The reducer-evaporator is an element of the installation responsible for the change of the fuel state. For this purpose, it uses heat from the cooling system, to which it is connected in series. In the reducers currently used, a common equipment is a temperature sensor, thanks to which you can switch to LPG in case, when the engine does not reach the correct operating temperature. Switching to LPG in an instant, when the coolant temperature is below 30 ° C, could enter the LPG mixer in the liquid phase, which in turn would lead to an over-enrichment of the mixture and "flooding" of the engine.
In the line that connects the air filter and the manifold, just before the throttle, a mixer is mounted. Its construction, shape or expenditure are individual features depending on the type of engine. Evaporated LPG fuel (gas phase) it is transferred from the reducer to the mixer via a conduit, on which a needle valve that regulates the gas flow is mounted, controlled by a stepper motor.
The degree of valve opening is determined by the microprocessor of the central unit controlling the operation of the LPG system. The ignition map for the gas operation mode was also determined.
So that it is possible to run on gas fuel, it is necessary to cut off the gasoline supply system. Modern engines are equipped with auto-diagnosis systems, which would then detect "malfunction" of the injectors and prevent the engine from working. Therefore, LPG systems require the use of emulators, simulating the work of the injectors. Similarly, the control system of the gas installation "looks after" the Lambda probe. The fuel type is changed by switching the switch of the central unit located in the vehicle cabin.
Single-point LPG supply in the case of plastic intake manifolds poses the risk of their damage due to recurrent explosions. So, discharge valves are used – safety, discharging the high pressure created in the collector.
Third-generation installations are free from recoil explosions, supplying fuel just before the intake valves, separately for each cylinder. Currently, fully functional devices of this type are offered by the Koltec company, are mounted, among others. as factory equipment for Peugeot 406 LPG, which are only produced for a very specific engine management computer model, which seriously limits the possibility of their non-factory assembly. LPG installations with multi-point power supply are more expensive than second-generation installations. This is the result of the complexity of their construction, e.g.. by using a divider, dosing fuel to each of the cylinders.