GB2270361A

GB2270361A - Valve float with sealing hull and weighted keel

Info

Publication number: GB2270361A
Application number: GB9219022A
Authority: GB
Inventors: Anthony Carey Williams
Original assignee: CAMBRIAN PLASTICS Ltd
Current assignee: CAMBRIAN PLASTICS Ltd
Priority date: 1992-09-08
Filing date: 1992-09-08
Publication date: 1994-03-09
Anticipated expiration: 2012-09-08
Also published as: GB9219022D0; GB2270361B

Abstract

A valve member floats in a first liquid to allow flow of the liquid through an outlet 12, and sinks in a less dense second liquid to prevent flow to the outlet. A hull portion 20 of the valve member closes the outlet in the presence of the less dense fluid, and the valve member has a weighted keel 21 which orients the valve member. In the preferred embodiment the first fluid is water and the second fluid is petrol. The valve member may be housed in a chamber 16 defined by an enclosing filter 15. <IMAGE>

Description

Valve This invention relates to valves or closure devices which are particularly for use in drainage systems designed to prevent, for example, the discharge of petrol from a garage forecourt into the drainage system.

Currently such systems involve a reservoir into which the surface drains feed and which itself in turn debouches into the main drainage system. At the outlet of the reservoir or of an upstream part of a reservoir a valve or closure device is provided which consists of a chamber extending above the outlet and a ball which is contained within the chamber and dimensioned to seal off the outlet when it rests at the bottom of the chamber. By selecting the density correctly, the ball can be arranged so that it will float in water but will sink rapidly in the less dense oil or petrol and so as soon as the chamber becomes filled with the less dense liquid the ball will fall on to the outlet seat shutting the outlet off.In a more recent development the walls of the chamber are formed as a filter and the ball may close off an inlet in the chamber so that all the liquid passes through the filter during normal use.

Whilst this system works very well for small chamber outlets, the increase in ball diameter which is needed to meet an increase in outlet dimension is such that the balls rapidly become extremely heavy and for example a ball which would seal a one meter diameter outlet might weigh over 500 kilos. This makes handling a considerable problem and the whole unit takes up too much space. The balls are also expensive to manufacture and the joint line which is formed between the halves of the ball on assembly has to be extremely good if it is not to produce a leakage path. The result is that outlets have been restricted in dimension to a size which will not always adequately handle storm water.

According to the present invention there is provided a valve for allowing a first liquid to flow through an outlet and for automatically closing the outlet in the presence of a second less dense liquid; comprising an outlet, an inlet chamber extending above the outlet and valve body in the chamber, having an average density such that it floats in the first liquid and sinks in the second liquid to close the outlet wherein the valve body has a hull portion for closing the outlet and a weighted keel.

It will be understood that the weighted keel provides two advantages. First it can be made of very dense material, such as lead, reducing considerably the volume that is needed for the remainder of the valve body in order to achieve appropriate densities and secondly it will inherently define a floating or sinking orientation for the valve body and so the body no longer needs to be symmetrical about all axes.

Thus the hull portion can be generally in the form of a disc, which may be straight sided or in the form of a frusto-cone (eg like a bath plug) but preferably it is curved on at least those portions which are intended to engage a seat defined by the outlet. This curvature can generally remove or reduce the likelihood of the disc becoming jammed, if during manufacture or use, the seat is for any reason not appropriately orientated. It is generally preferred that the under surface of the disc is generally curved and the upper surface is generally flat.

Thus the under surface may be such that at any point the principle normal of the generating curve is normal to the under surface.

The hull portion may be solid, or alternatively it may be hollow so that it can be partly filled with water in order to allow for final adjustment of its weight and hence its effective density.

The invention also includes a containment vessel including a valve of this type and further includes a valve body having an average density such as it floats in a first liquid and sinks in a second liquid, wherein the valve body has a hull portion for closing the outlet and a weighted keel.

Although the invention has been defined above it is to be understood that it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and a specific embodiment will now be described by way of example with reference to the accompanying drawing which is a schematic vertical section through an outlet in a containment vessel.

In Figure 1 the vessel 10 is divided into a first tank 11 and an outlet section 12 which communicate through an outlet 13 in the tank 11. A valve unit 14 is mounted in the outlet 13 and comprises a filter enclosure 15 which defines a chamber 16 extending above the outlet 13 and a valve body generally indicated at 17. As has been indicated above, the valve body 17 is generally configured to float in water and therefore normally sits in the upper position shown in the drawing where it is retained in the filter enclosure 15 by an annular wall 18. If the chamber becomes filled with a less dense liquid the valve body rapidly falls to the lower position indicated in the Figure where it engages a seat 19 disposed within the outlet 13 and automatically shuts off the outlet 13.

The valve body 17 is constituted by a hull portion 20 and a weighted keel 21. The hull portion 20 is generally in the form of a disc having a curved under surface and would typically be made of plastics. The curvature on the under surface is such that the valve body 17 is self-seating on the seat 19, even if that seat is slightly tilted with respect to the axis of the outlet 13.

The most preferred arrangement is that at any point, the principle normal of the generating curve of the under surface 22 of the hull portion 20 is normal to that surface.

The hull portion 20 may be solid or it may be hollow to allow for adjustment of its density as mentioned above.

It will be appreciated that the construction of valve body described above considerably reduces the volume of valve body required for any particular outlet dimension and hence the weight needed to achieve the density which will float in water but sinks in oil or petrol. The construction also requires less material, is easier to use, and can ensure that any joint line will not need to engage the seat, because the seating orientation is pre-defined.

Claims

1. A valve for allowing a first liquid to flow through an outlet and for automatically closing the outlet in the presence of a second less dense liquid, the valve comprising an outlet, an inlet chamber extending above the outlet, and a valve body in the chamber having an average density such that it floats in the first liquid, and sinks in the second liquid to close the outlet, and wherein the valve body has a hull portion for closing the outlet and a weighted keel.

2. A valve according to claim 1, wherein the hull portion is generally in the form of a disc.

3. A valve according to claim 1 or claim 2, wherein the under surface of the disc is in the form of a frusto-cone.

4. A valve according to claim 1 or claim 2, wherein the under surface of the disc is curved on at least those portions which are intended to engage a seat defined by the outlet.

5. A valve according to claim 3, wherein the under surface of the disc is such that at any point the principle normal of the generating curve is normal to the under surface.

6. A valve according to any one of claims 1 to 5, wherein the top surface of the disc is generally flat.

7. A valve according to any one of claims 1 to 5, wherein the hull portion is hollow.

8. A valve according to any one of claims 1 to 5, wherein the hull portion is solid.

9. A valve according to claim 1 substantially as herein described with reference to the accompanying drawings.

10. A containment vessel including a valve of the type as defined in any one of claims 1 to 9.

11. A valve body having an average density such that it floats in a first liquid and sinks in a second liquid, wherein the valve body has a hull portion for closing an outlet from a valve chamber, and a weighted keel.