LPG (Liquefied Petroleum Gas) is a mixture of hydrocarbons consisting predominantly of a mixture of propane and butane, obtained by refining the petrol or directly from the extraction after it has been separated from the natural gas or oil with which it is mixed in petroleum fields.
The LPG is clean, does not contain water or other impurities, has a complete combustion and does not generate deposits on pistons, segments and spark plugs. In order to prevent and minimize fuel hazard, the LPG industry has developed a series of standards and rules in the design, production, and installation of components and equipment, which are constantly adapted to technological developments.
Liquefied Petroleum Gas is a safe and clean fuel that has been used for years for cooking and heating. It is non-toxic, non-poisonous and does not contaminate water and soil.
LPG has the smallest flammable radius of alternative fuels. Moreover, the ignition temperature is less than half that of gasoline. The autogas has a closed system in which there are valves that shut off and transport the fuel from the pump to the tank without exposure to the environment, which prevents leakage and evaporation.
The components of this system have been designed and manufactured for the perfect equipment of the vehicle, without altering the original operating mode. The development of the technique has led to solutions able to overcome all problems related to the use of gas in any kind of vehicle.
Recent innovations have introduced substantial improvements using the oxygen sensor for LPG as well. This device, used by “green” cars analyzes the exhaust gas and provides information to a microprocessor that, through a linear dispenser with motor (step by step) manages to ensure the correct process of mixing the fuel with the air at any time with notable advantages for reducing pollution, duration of use of catalytic converter and oxygen sensor as well as fuel economy.
In addition, major car companies are directly involved in the development and production of ultra-ecological engines, one of the immediately applicable solutions being the equipping of motor vehicles with LPG fueled engines.
Disadvantages, such as reduced space in the boot, the initial price of the installation, the dynamic performance of the car with approximately 10% lower, they are fully compensated by the economic, ecological and safety advantages offered in operation.
The main components of a gas car installation are presented below.
The reducer is an electro-pneumatic device with double pressure control, which allows the reduction and vaporization of the liquid gas coming from the tank so that it ensures a stable supply of the engine with a flow of gas suitable for the different conditions of use. The gas comes from the tank in a liquid state, with a pressure of 5-10 bar and is reduced in the first stage to 0.8-1,2 bar. The second stage allows to supply, depending on the depression created in the suction gallery, the adequate amount of gas.
2) LPG solenoid valve
It is a device that is mounted between the tank and the LPG reducer, which allows the gas flow to be blocked to the reducer when passing on gasoline. It also has the role of filtering the gas from impurities.
3) The switch
It is the device that allows the fuel to be selected to use LPG or gasoline. There is a wide range of such devices, which may or may not have indicators, to indicate the fuel level in the tank. Switching from gasoline to LPG is made by simply pressing a button or automatically (in case of injection).
4) Electronic control and control module
It is the electronic device equipped with a microprocessor that is programmed to check the signals from the oxygen sensor and the TPS acceleration sensor and which is able, with the help of the stepper motor, to manage the amount of gas sucked by the engine, so that they are maintained and in good operating conditions
The regulation of the carburetion is completely automatic, thus the correct parameters for the process of mixing the fuel with the air are stored and if necessary, depending on the operating conditions, the necessary corrections are made and the correct air/gas ratio is maintained.
5) The emulator
It is the electronic device that interrupts the voltage supply of the injectors, thus shutting off the gasoline supply when passing on the LPG.
6) The mixer
It is a mechanical device that, using the Venturi principle, ensures the correct air/fuel mix, both in dynamic and static conditions. depending on the position of the throttle.
Each mixer is specially designed for each type of motor vehicle part to ensure, together with an editor, optimum functioning both on gasoline and on LPG.
7) LPG tank
The LPG tank is the mechanical device that allows the storage of the LPG, being firmly fixed by the car body with metal straps. It does not change like a gas stove, but it is filled by the LPG fueling device at stations that have LPG skids.
The tank is made of 3.5 mm material chemically treated to avoid cracks in the event of an accident, it is equipped with a group of valves that prevents the filling with more than 80% of the capacity, thus allowing the gas to expand in case of high temperatures.
The tanks are equipped with multivalve valves with overpressure valves that open at pressures greater than 25 atm., leading the gas on the vent line outside the trunk, to the outside of the car.
The working pressure is 2-8 atm. (winter and summer). There is a wide range of tanks and different locations: cylindrical tanks:
- In the trunk, indoor toroidal tanks;
- In the trunk instead of the spare wheel;
- Exterior toroidal tanks;
- Under the car instead of the spare wheel.
- Cylindrical tanks – indoor and outdoor toroidal tanks
Multivalve is actually a mechanical group made of bronze and other gas-resistant materials, which is visibly mounted outside the tank and which has the role of limiting the supply to 80% of the capacity tank.
This system has a solenoid valve with the role of blocking the gas in the tank when the power supply is interrupted. LPG, inside, a suction for supply, as well as two valves with manual actuation with the role of the permanent closing of the multivalve.
9) Sealed housing
It is the watertight housing mounted on the multivalve tank assembly, with the role of eliminating any possible gas leaks from the installation.
10) The power supply device
It is a device with a check valve, made of bronze alloy connected to the multivalve through a plasticized copper tube, with the role of ensuring the filling of the gas tank.
The feeding is done with a special gun that is hermetically coupled to the mouth of the fuel, the losses of fuel in the environment being zero.