GB2547709A - Freezing of pipes - Google Patents

Abstract

A pipe-freezing sleeve comprising a shell 26 shaped to seat upon a pipe (24, Fig 5) so as to define an internal cavity between an inner surface 32 of the shell 26 and an outer surface of the pipe. A deflector 60 is disposed in the internal cavity and arranged such that cooling gas emerging from an inlet port 54 impinges on the deflector 60 and is deflected along a direction circumferential to the pipe. The deflection of the gas helping it to be distributed evenly around the pipes circumference, giving more even and efficient cooling. Preferably, two deflectors 60a,b - each providing a deflector surface 62a,b that is inclined to the pipes longitudinal axis 58 - are provided to deflect the gas in opposite circumferential directions. A temperature indicator (64, Fig 5) for providing an indication of temperature in the internal cavity may also be provided in the shell 26. A kit of parts comprising a sleeve and a canister for delivery of coolant gas is also taught.

Description

FREEZING OF PIPES

The present invention is concerned with the freezing of water in pipes to prevent escape of water.

When working on plumbing it is often necessary to disconnect an item from a water-filled pipe. In some such cases the pipe is pressurised. To avoid discharge of water the relevant section of pipe needs to be isolated in some way. In some cases this can be achieved by means of an isolating valve incorporated in the plumbing. In other cases no isolating valve is provided. One possible solution is to disconnect the whole system from the mains water supply using the mains stopcock and then drain the system before disconnecting the relevant item. This can be time consuming, it involves an interruption in supply which may be problematic for occupants of the building, and it is not possible in all cases to gain access to the stopcock so this approach is not always feasible. A known alternative is to locally freeze the water in the pipe upstream of the point at which disconnection is to be made. The frozen water in the pipe forms a plug preventing water discharge for the duration of the relevant work, and thaws subsequently to open the pipe to water flow.

One way to freeze the pipe is to use of an electrically driven refrigeration device to cool contact pads applied to the pipe. Such devices are somewhat costly.

Another approach involves the use of a pressurised gas container to release gas in the vicinity of the pipe. The gas cools on release due to its expansion, and so cools the pipe. Simple kits for this purpose have been commercially available for decades and include a portable gas canister akin to an aerosol spray can, along with a simple sleeve to be placed around the pipe. The sleeve in one commercial example comprises a flexible rectangular sheet of plastics material and a foam liner. The two long edges of the plastics sheet are each provided with a clip, allowing the sleeve to be placed around the pipe with the foam liner inside, after which the long edges of the sheet are clipped to one another to retain the sleeve in position. A nozzle tube projecting from the gas canister is then introduced by the user between the foam liner and the pipe, and release of gas is initiated to freeze the pipe.

Various problems are encountered in practice. The tube through which gas is released is typically aligned roughly along the length of the sleeve and pipe. The effect can be to project the gas and/or its condensate through the sleeve and out of its other end, which is wasteful and inefficient. Also this direction of gas release gives a cooling effect which is greater on one side of the pipe than its opposite, which often means that the side of the pipe directly exposed to the gas flow cools quickly but the opposite side much more slowly. This slows the process of freezing of the water in the pipe and makes it less effective.

There is little control provided over the direction of release of the gas, which may make it harder to obtain reproducible effects.

The known kit gives the user no indication of whether the required ice plug has formed.

There is also a problem in ensuring - while work is underway - that the plug of ice in the pipe does not thaw prematurely, which could allow unwanted discharge from the pipe. If the user suspects that the plug is close to thawing then he/she may choose to release more gas into the sleeve to prevent that from happening, but the user receives no warning of when thawing is taking place. The consequences of uncontrolled discharge of mains water can be alarming and very damaging to decoration, furnishings, carpets and so on.

In accordance with a first aspect of the present invention there is a pipe-freezing sleeve according to appended claim 1.

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

Figure 1 is a schematic representation of a gas canister of known type;

Figure 2 shows the exterior of a shell used in a pipe-freezing sleeve embodying the present invention;

Figure 3 shows the interior of the shell;

Figure 4 is an enlarged view of part of the interior of the shell;

Figure 5 is a schematic representation of a sleeve embodying the invention mounted upon a pipe for use; and

Figure 6 is a side view of the sleeve; and Figure 7 is a view of the sleeve from one end.

The gas canister 10 depicted in Figure 1 belongs to the prior art and is conveniently sized to be held in the hand and carried in a tool kit. It has a valve mechanism 12 atop a pressure vessel 14 and having a push button 16 to be depressed by the user to release gas. Gas emerges through a nozzle tube 18 which is push fitted into the valve mechanism 14. The drawing shows the form of the gas plume 20 created by this arrangement, which is concentrated along the line of the tube 18. As mentioned above, when using the known sleeves for pipe freezing the gas tends to impinge predominantly on one side of the tube. In addition there is a tendency for the gas to pass through the sleeve and emerge from its end, in gaseous form or as a condensate. It will be apparent that the shape of the plume provided by release of the gas from the tube 18 contributes to both problems.

The present invention provides an improved pipe-freezing sleeve 22 to be mounted on a watercarrying pipe 24 (which is seen in Figure 5). The sleeve is configured to serve several functions: - it increases the residence time of the coolant gas in the vicinity of the pipe 24 to promote cooling; - it controls the direction of release of the gas; - it directs the gas within the sleeve in a manner which helps to distribute it around the pipe's circumference, giving more even and effective cooling; - it resists egress of the gas/condensate form the end of the sleeve; and - it gives the user a temperature indication. This helps the user to judge whether the necessary temperature for formation of the ice plug has been achieved during the cooling process, and whether it is being maintained subsequently.

Looking at Figures 2 to 7, the sleeve 22 comprises a shell 26. In the present embodiment this is a substantially rigid item, not being required to flex significantly in use. It is formed as a unitary injection moulded plastics body although it could be manufactured in other ways. The shell 26 seats upon the pipe 24 in use although it need not make direct contact with the pipe since it may be separated from it by a foam insert 28 (which is seen in Figure 5). In the present embodiment the shell comprises a part-cylindrical outer wall 30 whose convex inner face 32 carries a first end wall 34 and a second end wall 36, the end walls lying in a radial plane and each having a respective part-circular cut-away 38 to accommodate the pipe 24. When the shell 26 seats upon the pipe 24 it thus defines a part-annular internal cavity between the pipe and the said inner face 32.

In the present embodiment the shell 26 is to be secured to the pipe 24 using a flexible panel 40 as seen in Figures 5, 6 and 7. The shell 26 has a shallow rebate 42 along a first edge of the outer wall 30 (see Figure 3 in particular) to which a first edge of the flexible panel 40 is secured by means of adhesive. The rebate gives a tidy appearance to the finished product but is an optional feature, and the two parts may be joined in other ways, as will be apparent to the skilled person. A second edge 46 of the flexible panel 40, parallel and opposite to its first edge, is releasably securable to the shell 26. This may be achieved by means of hook and eye fasteners (for example the well-known fastener sold under the registered trade mark Velcro). An area 48 of the fastener material is provided on the exterior of the shell 26 (see Figure 7). A complementary area 50 of fastener material is provided adjacent the second edge 46. Other types of fastener may be used for this purpose.

The shell 26 has an inlet port for receiving the tip of the nozzle tube 18. This comprises a through-going passage 54 in the shell's outer wall 30 so that gas can be injected from the outside into the aforementioned part-annular space within the shell 26. The passage 54 is somewhat elongate, being formed through a protuberance 56 on the exterior of the shell 26 and inclined toward axis 58 of the shell and the pipe 24. The passage 54 serves to control the angle formed by the nozzle tube 18 to the pipe 24 and so to control the direction of projection of the gas.

Within the shell 26, gas deflectors 60a, 60b serve to direct the flow of gas along directions which have a circumferential component. In the present embodiment the gas deflectors are adjacent the inner end of the passage 54 and arranged so that gas emerging from the passage impinges upon them. A deflector surface 62a of gas deflector 60a is inclined to the shell's axis 58 such as to direct gas flow along a direction having a clockwise component. A deflector surface 62b of gas deflector 60b is oppositely inclined to direct gas flow along a direction having an anti-clockwise component. The arrangement is symmetrical about an axial plane, to send roughly equal quantities of gas in the opposite directions. The effect is to distribute cooling gas around the circumference of the pipe 24, helping to ensure that the side of the pipe remote from the inlet port 54 receives a flow of gas and is cooled. In this way a more even and rapid cooling effect is provided. In addition the above mentioned tendency, associated with the prior art, for the gas to pass through the sleeve and escape from its end is reduced because the main direction of travel of the gas is, due to the action of the deflectors 60a, 60b, not along the length of the pipe 24. Rather, the deflected gas tends to follow a helical path about the pipe 24. The end walls - and especially the second end wall 36 toward which the gas flow is directed - also help to resist premature escape of the gas and its condensate. Increased residence time of the gas in the vicinity of the pipe 24 helps to improve its cooling effect.

The sleeve 22 embodying the invention can be considerably shorter in length than the known type of freezing-sleeve described above formed of flexible plastics sheet. As a result it is more compact and easily stowed and carried, but it also provides a more localised and rapid cooling effect.

As noted above a foam insert 28 is provided. This may be separate from the shell 26 and flexible panel 40 and can simply be loosely arranged inside them when the sleeve 22 is mounted on the pipe 24. The foam insert may be shaped with longitudinally extending ribs and troughs. It extends around the full circumference of the pipe 24 as seen in Figure 5. Materials other than foam may be adopted in other embodiments.

The shell 26 carries a temperature indicator 64 to provide the user with an indication of temperature at or close to the surface of the pipe 24. Figure 2 shows a through-going opening 66 in the outer wall 30 of the shell for receipt of the temperature indicator 64, whose visual output it thus visible to the user while its temperature sensing component is exposed to temperature in the region of the pipe 24 within the sleeve 22. In the present embodiment the temperature indicator 64 is a conventional thermometer with a dial readout although other suitable devices may be adopted.

In use it is observed that displayed temperature falls quickly when gas delivery is initiated and rises somewhat when delivery ceases. This is because of the transient cooling effect of the gas upon the temperature indicator. However, once a stable displayed temperature below a certain level is achieved, that can be interpreted as indicative of freezing. While the pipe 24 is disconnected and work is going on, the sleeve 22 is typically left in place and the user can periodically check the displayed temperature. A displayed temperature above a certain level is to be interpreted as a warning that further cooling is required to prevent thawing of the pipe.

Use of the improved sleeve 22 is straightforward. First the combination of the shell 26 and the foam insert 28 is placed upon the pipe 24. The flexible panel 40 is passed around the pipe and attached to the shell using the fasteners 48,50 under some tension, to keep the entire sleeve 22 in position. Nozzle tube 18 of gas canister 10 is inserted into the inlet port 54 and gas delivery is initiated by depressing push button 16. After a prescribed period the user releases the push button to stop gas delivery and observes the displayed temperature, which will then rise somewhat. If the displayed temperature stabilises below a prescribed value, that is interpreted as indicative of freezing of the pipe so that it can be disconnected. If the displayed temperature rises above the prescribed level then gas delivery is re-commenced and the procedure is repeated until a stable low displayed temperature is achieved.

While subsequent work is ongoing, a periodic check is made on displayed temperature. If it rises above a prescribed value then further gas delivery can be used to re-cool the pipe and so guard against thawing.

The sleeve 22 may be supplied to users in a pipe-freezing kit including the gas canister 10, although these items may be sold separately. A kit may contain two sleeves - one for freezing a water feed pipe and one for the return pipe. The sleeve 22 may be re-usable.

Claims (12)

1. A pipe-freezing sleeve comprising a shell shaped to seat upon a pipe and so to define an internal cavity between an inner surface of the shell and an outer surface of the pipe, and a securing arrangement for releasably securing the shell upon the pipe, the shell comprising an inlet port for supply of coolant gas from the exterior of the shell to the internal cavity and at least one deflector disposed in the internal cavity and arranged such that gas emerging from the inlet port impinges on the deflector and is deflected by it toward a direction having a component along a direction circumferential to the pipe.

2. A pipe-freezing sleeve as claimed in claim 1 in which the deflector provides a deflector surface which is inclined to the pipe's longitudinal axis in use.

3. A pipe-freezing sleeve as claimed in claim 1 or claim 2 comprising at least two deflectors arranged to deflect gas toward respective, opposite circumferential directions.

4. A pipe-freezing sleeve as claimed in any preceding claim in which the inlet port comprises an elongate through-going passage inclined to the pipe's longitudinal axis in use to deliver gas toward the pipe.

5. A pipe-freezing sleeve as claimed in claim 4 in any preceding claim in which the shell comprises a part-cylindrical outer wall and a pair of end walls.

6. A pipe-freezing sleeve as claimed in any preceding claim in which the securing arrangement comprises a flexible part arranged to be passed around the pipe to secure the shell to it.

7. A pipe-freezing sleeve as claimed in claim 6 in which the flexible part comprises a flexible panel.

8. A pipe-freezing sleeve as claimed in claim 7 further comprising a liner for arrangement between the pipe and the shell in use.

9. A pipe-freezing sleeve as claimed in any preceding claim in which the shell carries a temperature indicator for providing an indication of temperature in the said internal cavity.

10. A kit of parts for pipe-freezing comprising at least one sleeve as claimed in any preceding claim and a pressurised canister for delivery of coolant gas.

11. A kit of parts as claimed in claim 10 when dependent on claim 4 in which the pressurised canister is provided with a nozzle tube receivable in the through-going passage, so that the through-going passage controls direction of release of gas into the sleeve.

12. A pipe-freezing sleeve substantially as herein described with reference to and as illustrated in the accompanying drawings.