초록 ▼

An improved capacitance level probe is shown which can be positioned within the return vapor passage of a coaxial vapor recovery refueling system for detecting changes in liquid level within an underground fuel storage tank. The level probe has an outer conductor, a spaced inner conductor, a closed

An improved capacitance level probe is shown which can be positioned within the return vapor passage of a coaxial vapor recovery refueling system for detecting changes in liquid level within an underground fuel storage tank. The level probe has an outer conductor, a spaced inner conductor, a closed upper end and a lower end with an end opening which allows liquid to enter and leave the interior of the probe as liquid level changes within the underground tank being monitored. A tubular impact vent is located at the upper end of the outer conductor and collects tank vapors from the return vapor passage in order to conduct such vapor pressure to the open interior of the outer conductor above the level of liquid within the outer conductor. This action prevents sudden pressure drops within the outer conductor as the level of fuel changes within the underground storage tank, thereby eliminating inaccuracies in the sensed capacitance of the unit.

대표청구항 ▼

An improved capacitance level probe positionable at least partly within the return vapor passage of a coaxial vapor recovery refueling system for detecting changes in liquid level within an underground fuel storage tank, the capacitance level probe comprising: an elongated outer conductor having a g

An improved capacitance level probe positionable at least partly within the return vapor passage of a coaxial vapor recovery refueling system for detecting changes in liquid level within an underground fuel storage tank, the capacitance level probe comprising: an elongated outer conductor having a generally cylindrical exterior, an open interior, a closed upper end and a lower end; an elongated inner conductor located within the open interior of the outer conductor and initially separated therefrom; spacer means located within the open interior of the outer conductor for securing the inner conductor within the open interior thereof and for insulating the inner conductor from the outer conductor; wherein the lower end of the outer conductor includes an end opening for allowing the ingress and egress of liquid as the level of liquid changes within the underground fuel storage tank, the presence of liquid within the open interior of the outer conductor serving to make electrical contact between the inner and outer conductors; a tubular impact vent connected proximate the upper end of the outer conductor by means of a connecting end with a connecting opening which communicates with the open interior of the outer conductor, the tubular vent also having a collecting end with a collecting opening which collects and concentrates tank vapors from the return vapor passage and conducts such vapor pressure to the open interior of the outer conductor above the level of liquid within the outer conductor, thereby preventing sudden pressure drops within the outer conductor as the level of fuel changes within the underground storage tank; and wherein the connecting end of the tubular impact vent extends outwardly from the cylindrical exterior of the outer conductor generally normal thereto and wherein the tubular impact vent also includes a curved portion between the connecting end and the collecting end, whereby the collecting end is oriented generally parallel to the cylindrical exterior of the outer conductor and extends in the direction of the lower end thereof.