GB2290076A

GB2290076A - Device for releasably holding an overfill prevention device in a fuel tank

Info

Publication number: GB2290076A
Application number: GB9511149A
Authority: GB
Inventors: Barry C Risbridger
Original assignee: W&J Risbridger Ltd
Current assignee: W&J Risbridger Ltd
Priority date: 1994-06-07
Filing date: 1995-06-02
Publication date: 1995-12-13
Anticipated expiration: 2015-06-02
Also published as: GB2290076B; GB9411401D0; GB9511149D0

Abstract

A cage 9 - 13, which is removable through an inspection port 2 of a junction piece 1 connecting a drop tube 6 to an underground tank and to an offset inlet pipe 5, consists of an abutment member 9 and a pivotally linked latch member 12 and holds a liner tube 7 incorporating an overfill device within tbe drop tube. The abutment member is preferably a ring which bears on the top of the liner tube and the latch member is a bar which is moved between a locking position, in which the ends of the bar engage in the internal junction of the junction piece (figure 2), and a position which allows for cage removal by turning a set screw at the top of a tapped rod 11 which is fixed to a cross bar at the centre of the ring. The overfill device is preferably a two stage shut off valve operated by a float and is filled between upper and lower sections of an alloy liner tube. The inspection port may be closed by a plug 3, removal of the cage through the inspection port allowing servicing of the overfill device. <IMAGE>

Description

A SECURING CAGE FOR AN OVERFILL PREVENTION DEVICE This invention relates to a securing cage for an overfill prevention device for a fuel tank.

Overfill prevention valves are known and are now required under current regulations to be fitted to new underground fuel storage tanks. They are conventionally fitted to the standard drop tube which extends from the tank fill point to the tank bottom. One example of an overfill prevention valve is that manufactured by the OPW Company as the 61-SO overfill prevention valve. The overfill prevention valve is fitted to the alloy drop tube in the fuel tank and operates to actuate a shut-off valve when fuel in the tank exceeds a predetermined level. Normally, the drop tube, which incorporates the overfill prevention valve, is held in the tank by a cage which has threads engaging with threaded surfaces on the inspection access port. These cages, however, have the disadvantage that they are often very difficult to remove for servicing the overfill prevention valve.

It is, therefore, an object of the present invention to provide a securing cage for an overfill prevention valve which can be easily and rapidly fitted and removed.

According to one aspect of the present invention there is provided a securing cage for releasably retaining an overfill prevention device in a liquid storage tank wherein an upright inlet pipe is connected to the tank at one end and to an offset fill pipe at the other by means of a connector piece which includes a port for connection to the offset fill pipe, said cage comprising an abutment member adapted to abut one end of a liner tube which is associated with an overfill prevention device and which extends into the inlet pipe, said abutment member including a latch member which is pivotally linked to the abutment member and engageable in said port to hold said abutment member against the end of said liner tube.

The abutment member preferably has a curved portion which conforms approximately with the end of the liner tube. Generally, it will be circular or part circular and will have an open inner portion to allow liquid to pass into the tank.

The latch member is preferably connected to a cross or bridge piece which extends across the ring or separate portions forming the abutment.

One embodiment of a securing cage in accordance with the invention will now be described, in which: Figure 1 is a vertical section through the T-piece at the inlet of an underground fuel storage tank, and Figure 2 is a plan view in the direction of the arrow A in Figure 1.

Referring to the drawings, an underground fuel storage tank has a "T" piece 1, including an inspection port 2, normally closed with a plug 3. The side port 4 of the "T" piece is connected to an offset fill pipe 5 which can be connected to a tanker's fuel line at the end remote from the "T" piece. The "T" piece is screwed to a down tube or nipple 6 which is connected to the top of the tank (not shown). In order to ensure that fuel which enters the "T" piece is taken to the bottom of the tank, so as to avoid foaming during filling, an alloy drop tube 7 is fitted within the tube 6 and extends to a point at or close to the bottom of the tank. An "O" ring 8 provides a seal between the top end 6 and a turned-over flange of the alloy drop tube 7.

An overfill prevention device such as that manufactured by the OPW Company, is fitted to a mid-section of the alloy drop tube by screwing to upper and lower sections of the alloy drop tube. The device has an internal passageway which permits a dip tube to pass through the alloy tube to the bottom of a tank so that the tank can be dipped after removing the plug 3.

The overfill prevention device incorporates a two stage shut-offvalve operated by a float. When the liquid level rises to approximately 95% of tank capacity, the valve mechanism is released and the valve closes automatically with the flow. A by-pass valve allows filling to continue at a slow rate which alerts the operator to the fact that the tank is close to filled capacity. If the liquid rises to about 98% capacity, the by-pass valve closes and no additional liquid will flow into the tank.

The alloy drop tube, including the overfill prevention valve, is held in place by a cage which includes a ring 9 contacting the upper surface of the flange on the top ofthe droop tube 7. The ring 9 incorporates a cross bar lqO, to the centre of which is fitted a pivotable rod with a female tapped rod 11.

The top of the rod is fitted with a set screw onto which the latch bar 12 is loosely attached by adjustable lock nuts. By turning the set screw, the latch bar can be adjusted in or outwards to lock or unlock the device into the "T" pieces.

The cage is held in place by swinging the latch bar 12 towards the offset fill pipe 5 so that the ends of the bar engage in the internal junction of the side "T" piece as shown in Figure 2. The drop tube can be released, e.g.

for removing the valve for servicing simply by swinging it in the direction of the arrow X in Figure 1, and lifting the cage out ofthe "T" piece.

Claims

CLAIMS:

1. A securing cage for releasably retaining an overfill prevention device in a liquid storage tank wherein an upright inlet pipe is connected to the tank at one end and to an offset fill pipe at the other by means of a connector piece which includes a port for connection to the offset fill pipe, said cage comprising an abutment member adapted to abut one end of a liner tube which is associated with an overfill prevention device and which extends into the inlet pipe, said abutment member including a latch member which is pivotally linked to the abutment member and engageable in said port to hold said abutment member against the end of said liner tube.

2. A cage as claimed in claim 1 wherein the abutment member is in the form of a partial or complete ring.

3. A cage as claimed in claim 2 wherein the latch member is linked to a cross piece which extends across said ring.

4. A cage as claimed in any one of the preceding claims wherein the latch member comprises a bar which is movable into a position in which it engages in said port.

5. A fuel storage tank having an inlet tube and an offset fill pipe connected at a junction piece, a drop tube extending into the inlet pipe and into the tank and being associated with an overfill prevention device located within the tank, said drop tube being removable through the junction piece and being secured in position in the inlet tube by a securing cage as claimed in any one of the preceding claims.

6. A fuel storage tank as claimed in claim 5 wherein the inlet tube is substantially upright and the junction piece is a T-piece.

7. A fuel storage tank as claimed in claim 6 wherein the overfill prevention device is incorporated in the drop tube and includes a float which is operable to close the drop tube when the fuel in the tank reaches a predetermined level.