NB/SH/T 0764-2023 Diesel engine nozzle coking test method XUD-9 method

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Incomplete source card: Sections 10, 11, 12, 13, 14 are absent from the available source. Only available content is translated; source completion is pending.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: NB/SH/T 0764—2023
• Chinese full name: Diesel engine nozzle coking test method XUD-9 method
• English name: Test method for diesel engine injector nozzle coking test XUD-9
• Replacement relationship: replaces SH/T 0764—2005 "Diesel engine nozzle coking test method (XUD-9 method)"
• Publication/implementation: published on 2023-02-06, implemented on 2023-08-06
• Previous versions: first published in 2005 as SH/T 0764—2005; this is the first revision
• Custodianship: National Technical Committee for Standardization of Petroleum Products and Lubricants, Subcommittee on Petroleum Fuels and Lubricants (SAC/TC280/SC1)
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafters: Tian Huayu, Song Haiqing, Yang He, Ding Xiaoliang, Zhang Zhenhua, Miao Qile, Lu Wentong, Zhang Jianrong

2. Scope of application and non-applicability

• This document specifies a bench test method for evaluating the effect of automotive diesel and biodiesel on diesel engine nozzle coking.
• It is applicable to evaluating the detergency performance of automotive diesel and biodiesel, and also to evaluating the nozzle cleanliness of diesel detergents.
• Not applicable: no explicit non-applicability clause is provided in the available source.
• Warning: the use of this document may involve certain hazardous materials, operations, and equipment, but it does not address all safety issues; users should establish appropriate safety precautions before use and determine the applicability of relevant regulatory restrictions.

3. Method principle

• 4.1 A clean nozzle that has passed the flow check is installed on the engine, and under the operating conditions specified in the method, the engine is run for 10h. The change in nozzle air flow before and after the test is measured to determine the effect of the fuel on nozzle coking performance.
• 4.2 The test result is expressed by the air flow loss rate after the test for all nozzles at 0.10mm, 0.20mm, and 0.30mm needle lift, but the criterion for judging the fuel depends only on the average air flow loss rate of 4 nozzles at 0.10mm needle lift.

4. Reagents and materials (purity / preparation)

4.1 Reference oil

• 5.1.1 The reference fuel number is RF-96-08, the type is low-sulfur diesel, and the technical parameters are shown in Table 1.

Table 1 RF-96-08 Technical parameters

ᵃ It may also be determined using GB/T 11140 and NB/SH/T 0842; in case of dispute, the SH/T 0689 method shall prevail.

• 5.1.2 The reference lubricating oil shall use CEC RL254 or an equivalent lubricating oil. The typical technical parameters of CEC RL254 are shown in Table 2.

Table 2 CEC RL254 Typical technical parameters

Note: The technical parameters of different batches of CEC RL254 may vary.

• 5.1.3 The nozzle coking rate measured by all laboratories using the reference oil at 0.1mm needle lift shall be within the following limits: 71%±4%.

4.2 Test base fuel

• 5.2 The range of nozzle flow loss of the test base fuel at 0.1mm lift shall satisfy 87%±4%. The technical parameters that the test base fuel shall meet are shown in Table 3.

Table 3 Technical parameters and limits of test base fuel

Note: The technical parameters of different batches of test base fuel may vary. ᵃ It may also be determined using GB/T 11140 and NB/SH/T 0842; in case of dispute, the SH/T 0689 method shall prevail.

4.3 Coolant

• 5.3 During the test, a coolant prepared by mixing 50% of water and 50% of ethylene glycol shall be used. The coolant shall have an appropriate level of corrosion protection.
• 6.6 The engine coolant shall be a mixture that, when mixed with water at a volume ratio of 1:1, has a freezing point of -40℃±5℃. The freezing point of the mixture shall be checked every six tests. Measure the freezing point by referring to the SH/T 0686 method. New coolant shall be replaced every eighteen tests.

4.4 Other Materials

• n-Heptane or SBP3 (for nozzle cleaning, see Appendix C)
• Decon 90 dispersant solution (concentration 50%, for repeated use in nozzle cleaning, see Appendix D)
• Copper-based grease (recommended for lubricating injector threads, see 8.1.1 g))

5. Apparatus and Equipment

5.1 Test Engine

• 6.1.1 The test engine is an engine dedicated to the diesel nozzle coking test, model PCM XUD9 A/L, an in-line four-cylinder, four-stroke 1.9L naturally aspirated indirect-injection diesel engine.
• 6.1.2 The cylinder nearest the flywheel end is cylinder 1.
• 6.1.3 A detailed list and ordering of engine components are given in Appendix A.
• 6.1.4 If exhaust gas recirculation is already fitted, the exhaust gas recirculation system shall not be used.
• 6.1.5 The following injectors and nozzles shall be used: a) Injector: LCR 67307; b) Nozzle: RDNO SDC 6850.
• 6.1.6 Flat-tip nozzles with the letter “C” after the nozzle number (e.g., 6850C) shall not be used. Measure the nozzle opening pressure using a calibration fluid, and confirm that the nozzle opening pressure is within the range of 11500kPa±500kPa.
• 6.1.7 A diesel engine fuel pump shall be used (pump number: DCP R 84 43 B910A).

5.2 Test Bench

• 6.2.1 The test engine shall be installed on a suitable support, ensuring as far as possible the correct engine inclination angle (from vertical toward the exhaust is 30°).
• 6.2.2 The engine may use a manual gearbox or may be directly connected to a coupling shaft. A suitable dynamometer shall be installed to control the engine so that the engine can operate under the conditions required by the test procedure.
• 6.2.3 The inertia of the dynamometer shall be less than 0.55kg·m².

5.3 Fuel System

• 6.3.1 The test bench fuel system shall be capable of measuring fuel flow and of delivering the return fuel from the injectors and fuel pump to a fuel cooler or fuel tank.
• 6.3.2 The fuel temperature shall be automatically controlled using an external cooler; for example, FH21 or equivalent equipment may be used.
• 6.3.3 A standard-configuration fuel heating/filter assembly may be used, and an additional preheater may be used to preheat the fuel, but the preheater shall be installed upstream of the fuel cooler, and electric heaters shall not be used to heat the fuel.
• 6.3.4 The fuel supply pressure before the fuel pump and the fuel return pressure shall be measured.
• 6.3.5 A valve shall be installed at a low position on the fuel return line to facilitate draining the fuel recirculated during flushing, and it may also be used to drain fuel remaining in the line from the previous test before testing.
• 6.3.6 The fuel flushing efficiency shall be at least 98%. The recommended flushing procedure is given in 8.2.5 and 6.3.6 a) to f).

5.4 Electrical System

• 6.4.1 The engine electrical connections shall meet the basic requirements for vehicle application, but some modifications are required.
• 6.4.2 The alternator may be adjusted to tension the belt, but it shall not be used to supply power. Electric heaters shall not be used to heat the fuel; therefore, the alternator connections to the outside shall be disconnected.
• 6.4.3 The glow plugs shall be switched on before each engine start, for preheating 7s to 10s.

5.5 Cooling System

• 6.5.1 The closed pressurized test bench cooling system shall use a pressure relief valve with an opening pressure of 80kPa to 100kPa.
• 6.5.2 The original coolant thermostat valve shall be modified to a fully open state.
• 6.5.3 The coolant line that supplies heat to the vehicle heater on the vehicle shall be blocked off at the engine end. It is prohibited to connect the coolant inlet and outlet to the vehicle heater with hoses.
• 6.5.4 A flow control valve may be installed on the coolant outlet pipe between the engine and the cooler to adjust the coolant inlet-outlet temperature difference. It is recommended to install a coolant flow meter as shown in Figure 2 and Figure 3. Ensure that the coolant flow measurement accuracy reaches class A (refer to Chapter 10).

5.6 Exhaust System

• 6.7.1 A standard vehicle or test bench exhaust system may be used. If a bench exhaust system is used, it shall be capable of providing suitable exhaust backpressure.
• 6.7.2 It is recommended that the exhaust backpressure valve be installed at a distance of 1.5m to 4.0m from the engine.
• 6.7.3 Regardless of the exhaust system used, a smoke sampling probe shall be provided and positioned according to the manufacturer's requirements, usually installed after the backpressure valve (see Appendix B, B.4 for installation of the exhaust smoke probe).

5.7 Oil Cooling System

• 6.8 An industrial cooler and appropriate methods shall be used to control the engine lubricating oil temperature.

5.8 Air Filtration System

• 6.9 The test bench shall use the standard vehicle air cleaner, filter element, and intake pipe. It is recommended that the engine intake pressure be controlled at 95kPa±1kPa. It is suggested that intake pressure control be disabled during the 4000r/min and full-load pre-test check stage to ensure that the intake is unrestricted at full load.

5.9 Crankcase Ventilation System

• 6.10.1 The engine closed crankcase ventilation system shall be maintained in the standard state; only when measuring crankcase blowby may the blowby system be temporarily disconnected and open to the atmosphere.
• 6.10.2 Alternatively, a three-way valve may be used to measure crankcase blowby, so that crankcase ventilation during normal operation is not affected.

5.10 Engine Fuel Pump Modification

• 6.11.1 The engine fuel pump shall be modified after the engine has completed the break-in procedure.
• 6.11.2 Modify the fuel pump injection timing advance mechanism to ensure that the injection timing is fixed under all test conditions.
• 6.11.3 Steps for modifying the fuel pump: a) Record the position of the fuel pump on the engine; b) Remove the fuel pump from the engine; c) Lock the Lucas DPC injection timing device as described in B.1 of Appendix B; d) Reinstall the modified fuel pump to the previously marked position on the engine.

5.11 Engine Fuel Pump Calibration

• 6.12 Ensure that the modified fuel pump delivers a maximum fuel quantity per stroke of 31.5mm³±0.5mm³ at full throttle, at an engine speed of 4000r/min, and when tested on the test bench. This verification shall be carried out periodically. The limit value is determined by the test bench measured value.

5.12 Control

• 6.13 It is recommended to use suitable control equipment to control the operating parameters (see Chapter 9).

5.13 Measurement of Nozzle Mass Flow

• 6.14 Injector nozzle coking depends on the air flow loss rate of the nozzle measured before and after the test (see Appendix C, C.1). Only a mass flow meter may be used to measure air flow. The precision of the mass flow meter shall reach 2% of the measured value.

5.14 Measuring Equipment

• 6.15 All measuring equipment shall meet the precision requirements in Chapter 10.

5.15 Measurement Locations

• 6.16 The measurement locations of the relevant parameters to be monitored during the test are given in Table 4, Table 5, and Table 6.

Table 4 Pressure Sensor Locations

Note: A class: requires that all controlled test parameters be calibrated using currently valid calibration techniques for measuring instruments; B class: test parameters marked “record” and “check” may be calibrated using lower-precision measuring instruments.

Table 5 Temperature Sensor Measurement Locations

Table 6 Other Measurement Locations

6. Recommended operating conditions

6.1 Calibration test

• 7.1 New engine or newly assembled test bench: For a newly assembled test bench or a test bench with a new engine installed, two calibration tests shall be completed using RF-96-08 fuel. The average nozzle 0.1mm lift results of both tests shall fall within the range of 71%±4%.
• 7.2 Routine calibration test:
  • 7.2.1 The calibration test shall be performed at least once per year.
  • 7.2.2 Once the engine is installed and calibrated, calibration shall be performed periodically.
  • 7.2.3 A calibration test shall be completed at least every fifteen tests.
  • 7.2.4 If the test results fall outside the control range, the tester shall provide the reason, and if necessary, adjust the injection timing and repeat the calibration test once.
  • 7.2.5 If there is any adjustment or replacement of the fuel pump, a calibration test shall be performed.
• 7.3 Calibration test result report:
  • 7.3.1 Report the average air flow loss rate of 4 nozzles at 0.1mm needle valve lift.
  • 7.3.2 Report the air flow loss rate of 4 nozzles at 0.1mm needle valve lift separately.
  • 7.3.3 The average air flow loss rate of 4 nozzles at 0.2mm, 0.3mm needle valve lift may be reported.

6.2 Test preparation

• 8.1 Injectors:
  • 8.1.1 Check the injector nozzle flow rate (see C.1 in Appendix C), and select nozzles according to the following criteria:
    • a) When the nozzle is at 0.1mm needle valve lift, the air flow of each of a group of four nozzles shall be between 250mL/min～320mL/min;
    • b) The nozzles shall be inspected to ensure they can be used for the test (see the cleaning method for used injectors in C.6 in Appendix C);
    • c) The nozzles need to be installed on the injector body, and when the opening pressure test is performed using calibration fluid, ensure their opening pressure is 11500kPa±500kPa;
    • d) Each injector assembly shall be numbered according to the cylinder position;
    • e) Only the copper thermal protection gaskets of 2.20mm±0.05mm and the steel gaskets with a semicircular face provided by Peugeot and Citroën Group (PSA) may be used. The semicircular face of the sealing gasket shall be placed facing up;
    • f) The tightening torque for installing the injector on the engine is 75Nm (not the manufacturer-specified 90Nm), to prevent the gasket from being pressed into the cylinder head and becoming impossible to remove;
    • g) It is recommended to use copper-based grease to lubricate the injector threads, reducing wear caused by frequent installation and removal of the injector;
    • h) The copper gasket step at the injector port of the cylinder head shall be checked frequently to ensure that it cannot be deformed due to carbon deposits (e.g., becoming arched). Deformation of the step will seriously affect the test results;
    • i) The injector port shall be inspected and cleaned regularly;
    • j) New nozzles shall be installed 20h before the test, and each nozzle shall be used for at most 30 tests.
  • 8.1.2 After a new nozzle is installed, the air flow at 0.1mm needle valve lift shall be measured three times, and the nozzle shall be reinstalled for each measurement. The measured values shall be within the range of ±5mL/min. The average of the three measurements shall be taken as the reference flow of the nozzle. After each cleaning, the air flow of the nozzle at 0.1mm needle valve lift shall be within the range of ±15mL/min of the reference flow; if it is not within the range, the nozzle shall be cleaned again or discarded.
  • 8.1.3 If a nozzle is damaged or excessively worn, a nozzle with a flow difference within 10mL/min may be used as a replacement. However, once a nozzle is replaced, the service life of the nozzle group shall be based on the nozzle with the maximum number of uses in the nozzle group. For example, if a group of nozzles has been used 15 times and one nozzle is replaced by a nozzle that has been used only 2 times, this group of nozzles may be used at most 15 more times. For another example, if a group of nozzles has been used 10 times and one nozzle is replaced by a nozzle that has been used 20 times, this group of nozzles may be used at most 10 more times.
• 8.2 Engine:
  • 8.2.1 Engine running-in: Before the test, all new engines shall be run in according to the running-in procedure in Appendix E.
  • 8.2.2 Engine fuel pump injection timing measurement and adjustment:
    • a) Ensure the fuel pump is modified according to clause 6.11;
    • b) Use the test base fuel or the test base fuel with additives;
    • c) Start and warm up the engine. After 5min under the pre-test conditions 3000r/min and 50Nm, loosen the fuel pump positioning bolts, adjust the fuel pump position, and bring the engine state to the following requirements: 1) Mandatory parameter: fuel consumption is 4.85kg/h±0.15kg/h; 2) Recommended parameter: exhaust temperature is 36℃±20℃ (requires confirmation against the source standard (source-text extraction), suspected to be 360℃±20℃); smoke opacity is 0.8FSN±0.2FSN.
  • 8.2.3 Before each test and engine maintenance:
    • a) Ensure the engine lubricating oil level is not more than 3mm from the middle position of the oil dipstick scale, but it must not exceed the highest position of the scale (total capacity approximately 5L);
    • b) Replace the lubricating oil and filter element every six tests;
    • c) Check the tail end hole diameter of the high-pressure fuel pipe. If it is not 2.5mm, adjust the hole diameter with a 2.5mm drill bit, and blow out debris backward with compressed air;
    • d) Check and adjust the valve clearance after every 300h of engine operation: 1) Intake (cold): 0.15mm±0.04mm; 2) Exhaust (cold): 0.30mm±0.04mm;
    • e) Replace the glow plug every 60 tests;
    • f) Check the freezing point of the coolant every 6 tests, and replace the coolant every 18 tests;
    • g) Check the timing belt tension according to the manufacturer's requirements every 18 tests.
  • 8.2.4 Fuel system preparation for each test: a) Install the pre-test injectors; b) Ensure all fuel system components have drained the previous test oil (depending on the actual situation); c) Fill the fuel system with the fuel for this test.
  • 8.2.5 Fuel system flushing procedure:
    • a) Energize the glow plugs for 7s～10s, discharge some fuel at the end of the high-pressure fuel pipe, then start the engine and run the flushing procedure in the following two stages: 1) Stage 1: 5min, no-load idle; 2) Stage 2: 10min, 34Nm torque 2000r/min speed.
    • b) Immediately after starting the engine, open the vent valve of the fuel return pipe to discharge 10L test fuel, so that the engine can flush the fuel pump with the test fuel. The actual amount of flushing fuel is determined by the procedure specified in clause 6.3. The above procedure shall be carried out. Note: The valve layout shall be able to discharge all fuel returning from the fuel pump and injectors, and recirculation is not allowed.
  • 8.2.6 Pre-test inspection:
    • 8.2.6.1 After the flushing procedure, bring the engine to 3000r/min, 50Nm, stabilize the conditions and operate for 15min under the conditions specified in 6.1.2. Then perform the following inspection and adjustments:
      • a) Ensure the fuel inlet pressure is between -5kPa～10kPa, and the outlet pressure is between -10kPa～10kPa;
      • b) Check the coolant flow rate is 85L/min±5L/min;
      • c) Check the exhaust back pressure is 5kPa±1kPa;
      • d) Check the crankcase blow-by gas amount does not exceed 30L/min;
      • e) Check the fuel consumption is 4.85kg/h±0.15kg/h;
      • f) Check the intake pressure is 95kPa±1kPa;
      • g) Check the exhaust smoke opacity value is 0.8FSN±0.2FSN; (not mandatory)
      • h) Check the exhaust temperature is 360℃±20℃; (not mandatory)
      • i) Record the following parameters during these inspections, and all these parameters shall be reported: 1) Temperature: coolant outlet, main oil gallery, air inlet, fuel, exhaust; 2) Pressure: fuel pump inlet and outlet, exhaust back pressure; 3) Others: coolant flow rate (L/min), fuel flow rate (kg/h), crankcase blow-by gas amount (L/min), exhaust smoke opacity value.
      • j) After bringing the engine to the conditions of 1000r/min, 10Nm, operate for 5min, then stop the engine;
      • k) Install 1 new fuel filter elements. Start the system and operate the engine at idle for at most 5min, ensuring all gas is expelled from the fuel system.

6.3 Operation test

• 9.1 Install the formal test injectors on the engine, mark the corresponding cylinder numbers, and use new sealing gaskets and copper thermal protection gaskets (see 8.2.1 injector installation details).
• 9.1.1 Warm up the engine:
  • 9.1.1.1 Energize the glow plugs for 7s～10s, and start the engine.
  • 9.1.1.2 Warm up the engine according to the following conditions: a) 5min, no-load idle; b) 10min, at 34Nm torque for 2000r/min; c) 10min, at 50Nm torque for 3000r/min; d) During the above warm-up stages, record all test parameters.
• 9.1.2 Operating conditions:
  • 9.1.2.1 After the warm-up procedure, immediately run the following test cycle 134 times, with a total test time of 603min; the test stages are shown in Table 7.

Table 7 Test stages

• 9.1.2.2 The speed and torque of stage 1 shall be reached within 15s, and those of each other stage shall be reached within 30s. The condition transition time shall be included in the time of each stage.
• 9.1.2.3 Other operating parameters are shown in Table 8 and Table 9.

Table 8 Mandatory parameters

Table 9 Recommended parameters

• 9.2 Recording frequency: during each cycle, record data at least once per step.
• 9.3 End of test: after completing 10h tests, decelerate the engine to stage 1, run for 5min, and then shut down. Remove the injectors from the engine (between 0.5h and 1h after engine shutdown).

7. Sampling and specimen preparation

• The test sample is automotive diesel, biodiesel, or test fuel blended with diesel detergent additive.
• The range of nozzle flow loss of the test base fuel at a needle lift of 0.1mm shall satisfy 87%±4% (see 5.2).
• Before the test, ensure that all fuel systems have been drained of the previous test oil and filled with the fuel for this test (see 8.2.4).
• For the fuel system flushing procedure, see 8.2.5.
• Sampling amount: not provided in the available source.

8. Analysis procedure

• Carry out the running test in accordance with Chapter 9.
• 9.1 Install the injectors for the formal test on the engine, mark the corresponding cylinder numbers, and use new gaskets and copper heat shields.
• 9.1.1 Warm up the engine (see Section 6.3).
• 9.1.2 Operating conditions: run the test cycle 134 times, total test time 603min; test stages are shown in Table 7; other operating parameters are shown in Table 8 and Table 9.
• 9.2 Recording frequency: during each cycle, record data at least once per step.
• 9.3 End of test: after completing 10h tests, decelerate the engine to stage 1, run for 5min, and then shut down. Remove the injectors from the engine (between 0.5h and 1h after engine shutdown).
• 10.2.1 After the test ends, remove and disassemble the injector assembly within 30min to 60min. After the nozzle stabilizes to ambient conditions, re-measure the nozzle air flow at the same needle lift as the first measurement before the test. For the measurement procedure, see C.1 in Appendix C. Express the results for all needle lifts of each nozzle as the air flow loss rate.

9. Qualitative and quantitative determination and calculation formulas

9.1 Test validity

• 10.1.1 If the test run falls outside the conditions described in Chapter 6, the test is considered invalid.
• 10.1.2 Any shutdown during the final 2h for any reason will invalidate the test.
• 10.1.3 For other parameters outside the range, a reasonable judgment shall be given.

9.2 Test report

• 10.2.2 Each test shall have a complete test report. In principle, the test report consists of three parts.
• 10.2.2.1 Basic contents of the test report: a) laboratory name and address; b) customer name and address; c) unique identification of the report, such as test number; d) identification of each page and total number of pages of the report; e) date of receipt of the test sample; f) date of report; g) signature of the approver; h) test base fuel number; i) engine oil used in the test; j) description and identification of the test; k) description of the test procedure; l) test validity; m) technical parameters of the test base fuel; n) test results; o) any other available information required by the customer regarding test validity.
• 10.2.2.2 Contents of the operating data report: a) start of test (S.O.T); b) average values of the operating data obtained for each stage of the test cycle; c) inspection data at the end of the test; d) report all operating examples that fall outside the specified range; e) report all abnormal events including engine shutdown; f) report all data recorded in the pre-test inspection, see 8.2.6.
• 10.2.2.3 Contents of the test evaluation report: a) at the start of the test, the air flow measurement value of each injector (L/min); b) at the end of the test, the air flow measurement value of each injector (L/min); c) the flow percentage of all 4 nozzle needles at lifts of 0.1mm, 0.2mm, 0.3mm; d) the average nozzle flow percentage of all 4 nozzles at a lift of 0.1mm; e) nozzle identification numbers; f) ambient pressure and temperature conditions during the nozzle flow measurement.

9.3 Calculation formulas

• Calculation of flushing efficiency (Formula 1): S = (A - C) / (A - B) × 100% Where: S — flushing efficiency, %; A — sample 1