EP0509081A1 - Pressure washing of soiled articles - Google Patents

Abstract

Cleaning cabin for articles such as industrial garbage cans or vehicles, said cabin (31) comprising an enclosed platform (11). An article can be placed on this platform while being oriented in a predetermined direction with respect to at least one nozzle (6) for discharging cleaning liquid, which nozzle is adapted to direct a jet of cleaning liquid onto the article to clean. The cabin also includes a tank (18) for collecting used cleaning liquid and; a recirculation device (28) used to return the used cleaning liquid under pressure to the nozzle (6), said device being provided with a filter (17/29) capable of cleaning said liquid before its reuse. If this cleaning method is used for washing vehicles, a mobile scaffold (37/43) is provided for directing cleaning liquid onto the article to be cleaned when it moves relative thereto. this. This device eliminates the need for rotary washing brushes which can damage paintwork and other parts of automobiles.

Description

PRESSURE WASHING OF SOILED ARTICLES.

The present invention relates to the pressure washing of soiled articles.

The washing of soiled articles with a pressure washer incorporating a high pressure pump and a trigger operated washing jet is well known. Similarly the cleaning of automobiles utilizing relatively low power jets of cleaning liquid associated with washing brushes spinning at a relatively high speed is also known.

The present invention seeks to provide a self-contained unit with a re-circulation facility which enables the soiled articles to be efficiently cleaned in a generally closed environment utilizing essentially only pressurized washing liquid. The soiled article referred to here in may be any article which may be at least partially cleaned by process including pressure washing. Such articles may include refuge bins and with modifications, vehicles.

There is an ongoing problem with refuse bins which, particularly in summer, can be malodorous. This is particularly so with restaurant waste and similar industrial refuse. Accordingly, it has been proposed to clean such refuse bins utilizing a pressure washer on a periodic basis. The problem with such an arrangement is that the pressure washing include large numbers of unwanted microorganisms and other wastes with a high B.O.D. requirement, which enter adjacent storm drains and hence flow into watercourses with unacceptable effects on the environment. Although arrangements can be made to take the pressure washing to the sewer this can only be done at a previously prepared site. Since it is not practical to collect refuse bins for cleaning at a predetermined site, in practice refuse bins tend to remained unwashed.

The invention also relates to a similar arrangement for cleaning of automobiles and trucks. Vehicle washers are widely available but all include a rotating brush which is not only expensive to install, but also tends to damage paintwork, mirrors and car aerials in operation.

The invention provides in one aspect an arrangement for cleaning automobiles or trucks in which the operative working parts of the washing apparatus do not contact the vehicle to be cleaned, thereby to reduce abrasion of the operation of the paintwork and to prevent contact damage to the vehicle.

In order to address this problem, the invention provides a article cleaning booth including an at least partially enclosed washing area, wherein the pressure washings are filtered and returned for use so that cleaning liquid may be voided to the sewer after a predetermined period, for example at the end of a working day. Mounting such a cleaning booth on a vehicle or vehicle trailer allows it to be transported about a locality to clean a plurality of soiled articles. If desired, the booth can be mounted directly on a vehicle chassis or maybe an immovable structure. As an adjunct to this process utilising a moveable cleaning booth, there is also provided a quality control method to readily indicate to a passing supervisor whether or not an article such as a bin has been cleaned.

In a further aspect of the present invention the article cleaning booth is adapted to receive a vehicle. It has been found that by careful adjustment and positioning of pressure jets and their operating pressures, a cycle can be provided which cleans even the most soiled vehicles without the need for recourse to rotating brushes. Not only are such vehicle cleaning booths cheaper to install and maintain those with rotating brushes, but also by avoiding the use of rotating brushes, abrasion of the paintwork of the vehicle is avoided.

Accordingly, therefore to the first feature of the present invention, there is provided an article cleaning booth, said booth comprising an enclosed deck upon which the article reposes in a predetermined orientation relative to at least one liquid delivery jet, tank means for the collection of used cleaning hquid, means for recirculating the used cleaning liquid under pressure to said jet, said recirculating means including filter means adapted to remove detritus from the cleaning liquid before re-use. The article cleaning booth maybe disposed upon a wheeled frame or maybe provided with attachment means whereby the booth may be readily moved, by a small lorry mounted crane for example.

When the booth is disposed on the wheeled frame, the wheeled frame may be arranged to have at least two booths thereupon each operating independently. It is most preferred that a booth is closed during operation in a generally watertight fashion. Within the booth, and situated above the deck, a plurality of jets may be disposed in a predetermined interrelationship, each jet being controlled by a hquid control valve such as a solenoid valve, or a variable aperture valve. Each valve maybe opened or closed according to a predetermined cycle and may eject liquid at a predetermined pressure depending upon said cycle.

The means for collection of the used hquid may be a baffled tank inferior to the deck. In a preferred form of the invention the baffled tank is overlaid by the deck which may be generally watertight, whereby used cleaning liquid flows over the deck towards a liquid collector which passes the hquid, via a coarse filter and a serpentine flow sedimentation tank, and optionally to a fine filter before being pressurized for ejection from the jets once again.

Preferably the said deck is provided with at least one channel for delivering used liquid to the coarse filter. Preferably there are two channels. One disposed at each outer periphery of the deck and each delivering liquid via a respective coarse filter to a sedimentation tank. Liquid may flow in said tanks in a mutually opposed direction, whereby the flow from each tank is both slowed and caused to meet the flow of the other sedimentation tank to create a point at which the flow component in a horizontal sense is substantially zero thereby to promote sedimentation. The booth may also comprise means for voiding the liquid to the sewer after use.

Preferably the recirculation means comprises a pump adapted to impel cleaning liquid about a main at a predetermined operating pressure, said main optionally also operating back flushing devices in use. Said main may also comprise a plurality of valves each individually controlled to eject cleaning hquid according to a microprocessor controlled sequence thereby to control the position and power of the jets. Said microprocessor may also control means for backwashing one or more filters at a predetermined or random time interval. Heating means may also be provided in liquid delivery system if desired; in which case the booth may be insulated.

Where the soiled articles comprises a significant hydrocarbon component (petrol, diesel, oil etc.), the baffled tank may be formed with means for skimming off hydrocarbons which are lighter than water. This may comprise means for removing the upper layer of liquid in the baffled tank, as by bleed channels, or more directly by means of a doctor-knife. Such a doctor-knife is adapted to extend over the width of the upper face of the tank and to be a sliding sealed fit with the longitudinal edges thereof. The lower edge of the blade dips below the surface of the soiled cleaning liquid in the tank by a predetermined amount.

At a point in this cleaning cycle the doctor-blade is driven rapidly down the length of the tank thereby to cause the upper layers of liquid to overflow said baffled tank into a secondary container. The oil products may then be allowed to float to the surface of the secondary container before secondary separation prior to the disposal.

The arrangement allows traffic film, diesel etc to be removed from the vehicles and to be concentrated on a periodic basis so that oil products do not get discharged to a sewer and hence to waterways in significant quantities.

Soiled articles, such as domestic industrial bins or vehicles are best treated by a high pressure washing hquid on an individualised basis. Thus it is much preferred that the cleaning jets are controlled to clean portions of a vehicle, for example, by the application thereto of a higher or lower pressure utilising a suitable concentration of nozzles for the purpose envisaged. This arrangement may be achieved in accord with the invention, by means of a gantry comprising a pair of uprights spaced apart and extending upwardly of the longitudinal edges of the cleaning deck, and supporting an upper, and optionally a lower, crosspiece. The uprights and the crosspieces are all provided with one or a plurality of cleaning liquid jets at spaced intervals.

The spaced jets are all operatively connected to the main and are controlled to provide jets of cleaning fluid at a controlled pressure and flow rate so as to provide, if desired, a pulsed and/or arcuate flow of cleaning hquid to the article to be cleaned.

In a preferred form of the invention the uprights are individually movable longitudinally and in a direction towards and away from each other (and perpendically to the longitudinal axis of the deck. Further the uprights can be accurately rotated either to a fixed position or continuously in accordance with a washing sequence. This allows the uprights to move toward and away from the soiled article, to move longitudically along the article during the washing cycle and causes the jets to move accurately to increase the washing effect during longitudinal movement.

The crosspieces are operatively interconnected between the uprights and again are moveable vertically up and down and arcuately. In a preferred aspect of the invention the upper crosspiece on movement in a downward direction automatically disenables jets situate superior to its position thereby preventing waste of energy and liquid. Similarly the lower cross piece may disenable all jets below its position thereby enabling the underside of trucks etc to be washed if facility. If desired water pressure maybe utilised to generate arcuate, or other, movement of the gantry.

The gantry is preferably microprocessor controlled for optimum performance. It is particularly preferred that an operator should input information pertaining to the soiled article prior to the washing cycle. For example if a vehicle such as a Ford Escort motorcar is to be cleaned, the operator may input the code for "vehicle; Ford

Excort" into the microprocessor. When the vehicle reaches a predetermined point and the washing cycle is initiated, the uprights and cross pieces of the gantry will move into their correct position to effect the best washing sequence for a Ford Escort without, however, mechanically touching the body work.

The gantry may preferably be operated by stepping motors controlled by a microprocessor in a well known fashion.

Although just described with reference to a motor vehicle the system can equally well operate on a truck or an industrial waste bin for example.

The cleaning fluid may be water to which cleaning additives have been added, for example a traffic film remover or hot waxing agent.

The gantry may clean the article in single pass or in a plurahty of passes if desired. Where a hot cleaning fluid liquid is used, it is possible to make the last pass of the gantry past the soiled article a hot wax pass; usually with a cleaning liquid at a temperature between 55" and 85oC.

Where the cleaning booth is designed for use on small readily positioned articles such, as for example only, domestic waste bins, the gantry may be relatively fixed. Where the gantry is fixed jets may be switched on or off in accord with a predetermined wash cycle; which cycle can be changed at will to accommodate other sizes and shapes of soiled article.

Generally such a fixed gantry is utilised on a wheeled frame, for example being formed as part of a vehicle or a vehicle trailer. Such an arrangement is useful for cleaning domestic and industrial waste bins in situ to which end, in a further feat -ire of the invention means are provided to allow the booth of the invention to be put into more effective practice.

In a further aspect of the invention there is provided a method of indicating that a refuse bin is ready for cleaning, which method comprises the steps of;

(A) Cleaning the bin utilizing a pressure washing apparatus,

(B) Fixing to said cleaning bin a rainfast label, said label bearing a desired indication thereupon; optionally of a desired period for the next cleaning step;

(C) Repeating step (A) in a fashion which removes the label, and subsequently repeating step (B) with a new label being fixed to the bin indictive of new desired information. The label bearing the indication may be colour coded or printed, for example with a time period. The label may be self-adhesive or a printed indicia.

The invention will now be described by way of illustration only, with reference to the accompanying drawings wherein; Figure 1 shows a schematic plan of the pumping system in accordance with the present invention;

Figure 2 shows a plan view of a cleaning deck for the above in part section,

Figure 3 shows a vertical cross-section through the sedimentation tank utilized in Figure 2; and

Figure 4 shows a side elevation from above in part cross-section, of a vehicle washing apparatus in accordance with another embodiment of the invention.

With reference to the Figures 1 to 3 of the accompanying drawings a mobile booth is provided. Although not shown in the drawings, this booth is mounted upon a trailer for towing behind a vehicle. The booth comprises a watertight enclosure adapted to receive one or more refuse bins and is provided towards its rear end with a closeable tailgate.

As best shown in Figures 1 and 2, the lower portion of the enclosure is provided with a filter tray (10) being overlaid by a deck (11). Jets (6) are provided within the enclosure in a predetermined interrelation and adapted to eject cleaning liquid toward the refuse bin in accordance with a predetermined sequence and at a predetermined pressure. Accordingly, the refuse bin can be inserted through the tailgate and the sequence initiated, optionally on closing of the tailgate, to clean the refuse bin in a very short period of time. Referring now to Figure 1, the trailer also is provided with a top up water tank (1) which feeds water into the system in order to replace cleaning hquid removed from the system as necessary. This water storage tank top up system is necessary because a certain amount of cleaning liquid is lost with a cleaned bin by evaporation etc, The trailer is also provided with a 2000 psi water washing unit (Honda) driven by a petrol engine (from a petrol store (3)). The liquid is supplied under pressure to a timer unit (4) through which the hquid flows. The flow of hquid through the timer is necessary to actuate the timer to ensure that the pressure washer unit does not burn out. The timer (4) is provided with a microprocessor whereby solenoid controlled valves from a manifold (5) open and close to supply cleaning liquid to the jets (6) in accordance with the predetermined sequence. Since the washer in this case provides hquid at about 2000 psi, each of the five jets (6) shown in Figure 1 will deliver liquid at about 400 psi. Equally of course, two jets will deliver liquid at about 1000 psi and 10 jets will deliver liquid at about 200 psi. This means that the jets can be both time and pressure controlled by the timing device so as to deliver a jet of a desired pressure to a desired portion of the article to be cleaned.

Additionally, the timer controlled solenoid manifold controls a high pressure filter backflush (7) and low pressure filter backflush (8) respectively via conduits (13) and (14). These are adapted to operate when all the jets (6) are switched off so that the system is in continual operation either to clean the article or to backwash the filters.

The water flowing from the refuse bin and including detritus therefrom flows on to the deck (11) which overlays filter tray (10). The filter tray, as best seen in Figure (2), is provided with a series of perforated baffles (15) and with self-sealing flap assembly (21) to prevent cleaning hquid destabilizing the trailer during travel. The deck (11) overlays the baffles (15) and is water tight. Water therefore flows from the deck (11) towards peripheral channels (16) which carry the used cleaning water by gravity to a coarse filter (17), which may be formed of a plurality of units for ease of cleaning. The cleaning liquid from the coarse filter (17) flows into a primary sedimentation tank (18) and from there into a secondary sedimentation tank (19) before returning to the main reservoir in the filter tray (10). Drain valve (20) is provided at the rear of the secondary sedimentation tank (19) to void the cleaning liquid to a sewer at the end of each working day.

The liquid in the filter tray (10) flows forward via a secondary coarse filter (23) and return line (12) via an optional (25 micron) fine filter (28) to the pressure washer again.

The filter tray (10) is also provided adjacent the coarse filter (23) with a low pressure filter backflush arrangement (24), and with high pressure filter backwash arrangement (22) actuated via high pressure filter backflush line (13).

Turning now to filter arrangement (10) as shown particularly in Figure 3. Figure (3) shows one half of a filter arrangement shown in Figure 2 and comprises a coarse filter (17) and a sedimentation tank (18).

The coarse filter (17) is formed of a coarse wire basket, or interfitting baskets, adapted to collect large items such as crisp packets etc. which fall to the bottom of the primary coarse filter (17) and may be removed by removing the basket from the enclosure (17) and manually tipping the collected detritus into the storage bin at appropriate intervals.

In the upper portion of the primary coarse filter (17) is intermediate filter (26) which allows cleaning liquid to be admitted to the sedimentation tank (18). The sedimentation tank (18) is provided with a plurality of parallel spaced vertically disposed baffles (25) imposing a serpentine flow upon the hquid flowing through the sedimentation tank. It will be noted that the remote ends of each baffle plate are turned inwardly against the flow thereby causing articles within the flow to separate out and fall to the floor of the sedimentation tank (18). At the end of the sedimentation tank (18) is a fine filter (29) which further slows the rate of flow of the hquid as it flows into the secondary sedimentation tank (19).

As will be apparent from Figure 2 there are two coarse filter and sedimentation tank assemblies in mutually opposed interrelationship to the secondary sedimentation tank (19). As the liquid flows in each case from the fine filter (29), it meets an equal an opposite flow from the other sedimentation tank (17). This causes horizontal flow to essentially stop thereby further de-entraining particles before the liquid is allowed to flow via the flap valve (21) into the filter tray (10).

In use a refuse bin is positioned in a predetermined orientation on the deck (11) and the cycle operated whereby jets (6) clean the bin at high pressure from predetermined positions. A cleaning hquid with entrained detritus flows out on to the deck (11) and via channels (16) to the coarse filter (17). The cleaning liquid then flows via the sedimentation tank (18), secondary sedimentation tank (19), and back via flap valve (21) into the filter tray. Water is drawn by the pressure washer (2) from return line (12) and optionally filter (28), via coarse filter (23) so that the cleaned hquid is supplied to the pressure washer and then to the timer (4) and via the solenoid manifold (5) to the jets (6) again. During this process, and at a period when the jets are out of use, the fine filter (29) is cleaned via backflush (22) and line (13) and coarse filter (23) is cleaned by the coarse filter backflush (24) supplied via low pressure filter backflush hquid supply line (14). By these means refuse bins can be readily cleaned and returned to their owners in a very short period of time. As previously stated labek can be applied to a cleaned bin which serve as a quality control aid and an indication of next occasion upon which each bin is to be cleaned by an operative.

Similar arrangements can be utilized for motorcars although certain changes in the washing unit and the number of jets and of the microprocessor control are required.

It will be appreciated that the use of this method, foul water can be reused a number of times before being voided to the sewer at a convenient point. Thus units can be utilized where ready access to the sewer cannot be provided. Further by utilization of two booths on a trailer it is possible to double the work rate available by use of a single operative because one bin can be cleaning while the operative collects the next bin for cleaning. When the booths in the present invention are static for car cleaning for example, it will be appreciated that in freezing conditions it is possible to use heated hquid in an energy conservative way and to use additives to the cleaning liquid which might be harmful in aerosol form. Another advantage of the present invention is economic, in that working units of the present invention are cheaper to install and maintain than those now available which are also capable of fulfilling environmental requirements.

A further embodiment of the invention is now described with reference to Figure 4. Figure 4 shows a vehicle washing apparatus for utilising the present invention.

Figure 4 shows an arrangement basically similar to Figure 1, but in which a gantry arrangement and means for the removal oil has been added. The arrangement Figures 1 to 3 has been in substance incorporated into Figure 4, so the individual features of these Figures have not been separately described. The further features of the arrangement to Figure 4 are as follows.

An enclosure shown generally (31) comprises an essentially rectangular housing provided with opening (33) at each end, each opening being closeable during the washing cycle by means of roller shutter (32) in accordance with known procedures. As previously described with reference to Figures 1 to 3 the sedimentation tank (18) is provided with a filter tray (10) and a deck (11). The deck (11) may be pierced by a plurahty of slots to allow cleaning liquid to flow into the sedimentation tank (18), or may be provided with drainage channels to achieve the same end. The recirculation arrangements are substantially identical in all but small details. Disposed longitudinally of the sides of the sedimentation tank (18) are a pair of gantry tracks (36) each provided with a worm drive extending the length of track. Interfitted in the gantry track (36) on each of the longitudinal faces thereof is a upright stepping motor casing (34) disposed in casing, and adapted to be driven by means of the wonn drive in the gantry track (36) by means of gantry stepping motors (35). The gantry stepping motors (35) are driven in synchronism by means of outputs from a microprocessor control (30) so that the gantry can be driven longitudinally of the sedimentation tank (18) at a predetermined speed and returned either in a non- operative or in a secondary pass condition.

The upright stepping motor (34) housed in its housing is in operative connection with the gantry track (36), and is adapted to operate the upright (43). The upright stepping motor (34) has associated gearing within its casing adapted in a primary mode to engage a worm drive extending upwardly of the uprights (34) and in operative connection with the crosspiece (37). Accordingly the stepping motor (34) can in a first mode drive the crosspiece (37) upwardly or downwardly. Gearing is also provided associated with the stepping motor (34) to cause the stem of the upright (43) to move to an arc of generally 45°, although it can be greater or less than this, in order that jets (6) fixedly disposed upon the upright (43), can be caused to move through an arc and thereby execute a washing action. This arc may be intermittent or continuous depending upon the style of cleaning selected.

Further the stepping motor (34) has a third associated form of gearing in which a cam is engaged (not shown) which causes the uprights (34) to move towards or away from each other thereby to approach or move away from each other. This allows the jets to be brought automatically to an optimum distance from the object being washed.

It will be noted that the deck (11) is shown broken away so as to display the used cleaning fluid (40) comprising in this particular instance an oil and water mix in the sedimentation tank (18). To the right hand side of the sedimentation tank (18) is positioned a doctor-blade (38) driven by means of a coarse worm drive (39) along a doctor-blade track from one end of the sedimentation tank to the other. The doctor- blade (18) extends downwardly below the level of the liquid (40) in the sedimentation tank (8), whereby the lowermost edge of the doctor-blade passes over the tops of the baffled (25) in the tank.

Periodically in operation the microprocessor control (30) causes the doctor-blade (38) to move rapidly across the surface of the oil and water mix in the sedimentation tank (18) towards a lowered sill (44). Because oil and water mix floats to the surface of the used cleaning liquid, the action of the doctor-blade has the effect of driving the pil and water mix or emulsion from the sedimentation tank over sill (44) and into a holding tank (45). The oil and water mix in the holding tank (45) tends to separate into the hghter hydrocarbon components at the top of the tank and water at the lower levels. Left over night this separation can be fairly complete whereupon the water can be drained off to leave the hydrocarbons for alternative disposal.

In use an automobile enters the enclosure (31) via an opening (33) by driving up access ramp (41). The vehicle is positioned on the deck (11) and its parameters are fed into the microprocessor control (30). For example software is prepared for all the main makes of automobile so that the stepping motor (34 and 35) can together with the valve-controlled jet (6) supply the necessary high pressure cleaning liquid to the relevant portions of the automobile.

With the vehicle in its correct orientation the operator actuates the microprocessor (3) which causes the stepping motors (34 and 35) to adopt their preliminary positions. After a short period cleaning hquid is supphed via the jets (6) in accordance with a predetermined schedule. If desired the uprights (43) can be moved arcuately during the washing process, while the stepping motor (35) drives the gantry longitudinally to make a first pass. During this pass the crosspiece (34) may be moved up and down while the stepping motor (34) can be utilised to cam the uprights inwardly and outwardly as demanded by the shape of the article being cleaned.

After a first pass the stepping motors (35) reverse to repeat the process thereby providing a second pass. One, two or many passes may be used depending upon the precise circumstances. At the end of the washing process a hot air drying step may be provided (not shown), prior to exit of the vehicle from the opening (33) via ramp (42). Traffic film, diesel, oil etc. result in a film forming on the sedimentation tank (18). This film can be removed by means of the doctor-knife (38) in a fashion previously described at regular intervals leaving the cleaning liquid substantially free from polluting hydrocarbons.

It will be appreciated that whereas a microprocessor is desirable it is also possible to manually control the gantry by means of a suitable 3 way control mechanism such as that utilised for example in digging machines etc.

By means of the arrangements in accordance to the present invention automobiles can be readily cleaned without mechanical contact and in a way which does not damage mirrors, aerials etc.

The operating pressure of the jets can be changed if desired on a microprocessor control basis but generally it is desirable to use a pressure of about 2250 psi for heavily soiled portions of an article such as vehicle wheels, whereas 1500 psi is satisfactory for cleaning body work portions.

By means of the recirculation of the cleaning liquid, by topping up, as necessazy, with detergent and other additives, it is possible to utilise the same cleaning fluid for a considerable period particularly if hght hydrocarbons are removed in the fashion suggested.

Claims

1 An article cleaning booth, said booth comprising an enclosed deck upon which an article is adapted to repose in a predetermined orientation relative to at least one cleaning liquid delivery jet adapted to direct a stream of cleaning hquid to the article to be cleaned;

tank means for the collection of used cleaning liquid falling on said deck.

means for recirculating the used cleaning liquid under pressure to said jet, said recirculating means including filter means adapted to remove detritus from the cleaning liquid before reuse.

2. A booth according to Claim 1 disposed upon a wheeled frame and comprising a gantry provided with a plurahty of spaced jets thereupon.

3. A booth according to either preceding Claim wherein there are provided a plurality of jets in a predetermined spaced interrelationship, each jet being controlled by a liquid control valve, and wherein each valve is opened and closed according to a predetermined cycle to jet liquid at a predetermined pressure in a predetermined direction.

4. A booth according to either of Claims 2 or 3 wherein the gantry comprises a pair of uprights extending upwardly of the deck and supporting a crosspiece therebetween; wherein the gantry is movable longitudinally relative to the deck; and wherein the uprights are at least rotatable about their respective axes to provide arcuate movement of the jets attached thereto.

5. A booth according to Claim 4 wherein the arcuate movement of the jets is effected on a continuous reciprocating basis thereby to provide arcuate jets of cleaning liquid directed at the article to be cleaned.

6. A booth according to any preceding Claim wherein the means of collection of the used liquid is a baffled tank inferior to the deck.

7. A booth according to any preceding Claim wherein the used liquid

10 flowing from the deck passes through a coarse filter, a serpentine flow sedimentation tank, and a fine filter before being ejected by the jets again.

8. A booth according to Claim 7 wherein the deck is provided with a channel for the delivery of used liquid to a coarse filter, wherein there

15 are provided at least two sets of sedimentation tanks in which liquid flows in mutually opposed directions whereby the flow from each tank is slowed and caused to meet a flow of a generally equal and opposite force to create a point at which the flow component in the horizontal sense is substantially zero.

*

20 9. A booth according to any of Claims 3 to 8 wherein the recirculating means comprises a pump adapted to impel cleaning liquid about a main at a predetermined operating pressure, said main optionaUy voiding either to the tank or to backwashing means in use,

said main comprising a plurality of valves each controlled to eject cleaning liquid according to a microprocessor control sequence thereby to control the position and power of jets, said microprocessor also acting to control backwashing of one or more filters at a predetermined or random time interval.

10. A booth according to any of the preceding Claims wherein the filter means includes means for the separation of hydrocarbons from the used cleaning liquid.

11. A booth according to Claim 10 wherein the separation means include a doctor- knife associated with the sedimentation tank and/or a secondaiy container for the containment oil/water mixture prior to final separation and disposal.

12. A method of indicating that a refuse bin is ready for cleaning, which method comprises the steps of,

(a) cleaning the bin utilizing a pressuring washing apparatus,

(b) fixing to said clean bin a rainfast label, said label bearing an indication thereupon,

(c) repeating step (a) in a fashion which removes the label and subsequently repeating step (b) with a new label being applied thereto.

13. •• A method according to Claim 12 wherein the label is selfadhesive and is colored and/or is provided with printed indicia.