The fuel nozzle (Nozzle) of the fuel pump can also have other control functions by using the equipment that is installed on it. For example, the fuel pump nozzle can be equipped with a mechanism that does not allow fuel to pass until the nozzle is inside the tank filler pipe. Or some nozzles are equipped with a pressure sensor that does not allow fuel to pass through the nozzle until the fuel system reaches the appropriate pressure.
The last two control functions presented above are fully automatic and do not require operator intervention. When the nozzle is closed, the fuel flows only in parts of the suction pump, and the outlet valve is the nozzle that directs the flow of fuel to the entire fuel transfer system. This valve should also adjust the amount of fuel flow out of the nozzle. Therefore, its opening interval should be continuous.
Also, dispensers used in fuel stations should be equipped with an automatic cut-off device that prevents overfilling of the tank. The use of these valves reduces the possibility of the tank tipping over and spilling fuel on the ground, which is very dangerous.
Fuel vapor transfer method
Transferring fuel vapor to the tank is possible in two ways. In a steam method, the fuel is transferred from the tank to the tank by creating a small negative pressure in the tank and a small positive pressure in the car tank. But in another method, we take the help of a vacuum pump and the fuel vapor in the tank is sucked by the pump and transferred to the tank.
As you can see in the figure, the nozzle for each of these models will be different. A nozzle that works with a vacuum pump has a smaller hose that does most of the job of a funnel, and there is no need to tightly seal the nozzle to the vehicle's tank. Due to the small positive pressure inside the tank and negative pressure inside the tank, they usually use the second method, that is, a vacuum pump.
It is difficult to recognize the nozzles of the Kahab design that use the suction system. Because some of these models do not even have a hose and there are only holes in the head of the nozzle through which steam is sucked and transferred to the dispenser by a thin tube coaxial with the nozzle tube. Therefore, in this model, we have a smaller hose than the model without a vacuum pump.