Gas regulator pressure When I open the gas regulator, it pushes the pin and depress the valve in the cylinder which releases the gas out (am I right on this?). If that is the case, is gas released even when there is no hose attached to it? Assuming valve is on/open mode. Why or why not? What is the physics behind this?
This is my gas regulator.
 A: Most gas valves have a hose-leak-interrupter that stops the flow of gas if it exceeds a certain amount of flow.
The principle is very simple. In the flow path, a valve is installed that can be shut by the dynamic gas pressure and kept shut by the static gas pressure, provided the first overcomes the force of a spring pushing the valve open against the flow. Since the dynamic pressure raises with the flow, a torn hose will cause it to do so. It does not protect much against leaks due to porosity, so keep an eye on your hoses.
Taking the entire regulator assembly off the bottle allows the static pressure to escape and the interrupter to reset. Different regulators have different variations of this principal.
In any case, RTFM like its a life style. Being born and raised in the absolute undisputed number one gas loving nation on the planet and having first hand experience with almost everything that can go wrong with it, I can assure you its the best advice anyone can possibly give you.
BTW The regulator you referred to has such a safety device. Its a Malaysian regulator of a well established brand, mainly used on cooking equipment in preparation of street food, which is big business in that part of the world.
