It is to shut off the gas stove gas tank valve or the first main valve?

First off gas gas stove valves, then close the main gas tank valve!
Stove tempering problem mostly occurs on artificial gas (gas) stove (liquefied petroleum gas, natural gas stove safety tempering phenomenon is rare). Artificial gas stove and no valve. Tempering: When the speed of the gas leaving the fire hole is less than the burning speed, the flame will be retracted into the fire hole inside, resulting in a mixture in the combustion burner, heating, undermine the primary air ejector, and the formation of incomplete combustion. Tempering will destroy combustion stability, and easy to damage the stove.
Tempered with a degree preheated air coefficient, gas source nature, components and gas-air mixture, the fire hole diameter, fire orifice discharge velocity.