Method and system for assessing the operating condition of a pressure regulator in a corrosive gas distribution system

• US 5,677,480 A
• Filed: 02/24/1995
• Issued: 10/14/1997
• Est. Priority Date: 02/24/1995
• Status: Expired due to Term

• Current Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Original Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Inventors: Liyanage, A. Nimal, Ozawa, Eiichi, Yokogi, Kazuo, Friedt, Jean-Marie
• Primary Examiner(s): Brock, Michael
• Assistant Examiner(s): Politzer, Jay L.
• Application Number:
  US08/393,684
• Time in Patent Office: 963 Days
• Field of Search: 73/49.2 R, 73/46, 73/4 R, 73/49.1, 73/3, 73/37
• US Class Current: 73/46
• CPC Class Codes: G01M 3/2876 for valves G01M3/30 takes precedence

Abstract

A method of detecting a malfunction or failure of a pressure regulator in a corrosive or reactive gas distribution system while in use involves continuously measuring or monitoring the output pressure of the pressure regulator, both in the presence and the absence of gas flow. The onset of a malfunction of the pressure regulator can be predicted when the differential output pressure between flowing and non-flowing gas fluctuates highly and increases gradually. Failure of the pressure regulator or of the total system is detected when the differential output pressure in the presence and absence of flowing gas exceeds some experimentally determined value.

Claims

1. A method of detecting a malfunction or failure of a corrosion sensitive element due to a internal leak in a non-inert gas distribution system while in use, comprising:

flowing non-inert gas through said gas distribution system which is provided with a corrosion sensitive element;

determining an operating output pressure of the corrosion sensitive element in the gas distribution system while the non-inert gas is flowing through the system;

turning off the gas flow in the gas distribution system at a point downstream of the corrosion sensitive element;

measuring the output pressure of the corrosion sensitive element in the absence of gas flow through the gas distribution system;

determining the existence of a malfunction or failure of the corrosion sensitive element when the output pressure of the corrosion sensitive element in the absence of gas flow exceeds the operating output pressure of the corrosion sensitive element in the presence of gas flow and when a pressure differential between the operating output pressure of the corrosion sensitive element in the presence of gas flow and the output pressure of the corrosion sensitive element in the absence of gas flow exceeds a predetermined value.

2. Method according to claim 1, wherein said step of determining the existence of a malfunction or failure of the corrosion sensitive element includes determining the onset of a malfunction of the corrosion sensitive element when said pressure differential exceeds said predetermined value which is a first predetermined value, and determining that a failure of the corrosion sensitive element has occurred when said pressure differential exceeds a second predetermined value that is greater than the first predetermined value.

3. Method according to claim 1, wherein said predetermined value is 0.5 kgf/cm² and said step of determining the existence of a malfunction or failure of the corrosion sensitive element includes determining the existence of a malfunction of the corrosion sensitive element when said pressure differential is between of 0.5 kgf/cm² and 1.0 kgf/cm².

4. Method according to claim 1, wherein said predetermined value is 1.0 kgf/cm² and said step of determining the existence of a malfunction or failure of the corrosion sensitive element includes determining the existence of a failure of the corrosion sensitive element when said pressure differential is greater than 1.0 kgf/cm².

5. Method according to claim 1, wherein the non-inert gas is selected from the group consisting of corrosive and reactive gases.

12. Method according to claim 1, wherein said step of flowing non-inert gas through said gas distribution system includes flowing a gas other than air.

6. A method of assessing the operating condition of a corrosive or reactive non-inert gas distribution system that includes a mass flow controller and a pressure regulator for regulating gas pressure, the pressure regulator having an outlet and being positioned upstream of the mass flow controller with respect to the direction of gas flow, and a line connecting the pressure regulator with the mass flow controller, comprising flowing non-inert gas through the gas distribution system so that the non-inert gas flows through the pressure regulator, stopping gas flow through the gas distribution system at a point downstream of the pressure regulator, monitoring the outlet pressure adjacent the outlet of the pressure regulator during flow of non-inert gas through the line and in the absence of gas flow through the line, and determining the operating condition of the system based on changes in the outlet pressure of the pressure regulator in the absence of gas flow through the line.

7. Method according to claim 6, wherein said step of determining the operating condition of the system includes determining that the system is malfunctioning if a pressure differential between the outlet pressure of the pressure regulator when the gas is flowing through the line and the outlet pressure of the pressure regulator in the absence of gas flow exceeds a first predetermined value.

8. Method according to claim 7, wherein said step of determining the operating condition of the system includes determining that the system has failed if a pressure differential between the outlet pressure of the pressure regulator when gas is flowing through the line and the outlet pressure of the pressure regulator in the absence of gas flow exceeds a second predetermined value which is at least equal to said first predetermined value.

9. A method according to claim 8, wherein said second predetermined value is greater than 1.0 kgf/cm².

10. A method according to claim 7, wherein said first predetermined value is comprised between 0.5 kgf/cm² and 1.0 kgf/cm².

13. Method according to claim 6, wherein said step of flowing non-inert gas through said gas distribution system includes flowing a gas other than air.

11. A method for assessing the operating condition of a pressure regulator in a non-inert gas distribution system which regulates gas pressure, the pressure regulator having an outlet, comprising flowing non-inert gas through the gas distribution system, stopping the flow of non-inert gas through the gas distribution system at a point downstream of the pressure regulator, determining the gas pressure adjacent the outlet of the pressure regulator downstream of the pressure regulator both during the flow of non-inert gas through the gas distribution system and in the absence of gas flow through the gas distribution system when the flow of non-inert gas has been stopped, identifying the existence of a malfunction or failure in the pressure regulator when the gas pressure adjacent the outlet in the absence of gas flow is greater by a predetermined value than the gas pressure adjacent the outlet during the flow of non-inert gas through the gas distribution system.

14. Method according to claim 11, wherein said step of flowing non-inert gas through said gas distribution system includes flowing a gas other than air.