Liquid dispensing apparatus and method

Abstract

 A method and apparatus for dispensing corrosion inhibitor liquid to a pipework system such as a central heating system includes a retro-fit Tee connector 17 able to be attached to the pipe section 29 and to be communicated with the interior of the pipe section 29 by means of a separate drilling tool screwed on to a fitting 33 of the body 27, and an adapter 19 able to be releasably connected to a flowline 9 forming part of the dispensing apparatus 1 through which liquid under pressure can be pumped from the bottle 3 of the dispensing apparatus 1.

Description

[0001] The present invention relates to an apparatus and method for dispensing liquid, such as a corrosion inhibitor, to a pipework system, which contains a pressurised liquid. One example of such a system is a central heating system, in which a heat carrier liquid is present.

[0002] It is a known requirement to dispense an additive such as a corrosion inhibitor compound, a scale inhibitor composition, a biocide, or a dispersing agent, to an existing pipework system such as a central heating system, and to effect this without the need to drain down the liquid from within the pipework system.

[0003] One prior way of effecting this dosing with a corrosion inhibitor is to gain access to a feed and expansion tank in the case of an open central heating system, but frequently this involves gaining access to the highest point in the building, and would involve intrusion on the privacy of the occupants of the building or disturbance of surrounding material such as heat insulation over the header tank.

[0004] It has previously been proposed, in GB-A-2162164, to introduce corrosion inhibitor into a central heating system by isolating one radiator using its flow control wheel valve and its "trimming" lock shield valve, and then to replace the normal air bleed screw of the radiator by an adapter connected to a pressurizable container of corrosion inhibitor. When one of the two valves used to isolate that radiator is opened, the radiator is again in communication with the rest of the central heating system and the corrosion inhibitor can be pumped under pressure from its dispensing container through the air bleed valve port into the radiator and hence into the system as a whole. Once all the liquid has been pumped into the system, the radiator can once again be isolated from the rest of the central heating system, the adapter can be disconnected and the air bleed screw replaced and tightened, and then the two radiator valves can be opened to allow the system pump to run for a required period of time necessary to distribute the corrosion inhibitor throughout the whole central heating system. Throughout this corrosion inhibiting operation the pump of the central heating system can be in continuous operation so that only the one radiator is interfered with.

[0005] Nevertheless, there is a risk of contamination of the area around the radiator in the event that the adapter does not seal first time in the internally threaded air bleed screw port, and in any case the corrosion inhibitor introduction process, usually carried out at regular intervals (for example annually), will each time involve the same duration of the sequence of steps described in GB-A-2162164.

[0006] In some cases, existing pipework systems such as central heating systems either have no air bleed vent pins or plugs (screws), or they may have such features in locations which may be inaccessible without great difficulty.

[0007] It is an object of the present invention to allow dispensing of the corrosion inhibitor rapidly each time, and to minimize the extent of any pipe connection operations during subsequent corrosion inhibition operations.

[0008] Accordingly, one aspect of the present invention provides a method of introducing a liquid to a pipework system comprising attaching a retro-fit connector to a portion of pipe of said system, drilling through the connector into the pipe to provide communication with the interior of the pipe, attaching a pressurizable reservoir of liquid to said Tee connector, and dispensing said liquid under pressure from the reservoir into the pipe.

[0009] Furthermore, a second aspect of the present invention provides apparatus for dispensing liquid to a pipework system, comprising a pressurizable dispenser reservoir, a retro-fit connector for attachment to a section of pipe of said system, a shut-off valve to isolate the interior of said pipe section from the exterior of the connector, and a flow line between said pressurizable reservoir and said connector for conveying pressurized liquid into the pipe section through said connector.

[0010] In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawings, in which:-

FIGURE 1 is a perspective, partly exploded, view of apparatus for dispensing corrosion inhibitor into a central heating system as a preferred embodiment of the present invention; and

FIGURE 2 is an enlarged perspective view of the further exploded adapter before attachment to the pipework of the central heating system.

[0011] In order for the dispensing of corrosion inhibitor to a central heating system to be effected, the apparatus generally designated 1 in Figure 1 is proposed.

[0012] The apparatus 1 includes a pressurizable bottle 3 of rigid plastic, preferably transparent, material and equipped with a reciprocating pressurizing pump 5 operated manually by a handle 7 atop the bottle. Liquid contained within the bottle 3 can be pumped from the bottle along a flexible flow line 9 dipping at 11 into the bottle near its floor, and connected in a leak-tight manner to the sidewall of the bottle by means of an adapter 13. In order to allow pressure within the bottle 3 to be conveniently released, when desired, the bottle is further equipped with a pressure release valve 15 which may combine the functions of a pressure relief valve and a manually operated pressure release valve.

[0013] Thus far the apparatus 1-15 constituting the dispenser 1 is similar to a conventional commercially available dispenser for horticultural insecticide or fungicide compositions.

[0014] Access to the central heating system is obtained by way of a retro-fit Tee fitting generally referenced 17, and in particular by way of an adapter in the form of a cap nut 19 having an integral tubular inlet stem 21 on which the end of the flow line 9 can be attached by means of a compression ring 23 and a nut 25. However, in order to permit the cap nut 19 to be fastened to the rest of the retro-fit Tee connector 17, it is preferable for the clamp nut 25 to be only loosely tightened down while the cap nut 19 is screwed on to the body of the Tee connector, and then subsequently the clamp nut 25 can be tightened when the rest of the screw connections have been made.

[0015] The manner of attaching the body 17 of the Tee connector 17 to a section of pipe 29 forming part of the central heating system is best appreciated from Figure 2 where the Tee connector 17 is illustrated in an even more exploded condition than that of Figure 1. From this it can be clearly appreciated that the Tee connector 17 has a pair of diametrically opposite slots 31 formed at one end which is remote from an externally threaded end fitting 33 on to which the cap nut 19 is screwed during assembly of the corrosion inhibitor dispensing apparatus.

[0016] These slots 31 have semi-circular ends 35 which snugly engage the exterior of the pipe 29 when the body 27 of the Tee connector 17 is slipped over the pipe 29. Before this operation a saddle member 37 shown in Figure 2 will have been removed from the body 27, although in Figure 1 the saddle 37 is shown in place. Once the body 27 has been thus placed over the pipe 29, the saddle 37 can be inserted into the externally threaded end of the body 27 where the slots 31 are formed, so that a cylindrical cutout 39 in the saddle tightly holds the pipe 29 by the hemi-cylindrical part remote from the part engaged by the two semi-circular slot ends 35. This tight clamping operation is achieved by subsequent screwing down of a blank cap nut 41 on to the saddle thanks to threaded engagement of internal threads of the blank cap nut 41 on the external threading 36 of the connector body 27. The radius of curvature of the semi-circular slot ends 35 and that of the cut out 39 in the saddle 37 will be equal to the radius of the pipe section 29 with which the Tee connector 17 is to be used.

[0017] A separate tool, not shown, commercially available from Conex Sanbra Limited and marketed under the name "CONEX TEE BREAK TOOL KIT", which has its own sealing system can then be attached to the threaded end 33 of the connector body 27 so as to seal the end 23 following which a shut-off valve (not shown), in this case a rotary plug valve, housed within the body 27 can be opened by means of a control screw 43 shown in Figure 2. The tool is then operated to drill a hole in the right hand side of the pipe 29 by intrusion of the drill through the aperture left by the open plug valve. In a known manner, the disc of pipe material cut free during this drilling operation is removed through the aperture in the plug valve to within the tool, and the tool cutter is itself retracted into the body of the tool, following which the plug valve can be closed by means of the screw 43.

[0018] The adapter comprising the cap nut 19 and tubular inlet stem 21 of the apparatus shown in Figure 1 is then reinstalled on the threaded end fitting 33 shown in Figure 2, and the Tee connector 17 is then ready for use during several corrosion inhibition operations at the appropriate intervals.

[0019] Each time a further inhibition operation is to be carried out the dispensing apparatus 1, with its bottle 3 unpressurized, is placed alongside the Tee connector 17 and the end of the flow line 9 is connected to the tubular inlet stem 21 by means of the clamp nut 25 and plastic compression ring 23. By means of the handle 7 the pump 5 can then be operated to pressurize the bottle 3 and the liquid in the bottle 3 can then be placed under a pressure which is preferably at least as high as the internal pressure within the pipe 29 of the central heating system. By selecting, for the tubing 29, a location of the heating system near the top of the building to be heated, it is possible to ensure that the pressure within the pipe 29 will be relatively low by virtue of the reduced hydrostatic head above that particular location.

[0020] In order to allow dosing of the central heating system with corrosion inhibitor liquid from within the bottle 3 it is sufficient to open the plug valve within the Tee connector 17 by means of the screw 43, so that the pressure already built up inside the bottle 3 will drive the desired quantity of corrosion inhibitor into the central heating system via the flow line 9 and Tee connector 17. If necessary, the bottle 3 may be repressurized, partway through the dispensing operation (preferably while the plug valve is temporarily closed), and the dispensing operation can resume.

[0021] As indicated above, once a central heating system has been equipped with this retro-fit Tee connector 17 it is a simple matter to disconnect the dispensing apparatus 1 and the adapter 19, 21 at the end of one corrosion inhibition operation and to reconnect it at the start of the next such operation, in order to allow several subsequent corrosion inhibition treatments to be effected. A blanking cap nut may be attached in place of the removed adapter 19, 21, if desired.

[0022] With the system illustrated, it has been found that where recirculating liquid within a heating system is at a static pressure of less than 124 kPa it is possible to introduce corrosion inhibitor liquid without the need for localized freezing of the recirculating liquid, or any draining down of the system, and while the system remains under pressure and even under the influence of the recirculating pump of the heating system. For higher pressures it may be necessary to provide a more robust dispensing apparatus 1 which should present no problems, but the risk of any leakage is obviously reduced where the retro-fit Tee connector is attached at a high point in the system where the hydrostatic pressure is low.

[0023] The operation of screwing the adapter 19, 21 on to the externally threaded end fitting 33 is advantageously carried out with the assistance of polytetrafluoroethylene tape first of all wrapped round the externally threaded end fitting 33 in order to ensure a liquid-tight joint at the adapter/fitting interface. If desired, the adapter 19, 21 may be left in place for future operation so that this threaded attachment of the adapter, effected after extraction of the boring tool, can be left undisturbed.

[0024] Although throughout the present description the connector 17 has been referred to as a Tee connector, it is of course possible for the connector to be other than a right angle T configuration provided that some means is available for ensuring that the connector can be installed as a retro-fit to the pipework system.

[0025] Instead of a plug valve, any other suitable type of valve (for example a gate valve) may be used as the shut-off valve within the body 27.

[0026] As explained above although the above description refers to the addition of a corrosion inhibitor to a central heating system, it is possible for the liquid additive to be of some other form, and typical non-limiting examples would be scale inhibitors or biocides.

[0027] Likewise, the invention has broader application than simply to a central heating system and in general it may be applied to any existing pipework system in which a liquid under superatmospheric pressure is already present and it is desirable to introduce a liquid without draining down the system. Particularly appropriate non-limiting examples are cooling water systems, industrial process water systems, low pressure boiler systems, oil refining systems, and paper pulp treatment systems.

Claims

1. A method of introducing a liquid to a pipework system comprising attaching a retro-fit connector to a portion of pipe of said system, drilling through the connector into the pipe to provide communication with the interior of the pipe, attaching a pressurizable reservoir of liquid to said Tee connector, and dispensing said liquid under pressure from the reservoir into the pipe.

2. A method according to claim 1 wherein the connector includes a shut-off valve which can be closed after the drilling operation, opened temporarily to allow pre-pressurized liquid to be introduced through the valve into the pipe, and subsequently closed in order to re-seal the pipework system.

3. A method according to either one of the preceding claims, comprising several subsequent operations of introducing pressurized liquid into the pipework system through the same said connector.

4. Apparatus for dispensing liquid to a pipework system, comprising a pressurizable dispenser reservoir, a retro-fit connector for attachment to a section of pipe of said system, a shut-off valve to isolate the interior of said pipe section from the exterior of the connector, and a flow line between said pressurizable reservoir and said connector for conveying pressurized liquid into the pipe section through said connector.

5. Apparatus according to claim 4 wherein said connector is a Tee connector and includes said shut-off valve within the body of the connector.

6. Apparatus according to claim 5 wherein said shut-off valve is a plug valve.

7. Apparatus according to claim 5 or 6, wherein said pressurizable dispenser reservoir includes a pressure release valve.

8. Apparatus according to any one of claims 5 to 7, and including means for releasably attaching said flow line to said connector to allow a single said pressurizable dispensing reservoir to be transported to various said pipework systems for use therewith, as and when required, for introducing liquid from said reservoir.

Drawing