Gas flow control

Patent metadata

Field	Value
Publication number	US-10388498-B2
Application number	US-201715837188-A
Country	US
Kind code	B2
Filing date	Dec 11, 2017
Priority date	Dec 15, 2016
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

The present invention relates to a gas inlet system for an analytical apparatus. The gas inlet system comprises switchable flow restrictions for regulating gas flow rate. The invention also provides a system for calibrating gas flow rate in gas inlet systems, the system comprising a calibration line that comprises a gas flow meter, and that is arranged downstream of gas flow controllers in the gas inlet system. Methods of adjusting gas flow rates and methods of calibrating gas flow rates are also provided.

First claim

The invention claimed is:

1. A gas inlet system for providing a stream of gas into an analytical apparatus, comprising:
a gas inlet line, for delivering gas into the analytical apparatus, the gas inlet line being connectable to the analytical apparatus to introduce gas into the apparatus, and to at least one gas supply, to deliver gas into the gas inlet line;
at least one gas flow restriction assembly that is arranged on, or fluidly connected to, the gas inlet line, the flow restriction assembly comprising at least two switchable flow restrictions;
at least one control line that is fluidly connected to the gas inlet line at a control line junction, downstream from the at least one gas flow restriction assembly, the control line comprising at least one back pressure regulator and at least one valve for regulating gas flow into the control line, and at least one vacuum pump that is arranged downstream from the back pressure regulator; and
at least one inlet gas flow restriction that is arranged on the gas inlet line, between the control line junction and the analytical apparatus.

2. The gas inlet system of claim 1 , wherein the flow restriction assembly is provided as a parallel arrangement of flow restrictions, the flow restrictions being arranged on separate flow restriction gas lines that meet at a first restriction junction upstream from the flow restrictions and a second restriction junction downstream from the flow restrictions on the gas inlet line, upstream from the control line junction.

3. The gas inlet system of claim 1 , wherein the flow restriction assembly is provided as a parallel arrangement of two flow restrictions, wherein one of the flow restrictions is arranged on the gas inlet line and wherein the second of the flow restrictions is provided on a bypass gas line that is arranged parallel to the gas inlet line and that meets the gas inlet line at a first restriction junction upstream from the flow restrictions and a second restriction junction downstream from the flow restrictions, upstream from the control line junction.

4. The gas inlet system of claim 1 , wherein the flow restriction assembly is provided as a parallel arrangement of two flow restrictions, wherein one of the flow restrictions is arranged on the gas inlet line and wherein the second of the flow restrictions is provided on a bypass gas line that is arranged parallel to the gas inlet line and that meets the gas inlet line at a first restriction junction upstream from the flow restrictions and a second restriction junction on the control line, between the mass flow regulator and the control line junction.

5. The gas inlet system of claim 4 , further comprising at least one further flow restriction, wherein each such further flow restriction is arranged on a separate further gas line that is arranged parallel to the first and second flow restrictions in the flow restriction assembly.

6. The gas inlet system of claim 4 , wherein the flow restriction assembly comprises two or more parallel flow restrictions that are adapted such that the ratio of gas flow through any two of the flow restrictions, for the same pressure difference across the restrictions, is in the range of about 1:20 to 1:1.5.

7. The gas inlet system of claim 1 , wherein the analytical apparatus is a mass spectrometer.

8. The gas inlet system of claim 7 , wherein the gas inlet line is fluidly connected to a collision cell of the mass spectrometer.

9. The gas inlet system of claim 1 , wherein the vacuum pump is fluidly connected to the control line and is part of a vacuum pumping system of a mass spectrometer.

10. A system for calibrating gas flow in a gas inlet system for an analytical apparatus, the system comprising:
a gas inlet line, for providing gas into an analytical apparatus;
a gas flow calibration line that is fluidly connected to the gas inlet line via a first calibration junction, the gas flow calibration line comprising at least one gas flow meter; and
at least one valve, for selectively directing gas flow either into the analytical apparatus via the gas inlet line or into the gas flow calibration line via the first calibration junction;
such that gas flow in the system can, in a first gas flow setting of the at least one valve, be directed into the analytical apparatus via the gas inlet line, bypassing the gas flow calibration line, and in a second gas flow setting of the at least one valve be directed via the gas flow calibration line into the analytical apparatus,
whereby gas flow that is measured in the gas flow calibration line in the second gas flow setting is, given a constant gas flow in the gas inlet line towards the calibration junction, a measure of the gas flow into the analytical apparatus in the first gas flow setting.

11. The system of claim 10 , wherein the gas flow calibration line is further connected to the gas inlet line at a second calibration junction, such that gas flow in the system is, in the second setting, directed through the gas flow calibration line, from the first calibration junction to the second calibration junction, and into the analytical apparatus via a gas inlet junction that connects the gas inlet line to the analytical apparatus, downstream from the second calibration junction.

12. The system of claim 10 , wherein the gas flow calibration line is further connected to the analytical apparatus through a calibration inlet junction that is fluidly separate from a gas inlet junction, between the gas inlet line and the analytical apparatus, such that gas flow in the system is, in the second setting, directed through the gas flow calibration line, from the first calibration junction to the calibration inlet junction and into the analytical apparatus.

13. The system of claim 10 , further comprising a housing that is adapted to enclose the system and that further comprises means for maintaining the system at a constant temperature.

14. The system of claim 13 , wherein the housing encloses at least the gas flow calibration line and the portion of the gas inlet line that stretches from the first calibration junction to the analytical apparatus.

15. The system of claim 10 , wherein the analytical apparatus is a mass spectrometer.

16. The system of claim 15 , wherein the gas inlet line and the calibration line are fluidly connected to a collision cell of a mass spectrometer.

17. The system of claim 10 , further comprising at least one controller, for controlling the position of valves and/or gas flow regulators or controllers in the system.

18. A method of adjusting gas flow in a gas inlet system of an analytical apparatus, the method comprising steps of:
flowing gas at an inlet pressure (P in ) from at least one gas supply into a gas inlet line that provides gas into an analytical apparatus;
regulating flow rate in the gas inlet line by splitting away a portion of the gas flow in the gas inlet line into a gas control line that is arranged on the gas inlet line and that meets the gas inlet line at a control line junction, such that a portion of the gas flow in the gas inlet line flows through the gas control line, and wherein gas flow in the gas control line is controlled by means of a back pressure regulator, whereby at a first setting of the gas flow controller gas flow rate in the gas inlet line and/or a pressure (P A ) at the control line junction reaches a constant first value;
adjusting the flow controller to a second setting and while the flow controller is in the second setting, flowing gas from the gas supply at least into one or more bypass gas line that is fluidly conn

Assignees

• Thermo Fisher Scient Bremen Gmbh

Inventors

• Schuethe Thorben

Classifications

• H01J49/105

  using high-frequency excitation, e.g. microwave excitation, Inductively Coupled Plasma [ICP] · CPC title

• H01J49/24

  Vacuum systems, e.g. maintaining desired pressures · CPC title

• G01F1/00

  Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow (measuring a proportion of the volume flow G01F5/00) · CPC title

• F15B13/00

  Details of servomotor systems ({F15B1/04, F15B1/26, F15B3/00, F15B7/08, F15B11/02, F15B11/10,} F15B15/00 take precedence){; Valves for servomotor systems} · CPC title

• G05D7/00 Primary

  Control of flow (level control G05D9/00; control of flow ratio G05D11/00) · CPC title