Apparatus for measuring the mass flow of gases

Claim 2

Flow-measuring apparatus for determining the mass rate of flow of a gas comprising: a reservoir vessel having an inlet connection for connection to a pressured source of gas and an outlet connection; a critical flow nozzle coupled to said reservoir outlet connection for passing pressured gas from said reservoir vessel through said flow nozzle under critical flow conditions to a region of low pressure downstream of the outlet of said flow nozzle; first valve means coupled to said pressured source of gas for controlling the passage of pressured gas from said pressured source of gas to said reservoir vessel; second valve means coupled to said flow nozzle outlet for controlling the passage of pressured gas from said reservoir vessel through said flow nozzle; first measuring means coupled to said reservoir vessel for measuring the density of pressured gas passing from said reservoir vessel through said flow nozzle and providing first signals representative of said gas density; second measuring means coupled to said reservoir vessel for measuring the pressure of pressured gas passing from said reservoir vessel through said flow nozzle and providing second signals representative of said gas pressure; and output means responsive to said first and second signals for providing output signals representative of said mass rate of flow.

Claim 3

The flow-measuring apparatus of claim 1 wherein said output signals are electrical signals, and said output means include electrical circuit means cooperatively coupled to said first and second measuring means and adapted for providing said output signals in response to said first and second signals.

Claim 4

The flow-measuring apparatus of claim 2 wherein said first and second signals are electrical signals, and said first and second measuring means respectively include first and second electrical means adapted for providing said first and second signals to said electrical circuit means.

Claim 5

The flow-measuring apparatus of claim 1 wherein said output means include electrical circuit means cooperatively coupled to said first and second measuring means and adapted for providing said output signals as a function of the square root of the product of said first and seconD signals, which square root is a function of said mass rate of flow.

Claim 6

The flow-measuring apparatus of claim 1 further including control means coupled to said second valve means and to said output means for simultaneously opening said second valve means and enabling said output means whereby said output means provides said output signals whenever said first valve means is opened.

Claim 7

The flow-measuring apparatus of claim 1 further including a second critical flow nozzle coupled to said reservoir vessel through a second outlet connection; and third valve means coupled to said second critical flow nozzle for controlling the passage of gas through said second critical flow nozzle.

Claim 8

The flow-measuring apparatus of claim 1 wherein said output means include means adapted for providing said output signals as a function of the square root of the product of said first and second signals so that said mass rate of flow can be determined by the equation: w 0.4727A Square Root Rho P gamma where, w mass rate of gas flow through said flow nozzle, lbs/sec. A throat area of said flow nozzle, sq.in. Rho density of gas in said reservoir vessel, lbs/cu.ft. P pressure of gas in said reservoir vessel, psia gamma k (2/k + 1)(k 1)/(k 1) k ratio of specific heats (cp/cv) of gas in said reservoir vessel.

Claim 9

Flow measuring apparatus for determining the mass rate of flow of a gas comprising: a reservoir vessel having an inlet connection for connection to a pressured source of gas and an outlet connection; a critical flow nozzle coupled to said reservoir outlet connection for passing pressured gas from said reservoir vessel through said flow nozzle under critical flow conditions to a region of low pressure downstream of the outlet of said flow nozzle; first valve means coupled to said pressured source of gas for controlling the passage of pressured gas from said pressured source of gas to said reservoir vessel; second valve means coupled to said flow nozzle outlet for controlling the passage of pressured gas from said reservoir vessel through said flow nozzle; first measuring means coupled to said reservoir vessel for measuring the density of pressured gas passing from said reservoir vessel through said flow nozzle and providing first signals representative of said gas density; second measuring means coupled to said reservoir vessel for measuring the pressure of pressured gas passing from said reservoir vessel through said flow nozzle and providing second signals representative of said gas pressure; control means responsive to said first signals representative of said gas density and connected to the first valve means to apply thereto control signals which are a function of said first signals and control said first valve means to maintain a constant mass per unit volume of the gas in said reservoir; and output means responsive to said second signals representative of the gas pressure in the reservoir for providing output signals representative of said mass rate of flow.

Claim 10

Flow measuring apparatus for determining the mass rate of flow of a gas comprising: a reservoir vessel having an inlet connection for connection to a pressured source of gas and an outlet connection; a critical flow nozzle coupled to said reservoir outlet connection for passing pressured gas from said reservoir vessel through said flow nozzle under critical flow conditions to a region of low pressure downstream of the outlet of said flow nozzle; first valve means coupled to said pressured source of gas for controlling the passage of pressured gas from said pressured source of gas to said reservoir vessel; second valve means coupled to said flow nozzle outlet for controlling the passage of pressured gas from said reservoir vessel through said flow nozzle; first measuring means coupled to said reservoir vessel for measuring the density of pressured gas passing from said reservoir vessel through said flow nozzle and providing first signals representative of said gas density; second measuring means coupled to said reservoir vessel for measuring the pressure of pressured gas passing from said reservoir vessel through said flow nozzle and providing second signals representative of said gas pressure; control means responsive to said first signals representative of said gas density and connected to the first valve means to apply thereto control signals which are a function of said first signals and control said first valve means to maintain a constant mass per unit volume of the gas in said reservoir; and output means responsive to said second signals representative of the gas pressure in the reservoir for providing output signals representative of said mass rate of flow.