Gas safety valve

A gas safety valve comprising a main body including a longitudinal through hole that defines a gas passage, the longitudinal hole having an inlet end adapted to be communicated with a gas source, an outlet end through which gas from the gas source exits, a first mediate section having smooth walls adjacent to the outlet end and including a shoulder integral therewith to which an end of the spring is attached, and a second mediate section between the first mediate section and the inlet end, a spring being mounted in the first mediate section, and a ball being movably mounted in the second mediate section, the first mediate section having a diameter greater than that of the outlet end, the second mediate section having a diameter greater than that of the first mediate section such that the ball is capable of partially protruding into the first mediate section to block the gas passage defined by the longitudinal through hole, a restraining member including an inlet communicated with the gas source and an outlet end that is unblockable by the ball such that a flow path of said outlet end of said retaining member is misaligned from said longitudinal through hole,

• whereby when no gas leakage occurs, a pressure difference between two ends of the ball is relatively small and thus forces the ball to a position not blocking the gas passage, and when gas leakage occurs, the pressure difference between the two ends of the ball is relatively high and thus forces the ball to move toward the outlet end of the main body and thus blocks the gas passage by partially protruding into the first mediate section.