Who counts the residual oil in the fuel hose?

The pipe of the refueling machine is so long that a part of it is still dragged on the ground when refueling, so a part of the gasoline must remain in the pipe after the end of refueling. And the metering mechanism of the refueling machine must be in the machine, which means that we have paid for this part of the gas in the pipe, but it is not added to the tank, we are not at a loss?

Before because of this thing also made jokes, refueling in order not to lose money, refueling in the front, we hold the pipe in the back, trying to put the oil in the pipe “along” into the tank.

In fact, we do not have to worry, there is oil in the fuel pipe, but that part of the oil does not belong to us, so we are not at a loss. Just talk about it, let’s talk about why it doesn’t hurt.

The following is a cross-section of the fuel gun, we only look at the handle, the main valve and the auxiliary valve on the line, the other is the control of the jump gun structure, the principle is a little complex, have the opportunity to talk about it.

When there is no vehicle refueling, the refueling gun is hung on the refueling machine, and this section of the pipeline from behind the auxiliary valve to the inside of the refueling machine is full of gasoline. You don’t have to worry about the gas leaking. It won’t. Because there is a spring behind the auxiliary valve, the seal is very tight, and the gasoline can not run out.

Now someone’s coming, set up 50 liters of 92 on the pump. If you’ve ever pumped gas, you know that the tanker starts buzzing after the fuel operator sets the number of liters, and that’s when the tanker starts pumping gas. But because the main valve is still closed, the gasoline still can’t get out. As can be seen from the figure below, the higher the gasoline pressure, the tighter the main valve is closed.

Now we press the handle, the main valve opens, the huge pressure of the gasoline suddenly pushes the secondary valve open, and the gasoline can flow out smoothly. From the moment the gasoline flows out of the auxiliary valve, the oil in the oil path also begins to flow outward at the same time, and the metering device of the refueling machine begins to count.

After adding enough 50 liters of oil, the metering device will disconnect the power supply of the oil pump, the gasoline in the fuel gun loses pressure, the auxiliary valve is closed under the action of the spring, the gasoline that has flowed out of the auxiliary valve continues to flow out under the action of gravity, and the gasoline behind the auxiliary valve is sealed in the fuel gun. Even if you do not release the handle, the gas will not continue to flow. Because the pump has been stopped, there is no pressure on the gasoline, and the secondary valve cannot be opened.

It can be seen from this process: before we refuel, the gas gun and the pipe are full of gasoline, and the gasoline is released immediately after pressing the handle. This is when the metering device starts counting liters. The metering device counts how much gas comes out of the gun, so there’s no shortage. The gas in the tube belonged to the gas station all along.