The CNG Cylinder, which stores the compressed natural gas, is one of the safest factors of using CNG as an alternative fuel.
The idea of natural gas being compressed to 3,600 psi and stored in a vehicle tends to frighten some people away. They're afraid of rupture or explosion, when in fact, the likelihood of either of those occurring is far slimmer with a CNG Cylinder than it would be with a gasoline or diesel tank.
Wise Gas, Inc. only works with approved CNG-cylinders. Our team is willing to inspect unapproved cylinders for consideration of pursuing approval certification, however, we will not install, repair or provide fuel to any vehicle using an unapproved cylinder for safety and legal reasons.
There is nothing scary about CNG or the cylinders that they are stored in. The fact is that CNG cylinders are put through exhaustive and extreme tests which include firing bullets at the canister, roasting it over a roaring bonfire and impact tests in which a crane drops the cylinder at multiple impact points. Compare this to the 1/16th of an inch thick, or plastic, gasoline tanks in today's vehicles containing a much more flammable and toxic substance.
It is, however, important to understand the cylinder and the basic safety facts - just as it's important to understand an electrical outlet in your home so that you don't stick a fork into it.
When using CNG, you ONLY want to use the proper authorized cylinder. NEVER TRY TO PUT CNG INTO ANY OTHER TYPE OF CYLINDER! CNG is more highly compressed than other options, like propane - putting CNG into a Propane cylinder, for example, would be (and has been) disastrous.
The general rule of thumb with CNG cylinders is the lighter the tank, the lighter your wallet - meaning lighter cylinders are more expensive.
There are 4 types of CNG Cylinders:
Type 1: Entirely made of metal (either steel or
aluminum). This is the most cost-effective, but heaviest choice.
2. Type 2: Metal liner reinforced with composite wrap (either glass or carbon fiber) around the middle of the cylinder ("hoop wrapped"). The liner and the composite each take 50% of the stress caused by internal pressurization. These cylinders are lighter than Type 1 cylinders, but more expensive.
Type 3: Metal liner reinforced with composite
wrap (either glass or carbon fiber) around the entire tank ("full
wrapped"). These tanks are lightweight, but more expensive than
Types 1 or 2.
Type 4: Plastic gas-tight liner reinforced by
composite wrap around the entire tank ("full wrapped"). The entire
strength of the cylinder is composite reinforcement. This is the
most lightweight tank, and likewise the most expensive in comparison to
Types 1, 2 or 3.
CNG CYLINDER TESTING:
The testing that CNG Cylinders undergo is extreme and should reassure even the biggest worrier.
CNG Cylinders: Fires & Collisions:
This photo shows Type 2 CNG Cylinders involved in a bus fire caused by an Engine Fire.
Note the 3 CNG Cylinders lying on the ground beside the bus and 2 on the roof of the bus, blackened and charred, but in tact and not ruptured.
This Natural Gas Civic was involved in a severe collision and crushed to just behind the driver's seat. (Remember that in most cases, CNG Cylinders are stored in the trunk or behind the rear seats).
The driver walked away.
There was no leak and no rupture of either the CNG Cylinder or the CNG Fuel System. Note the absence of any burn marks or scorch marks.
This CNG Vehicle was hit at a speed over 50 miles per hour by a gasoline-powered vehicle.
The Gasoline tank ruptured on the gasoline-powered vehicle and ignited, spreading flames across both cars.
The CNG Cylinder (shown in the
photo) safely vented the CNG into the atmosphere. The tank did not
explode or rupture.
Strobe-style headlights had been installed on this city-owned vehicle and caused an electrical fire. The entire cab and bed of the truck was engulfed in flames. The driver walked away, unharmed.
The plastic covering over the CNG Cylinder melted and burned away, exposing a large CNG Cylinder directly to the flames.
As you can see in this photograph, and the following images, the tank remained perfectly intact. No rupture or Explosion.
This photograph shows a closer look at the exposed CNG Cylinder and melted protective covering.