Patent ID: 6997202

Claim:
A gas supply system arranged for dispensing of gas at predetermined flow rate, comprising a gas source vessel characterized by decline in gas pressure during dispensing of gas therefrom when the gas source vessel is in a low inventory state, and gas dispensing flow circuitry coupled to said vessel, wherein the gas dispensing flow circuitry is arranged for dispensing gas at selectively variable gas flow conductance conditions, to maintain said predetermined flow rate of the dispensed gas in the operation of the system, and increasing the gas flow conductance of the gas dispensing flow circuitry to compensate for said decline in gas pressure during dispensing of gas from the gas source vessel when the gas source vessel is in a low inventory state, to maintain said predetermined flow rate, wherein the gas dispensing flow circuitry comprises a single point of entrance in fluid communication with an array of flow passages wherein all the flow passages comprise a flow control valve to open or block flow through the respective flow passage and each of the flow passages excepting one comprises a restrictive orifice having a fixed and different diameter relative to an adjacent orifice, wherein the one exception flow passage does not include a flow occlusion element and has the highest gas flow conductance of said flow passages.