QC/T 1266-2025Fuel cell electric vehicles - Specifications for online monitoring of onboard hydrogen systems (English PDF)

3.1 Online monitoring system of onboard hydrogen system

The system that monitors parameters such as hydrogen concentration, pressure, and temperature in real time, and features data acquisition, storage, uploading, and safety alarm functions.

NOTE: Hereinafter referred to as "monitoring system". See Appendix A for a schematic diagram of the online monitoring system of onboard hydrogen system.

3.2 Missing alarm rate

The percentage of times the system fails to issue an alarm signal or indicator for the designed alarm events out of the total number of tests.

3.3 False alarm rate

The percentage of times the system responds to an unplanned event by issuing an alarm signal or indication out of the total number of tests.

3.4 Upper-level data platform

Data management platforms for fuel cell electric vehicles built by government departments, industry organizations, or enterprises.

4.1 General requirements

4.1.1 The monitoring system shall monitor the hydrogen concentration, pressure, and temperature parameters of the onboard hydrogen system in real time, and shall have data acquisition, storage, uploading, and safety alarm functions.

4.1.2 The monitoring system shall operate normally with the vehicle started and not started.

4.1.3 The communication protocol between the monitoring system and the upper-level data platform shall comply with the requirements of GB/T 32960.3.

4.1.4 The sensors connected to the monitoring system shall include at least a hydrogen concentration sensor, a temperature sensor, and a pressure sensor. The use and installation of all types of sensors shall comply with the design technical requirements of the onboard hydrogen system. The recommended technical indices of all types of sensors should meet the requirements of Appendix B.

4.1.5 The monitoring system shall be equipped with a power failure protection device or other measures to support the normal operation of the monitoring system for no less than 12 hours when the vehicle is not started. It is advisable to select a vehicle power supply or an external power supply according to actual conditions.

4.2 Hydrogen concentration monitoring alarm

4.2.1 The monitoring system shall have an online monitoring alarm function for the hydrogen concentration of the onboard hydrogen system. The hydrogen concentration monitoring alarm shall meet the following requirements:

a) The hydrogen leakage status of the onboard hydrogen system is monitored in real time by a hydrogen concentration sensor, both when the vehicle is started and when it is not started.

b) An alarm will sound when the hydrogen concentration monitoring data exceeds the set alarm threshold.

c) Alarms shall be graded based on different risk level thresholds or the severity of exceeding the thresholds. At least two risk levels shall be set for hydrogen leakage alarms, and the judgment thresholds for each level shall be adjustable. The relationship between hydrogen concentration thresholds and warning signal levels is determined by the manufacturer based on vehicle type, operating environment, and requirements.

4.2.2 The hydrogen concentration sensor connected to the monitoring system should preferably be an existing sensor and shall meet the technical requirements of 4.1.2.1 in GB/T 24549-2020.

4.2.3 The missing alarm rate of the hydrogen concentration monitoring abnormality of the monitoring system shall be tested according to the test method specified in 5.2.2. The missing alarm rate of the hydrogen concentration monitoring abnormality shall not exceed 1%.

4.2.4 The false alarm rate of the hydrogen concentration monitoring abnormality of the monitoring system shall be tested according to the test method specified in 5.2.3. The false alarm rate of the hydrogen concentration monitoring abnormality shall not exceed 3%.

4.3 Pressure monitoring alarm

4.3.1 The monitoring system shall have the function of online monitoring of hydrogen pressure in the onboard hydrogen system, and the hydrogen pressure monitoring alarm shall at least meet the following requirements:

a) The hydrogen pressure state of the onboard hydrogen system can be monitored in real time through the pressure sensor when the vehicle is started and not started.

b) When the hydrogen pressure monitoring data reaches the set alarm threshold, a low-pressure or overpressure risk alarm will be issued.

c) Alarms shall be graded according to different hazard level thresholds or the severity of exceeding the set thresholds. Pressure alarms (including low-pressure alarms and over-pressure alarms) shall have at least two risk levels, and the judgment thresholds for each level shall be adjustable. The relationship between pressure thresholds and warning signal levels is determined by the manufacturer based on vehicle type, operating environment, and requirements.

4.3.2 The arrangement of pressure sensors shall meet the following requirements:

a) Pressure sensors for high-pressure monitoring and low-pressure monitoring shall be installed, respectively, according to different pressure levels.

b) The high-pressure sensor should be placed in a suitable position near the hydrogen storage cylinder opening, and the low-pressure sensor should be placed in a suitable position after the pressure regulator and near the fuel cell system.

c) Mechanical or electromagnetic interference shall be avoided, and ease of installation and maintenance shall be considered.

4.3.3 The missing alarm rate of the hydrogen pressure abnormality of the monitoring system shall be tested according to the test method specified in 5.3.2. The missing alarm rate of the pressure monitoring abnormality shall not exceed 3%.

4.3.4 The false alarm rate of the hydrogen pressure abnormality of the monitoring system shall be tested according to the test method specified in 5.3.3. The false alarm rate of the pressure monitoring abnormality shall not exceed 5%.

4.4 Temperature monitoring alarm

4.4.1 The monitoring system shall have the function of online monitoring of hydrogen temperature in the onboard hydrogen system, and the hydrogen temperature monitoring alarm shall at least meet the following requirements:

a) The temperature of the hydrogen in the onboard hydrogen system can be monitored in real time by a set temperature sensor, whether the vehicle is started or not started.

b) When the hydrogen temperature monitoring data reaches the set alarm threshold, a low temperature or over-temperature risk alarm will be issued.