A CNG cylinder stores fuel at high pressure, so its condition matters just as much as the rest of the conversion system. Periodic inspection and testing help trained technicians identify corrosion, physical damage, leakage or loss of structural integrity before the cylinder returns to service.
This guide explains product and selection principles. It does not confirm compatibility, replace model-specific documents or provide a repair procedure.
Visual inspection comes first
A technician checks the cylinder body, valve area, mounting points and protective fittings for dents, cuts, rust, heat exposure or unauthorised repair. The cylinder markings and test history should also remain legible so its identity and status can be confirmed.
Hydrostatic and leak testing
During hydrostatic testing, an authorised facility uses water and controlled pressure to assess how the cylinder responds under load. The valve and connected system are separately checked for leakage after reassembly; these procedures require calibrated equipment and must not be attempted at home.
Standards, records and next steps
Applicable BIS, PESO and transport requirements can change, so owners should confirm the current testing interval, approved facility and documentation with the competent authority or local RTO. Keep the test certificate with the vehicle records and replace any cylinder that an authorised examiner rejects.
Find a CNG testing station and check your certificate
Before booking a cylinder test
Start with PESO’s approved CNG cylinder testing-station list. Confirm the station’s current approval, address and cylinder-testing scope directly before booking; an older list entry does not establish that its approval is still valid.
Check a CNG cylinder test certificate online
PESO’s circular dated 7 July 2026 describes a public search for certificates covering CNG cylinders fitted to vehicles. On the PESO public portal, use the following route:
- Select Status.
- Under Rule, select Gas Cylinders Rules.
- Under Form Action, choose Search CNG Certificate by Vehicle Number, then follow the official form using your vehicle details.
PESO advises checking certificate validity before filling CNG. Cylinders that are due for periodic testing and examination must not be refilled. If the record is missing, expired or does not match your vehicle, ask the testing station to resolve it before refuelling.
Keep the two approval checks separate
Vehicle-kit approval documents and a cylinder test certificate serve different purposes. MIJO’s vehicle approval list helps you check the retrofitment application; it does not confirm that an individual cylinder’s periodic test is current.
Frequently asked questions
What is checked during a visual CNG-cylinder inspection?
The examiner checks areas such as the cylinder body, valve, markings, mountings and protective fittings for damage, corrosion, heat exposure or unauthorised repair.
What is hydrostatic testing of a CNG cylinder?
An authorised facility uses water and controlled pressure with calibrated equipment to assess how the cylinder responds under load.
Can a CNG-cylinder test be performed at home?
No. Cylinder testing, valve work, reassembly and leak checks require an authorised facility, trained personnel and appropriate equipment.