GB2461714A - Vacuum extraction unit - Google Patents

Abstract

An extraction unit 800 comprises a pressurised fluid line 802 terminating in a spray head 804, said spray head being surrounded by a duct 806, the duct having a first and a second aperture (808, 810), the first aperture being arranged adjacent to the spray head. The spray head generates a vacuum effect inside the duct which entrains fluid or gas 814 located externally of the first duct aperture into and along the duct to a preferred destination. The sprayed fluid 812 is channelled by the duct to fall through the second aperture 810. The extraction unit solves the problem of the removal of gas and its attendant odours from a toilet, urinal or other sanitary unit. Also included is a sanitary unit which comprises a pan, a cistern and an extractor for generating an extraction of gas from the pan area of a sanitary unit. The sanitary unit includes an extraction duct extending from said extractor for channelling extracted gas from said extractor to a destination site located remotely from said extractor; wherein said extractor is located within the cistern of said sanitary unit.

Description

Extraction unit and sanitary units featuring said extraction unit

Field of the invention

The invention relates to an extraction unit. The invention also relates to an extraction system incorporating the extraction unit. In particular the invention is concerned with an extraction system which may either be retrofitted into an existing sanitary system or built into a pre-existing sanitary system. More particularly the invention is concerned with providing a unit suitable for the removal of state air and odours from toilets by non-electrical means. Most particularly, the invention is concerned with providing a unit or system suitable for the removal of stale air and odours from toilets by means of a water powered air vacuum pump, where water is accelerated to high speed water particles via one or a combination of jets, where the said water particles will exert a force on the surrounding air, thus forcing the air in the same direction. The displaced air will then form a vacuum, drawing in air along it which will also be forced forward by the water jet spray.

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Background to the invention S.. * * *SS

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A number of methods and systems for deodorising toilets and urinals have been formulated over the years with the aim of removing gasses and unpleasant odours often found in toilets and urinals. A common system in widespread use is that of dispensing a fragrant substance from an aerosol or similar canister with the aim of masking or chemically neutralising the unpleasant smelts. Likewise pellets and tablets placed in urinals serve the dual purpose of sanitation and odour removal. Although widespread in use, the fragrance dispensing solution has often proven ineffective and further is contingent on the smell masking the odour being itself acceptable to the visitor and user. Further, airborne deodorising and disinfecting systems can have ill effects on a small percentage of the populace. Even where the inhalation of airborne deodorisers, fragrances and similar applications does not actually cause illness, the desirability of inhaling such substances is questionable from a health and safety perspective, particularly in relation to its impact on nasal and respiratory systems.

An alternative solution may be found in the fitting of an extractor fan to a toilet room or cubicle with the aim of removing the unpleasant odours from the toilet and moving them outside of the room or cubicle. These have proven to be far more effective but themselves have drawbacks. For example. the extractor fan can prove expensive to install in a building. While this may be acceptable for commercial properties, the costs of installing fans in residential properties may be prohibitive. The fitting of a conventional toilet extractor fan requires that the fabric of the building to which it is fitted be altered. This can itself be a labour intensive and costly business. An extractor fan is usually installed in the wall near or on the ceiling. The extractor fan then indiscriminately displaces large volumes of ambient air, moving it from the inside to the outside of the chamber. The two main draw backs of this system are as follows: * ** First, only ambient diluted air is removed where there is a very high ratio of fresh air with only a small proportion of toilet odour. Thus high volumes need to be displaced in order to purge the toilet odour. * *

Second, based on the first, the wall / ceiling fan is very environmentally unfriendly because S..

of the extensive loss of heat energy (for example, from the building heating system) in the form of warm air being displaced to the outside. The energy cost required to heat that air S...

is high. The opposite scenario may also occur, that is where in warm conditions buildings *S....

are cooled and large volumes of cool air are displaced outside the building, thus being effectively wasted. The extractor fan is truly a very inefficient way to remove toilet odours when considering the holistic impact on energy cost, be they incurred by heat or by cooling.

The Applicant is aware of International Patent Application WO 2008/020262 (TOILEIFRIEND INTERNATIONAL (PlY) LTD) and the US application US 5,575,019 (Kijewski).

It is amongst the objects of this invention to provide a solution to these and other problems.

Summary of the invention

According to a first broad independent aspect, the invention comprises an extraction unit comprising a pressurised fluid line terminating in a spray head, said spray head being surrounded by a duct with a first lateral aperture and a second lateral aperture, said first aperture being arranged adjacent to the spray head in such a way that when pressurised fluid passes through the spray head and a displacement effect is caused, fluid located externally from the duct is sucked through the first aperture and subsequently along said duct to a preferred destination site or sites, whilst the sprayed fluid is channelled by the duct to primarily fall through the second aperture.

Due to its robust characteristics, this unit can work in very harsh and demanding conditions. It can be used to vacuum liquid just as well as it can air. The invention is also of particular interest, because it is a device with spark free operation. It is therefore safe to use in an environment where there is a risk of ignition -for example on an offshore oil rig. *SS.

The invention solves the problem of the removal of gas and its attendant odours from a toilet, a urinal or another sanitary unit.

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The use of this unit also avoids the problems outlined above relating to the use of chemical scenting or deodorisation means and/or fan propelled methods. ****

* According to a second broad independent aspect, the invention comprises a sanitary unit comprising a pan; a cistern; an extractor for generating an extraction of gas from the pan area of a sanitary unit; and an extraction duct extending from said extractor for I. channelling extracted gas from said extractor to a destination site located remotely from said extractor; wherein said extractor is located within the cistern of said sanitary unit.

The invention solves the problem of the removal of gas and its attendant odours from a toilet, a urinal or another sanitary unit.

By locating the extractor in the cistern of the sanitary unit, the invention is one which may be easily installed, accessed for repairs and removed.

The use of this unit also avoids the problems outlined above relating to the use of chemical scenting or deodorisation means and/or fan propelled methods.

By locating the extractor in a cistern, the sanitary unit of the invention has a marked advantage over the invention disclosed in International Patent Application WO 2008/020262 in that said application discloses an electrically powered extractor unit to be fitted into a waste network" i.e. the sewer pipe-work that runs from the unit to a public sewer system, septic tank or other such apparatus. In accessing the cistern, the user avoids contact with unhygienic and possibly dangerous waste, as well as the hazards, expense, structural alterations and public access issues that gaining access to a waste network may entail.

FinalLy, there is a marked aesthetic advantage in that the extractor is not visible to the unit, and therefore makes no aesthetic contribution to its surrounds.

According to a third broad independent aspect, the invention comprises an extraction unit :. comprising an extractor for generating an extraction of gas from the pan area of a sanitary * unit; and an extraction duct extending from said extractor for channelling extracted gas *** * from said extractor to a destination site located remotely from said extractor; wherein said ** extractor is sized and shaped to fit within a cistern.

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This third independent aspect of the invention shares the advantages of the second independent aspect of the invention, outlined above, with the added advantage that as a retro-fit unit, it may be installed in existing sanitary units. Further, it is anticipated that the retrofitting will be a relative unproblematic task, involving only slight or no modifications to the sanitary unit in which it is to be incorporated.

Preferably, the invention further comprises a liquid line in fluid communication with an extractor, wherein liquid flows from the liquid line, through the extractor and towards the extraction duct thereby causing a movement of gas from the pan towards the extractor.

The use of a liquid line is advantageous in that the invention therefore does not need electricity to do its task of gas removal. As well as the cost savings, this avoids having to use electricity near or in water, which may be hazardous.

More preferably the movement of gas along the pan is caused by the creation of an area of low pressure in the extractor and the pan.

Advantageously, the extractor comprises a spray nozzle attached to the liquid line.

The use of a spray nozzle is particularly effective in generating the area of low pressure which lifts gas from the pan, and is certainly more effective than that generated by a simple stream or flow of water.

Preferably, the spray nozzle projects a spray cone of between 100 and 40°.

* ** This range is most effective, being the range within which a compromise between spraying water along in a particular direction and spraying water in a wide and diffuse spray cone *S..

may be reached. The Applicant estimates that a spray cone of approximately 20 -30° provides the optimal width. * S..

More preferably, the liquid line further comprises a switch governing the flow of liquid through said liquid line.

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* The switch allows the device to be switched on and off in accordance with the user's discretion, thereby saving water.

Advantageously, the invention further comprises a timer, which when the time period expires, closes the switch automatically.

This combination of timer and switch closure ensures that the unit is switched off after a set period of use, thereby ensuring that water is conserved.

Advantageously, the extractor is so sized and shaped as to enable retrofitting onto an overflow pipe in a toilet cistern.

The advantage of providing a simple retrofit further ensures that modification of existing toilet units is minimal and unobtrusive.

Preferably, the extractor is so sized and shaped as to fit around an overflow pipe in a toilet cistern and, in use, to project in a substantially downwards direction, thereby forming a seal with water present in the cistern when said cistern is in a functionally full state. This is a marked advantage in that, by forming the seal, the negative pressure exerted is almost entirely on the gas in the pan, rather than on the air in the cistern. Alternatively, the negative pressure may entirely be exerted on the gas in the pan.

More preferably, the unit further comprises a one-way valve between the pan and the extractor.

* ** The provision of a one-way air valve is advantageous in that it acts like a watertrap.

Because of this the gas will not be able to flow back into the pan after the unit has been *.S.

switched off. It therefore prevents foul air in the waste pipe from flowing back into the pan, or the wider environment.

* Still more preferably, the unit further comprises a subsidiary line in fluid communication **** with the extraction duct. * . * 30

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* The provision of a subsidiary line is advantageous in that it provides a line for water to be directed through after use in the extraction unit, while the gas continues to its destination site.

Advantageously, the extraction duct further comprises means for directing fluid away from the extraction duct and into the subsidiary line. This water may then be put to other use, rather than being wasted as a by-product of extraction. One such use is to supplement the cistern's flush level, in order that it may be used for flushing. Thus little or no waste is caused by the odour removal system.

The provision of directing means maximises the amount of water which is directed to the subsidiary unit.

Preferably, the liquid tine is a mains water supply.

This feature is advantageous because it dispenses with the need to provide a secondary means of water power, further aiding the fitting of the unit into an existing sanitary system.

The invention also comprises a unit substantially as herein described with reference to and as illustrated by any appropriate combination of the figures.

Brief description of the drawings

Figure 1 shows a diagrammatic cross-sectional side view of a sanitary unit of the invention.

* ,. Figure 2 shows a diagrammatical cross-sectional front view of a cistern of a sanitary unit of the invention. a.. * * *

Figure 2A is a diagrammatic plan-view of a part of a sanitary unit of the invention. a..

* Figure 3 shows a diagrammatic cross-sectional side view of an extractor unit of the invention. S...

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* Figure 3A shows a diagrammatic front view of a spray head of the invention.

Figure 4 shows a cross-sectional side view of an extractor unit of the invention when placed on an overflow pipe within a cistern.

Figure 5 shows an exploded cross-sectional side view of an extractor unit of the invention.

Figure 6 shows a cross-sectional front view of a cistern of the invention.

Figure 7 shows a diagrammatic side view of a water wheel of the invention.

Figure 8 shows a diagrammatic cross-sectional view of an extraction unit of the invention.

Specific Description of the Preferred Embodiments

Figure 8 generally shows an extraction unit indicated generally at 800 with a pressurised fluid line 802. This pressurised fluid line 802 ends in a spray head 804, said spray head 804 being surrounded by a duct 806 with a first lateral aperture 808 and a second lateral aperture 810, said first aperture 808 being arranged adjacent to the spray head 804 in such a way that when pressurised fluid 812 passes through the spray head 804 and a displacement effect is caused, fluid located externally from the duct 814 is sucked through the first aperture 808, towards the spray head 804 and subsequently along said duct 806 to a preferred destination site or sites (not shown), whilst the sprayed fluid 812 is channelled by the duct 806 to primarily fall through the second aperture 810.

Figure 1 shows generally a sanitary unit 2 of the invention which in this embodiment is a * ** modified toilet but may in other embodiments take the form of a urinal or other sanitary :::::: appliance. The sanitary unit 2 comprises a pan 4 with a pan area 5 and a cistern 6. The overflow pipe 9 runs between the pan 4 and the cistern 6. This forms part of extraction duct 8. The pan 4 leads on to a conventional U-bend 10 which itself leads to a waste pipe * 12. This embodiment of the invention further comprises an extractor 14. The extractor 14 in this embodiment is situated, in use, on top of and around the overflow pipe 9. The extractor 14 has been retrofitted into the sanitary unit 2, but in other embodiments, such as that shown in figure 2, the extractor 14 may be integral to the sanitary unit 102.

*** *** * , The extractor 14 has a liquid line 16 which supplies water to the extractor 14. The pressure of the water supply is governed by the pressure of the water source to which it is attached. In this embodiment liquid line 16 runs off the mains water supply 18 but clearly it could equally well run from a second water supply. Note here that the mains water supply also supplies the cistern 6 with cistern water 20. The liquid line 16 might optionally include means for impregnating the water with a chemical such as a disinfectant or scrubbing agent to remove odour from the processed air. Such impregnation means (not shown) will be known to the skilled man but may be inventive in this context.

The water supply line may incorporate water pressure generating means such as a pump.

Alternatively, it may incorporate a cylinder with means for pressuring the air contained in the cylinder and within the liquid outlet line; whereby as the air is pressurised in the cylinder the water in the cylinder is pressurised greatly above atmospheric pressure. This would allow the water to spray out of the liquid outlet line in a similar fashion to a so-called "garden sprayer" jet spray. The cylinder itself may be incorporated into the cistern cavity and its pressuring means with a button or handle would be accessible and may be actuated from outside the cistern by an operator. It is anticipated that a fully charged cylinder would allow continuous spraying for say 20 minutes. A further advantage of the cylinder system would be that it would avoid having to necessarily install a system for automatically cutting off the suction generating spray since the worst that could happen would be that the cylinder empties would require refilling and re-pressurising.

Returning to the embodiment of figure 1, also of note is a switch 22. This switch allows the user to switch the supply of water from liquid line 16 to extractor 14 on and off. A simple on/off valve suffices in this embodiment, but more elaborate means, including * ** hands-free sensing technology is envisaged Alternatively, means known to the man skilled in the art may be used. I... * a

In some embodiments the switch-valve may be fitted with a timer 30 which will close the * switch 22 subsequent to said switch 22 having been opened for a preset period. Other * embodiments of timer 30 might connect it to the flushing of sanitary unit 2. In such an embodiment, timer 30 will activate means to shut switch 22 a set period after flushing of a..

* 30 sanitary unit 2 has occurred.

****.* * . Sanitary unit 2 further features a channel 24 for channelling extracted gas froni said extractor 14 to a destination site located remotely from said unit. This destination site could be the S-bend 10 or it could be the waste pipe 12 or it could be in an alternative embodiment of the invention an exterior site.

In this embodiment of the invention the totality of the overflow pipe 9, the extractor 14-in particular its tubular portion 28 -and the channel 24 comprise the extraction duct 8. In all embodiments, the term extraction duct" 9 refers to the route along which gas is channelled during the extraction process.

At Figure 2 we see a further embodiment of the invention comprising a part of a sanitary unit 102, a cistern 104, an extractor 106, an extraction duct 108 comprising an overflow pipe 110, said extractor 106 and a channel 112. The channel 112 here is of particular interest. We note first that it has a subsidiary line 114 projecting from it. The presence of subsidiary line 114 provides that when sprayed water meets the walls of channel 112 prior to the bend and bend 122, it will tend to fall down the subsidiary tine 114 and back into the cistern 104, where it may be reused in flushing, rather than it fatting down channel 112 and thence to destination site 116. Attached to the subsidiary line 114 is a bowl or u-bend 120 acting as a water trap. In use, the water trap will fill up with water thereby stopping gas from escaping down the subsidiary line 114 and accumulating in the cistern 104, or leaking into the surrounding environment. After the bowl 120 first fills up with water it will then continuously overflow as water is gathered through subsidiary line 114 allowing the suction driving water to mainly if not entirely supplement the level of the cistern 18. S... * S S...

In this embodiment, channel 112 also features a bend 122. This bend 122 can be seen in close up at Figure 2A. Figure 2A shows a plan view of a part of a sanitary unit 102 comprising a cistern 104, an extractor 106, a channel 112 with a bend 122, with a fluid line 124 and a subsidiary line 114. The purpose of this diagram is to show a particularly S...

effective embodiment of the invention wherein the bend 122 is along a substantially horizontal plane. The effect of this is to better channel the spray of water into subsidiary line 114 and away from channel 112. The effect of this is to conserve still more water for reuse.

Returning to Figure 2 we can see that the tubular portion 124 of the extractor 106 is partially submerged in cistern water 118. Tubular portion 124 thereby forms a defacto seal with said cistern water 118 (when the cistern is functionally full), thereby ensuring that when the extractor 106 is working it only extracts gas from the overflow pipe 110 without simultaneously extracting gas from the cistern 104 at large. Also clearly of note here is the liquid line 130 which is here shown to run from clean water line 126, the function of said clean water line 126 being to fill the cistern 104. It should be noted that clean water line 126 can be substituted for any other supply of pressurised water. On/off switching valve 128 is also present. Note also that extractor 106 is here clearly mounted both on and around the overflow pipe 110 of a sanitary unit flushing mechanism 132, which in many preferred embodiments will be a flush valve.

In Figure 3 a cross-section of the side of an extraction unit 200 is shown in detail. The extractor comprises tubular portion 202 which is so sized and shaped as to fit onto and/or around an overflow pipe (not shown). The extraction unit 200 comprises a liquid line 204 through which water flows from a water source (not shown) which may comprise a pressurised cylinder. As the liquid line 204 feeds into the extraction unit 200 it is forced through a spray nozzle 206 which may be adjustable by rotation or fixed at a predetermined level. As a result, the water is turned into a spray 208. The passage of said liquid line 204 through the extraction unit 200 and subsequent conversion to spray 208 pushed the air otherwise present in the tube 210, thus creating an area of negative pressure which gas from the pan (not shown) rushes up the tubular portion 202 to fill. It is noted that spray head 206 and spray 208 are contained within a tube 210. This tube 210 **. has an aperture 212 which is formed as a cut-out in the upper portion of pipe 210. This . aperture is so positioned to be at the point where spray head 206 turns liquid line 204 into spray 208. Thus the area of negative pressure created within tube 210 advantageously substantially corresponds with the aperture 212. The area of negative pressure therefore . exerts a force on non-return valve 218 and draws gas from tubular portion 202 and the overflow pipe on which it has been placed (not shown). Therefore gas is drawn from the pan, up the overflow pipe via tube 202 and aperture 212 and into the spray 208 of the spray nozzle 206. The gas is subsequently pushed down tube 214 in the same direction as the spray 208 (shown by arrow 216). When the extraction unit 200 is turned off, non-return valve 218 closes, thereby stopping any back draft of gas and/or air which may still be present in the extraction unit, into the cistern (not shown) or worse, back into the pan.

The non-return valve takes the form of an annular member which is secured by friction or otherwise to the inside of the tube and incorporates a hinged disc which is of greater diameter than the inner diameter of the annular member in order to form a barrier to the return of air and to readily open when suction is generated by said spray nozzle, This function is often performed by a device called a watertrap which prevents the backflow of air. Also of note is top lid 220.

Shown here the spray 208 forms a cone of approximately 30°. It is suggested that the optimal spray cone is between 10° and 40°, although a range of 20-35° is even more favourable.

There are a number of variants of the headpiece of spray 208, and the majority of these will be known to the man skilled in the art. One non-obvious innovation is shown at figure 3A which shows a spray head 250 with multiple apertures 252 said apertures 252 being so sized as to allow only very fine jets of water through, is particularly good as displacing air, and in so doing creating a strong negative pressure, which itself makes odour removal more effective.

Figure 4 shows an extractor unit 300. Said extractor unit 300 is situated in a cistern environment 302 (not shown). The cistern 302 is partially filled with water 304, which for normal operation will be flush water. The extractor 300 has a tubular portion 306 which extends downward below the water level 304 on and around a cistern overflow pipe 308.

The water 304 forms a seal which further stops the back-draft or escape of gas which has *.,... been vacuumed or pulled up by the extractor unit 300. The tubular portion 306 fits over *. and around the overflow pipe 308, but does not hamper the functioning of the overflow pipe 308 at all. Indeed, the gap 310 between said tubular portion 306 and said overflow pipe 308 is sufficient to ensure that the overflow pipe 308 is able to function normally.

The non-return valve 312 is also positioned substantially above the upper inlet of overflow pipe 308 as not to hamper its overflow function at all.

Figure 5 shows in exploded view the components required to make an extractor 400.

Notably there is a spray head 402, a tubular portion 404, a non-return valve 406 (which although not essential for suction is recommended in order that foul air backflow is avoided) and an aperture carrying portion 408 featuring an aperture 410. Aperture 410 is covered by top lid (or sealing lid) 412.

Figure 6 shows a cistern 500 incorporating a suction device 501 located separately from said overflow pipe but designed to extract sufficient air from the cistern to draw air up through the overflow pipe 502. The suction device incorporates an outlet pipe 503 which may lead to the grey waste pipe or simply to a remote site such as outside of a building. In order to improve the extraction of gas through the overflow pipe, a seal 504 may be provided between the cistern's Lid 505 and the cistern's main body 506. The suction device further incorporates non-return valve 507 which in this embodiment is a flap valve. Non-return valve 507 ensures that odours do not creep back through the suction device 501, into the cistern 500 and thence into the external environment.

The suction device may be a powered fan (it may be either electric or water powered) or a spray nozzle of the kind envisaged in the preceding embodiment it is considered that the spray nozzle is particularly inventive. In some embodiments, the displacement of air could be achieved with a water wheel, actuated by the force of water flowing onto it. Such an arrangement is shown at figure 7. Unit 700 comprises a water wheel 702 with blades 704.

Water line 706 projects a jet of water which comes into contact with blades 704. The force of the water causes the water wheel 702 to rotate. The rotation of the water wheel 702 causes air to be displaced. Said water wheel 702 may be used to generate the negative pressure or suction effect.

The unit can be positioned inside the cistern with direct suction on the overflow pipe or outside the cistern where the suction opening can either be connected to the cistern above S... . . . . normal water level to ensure indirect suction via the overflow pipe or it may be connected :. to the pan or seat of a sanitary device in order to facilitate suction from the pan.

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Claims (16)

1. CLAIMS1. An extraction unit comprising a pressurised fluid Line terminating in a spray head, said spray head being surrounded by a duct with a first lateral aperture and a second lateral aperture, said first aperture being arranged adjacent to the spray head in such a way that when pressurised fluid passes through the spray head and a displacement effect is caused, fluid Located externally from the duct is sucked through the first aperture and subsequently along said duct to a preferred destination site or sites, whilst the sprayed fluid is channelled by the duct to primarily fall through the second aperture.
2. 2. A sanitary unit comprising a pan; a cistern; an extractor for generating an extraction of gas from the pan area of a sanitary unit towards the extractor; and an extraction duct extending from said extractor for channelling extracted gas from said extractor to a destination site located remotely from said extractor; wherein said extractor is located within the cistern of said sanitary unit.
3. 3. An extraction unit comprising an extractor for generating an extraction of gas from the pan area of a sanitary unit; and an extraction duct extending from said extractor for channelling extracted gas from said extractor to a destination site located remotely from said extractor; wherein said extractor is sized and shaped to *:*::* fit within a cistern. *... * * ****
4. 4. A unit according to any of claims 2 onwards further comprising a liquid line in fluid communication with an extractor, wherein liquid flows from the liquid line, through the extractor and towards the extraction duct thereby causing a movement of gas from the pan towards the extractor. * .
5. 5. A unit according to any of claims 2 onwards, wherein the movement of gas from the pan is caused by the creation of an area of low pressure in the extractor and the pan.
6. 6. A unit according to claim 4, wherein the extractor comprises a spray nozzle attached to the liquid line.
7. 7. A unit according to claim 6, wherein the spray nozzle projects a spray cone of between 10 and 400.
8. 8. A unit according to any of claims 2 onwards wherein the Liquid Line further comprises a switch governing the flow of Liquid through said Liquid Line.
9. 9. A unit according to cLaim 8 further comprising a timer, which when the time period expires, cLoses the switch.
10. 10. A unit according to any of cLaims 2 onwards wherein the extractor is so sized and shaped as to enable retrofitting onto an overflow pipe in a toilet cistern.
11. 11. A unit according to any of claims 2 onwards wherein the extractor is so sized and shaped as to fit around an overflow pipe in a toilet cistern and, in use, to project in a substantially downwards direction, thereby forming a seal with water present in the cistern when said cistern is in a functionally full state.
12. 12. A unit according to any of claims 2 onwards further comprising a one-way valve between the pan and the extractor.

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13. 13. A unit according to any of claims 2 onwards further comprising a subsidiary line in *.. fluid communication with the extraction duct. S...
14. 14. A unit according to any of claims 2 onwards wherein the extraction duct further comprises means for directing fluid away from the extraction duct and into the subsidiary line. S... * * S...
15. 15. A unit according to any of claims 2 onwards wherein the Liquid line is a mains water supply.
16. 16. A unit substantially as herein described with reference to and as illustrated by any appropriate combination of the text and/or figures.