Natural Gas Vehicles, General
Information
The vehicle can be equipped with a compressed
natural gas (CNG) fuel system, or a liquefied natural
gas (LNG) fuel system. CNG is made by compress-
ing natural gas to less than 1% of its volume at stan-
dard atmospheric pressure. LNG is created by con-
densing natural gas into a liquid by cooling it to
approximately -259°F (-162°C).
When vaporized at ambient temperatures, natural
gas is less dense than air, and it rises and disperses.
However, LNG is initially heavier than air due to its
cryogenic temperature. When released in large
amounts, it may drop or pool on the ground before
its temperature rises enough to vaporize. Cold at-
mospheric conditions may prevent natural gas from
dispersing quickly when released in large amounts.
Natural gas is nontoxic, but it can cause asphyxiation
if present in very large concentrations.
CNG often contains an odor-producing chemical,
while LNG does not have any odor. Users of natural-
gas-fueled vehicles should never expect to detect
natural gas leaks by scent.
For natural gas to burn, it must first vaporize, then
mix with air in the proper proportions (flammable
range is 5 to 15% by volume in air), and then be
ignited.
A typical natural gas fuel system consists of:
•
Fuel supply cylinders that store compressed
gas at high pressure (CNG), or a tank that
stores liquefied gas at an extremely low tem-
perature (LNG).
•
A vaporizer or heat exchanging device that
changes LNG to gaseous form (LNG fuel sys-
tems only).
•
Pressure relief and manual fuel shutoff valves.
•
A filling connection with a check valve that pre-
vents the gas from flowing back out of the fuel
filling line.
•
High-pressure and low-pressure fuel filters.
•
A pressure control regulator that reduces the
high fuel tank or cylinder pressure to the lower
pressure needed for the engine.
•
A fuel contents gauge that indicates the fuel
supply in the tank or cylinders.
Figure 25.1
shows the locations of various compo-
nents of a CNG installation.
Natural Gas Vehicles, Safety
Precautions
DANGER
Natural gas is highly flammable. Failure to ob-
serve the following safety precautions could lead
to the ignition of the natural gas, which could
cause serious bodily injury or death.
CNG systems should be maintained and inspected
exclusively by trained personnel with certifications in
accordance with the applicable codes. As with all
pressure vessels, CNG storage and fuel delivery sys-
tems are inherently dangerous and should be treated
as such. Individuals involved in any aspect of CNG
fuel system maintenance, emergency response, ser-
vicing, or testing must be properly trained and certi-
fied. Individuals who are not trained and certified in
all aspects concerning CNG fuel delivery systems
are not permitted to service, maintain, test, or inspect
a system in any way.
Follow these safety precautions when operating or
repairing a natural gas vehicle.
•
Only certified LNG personal can fuel LNG
trucks.
•
Do not start the engine if a natural gas leak is
detected.
•
Transferring fuel is only allowed as long as a
non-static hose is used. if a non-approved
hose is used, static can build up and ignite the
fuel. A correct hose can be obtained through
Agility fuel systems.
•
Do not attempt to cut any fuel supply piping
components.
•
Avoid open flames or sparks near a natural
gas vehicle.
•
Cover eyes and exposed skin when working on
a natural gas fuel system or fueling a natural
gas vehicle.
Natural Gas Vehicles
25.1
Summary of Contents for cascadia
Page 1: ...Driver s Manual CASCADIA Part Number STI 478 Publication Number STI 478 6 ...
Page 106: ...9 Cab Features Windows 9 1 Mirrors 9 1 Cab Amenities 9 1 Sleeper Amenities 9 2 ...
Page 163: ...16 Drive Axles Differential Locks 16 1 Two Speed Drive Axles 16 2 ...
Page 167: ...17 Steering System Power Steering System General Information 17 1 Power Steering Systems 17 1 ...
Page 180: ...19 Trailer Couplings Air Suspension Dump Valve 19 1 Holland Trailer Coupling 19 1 ...
Page 229: ...26 Specifications Fuses and Relays 26 1 Replacement Bulbs 26 3 Fluids and Lubricants 26 4 ...