A pressure regulator including a body having a body inlet, a body outlet and a fluid passageway defined therebetween for allowing a fluid to be dispensed therethrough, the body further including a pressure control chamber adapted to receive a control fluid at a control pressure; a valve disposed in the fluid passageway for restricting flow of the fluid through the fluid passageway; a regulating member operatively connected to the valve for adjusting the position of the valve so as to maintain the fluid in the fluid passageway at a nominal pressure; a pressure sensor disposed between the control chamber and the fluid passageway for sensing a difference between the nominal pressure and the control pressure; and a resilient shutoff member operatively connected to the valve and the pressure sensor for closing the valve when the difference between the nominal pressure and the control pressure is below a predetermined threshold value.

A pressure regulator including a body having a body inlet, a body outlet and a fluid passageway defined therebetween for allowing a fluid to be dispensed therethrough, the body further including a pressure control chamber adapted to receive a control fluid at a control pressure; a valve disposed in the fluid passageway for restricting flow of the fluid through the fluid passageway; a regulating member operatively connected to the valve for adjusting the position of the valve so as to maintain the fluid in the fluid passageway at a nominal pressure; a pressure sensor disposed between the control chamber and the fluid passageway for sensing a difference between the nominal pressure and the control pressure; and a resilient shutoff member operatively connected to the valve and the pressure sensor for closing the valve when the difference between the nominal pressure and the control pressure is below a predetermined threshold value.

A pressure regulating chamber and an atmospheric pressure chamber are divided with a diaphragm, a pressure regulating lever connected to the diaphragm through a diaphragm pin is included in the pressure regulating chamber, and a valve element provided in a tip end side of the pressure regulating lever regulates a fuel in the pressure regulating chamber to have a predetermined pressure near an atmospheric pressure and sends the fuel while opening or closing a fuel introduction port, as the pressure regulating lever swings following displacement of the diaphragm. Connection on the pressure regulating lever side or connection on the diaphragm side, of the diaphragm pin, is separable within a predetermined range in the atmospheric pressure chamber direction. The diaphragm pin is separated to cancel the connection between the diaphragm and the pressure regulating lever when at least the pressure regulating chamber has a positive pressure of a predetermined level or more.

A gas pressure regulator regulates a pressure of a gas system. The gas pressure regulator includes a first chamber, a first diaphragm which separates the first chamber into a first compartment and a second compartment, a second chamber, with a second diaphragm separating the second chamber into a third compartment and a fourth compartment, the fourth compartment being connected to, and in communication with, the first compartment of the first chamber. A movement of the first diaphragm causes a corresponding movement of the second diaphragm, and a change in the volume of the fourth compartment.