LPG Filling: Do we do it right and safe?

There is an issue that has caught my attention for a long time. I take note of the miles I traveled, the liter prices I bought. I noticed that there was playing among them. I read the articles about filling in the forum, but nobody gave information about how filling was done, so I opened the subject.

The problem is this: We have a habit of fuel or fuel oil. For example, before we go anywhere, we fuller the tank.

During the tank filling in LPG, I was wondering, "What is this?" I searched for other local forums and learned that this is a float.

So when I say fulle, the pump in firm X is pressing whatever God gave. My tank is 52 LT. The man does not interfere with the device at all and prints 47.6 LT. Of course, when I go this way, I go 550 KM in the city. It plays at values such as 9L / 100 km. But if you cut it as soon as the sound starts, then it gets 41-42L. Then the range drops to 42/9 = 467 km. They wrote in the forum or something, this is not true. Only 80% of the safe limit is exceeded and the gas pressure is pumped high. That is risky, it may also damage your float.

When I buy it from a Y company, the sound stops filling as soon as it sounds. I guess it already corresponds to 80%.

How do you fill it? Anyone pay attention to this? Doesn't it make sense to cut it safely when the sound sounds?

I would be glad if you share your opinions or even your experiments.

Best regards.