Abstract: Fluid flow valve assembly comprising a valve body having an external port and an inlet end having at least a first port, a second port, and a third port; a first valve disposed within the valve body and adapted to control fluid flow between the first and second ports; and a second valve disposed within the valve body and adapted to control fluid flow between the third port and the external port.

Abstract: A fluid control system for use with toxic or corrosive gases (for example) has been provided that includes a fluid pressure regulator comprising a fluid inlet; a fluid outlet; a first fluid flow path between the fluid inlet and the fluid outlet; a valve seat positioned in the first fluid flow path and dividing the fluid inlet and the fluid outlet; a valve element regulating flow through the valve seat; a generally cylindrical membrane defining an inflatable fluid cavity that moves axially, responsive to inflation; a wall portion of the cavity that moves responsive to inflation and deflation of the cavity; a second fluid flow path communicating between the cavity and a source of pressure outside the cavity; and a link transmitting the movement of the wall portion to the valve element, thereby moving the valve element with respect to the valve seat responsive to inflation and deflation of the cavity.