The subject invention pertains to an automatic fluid-mechanical actuated emergency stop valve for inhibiting fluid flow following a catastrophic rupture or other failure in a fluid delivery system carrying a fluid from an upstream source to a downstream destination. A fluidic stop valve which responds to a sudden downstream pipe rupture by closing is provided. The operating mechanism relies upon an increased Bernoulli force acting on a mass opposing a vacuum force tunable by a secondary flow damper. When the mass experiences sufficient Bernoulli force it is then brought up into position to block further fluid flow through the stop valve. The sensitivity of the stop valve to ruptures or sudden flow increases can be tuned by geometric parameters, the stop mass density, and an adjustable setting of the secondary flow damper.

A fluid control valve includes a valve body having first and second air passages. A first valve air passage is defined between the first air passage and the second air passage. An annular blocking portion is located between the second air passage and the first valve air passage. A second valve air passage is defined through the annular blocking portion and communicates with the first valve air passage. A magnetic ball is movably located in the first valve air passage. A ball holder has a mounting portion and a connecting portion which has an air passage and is connected to an inner wall of the first air passage. The magnetic ball is positioned between the annular blocking portion and the mounting portion which has a magnetic piece. When the fluid control is not in use, the magnetic ball is attracted to the mounting end by the magnet piece.