This International Standard specifies minimum requirements for serially produced light-weight refillable gas cylinders intended only for the on-board storage of high pressure compressed natural gas as a fuel for automotive vehicles to which the cylinders are to be fixed. The service conditions do not cover external loadings which may arise from vehicle collisions, etc.

This International Standard covers cylinders of any steel, aluminium or non-metallic material construction, using any design or method of manufacture suitable for the specified service conditions. This International Standard does not cover cylinders of stainless steel or of welded construction.

Cylinders covered by this International Standard are designated as follows:

• CNG-1 Metal
• CNG-2 Metal liner reinforced with resin impregnated continuous filament (hoop wrapped)
• CNG-3 Metal liner reinforced with resin impregnated continuous filament (fully wrapped)
• CNG-4 Resin impregnated continuous filament with a non-metallic liner (all composite)