Overflow and isolation valve

An overflow and isolation valve for use with the vapor recovery system of an underground liquid storage tank, the overflow valve being mounted on the storage tank and being in fluid-tight communication with the vapor recovery system, the storage tank having a liquid level therein, said valve comprising:

• a) a valve body having a chamber defined therein;
• b) an elongate leg member formed as an integral part of said valve body, said leg member having a proximal end sealed on said valve body and a distal end extending away from said valve body;
• c) a continuous bore defined within said leg member and extending from said distal end to said proximal end, said bore being in generally fluid-tight communication with the chamber within said valve body;
• d) an integral float assembly positioned on the distal end of said leg member, said float assembly being constructed and arranged for reciprocal movement from an open position for allowing vapors through said leg member and into said chamber, into a generally fluid-tight closed position on the distal end of said leg member in response to the increase of the liquid level within the tank;
• e) said float assembly including a float, an elongated stem having a proximal end fastened to said float and a distal end extending away from said float through a guide means for guiding said stem for reciprocal movement into said open and said closed positions;
• and
• f) a threaded annular ring defined within and formed as a part of said leg member, said threaded ring extending inwardly of said bore and being positioned intermediate the proximal end of said leg member and said float assembly.

An overflow and isolation valve assembly for use with the vapor recovery system of an underground liquid storage tank, said valve comprising:

• a) a valve body, said valve body having a chamber defined therein;
• b) an elongate leg member formed integrally with said valve body, said leg member having a proximal end sealed on said valve body and a distal end extending away from said valve body;
• c) a continuous bore defined within said leg member and extending from said distal end to said proximal end thereof, said bore being in generally fluid-tight communication with the chamber defined within said valve body;
• d) an integral float assembly mounted on the distal end of said leg member,
• e) a threaded annular ring defined within said leg member and extending inwardly of said bore, said annular ring being positioned intermediate the proximal end and the distal end of said leg member;
• f) a vapor recovery system riser opening defined within said valve body in substantial registry with said bore;
• and
• g) a threaded plug sized and shaped to be passed through said riser opening and said valve body toward, and to be threadedly received on said annular ring to form a fluid-tight seal of the chamber defined within said valve body from the storage tank.

A method of using an overflow and isolation valve assembly to isolate an underground liquid storage tank from a vapor recovery system in communication with the tank and used to vent vapor from the tank to the atmosphere, the overflow and isolation valve having a valve body sealed on the tank and a chamber defined within the valve body in communication with the vapor recovery system, said method comprising the steps of:

• a) passing a threaded plug through the valve body into an elongate bore defined within an elongate extending away from the valve body, the bore extending from a proximal end of the leg member sealed on the valve body to a distal end of the leg member on which a float assembly is supported;
• b) moving said plug into engagement with a threaded annular ring defined within said bore and positioned intermediate the proximal and distal ends of said leg member;
• c) threading the plug into the annular ring;
• and
• d) forming a fluid-tight seal between the chamber within the valve body and the storage tank in response thereto.