WO1992021914A1

WO1992021914A1 - Supply line assembly

Info

Publication number: WO1992021914A1
Application number: PCT/GB1992/000979
Authority: WO
Inventors: Alastair Cameron Donald
Original assignee: Alastair Cameron Donald
Priority date: 1991-05-29
Filing date: 1992-05-29
Publication date: 1992-12-10
Also published as: AU1772192A; GB9111489D0

Abstract

A supply line assembly comprising a pipe (1) surrounded by an outer sleeve (2). A pressure change in the outer sleeve (2) causes a supply in the pipe (1) to be shut off. The supply may be a fluid, in which case flow through the pipe is shut off, or may be electricity delivered along cables, in which case the power supply to the cables would be switched off by control circuitry.

Description

SUPPLY LINE ASSEMBLY

This invention relates to a supply line assembly which is such that the supply along the line may be terminated when a possible fault condition is detected. The term supply line as used generally herein covers lines for supplying a liquid, gas or other "commodity" such as electricity. Thus the term supply line encompasses pipes for conveying gas or liquid and conduits containing cables for the supply of electricity. The term supply line also encompasses an electricity cable. The term fluid supply line is however to be construed specifically as a line which conveys fluid (liquid or gas).

Previously it has been known to detect faults or damage in pipes or conduits by monitoring pressure or some other quantity in the pipeline itself. However, with the known detection devices any damage in the pipe may allow the outflow of substance from the pipe before the supply can be turned off and the pipe can be repaired. There may be a delay between detection of damage in the pipe and the supply being turned off.

According to a first aspect of the present invention there is provided a supply line assembly comprising a supply line, a chamber associated with the line, means for detecting a pressure condition in the chamber, and means for preventing further supply along the line if the detected pressure condition varies beyond a pre-defined limit.

The chamber may be filled with a gas or a liquid and the pressure condition being detected may be an elevated or reduced pressure. The means for preventing further supply along the line may comprise a microswitch connected to a control circuit. The control circuit may prevent further supply of electricity in a cable or may shut off a pump propelling the supply of fluid in the supply line.

According to a second aspect of the present invention there is provided a fluid supply line assembly comprising a supply line along which a fluid flows, a chamber associated with the line, means for detecting a pressure condition in the line, and means for preventing further supply along the line if the pressure condition therein changes beyond a predetermined value relative to a pressure condition in the chamber. Preferably the chamber is an outer sleeve co-axial with the supply line. Preferably the means for detecting a pressure condition comprises an annular ring and an annular pressure plate. Preferably also the annular ring is of U-shaped cross-section. The means for preventing further supply along the line may comprise an apertured plate, at least one piston valve and biassing means to urge the piston valve to close the apertured plate.

It will be appreciated that situating the means for detecting a pressure condition in the chamber ensures that the detector does not have to withstand conditions in the supply line itself. Further, detecting a change in the pressure in the line relative to the chamber above a pre-determined limit means that the supply to the line may be stopped before a serious problem occurs. It will also be appreciated that substantially the same detection device can be used on pipelines for electrical cables or pipelines for fluids and the like.

Specific embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a part longitudinal section of a first embodiment of a supply line assembly according to the first aspect of the present invention; and Figure 2 is a longitudinal section of a second embodiment of a supply line assembly according to the first aspect of the present invention; and Figure 3 is a schematic illustration of a third, embodiment of a supply line assembly according to the first aspect of the present invention. Referring to Figure 1, the illustrated supply line assembly comprises an inner pipe 1 surrounded by an outer sleeve 2 and having a terminal coupling arrangement 3 connected to the assembly of pipe 1 and sleeve 2 by a housing 4 incorporating a valve arrangement 5.

The inner pipe 1 and the outer sleeve 2 are both generally cylindrical. Sleeve 2 has a greater diameter than the pipe 1 and is co-axial therewith. As shown, the end of the outer sleeve 2 extends beyond the end of the inner pipe 1.

The housing 4 is generally cylindrical and has a projecting tubular spigot 6 which is a close fit within pipe 1. Additionally, housing 4 has a cylindrical collar 7 which is a close fit within sleeve 2. A sealant is provided between spigot 6 and pipe 1, and between collar 7 and sleeve 2 to prevent leakage. An annular recess 8 is formed between the outer wall of spigot 6 and the inner surface of collar 7, the recess being closed at one end by an annular wall 9. Four equiangularly spaced apertures 10 are provided in this annular wall 9.

An annular ring 11 of. U-shaped cross-section is seated in the annular recess 8 with its limbs pointing towards the outer sleeve 2. The annular ring is formed of a resilient material enabling it to deform under pressure. An annular pressure plate 12 is seated in the annular recess 8, between the annular ring 11 and the wall 9.

A lip 13 is provided on the inner surface of the housing 4, against which bears an apertured plate 14 located in position by a spigot 15 on the coupling 3. The apertured plate 14 is provided with four apertures 16 corresponding in position to the apertures 10 in the annular wall 9 of the housing 4. The apertures 16 are countersunk inwardly in a direction going towards the pipe 1.

The valve arrangement 5 incorporates four valve members 17. The valve members 17 each have an elongate stem 18 (which locates through a registering pair of apertures 10 .and 16) and a chamfered head portion 19. The free ends of the stems 18 bear against the pressure plate 12. The chamfer on the heads 19 of the valve members is capable of locating in the countersink of the apertures 16 to enable the heads to provide a good seal against fluids flowing through the housing. The valve members 17 are urged towards the pipe 1 by an annular closure spring 20 which locates within the spigot 15 (of coupling 3) and which on one face bears against the heads 19 as shown and on the other side bears against a wall 21 of the coupling 3.

The described arrangement is such that (in normal use) fluid may flow between the pipeline 1 and coupling 3 via the tubular spigot 6. The coupling is provided with an external screw thread 22 or the like to enable it to be screwed into place for example to a supply of fuel. In use, the outer sleeve 2 is pressurised thus causing deformation of annular ring 11 so that it urges the pressure plate 12 against the annular wall 9. As a result, valve members 17 move against the closure spring 20 so as to open apertures 16 to fluid flow. Thus, in normal use of the arrangement, fluid may pass from coupling 3 to the pipe 1 (or vice versa) via the centre of spring 20, the apertures 16 and the spigot 6.

If outer sleeve 2 is damaged (thus indicating possible damage to pipe 1), the pressure in the outer sleeve 2 drops. This releases the pressure on the annular ring 11 so that the closure spring 20 moves the valve members 17 until their heads 19 seat in the apertures 16. This closes the apertures, thus stopping the flow of fluid in the pipe. In a modification of the apparatus (not illustrated) the spring 20 may be omitted and the valve members 17 may be extended rearwardly (ie to the right in Fig. 1) by a stem projecting from the head 19. Each such projecting stem would locate in a respective guide channel in the coupling 3. A closure spring (eg a coil spring) would be provided for each valve member. The spring would be positioned around the projecting stem and would bear against the head 19 and the wall 21. The spring would thus bias the head towards the apertures 16. In use, the outer sleeve 2 is pressurised causing the annular ring 11 to urge the pressure plate 12 against the annular wall 9, as in the above described embodiment. Damage to the outer sleeve 2 releases the pressure on the annular ring 11, so that each closure spring moves its respective valve member until their heads seat in the apertured plate 14, thus closing the apertures.

An alternative embodiment of the invention (in accordance with the first aspect) is to have a pressurised outer sleeve with a supply tube allowing pressure to bear against a pilot actuator valve. The pilot pressure opens a flow valve situated in a fluid supply pipe. A drop in pressure in the outer sleeve allows the pilot actuator valve to move, shutting off the flow in the fluid supply line.

Referring now to Figure 2, the illustrated supply line assembly comprises a conduit 23 (carrying electrical cable - not shown), an outer sleeve 24, a housing 25 and switches 26, 27 incorporating respective actuators 26a and 27a.

The switches 26 and 27 are associated with a control arrangement (not shown) such that power is only supplied along the electrical cables (in conduit 23) when actuators 26a and 27a are depressed. The actuator buttons 26a and 27a are biassed outwards of switches 26 and 27 and are acted upon by a U-section annular ring 28 (similar to the ring 11 of Fig. 1).

In use, sleeve 24 is pressurised and the ring 28 causes actuators 26a and 27a to be depressed into the respective switches 26 and 27. Thus power can flow along the electric cable. If outer sleeve 24 is ruptured (this indicates possible damage to the electrical cables) pressure is lost and the ring 28 resiles away from the switches. The actuators of these switches thus move to a position at which the supply of electrical current .is cut off.

It will be appreciated that the embodiment of Fig. 2 could be modified so as to control fluid flowing through a pipeline, in which case the switches 26 and 27 control a pump which supplies fluid along the line.

Numerous modifications are possible for the illustrated embodiment. For example, a mechanism may be provided to pressurise the outer sleeve only when there is substance flowing through the line (eg a fuel line in a car where fuel is only supplied during running of the engine). Alternatively or additionally the sleeve 2 may be maintained at a reduced pressure so that rupture therof causes an increase in pressure to be detected. For this modification, suitable changes need to be made to ensure that the valve or switch arrangement are effective to terminate supply upon detection of the pressure increase.

Referring now to Figure 5, the illustrated supply line assembly comprises an inner pipe 29 surrounded by an outer sleeve 30. A pipe 31 is provided, perpendicular to the outer sleeve 30, and connected thereto at one end. At the other end of the pipe 31, contacts 32 are provided in a housing 33 associated with a control circuit (not shown).

In use, the outer sleeve 30 and pipe 31 are pressurised. This pressurisation urges the contacts 32 together, thus causing the control circuit to allow fluid to flow along pipe 29, or electrical current to flow along cables in pipe 29. If damage occurs to the sleeve 30, pressure is lost and the contacts 32 open, so that the control circuit shuts off a pump supplying the fluid in pipe 29 or shuts off the supply of electrical current in the cables in pipe 29.

It will be appreciated that the embodiment of Fig. 3 could be modified so that a number of pipeline and sleeve arrangements could be connected to one housing 33 containing contacts 32. Thus, only one detector and control circuit need be used to monitor several pipes. The outer sleeve 30 and connecting pipe 31 could be de-pressurised, thus ensuring that any damage to the sleeve would cause the pressure to rise within the sleeve.

An alternative embodiment of this invention (in accordance with the second aspect) is to have pressure detection means within a fluid line surrounded by a sleeve containing fluid at a known pressure. Any change in the pressure in the line beyond a pre-determined value as established by the pressure in the outer sleeve (t us indicating a possible fault in the supply along the line) would cause the supply in the line to be shut off.

It will be appreciated that the above described embodiment of the second aspect of the present invention could be used to detect an increase in the pressure in the line, and could therefore be used as a safety device to cut off the supply of fluid in the line should the pressure of the fluid rise above a pre-determined level.

Claims

1. A supply line assembly comprising a supply line, a chamber associated with the line, means for detecting a pressure condition in the chamber, and means for preventing further supply along the line if the detected pressure condition varies beyond a pre-defined limit.

2. A supply line assembly as claimed in claim 1, wherein the chamber is an outer sleeve coaxial with the supply line.

3. A supply line assembly, as claimed in claim 1 or 2, wherein the chamber is filled with a gas or a liquid.

4. A supply line assembly as claimed in any preceding claim, wherein the means for preventing further supply along the line comprises a microswitch connected to a control circuit.

5. A supply line assembly as claimed in claim 4, wherein the control circuit prevents further supply of electricity in a cable.

6. A supply line assembly as claimed in claim 4, wherein the control circuit shuts off a pump propelling the supply of fluid in the supply line.

7. A fluid supply line assembly comprising a supply line along which a fluid flows, a chamber associated with the line, means for detecting a pressure condition in the line, and means for preventing further supply along the line if the pressure condition therein changes beyond a predetermined value relative to a pressure condition in the chamber.

8. A fluid supply line assembly as claimed in claim 7, wherein the chamber is an outer sleeve co-axial with the supply line.

9. A fluid supply line assembly as claimed in claim 7 or 8, wherein the means for detecting a pressure condition comprises_^ an annular ring and an annular pressure plate.

10. A fluid supply line assembly as claimed in claim 9, wherein the annular ring is of U-shaped cross-section.

11. A fluid supply line assembly as claimed in any one of claims 7 to 10, wherein the means for preventing further supply along the line comprises an apertured plate, at least one valve which is preferably a piston valve, and biassing means to urge the piston valve to close the apertured plate.