CNG is an alternative fuel that has been gaining popularity recently due to its affordability and environmental friendliness.

However, before CNG can be used, it must undergo hydro-testing. In this blog post, we will explore what hydro-testing is and why it’s necessary for CNG cylinders.

We will also provide some helpful tips on how to ensure your CNG cylinder is properly hydro-tested. 

What is CNG Cylinder Hydro-testing?

CNG Cylinder Hydro-testing is a process of testing the strength and integrity of a CNG cylinder by filling it with water and pressuring it to check for leaks. This test is important because it ensures that the cylinder can safely hold compressed natural gas without leaking, which could lead to an explosion. 

To hydro-test a CNG cylinder, first, it is filled with water and then pressurized to about three times its normal operating pressure. If there are no leaks, the cylinder passes the test. If there is a leak, the cylinder fails the test and must be repaired or replaced.

CNG cylinders must be hydro-tested every five years to ensure they are safe to use.

Importance of Cylinder Hydro-testing

To ensure their structural integrity, it is crucial to safely operate compressed natural gas (CNG) systems that are regularly hydro-tested. A CNG cylinder hydro-test involves filling the cylinder with water and then pressurizing it to check for any leaks or weaknesses.

Cylinder hydro-testing is important because it:

1. Helps to ensure the safety of CNG systems by checking for leaks and weaknesses in cylinders.

2. Allows operators to identify any potential problems with a cylinder before it is used in service.

3. Ensures that cylinders can safely withstand the pressures they will be subjected to during use.

4. Helps to prolong the life of cylinders by identifying any issues early on.

5. It Is required by law in many jurisdictions to operate a CNG system.

How is CNG Cylinder Hydro-testing done?

CNG Cylinder Hydro-testing is a process in which the cylinder is pressurized with water to check for leaks. The test is done by connecting the cylinder to a water source and slowly increasing the pressure inside the cylinder until it reaches the specified limit. If there are no leaks, the pressure will remain constant. If there is a leak, water will be forced out of the cylinder.

The benefits of CNG Cylinder Hydro-testing

There are many benefits to CNG cylinder hydro-testing, including:

1. Ensures the structural integrity of the cylinder – Hydro-testing is the only way to test the structural integrity of a CNG cylinder.

2. Prevents leaks and explosions – Cylinders that have not been properly hydro-tested are more likely to develop leaks or even explode.

3. Prolongs the cylinder’s life- Hydro-testing helps ensure that cylinders will last for their full expected lifespan.

4. Reduces wear and tear on other components: Proper hydro-testing of cylinders reduces wear and tear on other system components, such as valves and regulators.

5. Saves money in the long run – Although hydro-testing may seem like an expensive proposition up front, it can save you money in the long run by preventing costly repairs or replacements.


Every five years, you must take your CNG cylinder to a hydro test to ensure it is safe. Hydro-testing involves filling the cylinder with water and pressurizing it to check for leaks. Our reputed company offers this service if you’re unsure how to hydro-test your cylinder. Ask for a few quotes before choosing a company to work with.