Relief valve for extracting sub-surface gas

Abstract

A relief valve for extracting sub-surface gas from beneath a geomembrane includes a valve body for permitting gas to flow therethrough and includes an inlet, an outlet, a vertical run communicating with the inlet, and a lateral run communicating with the vertical run and the outlet. A ball valve comprising a ball seat is positioned within the vertical run. A lightweight valve ball positioned within the vertical run. The valve ball is movable therewithin between a lowered position against a ball seat and an elevated position distal therefrom. The valve ball is lightweight enough that minimal upward gas flows within the vertical run cause the valve ball to rise and become unseated from the ball seat such that stoppage of such vertical flows or reverse flows cause the valve ball to drop back to its ball seat and seal against reverse flows through the ball valve.

What is claimed is: 
     
         1 . A relief valve for extracting sub-surface gas comprising:
 a valve body having an inlet, an outlet, a vertical run communicating with the inlet, and a lateral run communicating with the vertical run and with the outlet;   a ball valve comprising a ball seat positioned within the vertical run;   the ball valve further comprising a valve ball positioned within the vertical run and being movable therewithin between a lowered position against the ball seat and an elevated position distal therefrom, the valve ball being lightweight such that minimal upward gas flows within the vertical run cause the valve ball to rise and be unseated from the ball seat and such that stoppage of such vertical flows or reverse flows cause the valve ball to drop back to its ball seat and seal against reverse flows through the ball valve;   whereby large or small positive pressures beneath the inlet cause flow up through the ball valve and out through the outlet, but even small negative pressures below the inlet cause the ball valve to close and prevent flows down through the ball valve in the vertical run.   
     
     
         2 . The relief valve as claimed in  claim 1  wherein the lateral run includes a horizontal portion and a vertical portion. 
     
     
         3 . The relief valve as claimed in  claim 2  wherein the horizontal portion of the lateral run is partly horizontal and partly vertical. 
     
     
         4 . The relief valve as claimed in  claim 2  wherein the lateral run includes a first portion that extends laterally and downwardly. 
     
     
         5 . The relief valve as claimed in  claim 4  wherein the lateral run includes a second portion that extends downwardly. 
     
     
         6 . The relief valve as claimed in  claim 1  wherein the valve body includes a threaded portion adjacent the inlet for connecting the relieve valve to a header or conduit. 
     
     
         7 . The relief valve as claimed in  claim 1  wherein the valve ball is hollow. 
     
     
         8 . The relief valve as claimed in  claim 7  wherein the valve ball is filled with a lighter-than-air gas. 
     
     
         9 . The relief valve as claimed in  claim 1  wherein the valve seat is cup-shaped. 
     
     
         10 . The relief valve as claimed in  claim 1  wherein the valve seat is tapered. 
     
     
         11 . The relief valve as claimed in  claim 1  wherein the relief valve is operable to work at pressure differentials below 3 psi. 
     
     
         12 . The relief valve as claimed in  claim 1  wherein the relief valve is operable to work at pressure differentials below about 1.0 psi. 
     
     
         13 . The relief valve as claimed in  claim 1  wherein the relief valve is operable to work at pressure differentials as low as about 0.1 psi.