So outside we have a gas grill. There is a valve to turn when you want to use it. U can only hear the gas going when u turn the burner knobs but say u left the valve open and no knobs turned at all for 5 hours is gas escaping or does it only escape when the grills knobs are turned? Thanks
To answer your question directly, as long as the valve is open gas will continue to flow until its turned to the off position.
The valves on the grill itself are the ones that allow the gas to flow. As long as you have no leaks between the main valve and the grill valves, no gas will flow when the valves on the grill are turned to the off position.