What Is CNG Hydrotesting & why is it Important?

fuel, petrol, gas

CNG stands for Compressed Natural Gas. It is a fuel with a mixture of hydrocarbons, mainly methane in the range of 95%. Due to its low density, it is compressed to a pressure of 200 bar to enhance the vehicle’s onboard storage capacity. The properties of CNG make it a safe fuel. It is lighter than air, so in case of a leak, it just rises up and disperses into the atmosphere. There are over 3 million vehicles run on CNG which proves the fact.

CNG cylinders are designed and built in such a way so as to withstand high pressure. CNG cylinders are safe as they are manufactured as per specific requirements and tested before use, in accordance with international specifications and standards and they are duly approved by the Chief Controller of Explosives. Moreover, these have been provided with a ‘safety burst disc’ such that in case of inadvertent high-pressure/high temperature at the time of filing or at any other time, this disc is ruptured and pressure released. CNG cylinders are manufactured from a special steel alloy and are seamless in construction. Their compact size allows them to easily fit into a small vehicle. As per Indian Standard 8451, Gas Cylinder Rules & CCOE guidelines, CNG cylinder re-testing is required in the interval of every 3 years from cylinder manufacturing date or last re-testing date to ensure 100 % safety of CNG cylinder usage.

Hydrostatic Testing is a nondestructive test procedure used to check cylinders for leaks, structural flaws, durability, and corrosion. It is used to check a cylinder’s structural integrity. Testing consists of enclosing a cylinder filled with water inside a test jacket filled with water. Pressure is then applied internally to the cylinder, causing the cylinder to expand. The total and permanent volumetric expansions of the cylinder are determined by measuring the amount of water displaced by the expansion of the cylinder when under pressure and after the pressure has been released. An external and internal visual inspection of the cylinder is also performed.

If you want to convert your car into CNG check this post.

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