Patent ID: 7683271

Claim:
A system for accurately weighing a mass of material, comprising: a) a closed chamber ( 20 ) including a chamber gas inlet ( 22 ) and a gas outlet ( 24 ); b) an inert gas supply under positive pressure connected to the gas inlet ( 22 ); c) a scale ( 30 ) disposed in the closed chamber ( 20 ) ; and d) a vacuum powered pressure regulator ( 100 ) operatively connected to the gas outlet ( 24 ) to maintain a predetermined pressure level within the closed chamber ( 22 ) and to substantially inhibit pressure fluctuations within the closed chamber ( 22 ), wherein the vacuum powered pressure regulator ( 100 ) comprises: a container including a compartment ( 110 ) partially filled with a liquid ( 111 ) so as to define a head space above the liquid ( 111 ); a vacuum supply in fluid communication with the head space; a first dip tube ( 117 ) having one end extending into the liquid ( 111 ) and an opposite end operatively connected with the gas outlet ( 24 ); and a second dip tube ( 122 ) having one end extending into the liquid ( 111 ) and an opposite end operatively connected to a container vent.