Sealing method and apparatus

Abstract: A method and apparatus is provided for sealing chimneys. The apparatus comprises a spray device 16 positionable within a chimney 10, and operable to spray sealant from the spray device onto the internal walls of the chimney, there being means 15, 18 for moving the spray device along at least a part of the length of the chimney. There is a sealant feed pipe 15 which provides sealant to a spray head and can also be used to lower the device down a chimney. The device is guided and centralised by a sledge 18 which may be fitted with wheels and may be adjustable to suit different diameters of chimney.

Description: The invention relates to a method and apparatus for sealing chimneys, and a sealant for use with the method and apparatus. The need to seal chimneys is a problem which has been known for some considerable time. Old chimneys obviously deteriorate, from a combination of heat, acid attack, and ageing of brickwork and mortar. The consequences can prove disastrous, since toxic fumes can leak into the building. There are several known techniques for sealing chimneys to provide an efficient chimney flue. One possibility is to cut into the chimney stack and re-build it with a ceramic liner. This is however very disruptive and very expensive. Another possibility is to line the chimney with a flexible stainless steel liner, but this sort of liner is not suitable for all forms of heating. A third known technique involves inflating a rubber former within the chimney, the former having the shape of a long thin balloon. The liner is held clear of the chimney walls by steel spacers and a heat resistant sealing compound is then pumped into the chimney filling the space around the liner. This is a very effective system, but a lot of preparation work is required, and the process is quite lengthy to carry out. Published patent specification AT-A-379425 discloses a method of sealing a chimney, the method comprising the steps of positioning a spray device within the chimney, pumping sealant to the spray head through a first hose, spraying sealant from a spray head of the spray device onto the internal walls of the chimney and moving the spray device along at least a part of the length of the chimney. Apparatus for carrying out this method is also disclosed. We have now developed yet another system which is at least as effective as known systems, but is much easier to carry out. Accordingly, our invention provides a method of sealing a chimney, characterised by providing compressed air to the spray head through a second hose, rotating the spray head using a compressed air motor, and pumping the sealant under pressure through the first hose into the spray head which causes sealant to be thrown onto the internal walls of the chimney. The invention includes apparatus for sealing a chimney, characterised in that the spray head is rotated by a compressed air motor, which compressed air is provided through a second hose, whereby rotation of the spray head and pumping of the sealant under pressure through the first hose into the spray head causes sealant to be thrown onto the internal walls of the chimney. Means may be provided to guide the spray device along the length of the chimney. The guide means may be arranged to centralise the spray head in the chimney. The guide means may comprise a sledge having a plurality of skids spaced apart around the spray device, each skid being arranged to contact a part of the wall of the chimney. There may be two feed pipes, one to feed the sealant and one to feed compressed air. The sealant may be fed to the spray device by a sealant pump. Alternatively, the size of the sledge may be adjustable. The sledge may for example be adjustable to suit chimneys having diameters of 15 cm (6"), 23 cm (9") and 30 cm (12"). For some applications, a preliminary adhesive may be sprayed onto the internal walls of the chimney, to assist the bonding of the sealant to the chimney walls. The invention includes a spray sealant for use in sealing chimneys. The sealant may comprise 45% to 65% by volume of calcined alumina, 25% to 35% by volume of silica sand/flour, 7% to 15% by volume of plastic ball clay, reduced to a powder, and 4% to 10% by volume of a binder. The binder may comprise soluble silicate powder. The particle size of the calcined alumina may be 60 mesh. The particle size of the silica sand/flour may be 30 mesh. By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings in which :- Figure 1 is a diagrammatic illustration of an embodiment of method and apparatus according to the invention in use; and Figure 2 shows an alternative embodiment of centralising sledge. Figure 1 shows a typical brick built chimney 10, one leaking joint being shown, by way of example only, at 11. In serious cases, an entire chimney can be defective, for example because of broken or faulty mortar, and cracked or porous brickwork. The apparatus comprises a compressor 12, a sealant pump 13, an air line 14, a delivery hose 15, a spray device 16 having a spray head 17, and a centralising sledge 18. The compressor is connected to the spray device 16 by the air line 14. The sealant pump 13 is releasably connected to the spray device 16 by hose couplings 19 and 20. The spray head 17 is arranged to rotate at high speed on the spray device 16, driven by a compressed air motor within the spray device. Rotation of the spray head, coupled with pumping of the sealant under pressure into the spray head, causes sealant to be sprayed out onto the internal walls of the chimney 10. For some applications, where the material of the chimney is such that the sealant is unlikely to adhere securely to the chimney material, an adhesive spray nozzle is initially lowered down the chimney to spray preliminary adhesive over the internal walls of the chimney. This increases the degree of bonding between the sealant and the chimney walls. Once the chimney has been cleaned and is ready for sealing, the spray device 16 is lowered down to the bottom of the chimney by means of the delivery hose 15. The compressor 12 and sealant pump are then started, and as the sealant sprays out of the spray head 17, the device is gradually hauled back up the chimney until the entire length of the chimney is sealed. Alternatively, only a limited length of the chimney may be sealed if there is a single readily identifiable problem in a particular area. In order to ensure that the device 16 moves centrally along the chimney, adjustable skids 21 of the sledge 18 are moved to a position in which they lie adjacent to the internal walls of the chimney, with the spray device 16 centrally positioned between the skids. In this particular embodiment, the chimney sealant compound comprises 45% to 65% by volume of 60 mesh calcined alumina, 25% to 35% by volume of 30 mesh silica sand/flour, 7% to 15% by volume of plastic ball clay reduced to a powder, and 4% to 10% by volume of soluble silica powder. Further details of the process are as follows. If it is necessary to apply preliminary adhesive, the apparatus as shown in the Figure is used, except that the delivery hose 15 is connected to the adhesive spray nozzle, instead of to the spray device 16. A hopper 22 on the sealant pump is filled with a sufficient quantity of adhesive. The nozzle is initially held over the hopper 22, the pump is turned on, and then the speed of the pump is regulated until a good spray pattern is exhibited. During this test period, the adhesive sprays back into the hopper. The pump is then turned off, the nozzle is taken to the top of the chimney, and is inserted in the top of the flue. The pump is then turned on again, and the nozzle is lowered slowly down the flue, making sure that as much of the flue is sprayed as is possible. The pump 13 and delivery hose are then washed out ready for use in applying the sealant. One embodiment of adhesive that may be used is a soluble silicate liquid, compatible with the chimney sealant compound. The pump and compressor should be set up on level ground as near as possible to the chimney. The spray device 16 is reconnected to the pump using the delivery hose 15 and the air line is connected between the compressor and the spray device. The compressor 12 is turned on with its outlet valve closed. Approximately half a pint of water is placed in the pump and is pumped into the delivery hose. The mixed sealant is then loaded into the hopper 22 and pumping continues. The spray head 17 is initially positioned in a bucket to collect the water as it is pumped through the system and the pump is then switched off. The spray head 17 is then held in or above the hopper 22 and the pump 9 is switched on again until pump sealant runs out of the spray head into the hopper. The air valve on the compressor 12 is now opened and the spray pattern exhibited by the spray head 17 can be inspected. The compressor is then adjusted to vary the pressure until a satisfactory spray pattern is produced. It has been found that the optimum pressure is somewhere between one bar and five bar, for example two bar. The sealant should be allowed to pump back into the hopper for about three to four minutes to ensure that there is nothing in it that will block the spray head. The pump and air supply are then switched off, the spray head is taken to the top of the chimney and is lowered down inside it. The pump and air supply are then switched on again and spraying proceeds as already mentioned in the general description above. If necessary, the spray device 16 may be moved along the chimney more than once, to ensure full coverage. Other arrangements and configurations are of course possible. A different range of sledge sizes may be provided for example, as an alternative to an adjustable sledge. In general, the skids 21 should be set at a diameter 1" less than the internal diameter of the chimney. Turning now to Figure 2, an alternative form of centralising sledge 23 is shown. The sledge comprises a metal cylinder 24 which is about 100 mm in length. The spray head 17 can be secured within this cylinder by means of fixing bolts 25. At one end of the cylinder, there are four lugs 26, spaced apart at 90° intervals. The internal diameter of the cylinder is about 50 mm. Each lug 26 has a hole 27 therein. The sledge is shown in Figure 2 in exploded form. In use, each lug 26 has bolted thereto a pair of arms 28 and each arm carries at its free end a rotatable wheel 29. The arms are secured to the lugs by a bolt which passes through holes 30 in the arms and hole 27 in the associated lug. A butterfly nut (not shown) is secured to the bolt. For the sake of clarity, only two pairs of arms are shown in Figure 2, although it will be appreciated that in practise there are four pairs of arms. Thus, each end of the sledge is supported by four wheels which engage with the internal wall of the chimney. By slackening the butterfly nuts and pivoting the arms, the overall external dimensions of the sledge can be adjusted to suit many sizes of chimney. For particularly large chimneys, longer arms can be used. In use, the spray head is arranged to project from the lower end of the cylinder 24 to appoint lying below the lower wheels 29, so that the wheels do not hinder the spray pattern emerging from the spray head.

Claims: A method of sealing a chimney (10), the method comprising the steps of positioning a spray device (16) within the chimney (10), pumping sealant to the spray head through a first hose (15), spraying sealant from a spray head (17) of the spray device (16) onto the internal walls of the chimney (10) and moving the spray device (16) along at least a part of the length of the chimney (10), characterised by providing compressed air to the spray head through a second hose (14), rotating the spray head (17) using a compressed air motor, and pumping the sealant under pressure through the first hose (15) into the spray head (17) which causes sealant to be thrown onto the internal walls of the chimney (10). Apparatus for sealing a chimney (10), the apparatus comprising a spray device (16) positionable within the chimney (10), means for pumping sealant to the spray head through a first hose (15), and operable to spray sealant from a spray head (17) of the spray device (16) onto the internal walls of the chimney (10), and means (15, 18) for moving the spray device (16) along at least a part of the length of the chimney (10), characterised in that the spray head (17) is rotated by a compressed air motor, which compressed air is provided through a second hose (14), whereby rotation of the spray head (17) and pumping of the sealant under pressure through the first hose (15) into the spray head (17) causes sealant to be thrown onto the internal walls of the chimney (10). Apparatus as claimed in Claim 2, further characterised by including means (18) to guide the spray device (16) along the length of the chimney (10). Apparatus as claimed in Claim 3, further characterised in that the guide means (18) is arranged to centralise a spray head (17) in the chimney (10). Apparatus as claimed in Claim 4, further characterised in that the guide means (18) is adjustable to suit different diameters of chimney (10). A spray sealant for use in the method or apparatus as claimed in one of the preceding Claims, characterised by comprising 45% to 65% by volume of calcined alumina, 25% to 35% by volume of silica sand/flour, 7% to 15% by volume of plastic ball clay, reduced to a powder, and 4% to 10% by volume of a binder. A spray sealant as claimed in Claim 6, further characterised in that the binder comprises soluble silicate powder. A spray sealant as claimed in Claim 6, further characterised in that the particle size of the calcined alumina is 60 mesh and the particle size of the silica sand/flour is 30 mesh.

Inventors: BARNES ALLAN, BARNES, ALLAN
Applicants: NORTHERN CHIMNEY LINING SYSTEM, NORTHERN CHIMNEY LINING SYSTEMS LIMITED
Application year: 1991
Main classification: E04F21
IPC codes: E04F21