Characteristics of LPG
Liquefied petroleum gas (LPG), is the generic name for liquid
propane, a by-product of natural gas processing and petroleum
refining. LPG is a liquid mixture of at least 90 per cent
propane, 2.5 per cent butane and higher hydrocarbons, and some
ethane and propylene. It has the special property of becoming
liquid at atmospheric temperature if moderately compressed, and
reverting to gas when the pressure is sufficiently reduced.
This feature makes it easy to store and transport.
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Benefits of LPG
Excellent safety record
(see
Safety of LPG)
Minimal performance differences
(see
Performance of a vehicle running on LPG)
Considerable savings:
about half the fuel cost compared to petrol, with
negligible engine change. Also, in some cases LPG vehicles
qualify for cheaper road tax.
Environmental benefits:
when burned, LPG produces less carbon and nitrogen oxides and
unburned hydrocarbons than petrol or diesel oil, without
generating any aromatic hydrocarbons or sulphur dioxide. It has
about 50 per cent of the ozone-depleting potential of gasoline,
which means that the damage factor is reduced by half. Further,
the reduced level of particulate emission during combustion
implies less smoke, haze and smog in cities. In fact, LPG
vehicles are given the possibility of travelling in historic
centres during traffic bans due to pollution levels. You even
get a quieter ride: noise level are 50% less than with diesel
engines.
Longer life of the engine:
engine life is 50 per cent longer. This as a result of reduced
cylinder bore wear during cold starting since LPG does not wash
oil off the cylinder walls and the lubricating oil has a longer
life. Furthermore, LPG burns without leaving any engine carbon
deposits that lead to premature wear and extends the service
life of spark-plugs, valves and pistons.
Wide availability.
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Performance of a vehicle running on LPG
Minimal performance differences.
Very slight increase in the specific consumption compared to
petrol (it can change from 10% to 20% according to the engine
specifications).
A loss of power of roughly 4-7%, which translates into a loss of
speed of roughly 3%.
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Safety of LPG
The European regulations ECE/UN 67/01 guarantees safety
standards that even exceed those of petrol and diesel engines.
Tanks and systems used with LPG are to be tested at a pressure
of 30 bar even though the operating pressure oscillates between
3 and 6 bar. The cylinders must be equipped with a safety device
that allows the gradual outlet of fuel to eliminate the risk of
explosion. All components are not only subjected to functional,
dimensional and duration tests, but they are also put through
fire tests under extremely critical conditions.
In fact, the results of crash and fire tests show that in most
cases the LPG tank is safer than the petrol tank. Further, to
give LPG the space to expand, the tank cannot be filled above 80
per cent of its capacity.
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Filling up with LPG
Like diesel and petrol, LPG is stored as a liquid, purchased by
the litre and pumped into your fuel tank through a hose
Refuelling is carried out by inserting a special nozzle into the
gas filling point on the side or in the back of the car. The
shape of the gas filling point
differs in various countries (coupling type in Italy, bayonet
in Holland, and ACME for the United States, Canada, Germany,
Great Britain, Ireland, Austria and Belgium). It is possible to
fill 80% of the tank.
You can’t accidentally add petrol or diesel to the LPG gas tank
because only the LPG hose nozzle fits the car’s LPG filling
point.
Just like cars run on conventional fuels, LPG cars have a fuel
indicator. It’s built into the switch on the dashboard that
allows you to change-over between petrol and LPG.
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Engines that
can be converted to LPG
The LPG conversion systems can be installed on all types of
engines of petrol-powered cars: carburetted or injected, with or
without catalytic injection. The real important point is that
the car to be converted must run efficiently on petrol. In
particular, the ignition and electric system should be checked
before installing the system.
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Maintenance
No particular maintenance is needed. It is recommended to follow
the routine maintenance program with special attention focused
on the ignition and electric system.
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Characteristics of CNG
Compressed Natural Gas (CH4) is a mixture of hydrocarbon gases
that occurs with petroleum deposits, principally methane
together with varying quantities of ethane, propane, butane, and
other gases.
CNG is the ecological fuel and one of the most abundant found in
nature.
In fact, because it has no impurities, sulphur, lead compounds
or aromatic hydrocarbons, it generates a very limited amount of
polluting exhaust emissions that are odourless and contain no
particulates or combustion residues.
Thanks to its chemical composition, natural gas produces much
less CO2 than other fuels. It also reduces the formation of
ozone in the atmosphere and extends engine life.
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Benefits of CNG
Considerable savings:
about one third the fuel cost compared to petrol, which
translates into an actual saving
of roughly 50/60% compared to petrol.
Excellent safety record
(see
Safety of CNG)
Minimal performance differences
(see
Performance of a vehicle running on CNG)
Environmental benefits:
The cleanest fuel on the market.
It’s given the possibility of travelling in historic centres
during traffic bans due to pollution levels
It protects the engine:
the fuel is clean and therefore leaves no deposits in the
engine. Longer life of the lubricant oil. The use of a gaseous
mix, with strong knock suppressing power, translates into a
general improvement of the running conditions of the engine.
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Engines that
can be converted to CNG
The CNG conversion systems can be installed on all types of
engines of petrol-powered cars: carburetted or injected, with or
without catalytic injection. The real important point is that
the car to be converted must run efficiently on petrol. In
particular, the ignition and electric system should be checked
before installing the system.
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Performance of a vehicle running on CNG
Very slight increase in the specific consumption compared to
petrol (it can change from 10% to 20% according to the engine
specifications).
A loss of power of roughly 10-15% which translates into a loss
of speed of roughly 6%.
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Safety of CNG
CNG is much safer than traditional fuels: considering that it is
lighter than air it is rapidly dispersed upwards in the case of
leakage.
It does not ignite easily (the concentration of gas in the air
must be greater than that of traditional fuels).
Its self-igniting temperature is 540° compared to 228° of
petrol.
It is output at 200 bar, even if the cylinders in which it is
stored are tested at 300 bar and their resistance is tested at
up to 450 bar. All the components making up the system that
are subject to pressure are homologated and strictly tested at a
pressure of three times that of their normal working pressure.
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Filling up with CNG
Natural gas can be pumped by attaching the special connector to
the car’s refuelling valve. The types of connectors on the
market differ in various countries.
In most cases the filler valve is located in the engine
compartment, but may also be mounted on the exterior of the
vehicle.
Normally, natural gas is used at an operating pressure of 220
bar.
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Maintenance
No particular maintenance is needed. It is recommended to follow
the routine maintenance program with special attention focused
on the ignition and electric system.
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