GB2257131A - Overfill prevention and filler pipe drainage system and valve therefor - Google Patents

Abstract

A shut-off valve (3 Fig. 1) for use in an overfill prevention filter pipe drainage system for a liquid storage tank (5) and connected in use to the filler pipe (4) includes a biased-closed gate 11 which can be held open by a latching device 32, 33b presettable by a manual operating member 12 and responsive to a valve control signal provided by a potential tank overfill condition to release the gate. A lost-motion linkage enables the manual operating member 12 to return to a starting position (Fig. 2A) after presetting the latching device (Fig. 2D). The gate is movable by the member 12 into an intermediate position, after the gate has been released from the latching device and has moved into its closed position (Fig. 2B), so that the filler pipe can be drained. <IMAGE>

Description

OVERFILL PREVENTION AND FILLER PIPE DRAINAGE SYSTEM This invention relates to an overfill prevention and filler pipe drainage system and also to a shut-off valve which can be a part of such a system.

The system and the valve can be used, for example, to prevent spillage of liquid fuel when filling a storage tank at a service station and to enable a filler pipe to be drained into the tank before it is removed. However, the system and/or the valve may be used in connection with liquid storage tanks in other fields of applications.

Storage tanks in service stations are filled with, e.g.

petrol, either using gravity feed, or a pump to drain the petrol from a tanker through a hose connected to a filler pipe. The filler pipe is long enough to extend into the bottom of the storage tank, the upper part of the pipe normally being connected to a valve on the tanker for terminating the supply of petrol before the tank is full.

The volumetric content of the tank is preferably monitored during filling, so that the tanker driver can be asked to terminate the supply of petrol before the a predetermined tank level is exceeded. However, it is often the case that the driver will dump the contents of a tanker compartment into a tank which has sufficient room i.e.

besides any ullage present, to accommodate the volume of petrol. When the supply has been terminated, or the tanker compartment has been emptied, the driver can remove the filler pipe carefully to enable the residue, in the pipe, to drain into the tank. However, if the driver and/or tank operator are careless, and/or if there is insufficient ullage in the tank, a safe tank level can be exceeded and spillage can occur. Once the tank has been overfilled, it may not be possible to drain the residue in the filler pipe without causing more spillage, or drainage of the pipe may be very difficult involving the risk of an accident.

The present invention solves this problem by providing an overfill prevention and filling pipe drainage system for use with a liquid supply source and a liquid storage tank, the system comprising: a filler pipe; control means responsive to an input signal representing a potential overfill condition in the tank for providing a valve control output signal, said input signal normally being derived from a liquid level sensor used with the tank; and valve means connected to the filler pipe and adapted for connection to the liquid supply, the valve means including: (a) a gate movable between full open and fully closed positions; (b) a latching device which can be preset for holding the gate in its fully open position, the latching device being responsive to the valve control output signal to release the gate; (c) a manual operating member for presetting the latching device; (d) biasing means for urging the gate into its fully closed position when released from the latching device; and (e) a lost motion linkage which enables the manual operating member to return to a starting position after presetting the latching device; the gate being subsequently movable by the member into an intermediate position, between its fully open and fully closed positions, after the gate has been released from the latching device and the gate has moved into its fully closed position, whereby the filler pipe can be drained.

The invention further provides an automatic shut-off valve comprising: (a) a valve body; (b) a gate mounted for movement transverse to a direction of fluid flow through the body, said gate being movable between fully open and fully closed positions; (c) a latching device which can be preset for holding the gate in its fully open position, the latching device being responsive to an external control signal to release the gate; (d) a manual operating member for presetting the latching device; (e) biasing means for urging the gate into its fully closed position when released from the latching device; and (f) a lost motion linkage which enables the manual operating member to return to a starting position after presetting the latching device; the gate being subsequently movable by the member into an intermediate position, between its fully open and fully closed positions, after the gate has moved into its fully closed position.

A preferred embodiment of the invention will now be described with reference to the accompanying Drawings, in which: Fig. 1 schematically illustrates the principle of operation of an overfill prevention device incorporating the invention; Figs. 2A-2D are similar sectional plan views of a valve used in the system and shown in different stages of operation; Fig. 3 is an elevation view of the valve shown in Fig.

2; Fig. 4 is an enlarged plan view, in section, showing certain components of the valve; Fig. 5 is an elevational section through, part of the valve showing other components; Fig. 6 is a section through a part of the valve showing a manual operating lever and a latching mechanism; and Fig. 7 is a sectional plan view of on line 7-7 of Fig.

6 of an upper portion of the component shown in Fig. 5 with some components rotated through about 900 for greater clarity.

Fig. 1 schematically illustrates a system embodying the invention wherein a tanker 1 delivers liquid fuel, via a hose 2, a shut-off valve 3 and a filler pipe 4 to an underground storage tank 5. A liquid level sensing probe 6 depends into tank 5 to provide a liquid level signal which is supplied to a tank gauge 7 for monitoring the volumetric content of the tank 5. The tank gauge 7 provides a potential overfill signal, i.e. when the liquid level reaches a predetermined height in tank 5, to an overfill prevention controller 8. Controller 8 responds to the potential overfill signal so as to supply an output control signal to the valve 3 to cause it to shut-off the supply of liquid fuel.

The construction and operation of the sensing probe 6 and the tank gauge 7 are known and require no further explanation. The overfill prevention controller 8 essentially comprises means for responding to an electrical signal from the tank gauge 7 and for providing a pressurised hydraulic or pneumatic output signal to valve 3 for holding the valve open during filling. When the electrical input signal to controller 8 changes, in response to a potential overfill condition, then controller 8 disconnects or terminates the supply of high pressure fluid to valve 8 which is designed to close automatically in response to this potential overfill condition. Those skilled in the art will be aware of the construction and operation of suitable means for use of controller 8 to achieve this result and hence no further explanation will be given.

The construction and operation of the valve 8 will now be described but it will first facilitate understanding to consider Figs. 2A-2D and Fig. 3.

The valve 8 includes a body 9, in which there is a fluid passage 10. A planar gate 11 moves transversely across the direction of fluid flow in order to open and close the valve. A manual operating lever 12 is linked to the gate 11, (as will be explained below), the clockwise rotation of lever 12 being limited by the presence of a padlock 13 (only the hasp of which is shown in the Drawings). When the padlock is removed, as shown in Fig. 2D, the lever 12 can be rotated further, in the clockwise direction, in order to latch the gate 11 in its fully open position (shown in Fig.

2A), and then allowed to return before the padlock 13 is replaced. This operation is carried out by an authorised person, to open the valve 8, before the storage tank is filled.

Instead of using a padlock 13, any similar securing means can be used, such as a pin, or nut and bolt, which can only be removed by means of a key or a special tool.

Fig. 2B shows the gate 11 in its fully closed position, e.g. where the latching device has been released. In this position, lever 12 has been caused to rotate anticlockwise to a position spaced from the padlock 13.

Fig. 2C shows an intermediate position of the gate 11, where the lever 12 has been rotated (by the driver of the tanker) clockwise until it abuts the padlock 13. This limited amount of movement slightly opens the valve to enable the filler pipe 4 to be drained into the tank 5 after shut-off. The lever 12 must be held in the position shown in Fig. 2C, i.e. against spring bias (see below), to drain the filler pipe, since the gate 11 is biased into its fully closed position. However, the padlock 13 prevents any unauthorised re-latching of the valve into its fully open position (Fig. 2A).Moreover, the partially opened valve prevents any further substantial delivery of fuel due to the slight opening (which is exaggerated in Fig. 2C). The controller 8 must also be reset before the valve latching device will operate to enable the gate 11 to be latched into its fully opened position.

The construction and operation of the valve 8 will now be described in more detail with reference to Figs. 4-7.

As shown in Figs. 4 and 5, gate 11 is of rectangular construction and it is slidably mounted, at each side, on rollers 14 which facilitate transverse movement across the liquid flow through the passageway 10 in the valve body 15.

The gate 11 has a wedge-shaped cross-section and its sloping face mates with a corresponding inclined peripheral portion 17 bounding the passageway 10 in the valve body 15. A continuous seal 18 is attached to the gate to make a fluid tight seal when the valve is closed. By using this wedgeshape, the seal 18 is relieved of sealing contact until the valve is about to close i.e. as the gate 11 is driven fully to the left of the Drawing (Fig. 5).

As shown in Fig. 4, gate 11 is connected via a crank 19 and a link 20, to a shaft 23. The ends of the link are connected to respective pivots 21, 22, pivot 22 being attached to gate 11. Crank 19 is fast with shaft 23.

Lever 12, the operation of which has been explained with reference to Figs. 2A-2D, is mounted so that it can rotate relative to shaft 23 to enable the return movement shown by comparing Figs. 2A and 2D. A tension spring 24 (schematically illustrated) is connected between an anchor point 25 on valve body 15 and an attachment point 26 (on crank 19) which is spaced radially from the axis of shaft 23. When shaft 23 rotates clockwise, spring 24 is tensioned and this provides a return bias for closing gate 11 (i.e. when the latch has been released).

The latching device will now be described with reference to Fig. 6. Shaft 23 is shown in cross-section together with a section through a cylindrical cap 29 which is integral with lever 12 (and which acts as a housing). Cap 29 is mounted coaxially with shaft 23 by means of a bearing 30, so that the cap can rotate (over a limited arc) relative to the shaft. Cap 29 has depending lugs 31 (see also Fig.

7) which abut a cross-pin 28 that is fixed to shaft 23 i.e.

when the cap has rotated through a certain arc on the shaft.

An annular piston 32 moves axially in an annular cylinder, which is defined by an inner wall 33a and an outer wall 33b. Inner and outer piston rings 35, 36 provide sealing contact between the piston and cylinder. A coil spring 37 is located between the inner wall 33a and an inner side face 38 of piston 32, the spring 37 being confined by stops 39. The inner wall 33a is sealed to the shaft 23 by an seal 40. The annular piston 32 has anti-rotation lugs 41 which engage with corresponding recesses 41a in the outer wall 33b of the cylinder. Arcuate portions 42a, 42b of the piston are separated by slots 50a, 50b (Fig. 7) which receive respective ends of the cross pin 28 when the valve is latched open. A fluid inlet 43, for pressurised air or hydraulic fluid, communicates with an annular chamber 44 between confronting end faces of the piston and the cylinder.Admission of fluid under pressure to inlet 43 urges piston 32 towards the cross-pin 32 so that, when the cap 29 is rotated by lever 12, the pin 28 will enter the slots 50a, 50b to hold the shaft 23 in the latched position, i.e. with the valve fully open.

As shown in Fig. 7, the lugs 31 which depend from the inner face of cap 29 are arcuate in shape and extend over about 900 with respect to the rotational axis of shaft 23.

Therefore, rotation of cap 29, by lever 12 causes the lugs 31 to abut the cross-pin 28 at the limits of arcuate movement. This enables the cap to rotate in one direction to cause the cross pin 28 to engage with slots 50a, 50b in the piston and then in the other direction to return lever 12 to the position shown in Fig. 2A (i.e. due to lost motion).

When pressurised fluid is supplied to inlet 43, piston 32 is urged towards cross-pin 28. If the lever 12 is now rotated to the position shown in Fig. 2D, it moves the cross-pin 28 with respect to the piston until the cross pin is aligned with slots 50a, 50b whereupon the piston is displaced axially into the position shown in Fig. 6 (due to the pressure of fluid on input 43). The lever 12 can now be returned (due to lost motion) to the position shown in Fig. 2A, i.e. so that the padlock 13 can be attached.

During this lever movement, the shaft 23 does not rotate and it is held by the latching action so that the valve is fully open with the lever 12 shown in the position illustrated in Fig. 2A.

If tank gauge 7 now senses a potential overfill condition from sensor 6, controller 8 terminates the supply of high pressure fluid to inlet 43 and vents chamber 44.

Spring 37 then urges piston 32 away from the cross-pin 28 thereby releasing engagement between pin 28 and the piston 32, so that shaft 23 is released to enable gate 11 to move into its fully closed position (as shown in Fig. 2B).

However, limited movement of lever 12 is still possible (as shown in Fig. 2C), i.e. as far as the padlock 13. As lugs 31 abut pin 28 after the latch has been released, this limited movement of lever 12 causes shaft 23 to turn to move the gate 11 slightly back, i.e. into its intermediate position (Fig. 2C) which allows the filler pipe to be drained, but which prevents any further substantial supply of fuel to the tank. Any further latching of the valve is impossible unless the padlock 13 is removed to enable the lever 12 to be rotated to the position shown in Fig. 2D.

Although only one embodiment of the invention has been described, various modifications are possible within the scope of the invention. For example, the tension spring 24 could be replaced by a torsion spring to serve the same purpose.

Claims (22)

CLAIMS:

1. An overfill prevention filler pipe drainage system for use with a liquid supply source and a liquid storage tank, the system comprising: a filler pipe; control means responsive to an input signal representing a potential overfill condition in the tank for providing a valve control output signal, said input signal normally being derived from a liquid level sensor used with the tank; and valve means connected to the filler pipe and adapted for connection to the liquid supply, the valve means including: (a?) a gate movable between full open and fully closed positions; (b) a latching device which can be preset for holding the gate in its fully open position, the latching device being responsive to the valve control output signal to release the gate; (c) a manual operating member for presetting the latching device; (d) biasing means for urging the gate into its fully closed position when released from the latching device; and (e) a lost motion linkage which enables the manual operating member to return to a starting position after presetting the latching device; the gate being subsequently movable by the member into an intermediate position, between its fully open and fully closed positions, after the gate has been released from the latching device and the gate has moved into its fully closed position, whereby the filler pipe can be drained.

2. A system according to Claim 1, wherein the latching device includes: a shaft coupled to the gate, which shaft rotates between first and second angular positions corresponding to the fully open and fully closed positions of the gate; a latch mounted for rotation with the shaft; a catch mounted for movement relative to the shaft and movable between a first position at which it engages with the latch and a second position in which the latch is free.

3. A system according to Claim 2, wherein the catch comprises a piston movable within a cylinder, the piston and cylinder being coaxial with the shaft, said piston or cylinder acting as the catch.

4. A system according to Claim 3, wherein the latch is an arm extending radially from the shaft and wherein the piston acts as the catch and moves axially of the shaft, the piston having at least one recess to receive and thereby engage the arm, the cylinder being fixed and having a fluid input port.

5. A system according to Claim 4, including biasing means for urging the piston away from said arm, whereby fluid pressure causes the piston to engage the arm and a loss in fluid pressure enables the piston to be moved by the biasing means, hence enabling the gate to move into its fully closed position.

6. A system according to any of Claims 4 or 5, wherein the lost motion linkage includes at least one abutment on the manual operating member which is spaced from the arm to provide lost motion when the manual operating member is initially operated and before it engages the arm, the manual operating member being rotatable so as to position the latch in its first angular position at which the gate is fully open and the catch engages the latch, the operating member being subsequently rotatable to its starting position.

7. A system according to Claim 6, wherein securing means are provided, on the valve means, to allow only an authorised person to rotate the manual operating member so as to position the latch in its first position, said securing means preventing such rotation after the manual operating member has been returned to its starting position, except for a limited rotation of the manual operating member, to enable the gate to be moved into its intermediate position following closure of the gate.

8. A system according to Claim 7, wherein the securing means includes a device removably mounted on the valve means and to which the authorised person has access said device inhibiting movement of the manual operating member which would otherwise be necessary for presetting the latching device.

9. A system according to Claim 8, wherein the removable device is a padlock, the valve means having attachment points for the padlock which are disposed so that the padlock restricts the path of movement of the manual operating member unless the padlock is removed by the authorised person.

10. A system according to any of Claims 6-9 wherein the manual operating member is a lever integral with a cap, which cap houses the piston and the cylinder, said cap being coaxially mounted on the shaft.

11. A system according to Claim 10, wherein the cap has said abutments in the form of arcuate lugs which engage said arm when the cap is rotated, the lugs each being spaced from said arm so as to provide said lost motion.

12. A system according to any of the preceding Claims, wherein the gate is a planar member mounted on rollers for movement transversely of the direction of flow of the liquid through the valve means.

13. A system according to Claim 12, wherein the planar member has a chamfered peripheral portion to mate with a corresponding sloping peripheral portion on a body of the valve means, sealing means being provided on one or other of the latter portions to provide a liquid tight seal when the gate is in its fully closed position, the arrangement being such that the sealing means is relieved of sealing contact when the gate traverses the body of the valve means away from its fully closed position.

14. A system according to any of Claims 2-13, wherein the shaft is connected to the gate by a crank and link member.

15. A system according to Claim 14, wherein the biasing means for urging the gate into its fully closed position is a spring which acts between the shaft and a body portion of the valve means.

16. An automatic shut-off valve comprising: (a) a valve body; (b) a gate mounted for movement transverse to a direction of fluid flow through the body, said gate being movable between fully open and fully closed positions; (c) a latching device which can be preset for holding the gate in its fully open position, the latching device being responsive to an external control signal to release the gate; (d) a manual operating member for presetting the latching device; (e) biasing means for urging the gate into its fully closed position when released from the latching device; and (f) a lost motion linkage which enables the manual operating member to return to a starting position after presetting the latching device; the gate being subsequently movable by the manual operating member into an intermediate position, between its fully open and fully closed positions, after the gate has moved into its fully closed position.

17. A valve according to Claim 16 wherein the gate is a planar member mounted on rollers within the valve body.

18. A valve according to Claim 17, wherein the planar member has a chamfered peripheral portion to mate with a corresponding sloping peripheral portion on a body of the valve means, sealing means being provided on one or other of the latter portions to provide a liquid tight seal when the gate is in its fully closed position, the arrangement being such that the sealing means is relieved of sealing contact when the gate traverses the body of the valve means away from its fully closed position.

19. A valve according any of Claims 16-18 wherein the latching device includes a shaft coupled to the gate, which shaft rotates between first and second angular positions corresponding to the fully opened and fully closed positions of the gate; an arm extending radially from the shaft; a piston movable within the cylinder, the piston and cylinder being coaxial with the shaft, the piston moving axially of the shaft and having at least one recess to receive and thereby engage the arm, the cylinder being fixed and having a fluid input port; and biasing means for urging the piston away from the arm; the arrangement being such that the shaft can be rotated by the manual operating member to enable said recess or recesses in the piston to receive and thereby engage the arm when the cylinder is pressurized and that the biasing means urges the piston away from the arm, to disengage the latching device, to enable the shaft to rotate and thereby move the gate into its fully closed position.

20. A valve according to Claim 19 wherein the operating member incudes a lever which is integral with a cap, the cap housing the piston and the cylinder and including at lease one arcuate lug for engaging the arm, when the cap is rotated, said lug being spaced from the arm so as to provide lost motion.

21. A valve according to Claim 19 or 20, wherein the shaft is connected to the gate by a crank and a link member.

22. A valve according to any of Claims 16-21, wherein the valve body is fitted with securing means which inhibits movement of the manual operating member, after the latching device has been preset and the manual operating member has returned to a position in which the gate is fully closed, the securing means being releasable only by an authorised person to enable the latching device to be preset, but the inhibited movement of the manual operating member being sufficient to enable the gate to be moved into its intermediate position against the biasing means.