FLOW CONTROL FOR GAS ANALYZING APPARATUS

• US 3,712,111 A
• Filed: 07/10/1968
• Issued: 01/23/1973
• Est. Priority Date: 07/10/1968
• Status: Expired due to Term

• Current Assignee: Peter M. Llewellyn
• Original Assignee: Peter M. Llewellyn
• Inventors: Llewellyn, Peter M.
• Primary Examiner(s): Gill, James J.
• Assistant Examiner(s): Snee, III, C. E.
• Application Number:
  US04/743,852
• Time in Patent Office: 1,658 Days
• Field of Search: 73/23.1 250/41.9,41.9GS 23/232C,254E,255E 55/16,158
• US Class Current: 73/23.37
• CPC Class Codes: G01N 30/722 through a gas permeable barrier (membranes, porous layers)
• CPC Class Codes: G01N 30/84 Preparation of the fraction to be distributed
• CPC Class Codes: H01J 49/0427 using a membrane permeable to gases
• CPC Class Codes: H01J 49/0495 Vacuum locks; Valves valves per se F16K

Abstract

A gas chromatograph-mass spectrometer system including means for varying the amount of throughput from chromatograph to spectrometer without physically altering the flow path therebetween. A valve means is inserted in the effluent flow path of the chromatograph downstream of the spectrometer inlet system so that the exhaust port flow path may be constricted to unbalance the pressure differentials in the chromatograph detector flow path and the main flow path downstream of the splitter thus enabling the effective split ratio to be selectively varied without affecting the geometry of the flow stream connecting the chromatograph and spectrometer.

Claims

1. In a gas analyzing system including a gas chromatograph means, a mass spectrometer means, and an effluent flow path means extending therebetween, said flow path means including the input chamber of a membrane type separator means which serves as an inlet means to said mass spectrometer, and a viscous flow splitter means disposed in said flow path means between said chromatograph column and said separator for normally removing a small percentage of the effluent from said flow path for detection purposes, the improvement comprising:

throttle valve means disposed in said flow path means downstream of said separator for impeding the flow of gas in said flow path and thus increasing the percentage of the effluent which is caused to pass out of said flow path through said splitter means and therefore reducing the percentage of the effluent supplied to said inlet means of said mass spectrometer.

2. In a gas analyzing system as recited in claim 1 wherein valve control means responsive to the output of said gas chromatograph or said mass spectrometer are provided for controlling Said throttle valve means to control the amount of sample which is allowed to be introduced into said mass spectrometer.

3. In a gas analyzing system including a gas chromatograph means and a mass spectrometer means operatively coupled together by a gas flow means so as to serially perform an analysis on a sample of gaseous material, the output of said gas chromatograph being directly coupled through said gas flow means in flowthrough relation to the inlet system of said mass spectrometer, said gas flow means extending externally beyond said inlet system, and a fixed ratio splitter means disposed in the connecting path of said flow means between said gas chromatograph and said inlet system the improvement comprising:

throttle valve means disposed in the external portion of said gas flow means beyond said inlet system for controlling the actual division of gas flow through the respective flow passages of said splitter means without altering the physical relationship of said flow passages.

4. In a gas analyzing system as recited in claim 3 wherein throttle valve control means responsive to the output of said gas chromatograph or said mass spectrometer means are provided for controlling said throttle valve means to control the percentage of sample gas which is caused to flow through said inlet system.

5. In a gas analyzing system as recited in claim 4 wherein said inlet system is a permeable membrane type separator.

6. A gas analyzing system comprising:

a gas chromatograph means having an effluent orifice, a mass spectrometer means including an inlet means which separates certain materials from a sample gas caused to flow through an input chamber thereof, the downstream side of said input chamber having an exhaust port means through which said gas is exhausted after having passed through said input chamber, fluid flow path means connecting said effluent orifice of said chromatograph to said inlet means of said spectrometer, flow splitting means disposed within said flow path means for splitting off a portion of a gas passing through said flow path means, said portion ultimately being exhausted through a second exhaust port means, and throttle valve means disposed at at least one of said exhaust ports for controlling the split ratio of said flow splitting means by constricting the flow passage through which the gas is passed before being exhausted thereby altering the balance of pressure drops between the respective exhaust ports and the splitting means which as a consequence alters the split ratio of said splitting means.

7. A gas analyzing system as set forth in claim 6 wherein said inlet means is a permeable membrane type separator means.

8. A gas analyzing system as set forth in claim 7 wherein throttle valve control means are provided responsive to a predetermined characteristic of said sample gas so as to control the application of said gas to said inlet means.