Mounting a vent valve on a plastic fuel tank

Abstract

A method of mechanical twist lock attachment of a vent valve or fitting over an aperture in a plastic fuel tank having an embedded vapor barrier layer. A ring having circumferentially spaced internal lugs is secured to the tank by weldment around an aperture in the tank wall exposing an edge of the barrier layer. A seal ring on the vent valve is located in the aperture to seal the exposed vapor barrier edge. Outwardly extending projections on the vent valve attach the vent valve by twist locking engagement with the projections on the ring.

1 . A method of mounting a vent valve on a plastic fuel tank comprising: 
 forming an access opening in the wall of the tank, the access opening having an edge;    disposing a locking ring over the access opening and attaching the ring to the exterior of the tank, the locking ring having an undercut surface;    providing a vent valve with a resilient sealing ring thereon;    disposing at least one ratcheting surface on one of the vent valve and the locking ring and at least one pawl on the other of the vent valve and the locking ring;    disposing a portion of the vent valve in the access opening and locating the sealing ring on the edge of the access opening; and,    securing the vent valve against the undercut surface of the locking ring by twist locking the vent valve in the locking ring and preventing twisting in a reverse direction and retaining the sealing ring against the edge of the access opening.    
   
   
       2 . A system attachable to a fuel tank having an access opening with an edge in a wall of the fuel tank, the system comprising: 
 a locking ring that is attachable to an exterior of the tank over the access opening, over the access opening and attaching the ring to the exterior of the tank, the locking ring having an undercut surface; and    a vent valve with a resilient sealing ring adapted to be located against the edge of the access opening, the vent valve having an outwardly extending flange that secures against the undercut surface of the locking ring.    
   
   
       3 . The system of  claim 2 , wherein the fuel tank has an embedded vapor barrier, and wherein an edge of the vapor barrier is exposed at the edge of the access opening.  
   
   
       4 . The system of  claim 3 , wherein the sealing ring is located on the exposed edge of the vapor barrier.  
   
   
       5 . The system of  claim 2 , wherein the flange includes at least one outwardly extending projection and the locking ring includes at least one inwardly extending locking lug that forms the undercut such that the projection engages with the locking lug.  
   
   
       6 . The system of  claim 5 , wherein said at least one outwardly extending projection includes a plurality of circumferentially spaced projections and said at least one inwardly extending locking lug comprises a plurality of circumferentially spaced locking lugs.  
   
   
       7 . The system of  claim 2 , wherein the locking ring is configured to allow securing of the flange via a twist locking motion.  
   
   
       8 . The system of  claim 2 , wherein one of the flange and the locking ring includes at least one pawl and the other of the flange and the locking ring includes at least one ratchet that engages with said at least one pawl during a twist locking process to prevent twisting of the vent valve in a reverse direction.  
   
   
       9 . The system of  claim 2 , wherein the locking ring is formed of the same plastic material as the fuel tank.  
   
   
       10 . The system of  claim 2 , wherein an annular groove is formed on the vent valve and an o-ring is disposed in the groove.  
   
   
       11 . The system of  claim 2 , wherein the vent valve is a one-way valve.  
   
   
       12 . The system of  claim 2 , wherein the vent valve comprises: 
 a spud;    a one-way valve; and    an annular seal disposed between the spud and the one-way valve.