When refueling a vehicle that contains hazardous materials:
The engine should be left on.
The engine should be turned off.
The gas nozzle may be left unattended.
No other vehicles should be at the refueling station.
If you need to refuel a vehicle carrying hazardous materials, you must first turn off the engine. While refueling, someone must be at the nozzle and controlling the fuel flow at all times.