GB2206940A

GB2206940A - Isolating a section of a pipe by freezing to make repairs

Info

Publication number: GB2206940A
Application number: GB08714577A
Authority: GB
Inventors: Nils E V Martensson
Original assignee: Technotrend Ltd
Current assignee: Technotrend Ltd
Priority date: 1987-06-22
Filing date: 1987-06-22
Publication date: 1989-01-18
Anticipated expiration: 2007-06-22
Also published as: GB2206940B; GB8714577D0

Abstract

The apparatus and method employ clamping means having thermally conductive jaws 5a, 5b for attachment to the pipe section 1 and means for continously extracting heat from the jaws to cause freezing of the fluid in the pipe section. The heat may be extracted by either a Peltier effect device, or a refrigeration circuit. The clamping means may include arms 3a, 3b having integral or demountable jaws, a cold sink of the Peltier device or refrigeration circuit being coupled to one or both arms. <IMAGE>

Description

APPARATUS AND METHOD FOR ISOLATING A SECTION OF A PIPE TO MAKE REPAIRS This invention relates to apparatus and a method for isolating a section of a pipe to enable repairs to be made. The invention may be applied, for example, to piping systems which carry water and, in particular, to copper pipe central heating and water supply systems.

If a leak occurs in a central heating system, the conventional practice is to turn off the water supply and to drain the system before repairs can be undertaken.

After making the repair, the system must be refilled from the water supply and any air trapped in the system must be removed. This is an inefficient and time-consuming process, particularly where storage tanks need to be drained and refilled.

It is known to employ a carbon dioxide aerosol spray to freeze a section of a pipe, either on one or both sides (depending on where water is present), to enable a repair to be made without draining and refilling the system.

Usually, an insulating jacket is fitted around the pipe section and the cooling spray is applied inside the jacket. Steps are normally taken to ensure that no water is flowing in the pipe when the spray is used. Otherwise, the cooling efficiency of the spray may be insufficient to cause freezing. This technique has the disadvantage that several aerosol carbon dioxide containers may need to be used in order to maintain a frozen plug in the pipe over the period of time which is required for making the repairs. A plumber will also need to carry a sufficient supply of the aerosol containers, particularly where a number of repairs are made in the same day. There is also a risk of flooding if the supply of aerosol containers runs out before a repair is finished. These problems severely limit practical usage of the aerosol spray technique.

The invention overcomes the above-noted problems by providing a more simple and reliable technique which, in the long run, is less expensive to use in practice.

The invention provides apparatus for isolating a section of a pipe containing a freezable fluid, the apparatus comprising clamping means having thermally conductive jaws for attachment to the pipe section and means for continuously extracting heat from the jaws to cause freezing of the fluid in the pipe section.

The invention also provides a method of isolating a section of a pipe containing a freezable fluid, the method comprising the steps of attaching clamping means having thermally conductive jaws to the pipe section and continuously extracting heat from the jaws to cause freezing of the fluid in the pipe section.

The means for continuously extracting heat may be either directly attached to the clamping means, or remote from the clamping means. In the latter case, the clamping means may have a hollow portion which communicates, e.g.

via hoses, with the cold side of the heat extraction device.

The means for continuously extracting heat is preferably an electrically powered device which employs the Peltier effect. Such a device can be conveniently supplied with power from a domestic electricity supply (e.g. via a conventional circuit for providing a low-voltage, high current supply). Batteries could also be used (i.e. more advantageously than the aerosol containers of the prior art, since batteries would be more freely available at the site of repair).

According to one embodiment of the invention, the clamping means comprises a pair of arms made of thermally conductive material, such as copper, each arm having a respective jaw attached to one end, a Peltier effect device being thermally coupled to one or both arms to provide sufficient cooling of the jaws to cause the freezing of the fluid in the pipe section. The arms may be hinged or otherwise coupled together and/or securing means may be provided for ensuring that, in use, the jaws remain clamped to the pipe. The arms may not be necessary where, for example, the means for extracting heat can be directly coupled to the jaws.

Instead of being directly attached to the clamping means, a Peltier effect device may be provided in a separate heat-exchange housing which has hoses on a cold side for conducting a refrigerant, such as freon, to the clamping means, and hoses on a hot side to provide water cooling (as mentioned below). The clamping means may have a hollow portion connected to the refrigerant circuit on the cold side of such a heat exchanger. Alternatively, the refrigerant circuit can be connected to a coil or sleeve which surrounds, or is attached to at least a part of the clamping means.

As an alternative to using a Peltier effect device, a refrigeration circuit including a small electrically powered compressor may be used. It may also be feasible to employ a refrigeration circuit which is powered by either a domestic or bottled gas supply. Where such refrigeration circuits are used, a coil or sleeve may be provided for surrounding at least a part of the clamping means, or the clamping means may have a hollow portion as noted above.

An advantage of using either the latter-mentioned Peltier effect device or refrigeration circuit is that power can be continuously supplied to cause freezing of the fluid in the pipe for as long as it may be necessary to effect a repair.

A heat sink may be provided in order to conduct heat away from the hot side of the heat extraction device.

Such a heat sink could provide: (a) Air-cooling by means of convection; or (b) Air-cooling by a forced flow of air, e.g.

through a hollow heat sink connected to a fan; or (c) Water-cooling by means of a forced flow of water, e.g. through a hollow heat sink connected to hoses for respectively supplying water from the nearest domestic cold water supply and for discharging the water coolant to a drain (such water cooling is preferred since it is a cheap, convenient and effective method).

In order to accommodate pipes having different cross-sections, the clamping means may have demountable jaws of different corresponding sizes, or be of a variable geometry type.

Embodiment of the invention will now be described with reference to the accompanying schematic drawings, in which: Figure 1 illustrates an embodiment of the invention which employs a Peltier effect device, and Figure 2 illustrates an embodiment which employs a refrigeration circuit.

Figure 1 illustrates a part of a copper pipe 1 which carries water in a central heating system (not shown).

Clamping means 2 includes a pair of arms 3a, 3b, which may be connected by hinge 4, each arm having a semicylindrical jaw 5a, 5b adapted to provide a close fit with the exterior surface of pipe 1. The jaws and arms may be of integral or two-piece construction and made of a thermally conductive material,- such as copper. A Peltier effect device 6 is mounted on the clamping means 2 so that its cold side makes close thermal contact with one of the arms 3a. The hot side of device 6 has fins 7 to provide air cooling by means of convection. Instead of using fins 7, the hot side of device 6 may be fitted with an appropriate heat exchanger to provide for air or water cooling. A circuit 8, which can be connected to a main electrical supply via connector 9, provides device 6 with a low voltage high current supply.

In use, the jaws 5a, 5b are simply fitted around the required section of the pipe and secured together by suitable fastening means (not shown). A silicon compound, or the like, may be applied to the inner surfaces of the jaws 5a, 5b in order to improve thermal contact. When plug 9 is connected to the main supply, the Peltier effect device 6 extracts heat continuously from the clamping means 2, thereby cooling and freezing the water in the vicinity of jaws 5a, 5b.

Jaws Sa, 5b may be demountable from arms 3a, 3b, so that different sized jaws can be used to accommodate pipes of different cross-sections, or they may be of a variable geometry type.

In Figure 2, the clamping device is of similar construction except that one or both arms are hollow and are connected to inlet and outlet pipes 10, 11 which carry refrigerant from a cooling device 12. Device 12 may comprise a Peltier effect device, or a refrigeration circuit including a radiator, compressor and pump of conventional construction, for cooling the refrigerant flowing through pipes 10 and 11. The Peltier effect device or the compressor may be either air or water cooled and, in the latter case, hoses can be provided for respective connection to a water supply and drain.

Instead of making either or both arms 3a, 3b hollow, the arms may be of solid construction and received in a coil or sleeve (not shown) connected to the refrigerent circuit.

Thermal insulation may be provided, e.g. in the form of a jacket, around the clamping means 2 to assist in maintaining a frozen plug in the pipe 1.

Whilst exemplary embodiments have been described above, modifications and changes may be made without departing from the scope of the invention.

Claims

1. Apparatus for isolating a section of a pipe containing a freezable fluid, the apparatus comprising clamping means having thermally conductive jaws for attachment to the pipe section and means for continuously extracting heat from the jaws to cause freezing of the fluid in the pipe section.

2. Apparatus according to claim 1 wherein the means for continuously extracting heat is an electrically-powered device which employs the Peltier effect.

3. Apparatus according to claim 1 wherein the means for continuously extracting heat is a refrigeration circuit.

4. Apparatus according to claim 2 or 3 wherein said clamping means includes a pair of arms made of thermally conductive material, each arm having one of said jaws either integral with, or attached to one end, said means for extracting heat being coupled to either one or both of said arms.

5. Apparatus according to claim 4 wherein said jaws are demountable from said arms, said jaws being either part of a set of differently sized jaws, or being of a variable geometry type for accommodating pipes having different cross-sections.

6. Apparatus according to any of the preceding claims wherein said means for extracting heat has a cold sink coupled to said clamping means and a hot sink which is cooled: by natural convection; or by means for providing a forced flow of air; or by means for providing a flow of liquid coolant.

7. A method of isolating a section of a pipe containing a freezable fluid, he method comprising the steps of attaching clamping means having thermally conductive jaws to the pipe section and continuously extracting heat from the jaws to cause freezing of fluid in the pipe section.

8. A method according to claim 7 wherein said freezable-fluid is water, said pipe being part of a cold water supply or heating system and being made of thermally conductive material, such as copper.

9. A method according to claim 7 or 8 wherein said means for extracting heat comprises either a Peltier effect device, or a refrigeration circuit powered from either a mains supply, or a source of stored energy.

10. A method according to any of claims 7-9 wherein the heat which is continuously extracted from said jaws is continuously dissipated by means of air or water cooling.

11. Apparatus for isolating a section of a pipe containing a freezable fluid substantially as herein described with reference to either Figure 1, or 2 of the accompanying drawings.

12. A method of isolating a section of a pipe containing a freezable fluid substantially as herein described with reference to either Figure 1, or 2 of the accompanying drawings.