CNG Cylinders “Tanks”
Four Types of CNG Cylinders
CNG tanks are available in four types. Type 1 tanks are the heaviest and least expensive, with Type 4 tanks the lightest and most expensive – Type 2 and Type 3 tanks fall somewhere between. Tanks are available in a large range of sizes and configurations. It is also possible to install multiple tanks within one vehicle.
CNG is stored on board vehicles in high pressure (3,000 to 3,600 pounds per square inch) tube shaped cylinders. These cylinders meet very rigorous safety standards. They are made of high strength materials that are designed to withstand impact and puncture. If these tanks are exposed to fire, thermally activated pressure relief devices (PRDs) provide a controlled venting of the gas rather than letting the pressure build up in the tank.
CNG tank capacity is measured in gas gallon equivalents (GGE). Natural gas remains a gas, even when compressed, so a GGE of CNG is calculated based on it having the equivalent energy content of a gallon of gasoline.
Once in service, tanks need to be visually inspected by a certified tank inspector every three years or 36,000 miles (whichever comes first) for signs of damage and deterioration.
Decisions concerning tank choice will depend on various factors, such as available tank space, weight concerns, budget and desired travel range. Your Go Natural representative will be happy to discuss your options with you and suggest a package that will meet your needs.
Type 1 Tanks – All metal (aluminum or steel)
- Low cost, but heavy
Type 2 Tanks – Metal liner reinforced by composite wrap (glass or carbon fiber) around the middle (hoop wrapped)
- Liner takes 50% and composite takes 50% of the stress caused by internal pressurization
- Weighs less than Type 1, but more expensive
Type 3 Tanks – Metal liner reinforced by composite wrap around entire tank (full wrapped)
- Liner takes small amount of stress
- Lighter than type 1 & 2, but more expensive
Type 4 Tanks – Plastic gas-tight liner reinforced by composite wrap around the entire tank (fully wrapped)
- The entire strength of the tank comes from the composite reinforcement
- The lightest weight and the most expensive