Fluent material handling – with receiver or receiver coacting mea – Automatic control of flow cutoff or diversion – Level or overflow responsive
Reexamination Certificate
2000-06-14
2001-11-20
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Automatic control of flow cutoff or diversion
Level or overflow responsive
C137S430000
Reexamination Certificate
active
06318421
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a fill limiter for a liquid storage tank.
It is known practice for a buried or overhead storage tank intended to hold a liquid to be fitted with a fill limiter, the function of which is to interrupt the filling of the tank when the liquid in the said tank reaches a predetermined level, so as to prevent overflow which would be damaging to the surroundings of the tank. This is especially desirable when the tank that is to be filled is located in a service station delivering hydrocarbons of various types.
The simplest limiters in terms of structure comprise a body, a valve element mounted in the said body and able to move between an open position corresponding to the filling of the tank and a closed position corresponding to the interruption of the filling of the said tank; a float connected to the said valve element accompanies the rise of the liquid in the tank so as to close the valve when the liquid in the tank reaches a predetermined level.
Many improvements have been made to limiters according to whether the storage tanks are equipped with manholes or inlet orifices for positioning limiters inside the storage tank.
In American U.S. Pat. Nos. 1,289,490 and 1,689,066, the limiters comprise a tube body equipped with an internal partition to delimit two adjacent chambers arranged side by side, one of the chambers acting as a passage for the liquid that is intended to fill the tank and the other being used to accommodate a float which is connected to a valve element which can be moved from an open position corresponding to a low liquid level in the tank, located below the float, into a closed position that corresponds to a high liquid level in the tank, this level still being below the shut-off valve. In this prior art, the valve is always reopened manually. What is more, and this is a serious drawback, there is no possibility of reopening the valve when the person performing the filling does not interrupt his filling action when the valve is in the closed position.
Other limiters have recently been proposed. Such limiters are described, for example, in patent 89/16604, European patent 0,415,991, patent 0,312,320, and U.S. Pat. No. 4,667,711.
BACKGROUND OF THE INVENTION
Each of the limiters described in these patents or patent applications comprises a float which is connected to the valve element so that, as the liquid in the tank rises, it is moved away from the limiter body. When the limiter is introduced into the tank inlet orifice, the float is at least partially housed in the body so as to reduce the space occupied by the limiter.
However, such limiters, because of the travel of the float outside the body, cannot allow the tank to be filled to the maximum extent. This is because it is necessary to leave a minimum amount of space between the upper wall of the tank and the uppermost position of the float.
Patent FR-90/10353 describes a limiter in which the float is mounted in a chamber formed parallel to the duct through which the fluid passes and delimited inside the limiter body by a dividing partition, the said float being connected by a linkage to the valve element so that the float is moved mechanically as the liquid in the storage tank rises. When the float reaches a predetermined level of liquid in the tank, the rod connecting the float and the valve element pushes the latter into its closed position.
The devices briefly described hereinabove do not allow the liquid introduced into the tank to be ducted and do not allow the liquid to be prevented from raining down into the said tank, so as to eliminate excessive foaming in the storage tank. What is more, these devices are not always suited to reducing or even eliminating the risk of explosion which exists at the time of communication between the outside and the gaseous headspace in which the air and the gas are confined. This risk of explosion may occur if the float rises at an inopportune moment.
OBJECTS OF THE INVENTION
The object of the present invention is to overcome the aforementioned drawbacks and to provide a limiter which allows the liquid to be ducted as it passes along the dip tube so as to considerably reduce the extent to which the liquid rains down onto the bottom of the tank and thus reduce the foaming in the said tank.
SUMMARY OF THE INVENTION
The subject of the present invention is a limiter of the type comprising a fill limiter for a liquid storage tank, the said limiter being intended to be at least partially introduced into the said storage tank and comprising a hollow upper body, a dip tube secured to the said upper body, a valve element mounted in the said hollow upper body and capable of being moved between an open position and a closed position, a valve seat formed in the said hollow upper body and against which the said valve element rests in the closed position, a float which can move vertically in a chamber formed at least partially inside the dip tube, characterized in that the said float is secured to moving parts forming a piston, the said moving parts being moved by the thrust of the liquid exerted on one of their ends.
According to another feature of the present invention, the moving parts comprise the float and a piston body secured to the said float and in which an annular chamber is formed about a through passage, the said moving parts being placed in an internal tube which is housed inside the dip tube and which is secured to the upper body.
According to another feature of the present invention, a central bore is formed in the float and is approximately coaxial with the said through passage of the piston body, a tube being placed in the said central bore of the float.
According to another feature of the present invention, the float comprises at least one through passage, one end of which opens into a front chamber formed between an intermediate piece secured to the upper body and the said float, and the other end of which opens into the piston body.
According to another feature of the present invention, the valve element is of cylindro-conical shape and is equipped at the top of the cone with a passage to allow the front face and rear face of the said valve element to communicate.
According to another feature of the present invention, the intermediate piece comprises at the top, on the one hand, a limit stop against which the tube of the float abuts, and, on the other hand, two orifices, through which a downstream chamber formed at the rear of the piston can be connected to the inside of the said tube, the said tube being able to move in a central passage formed in the intermediate piece.
According to another feature of the present invention, the intermediate piece comprises at least one duct via which the front chamber can be connected to a lateral duct formed on one side of the said upper body, the said lateral duct being connected, via a valve, to the upstream side the valve element.
According to another feature of the present invention, the internal tube is closed at its lower end by a grating.
According to another feature of the present invention, the internal tube comprises, at its upper part, an air discharge orifice communicating with a vent orifice formed in the upper body.
According to another feature of the present invention, the piston body is equipped with a valve element at its lower end.
One advantage of the present invention lies in the fact that the parts are isolated from the action of the liquid when the storage tank is being filled.
Other advantages and features will become better apparent upon reading the description of a preferred embodiment of the invention and from studying the appended drawing in which the single figure depicts a sectioned view of the limiter, the valve element being in the closed position.
REFERENCES:
patent: 1289490 (1918-12-01), Lunstrom
patent: 1689066 (1928-10-01), Baxter
patent: 3625264 (1971-12-01), Swain
patent: 3929155 (1975-12-01), Garretson
patent: 4444230 (1984-04-01), Van Mullem
patent: 4667711 (1987-05-01), Draft
patent: 0312320 (1989-04-01), None
patent: 0415991 (1991-0
Douglas Steven O.
Lafon Production
Ostrolenk Faber Gerb & Soffen, LLP
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