taken to be when the ship is in operation. Data within that 30-day period either may be collected as a single test sequence across the required load points or may be obtained on two or more separate occasions when the engine load corresponds to that required by 6.4.6.
6.4.17 Form of approval
188.8.131.52 The Direct Measurement and Monitoring method shall be documented in an Onboard Monitoring Manual. The Onboard Monitoring Manual shall be submitted to the Administration for approval. The approval reference of that Onboard Monitoring Manual shall be entered under section 3 of the Supplement to the EIAPP Certificate. The Administration may issue a new EIAPP Certificate, with the details in section 3 of the Supplement duly amended, if the method is approved after the issue of the first EIAPP Certificate, i.e. following the pre-certification survey.
6.4.18 Survey of equipment and method
184.108.40.206 The survey of the Direct Measurement and Monitoring method shall take into account, but is not limited to:
- the data obtained and developed from the required measurements; and
- the means by which that data has been obtained, taking into account the information given in the Onboard Monitoring Manual as required by 6.4.14.