GB 17926-1999Road Vehicle Compressed Natural Gas Cylinder Valves
This standard applies to road vehicle compressed natural gas (CNG) cylinder valves (hereafter referred to as valves).These valves are used for the connection of CNG cylinder and the other components in CNG system.
The technical requirements of this standard include the dimensional and shape characteristics, strength tests, performance tests and other tests.
1 Dimensional and shape characteristics
1.1 Cylinder connection surface of the valve shall meet with the requirements of GB 5135.3.
1.2 Structure diagram and connection dimensions of the valve shall meet the requirements of Fig.1 and table 1.
TABLE 1 Dimensions (Unit：mm)
Fig.1 Schematic diagram of valve
1.3 Threads meet with the requirements of GB 7306-2005.
2 Strength Tests
2.1 Tensile Test The valve shall meet the requirements of GB/T 2423.3.
2.2 Service Test Test conditions： Temperature：15℃
Test pressure：5.5MPa Test time：5min
The valve shall keep undamaged and prevent leakage for the whole test period.
3 Performance Test
3.1 Gas tightness test
Test conditions：
Test pressure：5.5MPa
Ambient temperature：15℃
Test time：30min
After the test, the leakage axial displacement of valve shall not exceed 1.5mm.
3.2 Flow characteristics test Test conditions ：
Inlet MWP： 7MPa
Ambient temperature ：15℃
Pressure differential： 5MPa
The flow characteristics test should meet the requirements of Fig.2.
Fig.2 Flow characteristics test
3.3 Endurance test Test conditions：
Inlet MWP： 30MPa
Ambient temperature：15℃
Test period： 1600 cycle
The valve should be able to remain undamaged and no leakage throughout the test period.
4 Others Test
4.1 Appearance quality Test
The surface of valve shall be smooth, free of scratches, no pitting or cracks and no signs of excessive wear or any other contamination.
4.2 Impact Test
The impact performance test shall meet the requirements of GB/T 2423.32.
4.3 Reliability test
Reliability test of the valve should meet the requirements of GB/T 2423.3.
4.4 Low temperature performance test
Test conditions：
Ambient temperature：-10℃
Test pressure： 5.5MPa
Test procedure： two-way squeeze
The valve should be able to operate smoothly without leakage or deformation.
4.5 Temperature resistance test
Test conditions：
Heating temperature： 80℃
Ambient temperature： 15℃
Test pressure： 5.5MPa
The valve should be able to operate smoothly without leakage or deformation.
5 Inspection Rules
Valve should pass the inspection in accordance with GB/T2423.17 before they can be packed and shipped.
6 Mark
Valve should have an identifiable mark that includes the manufacturer, production batch and grade.
7 Packaging, storage and transportation
Valve should be packed and stored in accordance with GB/T 191.
