Pressure insensitive gas control system
AssigneeUnit Instruments, Inc.
InventorsDavid P. Sheriff, Chiun Wang
Life of this patent
Estimating the term…
Abstract
A pressure insensitive gas process device that includes a gas sensor and restrictions upstream and downstream of the gas sensor. The restrictions result in pressure drops upstream and downstream of the gas sensor which shield the gas sensor from upstream and downstream pressure changes, respectively, rendering the gas sensor and the entire gas process device insensitive to pressure changes. Gas process devices in which pressure insensitivity may be achieved include mass flow controllers as well as other types of devices.
Claims37
A gas process device, comprising:
- a gas inlet;
- a gas outlet;
- a first restriction having an inlet and an outlet, the inlet of the first restriction being fluidly coupled to the gas inlet of the gas process device;
- a flow sensor having an inlet and an outlet, the inlet of the flow sensor being fluidly coupled to the outlet of the first restriction, the flow sensor being constructed to provide a flow signal indicative of a flow of gas through the gas process device;
- and
- a second restriction having an inlet and an outlet, the inlet of the second restriction being fluidly coupled to the outlet of the flow sensor and the outlet of the second restriction being fluidly coupled to the gas outlet of the gas process device;
- wherein one of the first restriction and the second restriction includes a control valve that. modulates the flow of gas through the gas process device based on the flow signal.
A gas process device, comprising:
- a gas inlet;
- a gas outlet;
- a first restriction having an inlet and an outlet, the inlet of the first restriction being fluidly coupled to the gas inlet of the gas process device;
- a gas sensor having an inlet and an outlet, the inlet of the gas sensor being fluidly coupled to the outlet of the first restriction;
- and
- a second restriction having an inlet and an outlet, the inlet of the second restriction being fluidly coupled to the outlet of the gas sensor and the outlet of the second restriction being fluidly coupled to the gas outlet of the gas process device;
- wherein the second restriction is constructed and arranged to provide a pressure ratio of more than about 1.25 to 1 from the inlet of the second restriction to the outlet of the second restriction.
A gas process device, comprising:
- a gas inlet;
- a gas outlet;
- a flow sensor constructed to provide a flow signal representing a gas flow fluidly coupled to the gas inlet and the gas outlet;
- and
- first and second means for inducing a pressure drop fluidly coupled between the gas inlet and the flow sensor and between the flow sensor and the gas outlet, respectively;
- wherein one of the first restriction and the second restriction includes a control valve constructed to receive a control signal at least partially based on the flow signal.
A gas process device, comprising:
- a gas inlet;
- a gas outlet;
- a gas sensor fluidly coupled to the gas inlet and the gas outlet;
- and
- first and second means for inducing a pressure drop fluidly coupled between the gas inlet and the gas sensor and between the gas sensor and the gas outlet, respectively;
- wherein at least one of the first and second means includes means for accelerating a gas flowing through the at least one of the first and second means to transonic speed.
A gas process device, comprising:
- a gas inlet;
- a gas outlet;
- a gas sensor fluidly coupled to the gas inlet and the gas outlet;
- and
- first and second means for inducing a pressure drop fluidly coupled between the gas inlet and the gas sensor and between the gas sensor and the gas outlet, respectively;
- wherein the second means provides a pressure ratio of more than about 1.25 to 1 from an inlet of the second means to an outlet of the second means.
A pressure insensitive method of measuring a property of a gas in a gas process device having an inlet and an outlet, comprising acts of:
- a) receiving a flow of the gas at the inlet;
- b) dropping the pressure of the gas to produce a first reduced pressure gas;
- c) providing the first reduced pressure gas to a flow sensor;
- d) measuring a flow of the gas with the flow sensor;
- e) further dropping the pressure of the gas to produce a second reduced pressure gas;
- f) providing the second reduced pressure gas to the outlet;
- and
- g) regulating the flow of the gas based on act d with a control valve that also performs one of acts b and e.
A pressure insensitive method of measuring a property of a gas in a gas process device having an inlet and an outlet, comprising acts of:
- a) receiving a flow of the gas at the inlet;
- b) dropping the pressure of the gas to produce a first reduced pressure gas;
- c) providing the first reduced pressure gas to a gas sensor;
- d) measuring a property of the gas with the gas sensor;
- e) further dropping the pressure of the gas to produce a second reduced pressure gas;
- f) providing the second reduced pressure gas to the outlet;
- and
- g) regulating the flow of the gas based on act d;
- wherein act d is performed prior to the act of regulating.
A pressure insensitive method of measuring a property of at gas in a gas process device having an inlet and an outlet, comprising acts of:
- a) receiving a flow of the gas at the inlet;
- b) dropping the pressure of the gas to produce a first reduced pressure gas;
- c) providing the first reduced pressure gas to a gas sensor;
- d) measuring a property of the gas with the gas sensor;
- e) further dropping the pressure of the gas to produce a second reduced pressure gas;
- f) providing the second reduced pressure gas to the outlet;
- and
- g) regulating the flow of the gas based on act d;
- wherein the act of regulating includes an act of regulating the flow of the gas with a proportional metering valve.
A pressure insensitive method of measuring a property of a gas in a gas process device having an inlet and an outlet, comprising acts of:
- a) receiving a flow of the gas at the inlet;
- b) dropping the pressure of the gas to produce a first reduced pressure gas;
- c) providing the first reduced pressure gas to a gas sensor;
- d) measuring a property of the gas with the gas sensor;
- e) further dropping the pressure of the gas to produce a second reduced pressure gas;
- and
- f) providing the second reduced pressure gas to the outlet;
- wherein at least one of acts b and e includes reducing the pressure of the gas so that the flow of the gas is choked;
- wherein at least one of acts b and e includes an act of reducing the pressure of the gas with an orifice;
- and
- wherein at least one of acts b and e includes accelerating the gas to transonic speed.
A pressure insensitive method of measuring a property of a gas in a gas process device having an inlet and an outlet, comprising acts of:
- a) receiving a flow of the gas at the inlet;
- b) dropping the pressure of the gas to produce a first reduced pressure gas;
- c) providing the first reduced pressure gas to a gas sensor;
- d) measuring a property of the gas with the gas sensor;
- e) further dropping the pressure of the gas to produce a second reduced pressure gas;
- and
- f) providing the second reduced pressure gas to the outlet;
- wherein at least one of acts b and e includes an act of passing the gas one of through and over a baffle.
Dependencies are inferred from the claim text.