Precautions while filling the tank to FULL

The guy at the pump can't control the flow of the fuel coming out? What are you saying? I have been filling petrol at various petrol pumps (especially HP and Indian Oil) and always get it filled at a steady pace. But, yes I go late night generally for filling when there are not too many people in the queue. Most of the pump guys fill as per my instruction. In fact I have noticed it, when I get petrol filled normally, they take not more than 50-60 seconds to pump 35liters out while as per my instruction the filling take a little over two mintures. How?

Sensors of dispensers automatically slow down, the moment it detects the level of tank. It exists since last few years...

What was exact problem he came across ?

that's gr8 !!

@Kiran,

What if I say the flow of fuel is low from starting itself. And the guy filling the petrol doesn't do anything on the handle side (maybe some button on the control panel?). But I am sure All of them have a slow-mode. Many a times, the filler guy puts the nozel in a way that it resides perfectly inside fuel inlet section. He starts filling and then walks away. The dispencer keeps filling slowly until it reaches to a threshold (probably 95%?).

All petrol dispenser nozzles have variable locks for variable fill rates.

Here is brief about modern fuel dispenser:-

In older pumps, the turbine is physically coupled to reeled meters (moving wheels with numbers on the side).

1. Newer pumps turn the turbine's movement into electrical pulses using a rotary encoder.
2. An auto cut-off feature stops flow of fuel once the tank is full. This is done by having a second mechanical tube [First tube is computer used for commercial processing],  the sensing tube, runs from just inside the mouth of the nozzle.
3. While the tank is being filled, air displaced from the tank is drawn up this tube. Once the fuel level reaches the mouth of the sensing tube, air is no longer drawn up the sensing line.
4. A mechanical valve in the pump handle detects this change of pressure and closes, preventing the flow of fuel