GB2309767A

GB2309767A - Damped float valve

Info

Publication number: GB2309767A
Application number: GB9701951A
Authority: GB
Inventors: Barry Charles Risbridger; Paul Richard Chawner
Original assignee: W&J Risbridger Ltd
Current assignee: W&J Risbridger Ltd
Priority date: 1996-02-02
Filing date: 1997-01-31
Publication date: 1997-08-06
Also published as: GB9701951D0

Abstract

A float valve is disclosed which closes gradually in a non-concussive manner and which is intended for use in controlling the vent line from a fuel storage tank. The valve comprises an elongated float 332 movable in/on a tubular body 330. Movement of the float is damped by pressure of vapour within the tubular body, at least just prior to the valve closing onto its seat. A partition 333 may be provided in the float to define a chamber 335 (along with a deflecting cone 334) which changes volume as the valve closes and so damps the float movement.

Description

FLOAT VALVE This invention relates to a float valve for automatically closing a pipe fromaliquidtank.

Float valves are widely used to cut off the flow of liquid or vapour from a storage tank when the liquid level reaches a predetermined point. Valves of this type are frequently used in fuel storage tanks and are installed on the vapour vent line to automatically shut off the flow ofliquid into a tank and to restrict the flow of vapour back to the delivery vehicle when the storage tank has reached a desired fill leveL One of the difficulties with such valves is that they can close very suddenly which causes the transmission of severe hydraulic shocks through a fuel delivery system.

According to one aspect of the present invention there is provided a float valtje. especially for controlling a vent line from a tank containing liquid, said valve comprising an elongated float movable on a tubular body, wherein upward movement of the float is damped by pressure of vapour within the tubular body, at least just prior to the valve closing onto its seat. The float may be arranged to slide inside the tubular body and may comprise an elongated float movable within a tube and having a conically or part conically shaped valve seat.

The float valve may comprise an elongated float movable on a tube float valve, especially for controlling a vent line from a tank containing liquid, said valve comprising an elongated float movable on a tubular-body, wherein upward movement of the float is damped by pressure of vapour within the tubular body, at least just prior to the valve closing onto its seat.

In one embodiment, the invention includes a float valve, especially for controlling a vent line from a tank contaning liquid, said valve comprising a float arranged to slide on a tubular body and including a chamber formed by a wan of the float and a partition across the tubular body, said chamber being reduced in volume as the valve closes, thus exerting a damping action on the closure of the valve.

As a result of these designs, the improved valve gradually closes in a non-concussive manner.

One embodiment of a float valve in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a general arrangement drawing showing the layout of a fuel storage tank and delivery system, Figure 2 is a section through a float valve in accordance with the invention, and Figure 3 is a section through a second embodiment of float valve in accordance with the invention Referring to Figure 1, the fuel storage and delivery system comprises a storage tank 1 containing a liquid sseL The storage tank is connected to an offset fill line 2 (or direct fill point) through which fliel can loaded into the tank via a fuel fill point 3. Fuel from the storage tank can be delivered to a delivery pump 5 via a suction line 4 and vapour can be vented from the storage tank through a vapour vent line 6 which may be connected either to a single vent line 7 or a vent line manifold 8, connected to several other filel tanks. The vent line 6A may also include a branch line 6a connected to the delivery pump and intended for vapour recovery from ssel dispensed into a vehicle.

The float valve 10 is located within the ullage ofthe tank and is flitted to the lower end of the vapour vent line 6. Float valve 10 is intended to close the vent line when fuel in the tank rises to a predetermined leveL This prevents over-filling of the fuel tank The details of the float valve itself are shown in Figure 2 and it will be seen that the valve comprises a body 20 of generally tubular form having an upper threaded end 21 for screwed attachment to the vent line pipe 6 or to a suitable adaptor. Slidably contained within the tube 20 is a float 22, designed to move upwardly in the tube 20 as the liquid level rises in the tank towards a filled condiom In order to prevent fuel being driven out of the tank by over filling, the valve 10 is set to close when there is still a sufficient free head space at the top of the tank, e.g. when the tank is about 95% filled. Tube 20 is formed with one or more axially elongated slots 24 in the wall of the tube through which vapour may flow from the ullage through the vent pipe. As the float 22 moves up the tube 20, it reduces the area of the slots 24 through which the vapour is free to flow thereby gradually restricting the flow of vapour through the ven.

line.

The top of the float valve at 26 is tapered or frusto conical in shape to correspond with a similar tapered or frusto conical shape 28 on the upper ormer face of the tube 20. In the closed position, surfaces 26 and 28 correspond to close off the valve.

In order to prevent the float valve faIling out of the tube when the liquid in the tank falls substarctally below the level of the float, afloat stop pin 30 is provided which extends radially from the float into one er more of the slots 24.

Thus, at its furthest extent, the float valve is retained by the stop pin engaged in the lower part of the radial slot.

Figure 3 shows an alternative embodiment of float valve in accordance with the invention. The valve is also intended to be mounted in the head space of a fuel storage tank 1. The valve ofFigure 3 consists of a tubular valve body 330 having a slot-shaped opening 331 to allow vapour to escape from the tank into the vapour recovery line 7. A float 332 is arranged to slide up and down to control the size of the opening 331 as the liquid level in the tank changes.

However, instead of sliding within the tubular body as in Figure 2, the float slides over the body and forms an external sleeve valve. The float has a partition 333 and the tubular body a deflecting cone 334 forming a chamber 335 which damps the movement of the float. At its lower end, the tubular body has an enlarged and chamfered end 336 for guiding the float. A float stop pin 337 is attached to the lower end of the body and extends radially through a slot 338 in the float body.

The float valve may be used in a fuel delivery system as descried in UK Patent Application No. 9306893.0 (Publication No. 2265988). A valve such as shown in Figures 4A and 4B of the above application can be fitted in the pipe connecting float valve 10 to the vapour lines 6 and 6A, thereby enabling the vapour lines to be isolated and their integtity tested in the manner described in our above-mentioned application

Claims

CLAIMS: -

1. A float valve, especiany for controlling a vent line from a tank containing liquid, said valve comprising an elongated float movable on a tubular body, wherein upward movement of the float is damped by pressure of vapour within the tubular body, at least just prior to the valve closing onto its seat.

2. A float valve, especially for controlling a vent line from a tank containing liquid, said valve comprising an elongated float movable on a tube float valve, especially for controlling a vent line from a tank containing liquid, said valve comprising an elongated float movable on a tubular body, wherein upward movement of the float is damped by pressure of vapour vbqthin the tubular body, at least just prior to the valve closing onto its seat.

3. A float valve, especially for controlling a vent line from a tank containing liquid, said valve comprising a float arranged to slide on a tubular body and including a chamber formed by a wall of the float and a partition across the tubular body, said chamber being reduced in volume as the valve closes, thus exerting a damning action on the closure of the valve.