67
Fahrenheit. (NOTE: Most fill stations have a dome valve to automatically make the temperature correction.)
When fueling is complete, open the fill connector purge valve. Use only fuel filling couplings designed for
use with the CNG. Do not force damaged couplings together.
CAUTION: A check valve is included in the system behind the fill connector to prevent backflow of fuel
when purging and disconnecting the fuel nozzle
NOTE:
The tanks are full at 3000 psi or 3600 psi and 70 degrees Fahrenheit. The pressure will vary with
temperature. Decreasing with lower temperature and increasing with higher temperatures. Filling appara-
tus compensates for the temperature effect.
WARNING: Never fill to more than permissible pressure. Contact the manufacturer if an accidental
overfill occurs.
NOTE:
The fuel level is only accurate for tanks that are open. For example, if one tank is open and reads 1000
psi, then the fuel available to the engine is proportionate to the total capacity.
SPECIFIC GRAVITY
The specific gravity of natural gas relative to air (air=1.00) is 0.56 to 0.62 depending on gas composition.
This indicates that natural gas is lighter than air. In the event of a natural gas leak, the gas will rise and
dissipate given open conditions. There is no possibility of CNG accumulating in pools on the ground beneath
a spill.
NOTE:
Natural gas odorants allow its detection by humans before dangerous concentrations are reached.
In the case of LNG releases, the cold vapor initially released is heavier than the surrounding warmer air
and thus stays low, near the ground (a visible vapor cloud is often formed from the condensation of water in
the cold air-gas mixture). As the vapor cloud warms, it will increase in volume, become lighter than air, and
rapidly dissipate.
FUEL TOXICITY AND SAFETY
Natural gas is a nontoxic gas. It is flammable under proper conditions. Additionally, it can cause suffoca-
tion if enough oxygen is displaced. LNG has the added safety concern of being a cold (-260
o
F) liquid under
pressure. Severe frostbite may occur from contact with LNG or associated cold components. Furthermore,
many common materials change their strength characteristics when exposed to LNG temperatures, thus pre-
senting additional hazards.
WARNING: LNG tanks have the potential for explosions under circumstances such as those described
for LPG explosions.
Although natural gas has odorants to aid in detection of leaks, these odorants are removed during lique-
faction, thus LNG vapors can not be detected by smell. (NOTE: LNG odorants have been developed but are
not commonly used due to the relatively restricted use of LNG at this time).
FLAMMABILITY
Autoignition temperature for natural gas at atmospheric pressure is 1004
o
F compared to an autoignition
temperature range of 442 to 880
o
F for gasoline and approximately 500
o
F for diesel fuel. The risk of fire in the
presence of an ignition source exists when the ratio of air to fuel is within flammability limits (i.e., fuel can not
ignite if it is mixed with too much or too little oxygen). The flammability limits for natural gas are 5.3 to 15%
volume of gas in air. For comparison, the flammability limits of unleaded gasoline are 1 to 7.6% volume of
gasoline in air. As a practical matter, there is no oxygen present in CNG cylinders or LNG tanks, therefore
Содержание TC/2000
Страница 1: ...Owner s Manual TC 2000 ...
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Страница 106: ...105 NOTES ...
Страница 111: ...Part Number 1919331 Blue Bird Corporation P O Box 937 Fort Valley GA 31030 ...
