All components we use at LPGain are compliant with the Road Traffic Regulations, Irish standards IS 404 and highest safety standards.


The principle components of the system are:
1. Filling Valve: The filler valves can be fitted into the body work of the car or if space allows
inside the petrol filler cap.

LPG Filling valve mini  LPG_filling_valve_-_Dutch_bayonet
2.Tank: Filled with liquid phase LPG at the filling station with a pressure of around 15 bar. The tank is in made of high resistance electro-welded steel and
thermally treated in order to avoid fractures in the event of an accident. Toroidal tanks are now commonly used because they can be placed inside the hole for the spare tyre, but cylindrical tanks are also used.

Sizes and types of LPG tanks

     LPG toroidal tank  LPG tank toroidal vertical  LPG tank cylinder  lexus_rx_300_1_20130807_1145334752
3. LPG Tank Valves: Valves fitted to the tank allows gas to enter the tank through the filling valve and automatically stops filling when the tank is 80% full. There is a level indicator plus a manual service tap with a solenoid valve which closes when not running on lpg or when the engine is not running. A pressure relief valve stops excessive pressure build up in the tank .
All the valves are enclosed in a sealed sub compartment to avoid any gas leaking into the car (not necessary when the tank is mounted outside the car).


1/ Fuel level gauge. Electronic level indicator. The level indicator should be chosen according to the adopted ECU system.

2 / Non-return valve at the inlet. The non-return device is equipped with a double safety system: the first non-return valve is integrated in the 80% filling limiter,, the second device is located in the inlet fitting. These devices are aimed to avoid the back flow of gas from the tank toward the outlet of the filling device

3/ Pressure relief valve (PRV). The PRV is a safety device aimed to limit the maximum pressure inside the tank to 2.7 ± 0.1 MPa. The PRV is a valve with a retaining spring allowing, in case of overpressure, the discharge of the LPG from the tank in vapor phase. Pressure relief device is a safety device equipped with a thermo fuse element which melts at a pre-set temperature of 120 ° C ± 10 ° C. In case of fire, the fuse melts and opens a hole for the fast release of the LPG from the tank, preventing the risk of an explosion.

4/ Manual valve. The manual valve intercepts the outlet gas circuit upstream of the solenoid valve and is aimed to the maintenance of the solenoid valve. Excess flow valve is located in the withdrawal circuit , upstream the solenoid valve and is aimed to block the flow of LPG in the event of an accidental breakage of the LPG piping . After its intervention, for the automatic resetting of the valve, a residual flow is allowed.

5/ Shut-off solenoid valve This device is aimed stop the gas flow when one of the following conditions occurs: the engine is switched off or is working in petrol and the electric supply to the solenoid is switched off; in this condition, a spring inside the solenoid valve maintains the moving core in the closing position; while switching to LPG, the electric supply to the solenoid is switched on and the solenoid generates a magnetic field that attracts the plunger, allowing the opening of the multivalve hole and, consequently, the LPG flow.

FLOAT  Multivalve

Multivalve inside  Mulivalve in tank  LPG tank toroidal vertical
4. Reducer: Vaporises the gas from the liquid phase thus reducing and then stabilising the pressure to the optimum level for the injection rail. Fitted with an safety electrovalve which closes the circuit when the engine is switched off.

Reducer  Reducer prins
5. Gas Filter: Guarantees a flow of gas without impurities and oily residue to the rail and thus the cylinders. In the PRINS system it also has temperature, pressure and MAP sensors which optimises the function of the system. In STAG autogas systems the MAP, pressure and temperature sensor is separate installed after gas phase filter.

LPG filter  Filter liquid phase  Prins Filter
6. LPG injectors : Controlled by the ECU the rail injects the correct quantity of gas into each cylinder via injector operated in phase with the motor. We should always install the most accurate injectors.

keihin-kn9    SAMSUNG DIGITAL CAMERA  LPG injectors STAG_AC_STAG_AC_W02_i_W03


7. Gas/Petrol Changeover Switch: Allows driver to switch between gas and petrol and shows the level of gas held in the tank using a series of LEEs.
During normal operation the car starts on petrol and switches automatically to LPG without the driver noticing. This changeover happens when the water circuit reaches the requested temperature
(around 30-40°C). If ever the LPG runs out, the system switches automatically to petrol and alerts the driver with a bleep.

switch STAG  switch prins  switch eco

8. ECU (Electronic Control Unit): The gas ECU communicates with the petrol ECU and via signals received from the systems sensors, controls the gas injector by calculating the quantity of gas to inject and time of injection. The ECU is tuned during installation to the specific characteristics of the engine and is fitted with an auto learning programs which modify the parameters in function of how the car is driven or wear in the engine.

qmax  prins-vsi-2-ecu