The purpose of CNG cylinder testing is to verify its structural strength and safety under high pressure, and to ensure that CNG cylinders will not leak or explode due to fatigue, corrosion or manufacturing defects during long-term use. CNG cylinder testing typically includes four testing types:
1.CNG Cylinder Hydrostatic Test
To carry out CNG cylinder hydrostatic test, you need to use a water jacket method gas cylinder hydrostatic test machine. First, fill your CNG cylinder with water and place it in a sealed water jacket. Then, start the testing machine to pressurize the CNG cylinder to 1.5 times its nominal working pressure and hold the pressure for at least 30 seconds. After the pressure holding period, the machine will automatically calculate the residual volumetric deformation rate of the CNG cylinder. Generally, if the deformation rate of a CNG cylinder exceeds 10%, the cylinder must be scrapped and cannot refill natural gas.
2.CNG Cylinder Sealing Test
CNG cylinder sealing test, namely CNG cylinder leaking test, comes after the CNG cylinder has passed the hydrostatic test. It aims to verify the sealing performance of the CNG cylinder body and the cylinder valve under it working pressure, thus preventing natural gas leaking during subsequent use. CNG cylinder sealing test usually uses air or nitrogen as the test medium. And the test pressure must be equal to or slightly higher than the CNG cylinder’s nominal working pressure, a common test pressure is 20MPa. First, use a gas booster to inject 20MPa high-pressure nitrogen or air into a CNG cylinder. Tighten the cylinder valve and maintain the pressure for at least 10 minutes. If there is no excessive pressure drop during pressure holding period, the CNG cylinder’s sealing performance is qualified. Alternatively, you can use our Gas cylinder leak tester, which uses the bubbling method to determine if your CNG cylinder is leaking.
3.CNG Cylinder Burst Pressure Test
CNG cylinder burst test is a destructive test that involves continuously pressurizing the CNG cylinder until it ruptures, thereby measuring the cylinder’s yield pressure to verify the material’s ultimate strength. This testing method is only used by CNG cylinder manufacturers.
4.CNG Cylinder Cycle Pressure Test
CNG cylinder cyclic pressure test is also known as CNG cylinder fatigue test. It aims to simulate long-term filling gas and discharging gas conditions to evaluate the fatigue resistance of CNG cylinder, thereby preventing cracks caused by repeated pressure. This testing method is only used by CNG cylinder manufacturers.
Which CNG Cylinder Testing Type is Suitable for Me?
If you are a CNG cylinder user and need to inspect CNG cylinders that have been in use for some time, you should choose CNG cylinder hydrostatic test and sealing test. For CNG cylinder manufacturers, CNG cylinder sealing test, burst test and fatigue testing are mandatory to test newly manufactured CNG cylinders and ensure they achieve optimal performance before leaving the factory.
Frequently Asked Questions
What is the CNG cylinder test interval?
CNG cylinder test interval is 3 years, but regulations may differ between countries.
