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Liquefied Petroleum Gas
LPG engine emissions remain similar whether the engine is cold or hot. Also,
because LPG enters an engine’s combustion chambers as a vapor, it does
not strip oil from cylinder walls or dilute the oil when the engine is cold.
This helps LPG powered engines to have a longer service life and reduced
maintenance costs. Also helping in this regard is the fuel’s high hydrogento-carbon ratio (C 3 H 8 ), which enables propane powered vehicles to have less
carbon build-up than gasoline and diesel powered vehicles.
The LPG delivers roughly the same power, acceleration, and cruising
speed characteristics as gasoline. It does yield a somewhat reduced driving
range, however, because it contains only about 70–75% of the energy content
of gasoline. Its high octane rating (around 105) means that an LPG engine’s
power output and fuel efficiency can be increased beyond what would be
possible with a gasoline engine without causing destructive “knocking.”
Such fine-tuning can help compensate for the fuel’s lower energy density.
Fleet owners find that propane costs are typically 5–30% less than those of
gasoline. The cost of constructing an LPG fueling station is also similar to
that of a comparably sized gasoline dispensing system. Fleet owners not
wishing to establish fueling stations of their own may avail themselves of
over 3000 publicly accessible fueling stations nationwide.
7.8 LPG Safety Aspects
Technology for this fuel is well established, as there are already a significant
number of LPG powered vehicles on the road, using “autogas” filling outlets.
The major hazards are gross leakage under failure conditions of the main
fuel tank (pressure vessel) or piping, fugitive emissions while refueling, and
the potential for small continuous leaks from the installation. During refueling, the LPG is passed through a hose to a self-sealing connector that is
locked onto the refueling connection on the vehicle. The fuel is transferred
until the tank is full, at which point the transfer is stopped. Other hazards
are failure to disconnect the transfer hose before driving away, and leakage
of the self-sealing coupling allowing gas to escape. Icing due to the rapid
boil-off of liquefied gas can also present a hazard if rain-water has entered
the coupling. This can freeze self-sealing or self-locking parts of the coupling, and ice formation can cause a major fire hazard. Prevention by good
design is required, and the currently proposed standards for use with automotive LPG cover these aspects. Three systems coexist in Europe at present,
and adaptors are available at most LPG filling stations to accept nozzles that
are standard in other countries. Within the standards, potential for failure of
the pressure vessel is already well known, and the tank must be fitted within
the main strong section of the passenger cage, so that impacts to the vehicle
minimize the risk of striking the tank.
Liquefied Petroleum Gas
LPG engine emissions remain similar whether the engine is cold or hot. Also,
because LPG enters an engine’s combustion chambers as a vapor, it does
not strip oil from cylinder walls or dilute the oil when the engine is cold.
This helps LPG powered engines to have a longer service life and reduced
maintenance costs. Also helping in this regard is the fuel’s high hydrogento-carbon ratio (C 3 H 8 ), which enables propane powered vehicles to have less
carbon build-up than gasoline and diesel powered vehicles.
The LPG delivers roughly the same power, acceleration, and cruising
speed characteristics as gasoline. It does yield a somewhat reduced driving
range, however, because it contains only about 70–75% of the energy content
of gasoline. Its high octane rating (around 105) means that an LPG engine’s
power output and fuel efficiency can be increased beyond what would be
possible with a gasoline engine without causing destructive “knocking.”
Such fine-tuning can help compensate for the fuel’s lower energy density.
Fleet owners find that propane costs are typically 5–30% less than those of
gasoline. The cost of constructing an LPG fueling station is also similar to
that of a comparably sized gasoline dispensing system. Fleet owners not
wishing to establish fueling stations of their own may avail themselves of
over 3000 publicly accessible fueling stations nationwide.
7.8 LPG Safety Aspects
Technology for this fuel is well established, as there are already a significant
number of LPG powered vehicles on the road, using “autogas” filling outlets.
The major hazards are gross leakage under failure conditions of the main
fuel tank (pressure vessel) or piping, fugitive emissions while refueling, and
the potential for small continuous leaks from the installation. During refueling, the LPG is passed through a hose to a self-sealing connector that is
locked onto the refueling connection on the vehicle. The fuel is transferred
until the tank is full, at which point the transfer is stopped. Other hazards
are failure to disconnect the transfer hose before driving away, and leakage
of the self-sealing coupling allowing gas to escape. Icing due to the rapid
boil-off of liquefied gas can also present a hazard if rain-water has entered
the coupling. This can freeze self-sealing or self-locking parts of the coupling, and ice formation can cause a major fire hazard. Prevention by good
design is required, and the currently proposed standards for use with automotive LPG cover these aspects. Three systems coexist in Europe at present,
and adaptors are available at most LPG filling stations to accept nozzles that
are standard in other countries. Within the standards, potential for failure of
the pressure vessel is already well known, and the tank must be fitted within
the main strong section of the passenger cage, so that impacts to the vehicle
minimize the risk of striking the tank.