Fluid handling – Destructible or deformable element controlled – Destructible element
Patent
1997-05-30
1998-06-16
Ferensic, Denise L.
Fluid handling
Destructible or deformable element controlled
Destructible element
137 6812, 137797, 285 4, F16K 1714
Patent
active
057655871
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an automatically-operating valve, intended to close off a flow passage through the valve in the event that the valve is subjected to a significant shear force. In particular, but not exclusively, the invention is intended for use in connection with the mounting of a forecourt liquid fuel dispensing pump, on to a supporting base.
Fuel pumps for dispensing petrol or diesel fuel into the tank of a motor vehicle generally comprise a self-contained unit mounted on a base or plinth on a garage forecourt, the pump being connected by way of a pipeline to an underground storage tank from which the fuel is drawn during operation of the pump. Some fuel pumps operate simply by suction, so that there is a sub-atmospheric pressure in the pipe from the underground tank to the pump, whenever the pump is in operation. Other systems employ a pressure-feed system where fuel in the pipeline from the tank to the pump is under pressure, to ensure a uniform delivery of fuel to the pump. This system may be employed when there is a relatively long pipeline from the underground tank to the pump.
It is unfortunate that not infrequently, vehicles manoeuvring on a garage forecourt collide with a fuel pump and displace the fuel pump from its proper position. In order to prevent significant fuel spillage (which could be most substantial in the case of a pressurised delivery system) it is the usual practice to fit a shear valve in the pipeline delivering fuel to the pump, in the vicinity of the mounting of the pump on to the base or plinth. An example of such a shear valve is shown in U.S. Pat. No. 3489160. This shear valve has a weakened zone so that if the pump is subjected to a lateral displacement, the valve will shear across its weakened zone. An automatically-operating valve member within the shear valve then closes the delivery pipeline to prevent leakage of fuel.
There is however a problem with the known design of shear valve; in the event that a fuel pump is subjected to a minor impact which is sufficient to cause the valve body to shear along its weakened zone but not sufficient to displace the fuel pump significantly from its normal position, it can happen that the valve member is not released so the flow passage through the valve body is not closed. As the valve body has sheared at its weakened zone, there results a significant leakage of fuel.
It is a principal aim of the present invention to address the above-described problem, and so to provide a valve wherein the closing of a flow passage through the valve can be assured in the event that the valve body shears about a weakened zone provided therein.
According to the present invention, there is provided an automatically-operating valve comprising a body defining a flow passage and having a weakened zone around that passage, a valve member mounted within the passage for movement towards a closed position where the valve member closes the passage on one side of the weakened zone, spring means urging the valve member to said closed position, a brittle frangible link bridging the weakened zone, and a control mechanism bearing on the frangible link and controlling movement of the valve member under the action of the spring means.
The shear valve of this invention will hereinafter further be described particularly with reference to its intended use with a forecourt petrol or diesel pump, though the valve may find uses in other industries--for example in a chemical manufacturing plant.
It will be appreciated that in the automatically-operating valve of the present invention, the closing of the flow passage through the valve body is controlled by a brittle frangible link which bridges the weakened zone. In the event that the valve body is subjected to sufficient force to shear the valve body at its weakened zone, the brittle frangible link inevitably will also break, so freeing the control mechanism to allow the valve member to move under the action of the spring means, thereby closing the flow passage. In this way, closing of the flow passage may be assu
REFERENCES:
patent: 1044347 (1912-11-01), Carlson
patent: 2906280 (1959-09-01), Mount
patent: 2962035 (1960-11-01), Wright et al.
patent: 2965116 (1960-12-01), Boone et al.
patent: 3489160 (1970-01-01), Moore
patent: 3860025 (1975-01-01), Nelson
patent: 4995643 (1991-02-01), Rappart et al.
patent: 5193569 (1993-03-01), Moore et al.
patent: 5244006 (1993-09-01), Pettesch
Ferensic Denise L.
Kim Joanne Y.
LandOfFree
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