Apparatus and method for regulating gas flow

A system for delivering fluid from a source of liquified gas, said system comprising:

• a source storing fluid as liquified gas;
• a conduit connected in fluid flow communication with the source and operable for discharge of fluid from said source;
• a fluid flow control valve connected in fluid communication in said conduit fluid flow-wise downstream of the source and separating said conduit into an infeed conduit portion in which the fluid is in a liquid phase and an outfeed conduit portion comprising a liquid-to-gas vapor conversion means downstream of the fluid flow control valve in which the fluid changes at least partially to a gas phase with the outfeed conduit portion being fluid flow-wise downstream of the infeed conduit portion, said fluid flow control valve being operable to receive fluid in liquid phase and regulate the flow of fluid in liquid phase from the source to the outlet conduit portion;
• and
• a controller in fluid communication with the flow control valve and operable solely thru fluid communication between the controller and the flow control valve to control the flow of fluid from the source in liquid phase at least partially thru the flow control valve and to the outfeed conduit portion in response to flow of fluid in its gas phase in the liquid-to-gas vapor conversion means of the outfeed conduit portion, said controller being substantially completely powered with energy from the fluid in its gas phase wherein the controller includes a pressure sensor operable to sense the pressure of the fluid in the outfeed conduit and wherein the controller includes a pilot valve in fluid communication with the flow control valve and the pressure sensor and operable solely thru fluid communication in response to pressure in the outfeed conduit to control the amount the fluid flow control valve is open and thereby regulate the flow rate of fluid therethrough within a predetermined range.