Method for controlling overpressurization in a gas line

• US 5,391,209 A
• Filed: 11/23/1992
• Issued: 02/21/1995
• Est. Priority Date: 06/15/1990
• Status: Expired due to Fees

• Current Assignee: Leidy Hub Incorporated
• Original Assignee: Leidy Hub Incorporated
• Inventors: Pelkey, Mark J.
• Primary Examiner(s): KRATZ, PETER F
• Application Number:
  US07/980,472
• Time in Patent Office: 820 Days
• Field of Search: 48/191, 48/192, 48/173, 137/115, 137/489, 137/492, 137/492.5, 137/14, 137/24, 201/24
• US Class Current: 48/191
• CPC Class Codes: F17D 1/20 Arrangements or systems of devices for influencing or altering dynamic characteristics of the systems, e.g. for damping pulsations caused by opening or closing of valves fluid dynamics F15D; damping pulsations in fluids in pipes in general F16L55/04
• CPC Class Codes: G05D 16/163 using membranes within the main valve
• CPC Class Codes: Y10T 137/0396 Involving pressure control

Abstract

The invention relates to a gas pressure safety device used in the natural gas distribution systems leading to homes or other customers. This safety device is connected to a gas venting device that allows excess gas to exit therefrom. The safety device is made up of a needle valve, a pressure sensing pilot and a spring-diaphragm actuator. The needle valve is used to restrict the rate of gas flow into the actuator to a rate less than that that can be vented by the pressure sensing pilot. When an excess pressure is generated in the distribution system, the pressure sensing pilot senses when to exhaust the excess gas through the actuator and out of the gas venting device to the atmosphere.

Claims

1. A method for controlling overpressurization in a main gas line system which comprises a main gas line with a district pressure regulator therein, and an auxiliary gas line and a pressure safety device, each connected to the main gas line said pressure safety device comprising in gas flow connection a first normally closed gas venting means, a needle valve, a spring-diaphragm actuator and a pressure sensing pilot means, connecting said auxiliary gas line to the main gas line, and extending said auxiliary gas line in gas flow connection from a point upstream of said district pressure regulator to said needle valve, connecting in gas flow connection said needle valve said pressure sensing pilot means and said spring-diaphragm actuator, providing in said pressure sensing pilot means to detect any increase in pressure in said main gas line downstream of said district pressure regulator over a predetermined gas pressure and to use this increase in pressure to open a second normally closed gas venting means connected to said pressure sensing pilot means, and to thereby cause the venting of pressure in said spring-diaphragm actuator to atmosphere through said second normally closed gas venting means at a rate greater than said needle valve will allow replenishment of said spring-diaphragm actuator, and thereby providing a reduction in pressure in said spring-diaphragm actuator thereby allowing the spring in said spring-diaphragm actuator to force said first normally closed gas venting means to open, thereby allowing excess gas to be vented from the main gas line downstream of said district pressure regulator to the atmosphere, thereby reducing the gas pressure in said main gas line downstream of said district pressure regulator.

2. The method of claim 1 wherein said spring-diaphragm actuator has spring compressive force in mechanical connection to said gas venting means.