Balance System

The balance system uses a coaxial hose-within-a-hose. Fuel flows through the inner hose. Vapor flows through the outer hose. Liquid (created by splash-back or vapor condensation) will sometimes pool in the lowest part of the outer vapor hose. We invented and patented the venturi device to remove this liquid. The venturi is a standard part of our balance vapor recovery system.

The fueling customer places the nozzle in the vehicle fill pipe, presses down on the 'elephant trunk' bellows to seal the connection, and begins to dispense fuel.

Positive pressure forces vapors out of the vehicle fuel tank when fuel is pumped in. Negative pressure (vacuum) pulls vapor into the underground storage tank's empty space as fuel is pumped out.

This happens naturally as the positive and negative pressures try to balance - hence the name 'balance system.' As the pressure equalizes, vapor flows out of the vehicle fuel tank, into the bellows, up the flexible hose sheathing, down the dispenser piping and through the underground piping into the underground storage tank.

The venturi narrows the fuel flow path (like the narrow center section of an hourglass). A small hole in the center of that narrow section opens into a small tube running to the lowest portion of the outer vapor hose.

Fuel on its way to the nozzle speeds up when it squeezes through the venturi and creates a natural suction which draws the pooled liquid back into the fuel stream.

Hose and nozzle manufacturers license the Gilbarco® venturi technology from us.

-	Related Links and Documents


»	SP-2210B - Vapor Recovery Systems
»	EPA Stage II Areas

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