EP3938118B1 - Cleaning device for airless paint spray devices and method therefor - Google Patents

Description

The invention relates to a device and a method for cleaning airless paint sprayers.

State of the art and disadvantages

Paint sprayers are well known from the state of the art. The liquid to be applied (paint, stain, glue, etc.) in a container or tank is fed into a spray gun and atomized from a nozzle. The basic mechanism is the pressure difference between the liquid and the environment.

Paint sprayers have been around for a long time, where the liquid is pumped out of the nozzle using pressurized air and thus atomized. The advantage of very fine droplet formation is offset by the disadvantage of a fairly large spray mist. In addition, bubbles form on the wetted surface due to the air contained in the liquid.

One variant that has recently become increasingly popular is the so-called airless spraying technique. Here, the liquid is put under high pressure (50 to 250 bar) using a hydraulic pump without the addition of air. When it comes out of the nozzle, the liquid atomizes. The advantages of this technology include lower consumption due to less spray mist formation, as well as higher possible throughput. However, airless devices must be cleaned particularly thoroughly so that the particularly sensitive high-pressure components do not stick together after use due to paint residue, which renders the machines unusable, as they are expensive compared to other spray devices.

The cleaning of said airless devices is currently carried out as follows:
First, several containers of clean (tap) water are provided, which have previously been filled at a water tap, often located at a distance. Providing several containers is necessary because the total amount of liquid required for cleaning can be up to 40 liters or more, which exceeds the weight that an average person can carry at once. In some cases, up to four 25-liter containers are needed. used. The cleaning container itself must have a relatively large volume (at least 10-15 liters), otherwise it would be drained too quickly. During the subsequent cleaning process, there is also no time to refill a single container at the tap, unless the cleaning process is interrupted, which is undesirable. If several containers are ready to be refilled, it may be necessary to have another person available to refill the container in which the cleaning takes place; in addition, it is generally impractical to add water by refilling it while the cleaning is in progress.

Then the suction line of the airless sprayer, the so-called (suction) "trunk", which is arranged upstream of the high-pressure pump to suck in the liquid to be sprayed, is hung in a first bucket (cleaning container).

The end downstream of the high-pressure pump (spray nozzle) is also hung in a previously prepared container so that the grey liquid produced during the actual cleaning process can be collected; direct discharge into the sewer system is not permitted. It is clear that it is advantageous to have a sufficient number of such collecting containers so that all of the cleaning liquid can be collected.

The high-pressure pump is then switched on. The clear water is pumped through the spray device, where it gradually cleans the interior of the pipes and the high-pressure pump. The outside of the nozzle, which is often dirty with heavy paint residue, is manually wiped in fresh water, possibly with a brush, until it is clean. It is clear that only after the nozzle has been completely cleaned is there really clear water available, which is needed to really clean the spray device thoroughly.

The cleaning process is only finished when clear water comes out of the nozzle.

This approach has a number of disadvantages.

The amount of water required for cleaning is very high. The frequent need to carry the fresh water containers is tiring, and the containers represent obstacles that can become tripping hazards in a workshop or on a construction site. The same applies to the collection containers. In addition, bacteria can settle in standing water, which can lead to odors and health problems. DE 27 47 707 A1 concerns the flushing of a paint spraying system.

Task of the invention and solution

The invention is therefore based on the object of providing a device and a method which avoids the disadvantages of the prior art.

The object is achieved by a device according to claim 1, a facility according to independent claim 8, a system according to independent claim 9, and a method according to independent claim 10. Advantageous embodiments can be found in the respective dependent subclaims, the following description and the figures.

Description

The device is used to clean airless sprayers as described above. It comprises a container that is open at the top to hold fresh water and an inlet that can be connected to a water supply, and is characterized in that the container has a fill level control by means of which the level of the fresh water in the container can be maintained at a predetermined value.

The container is open at the top in such a way that the "trunk" contaminated with paint or another liquid can be immersed in the container, preferably so far that the contaminated parts can be completely immersed in the container filled with water.

The inlet can be designed as a component (bore) that passes through the wall of the container. However, it can also be provided by a component that runs over the edge of the container and is aligned so that the water exits into the interior of the container. The mouth of the inlet can therefore be below or above the edge of the container; a mouth below is preferred. The inlet can be mechanically connected to the fill level control described below and can also be integrated with it.

The level control comprises two subcomponents, namely a measuring device and a control device. The measuring device is used to measure the actual level, or to determine whether a specified target value has been reached or fallen below. The control is used to open or close the inlet using a valve or the like. It receives the signal to open exactly when the measuring device detects that the target value has been fallen below. Fresh water thus flows into the tank until the target value is reached again. The The measuring device detects this condition and the signal to open is switched off or the signal to close is sent to the control system. The inlet is closed.

The control can have two states (closed / open), or several (intermediate) states (closed / slightly open / half open / wide open / fully open), or be designed as a proportional control (valve position depends on the size of the setpoint deviation).

A simple control system has a float that is coupled to a valve, and this closes as soon as it has reached a certain height above the bottom of the tank (level) due to the rising water. A particularly robust control system is one that includes a pressure cell with a membrane, which is triggered when the water overflows. The control system can also include electronic components (e.g. conductivity measurement between two conductors protruding into the water), etc.

Furthermore, the device according to the invention is characterized in that the inlet opens into at least one nozzle, by means of which fresh water can be dispensed into the interior of the container. The term "nozzle" indicates that the speed of the escaping water is increased and the direction of the resulting water jet can be determined by aligning the nozzle. The term "nozzle" is to be understood broadly in this case; accordingly, this definition includes any opening that serves to specifically dispense fresh water (or another cleaning liquid), whereby the flow speed is increased, for example by a cross-sectional tapering. A speed at the outlet of the nozzle of 0.5 to 5 m/s, preferably 2 to 4 m/s, with a flow rate of 0.1 l/s to 1.0 l/s, preferably 0.3 l/s to 0.6 l/s, has proven to be advantageous.

The provision of a nozzle further increases the formation of the desired turbulence. In addition, the cleaning effect on the nozzle is better with a harder, directed jet than with water introduced at any point. It is particularly preferred that the at least one nozzle is directed in the direction of the nozzle, i.e. roughly towards the center of the container. To prevent water from splashing out, the water jet can also be directed slightly downwards. The nozzle is also arranged above the level so that the jet initially runs through the air and then optimally hits the water surface in the border area between the level and the nozzle. In this way, air bubbles are entrained, which further improves the cleaning effect.

The invention effectively avoids the disadvantages known from the prior art.

The invention allows for simple and very thorough cleaning of airless devices, eliminating the need to have several containers ready to refill the cleaning container and the need to interrupt the cleaning process in order to manually refill the cleaning container. This means that only one person is needed to use the device.

Since the cleaning container is refilled automatically, it is not necessary for it to be as large as the cleaning containers described above. This also means that water consumption is lower overall, as will be explained in more detail. Various embodiments of the invention are described in more detail below.

The volume of the container is between 0.5 and 20 liters, and preferably between 2 and 15 liters, and particularly preferably between 5 and 10 liters. Accordingly, the volume of the preferred and particularly preferred embodiment in particular is significantly smaller than that of the containers used according to the prior art.

Due to the fact that the container refills very quickly when the inlet is opened, the volume in the container, and thus the amount of water available there, only needs to be large enough to ensure that the nozzle of the sprayer has enough space and is sufficiently covered. This also means that the volume in the container - assuming the same suction power of the sprayer - is exchanged much more quickly. Therefore, although the water is initially more contaminated at the very beginning of the cleaning process (smaller volume for the same amount of dirt), it is then exchanged more quickly so that it is clean sooner. This leads to the desired reduction in water consumption.

According to one embodiment, the fresh water inflow rate is between 5 and 50 litres per minute, and preferably between 10 and 35 litres per minute, and particularly preferably between 15 and 25 litres per minute. This means that the inflow rate is relatively high. However, it should be noted that the inflow is only opened intermittently, since water is only supplied when the level is below the set level. The inflow rate therefore says nothing about the actual water consumption that occurs during the present invention is actually smaller than in prior art methods.

Typically, the control system has a hysteresis. This means that slightly more water is added than is necessary to reach the target level and/or that the inlet is only opened when the level falls below a level slightly below the target level. This means that there is a range between the upper and lower limits of which water is drawn from the sprayer without being immediately refilled. It is clear that the inlet rate must be at least slightly higher than the withdrawal rate (pump output in liters per minute) of the sprayer so that the target level can always be reached without the sprayer pump having to be temporarily switched off.

The advantages of a small volume of the container coupled with a high inflow rate, which is particularly preferably intermittent, are the following:
A high inflow rate allows a further reduction of the container volume, since even a very small container can always be refilled to the target level quickly enough.

If the inflow rate is particularly high, it is sufficient for the water to be added in bursts, but with sufficient force. These pulses repeatedly stir up sediment, which could otherwise collect on the bottom, and are pumped out of the container by the sprayer's pump.

The eddies and turbulence in the water prevent paint or other residues from sticking to the inside of the container; if the fill level changes slowly, as is more likely to be the case with large containers used in the state of the art, rings quickly form at the boundary layer between the liquid, air and container wall; these only dissolve again gradually, resulting in a significantly longer period of time during which the water in the container is not completely clean, so that the sprayer is also not completely cleaned until it is completely clear and the water flows through it. The turbulence also stirs up sediment, which is then carried away with the grey water. This also prevents the formation of unpleasant odors due to sediment deposits.

According to a further embodiment, the diameter (or diagonal, if applicable) of the (preferably round or rectangular) container is between 10 and 100 centimeters, and preferably between 20 and 50 centimeters, and particularly preferably between 25 and 30 centimeters. Accordingly, the diameter is small compared to prior art containers, which is associated with a correspondingly smaller volume.

The fill level control is designed to maintain a level of 5 to 30 centimeters, and preferably 8 to 20 centimeters, and particularly preferably 10 to 15 centimeters, measured from the bottom of the container. The optimal fill level is also determined by the typical level in paint containers and the like, since the nozzle of the sprayer is expected to become dirty up to this level. It is therefore sensible to keep the water that cleans the liquid in question at a comparable fill level in the container.

The level height can be adjustable according to one embodiment.

The height of the container is preferably between 2 and 25, preferably between 4 and 20, and particularly preferably between 5 and 15 centimeters more than the desired level. Typically, the container is preferably between 20 and 30 centimeters high overall. A container whose upper edge is too close to the target level tends to spill over; it is also advantageous if the jet emerging from the inlet initially runs through the air and also hits the water from the air in the interface between the nozzle and the level. This requires a rather high edge or a rather large distance from the upper edge of the container to the target level. According to another preferred embodiment, the inlet opens into a plurality of nozzles. Each nozzle can thus have a smaller cross-section, which leads to a more directed jet; the required inlet rate can still be achieved by having several nozzles that emit water in parallel. In addition, several nozzles allow the nozzle to be cleaned in several places (e.g. in several levels) at the same time. One nozzle, preferably the one closest to the bottom, can also be tilted sideways to create a rotating vortex on the bottom, which stirs up sediment even more effectively.

The nozzles can be arranged in a vertical and/or circumferential direction on the inner wall of the container.

When arranged vertically, the nozzle can be cleaned particularly effectively on several levels at the same time. If necessary, the nozzle or the container must be rotated to allow all sides to be cleaned.

When arranged in a circumferential direction, the nozzle can be cleaned particularly effectively from all sides at the same time. If necessary, the nozzle must be raised to allow cleaning on all levels.

A combination of vertical and circumferential nozzles is also possible. This makes it possible to provide a device that does not require the nozzle to be moved and cleans it on all sides and along its entire length.

According to a further embodiment, the inlet, optionally with the at least one nozzle, and the level control are connected to one another and can be moved in a vertical and/or horizontal direction. This means that both components are attached to a rail, a lift or the like so that the height above the container floor can be varied. It is clear that the position should not change automatically after adjustment has been made.

The advantage of this embodiment is that a dirty suction end can be cleaned along its entire length without having to move (raise) it vertically; instead, it remains in its original position in the container, and cleaning is carried out by vertically "moving" the suction end by moving the nozzle level control unit. Since the nozzle provided according to the invention, which is already optimally aligned, moves with the flow, there is no need to readjust it. By raising the level, the end of the suction end is cleaned first, then the sections closer to the pump are successively cleaned. Since the level moves with the flow, it is always optimally adjusted in comparison to the point of impact of the jet. Of course, it is also possible to start with a high level and then lower it. At the end of this process (suction end completely cleaned), the residual volume in the container is therefore minimal, which is again advantageous (see above).

Alternatively or additionally, the nozzle level control unit can also be moved horizontally.

If the nozzle level control unit includes several nozzles, these can be arranged at a fixed or variable distance from each other. In this way, depending on the size and degree of contamination of the suction end, the jets can be concentrated on a smaller area or distributed over a larger area.

According to a further embodiment, the device has a carrying handle which is arranged such that it is vertically above the inlet, with the handle firmly attached to the container and shaped so that its gripping surface is above the center of gravity of the container.

Since the handle is firmly attached to the container (i.e. cannot be folded), it is always in the same position. It is therefore always positioned above the inlet, so that the parts on the inside of the container are protected from mechanical damage by the nozzle. It is therefore preferable if the level control is also located in the area of the inlet, as it is then also protected by the handle. This is particularly important if the level control also includes mechanical components (e.g. floats) that are mechanically sensitive and must be freely movable.

The disclosure also relates to a device for cleaning airless sprayers, comprising an inlet of the type described above that can be connected to a water supply. The device is characterized in that it is intended to cooperate with an upwardly open container for receiving fresh water flowing out of the inlet and has a fill level control by means of which the level of the fresh water in the container can be maintained at a predetermined value.

Furthermore, the inlet opens into at least one nozzle, by means of which fresh water can be directed into the interior of the container.

In other words, the device comprises the components of the above-mentioned cleaning device, with the exception of the container. Instead, it is designed to interact with such a container in such a way that water can be released into the interior of the container in a directed and controllable manner, while at the same time the level can be regulated to a setpoint as described in detail above. Accordingly, a device corresponding to the above-mentioned device can be created by adding almost any container, such as an (empty) paint bucket.

It is clear that - as long as there are no structural contradictions - everything said with regard to the embodiments of the device also applies to the cleaning device. This applies in particular to the dimensions, the presence and positioning of one or more nozzles, as well as the type of level control. There is therefore no need to repeat this.

The invention also relates to a system for cleaning airless sprayers. This comprises a device for cleaning airless sprayers as described above.

The system also includes a recycling facility for treating grey water flowing from the end of the airless sprayer downstream of the high-pressure pump. In other words, the system includes all the essential components required for cleaning and subsequent treatment of grey water resulting from the cleaning of airless sprayers.

The invention also relates to a method for cleaning airless spraying devices; reference is made to the above explanations regarding such devices and the need for their thorough cleaning.

• Bereitstellen eines Behälters zur Aufnahme von Frischwasser;
• Einbringen des Ansaugendes des Airless-Spritzgeräts in den Behälter;
• Befüllen des Behälters mit Frischwasser bis zu einem vorherbestimmten Wert des Niveaus;
• Einschalten der Hochdruckpumpe des Airless-Spritzgeräts, so dass Frischwasser aus dem Behälter heraus und durch das Airless-Spritzgerät hindurch gefördert wird, so dass sich das Niveau reduziert;
• Detektieren der Reduzierung des Niveaus mittels einer geeigneten Messeinrichtung;
• Öffnen eines Zulaufs von Frischwasser in den Behälter mittels einer mit der Messeinrichtung verbundenen Steuerungseinrichtung, so dass sich das Niveau wieder anhebt;
• Detektieren des Erreichens des vorbestimmten Wertes des Niveaus und Schließen des Zulaufs.

The method, which is preferably carried out by means of the above-mentioned device, comprises the following steps:

• Providing a container for holding fresh water;
• Insert the suction end of the airless sprayer into the container;
• Filling the tank with fresh water to a predetermined level;
• Turn on the high pressure pump of the airless sprayer so that fresh water is pumped out of the tank and through the airless sprayer, reducing the level;
• Detecting the reduction in level by means of a suitable measuring device;
• Opening a fresh water inlet into the tank by means of a control device connected to the measuring device so that the level rises again;
• Detecting when the predetermined level is reached and closing the inlet.

The result of the last four steps is that, despite the continuous extraction of fresh water by the airless sprayer, the level of fresh water in the tank remains essentially constant. The associated advantages have already been explained above and therefore do not need to be repeated. The measuring device together with the The control device is preferably implemented by a level control of the type described above.

According to the invention, the fresh water is discharged into the interior of the container by means of at least one suitable nozzle arranged downstream of the inlet, creating turbulence.

This means that the suction end of the airless sprayer is freed of any liquid residues adhering to this suction end. In addition, sediment that would otherwise settle on the bottom of the container is stirred up and sucked in by the airless sprayer.

In addition, already contaminated water is continuously diluted and pumped out of the container, so that clean water is in the container earlier. This reduces water consumption compared to the current state of the art, according to which, when there is standing water in the cleaning container, the nozzle inserted there is repeatedly manually wiped off until it is sufficiently cleaned. Experience has shown, however, that areas are often overlooked and are only cleaned later, so that even at a late stage, when the actual cleaning already seems to be well advanced and a correspondingly large amount of water has been used, new dirt residues suddenly get into the water, which are sucked in and thus contaminate the spray device, which was actually already quite clean.

According to a further embodiment, the grey water flowing from the end of the airless sprayer downstream of the high-pressure pump is fed to a recycling facility. In other words, the grey water pumped from the container by the sprayer and coming out of the end intended for the spray gun in a contaminated state is fed directly to a recycling facility. This eliminates the need to collect the grey water in separate containers; discharging it into the sewage system is not permitted anyway for environmental reasons.

Character description

Figur 1

eine schematische Darstellung einer Ausführungsform der Erfindung bei geöffnetem Zulauf;

Figur 2

die Ausführungsform aus Fig. 1 bei geschlossenem Zulauf.

Figur 3

eine Ausführungsform der Erfindung mit einhängbarer Düsen-Füllstandsregelungs-Einheit,

Figur 4

eine Anlage, umfassend die erfindungsgemäße Vorrichtung und eine Wiederaufbereitungseinrichtung für Grauwasser.

The invention is explained below by way of example using figures.

Figure 1

a schematic representation of an embodiment of the invention with the inlet open;

Figure 2

the embodiment of Fig.1 with the inlet closed.

Figure 3

an embodiment of the invention with a suspendable nozzle level control unit,

Figure 4

a plant comprising the device according to the invention and a grey water recycling device.

In the Figure 1 A schematic representation of an embodiment of the invention with the inlet open is shown.

The container 1 is round and has an inlet 2 on its inner wall 5, which is fed with fresh water W and includes a valve (not shown). The valve is part of a control device 9. This is connected to a measuring device 8, which is used to measure the level N of the fresh water W in the container 1. The control device 9 and the measuring device 8 can be combined to form the fill level control 3. This can be adjusted in the vertical direction, as indicated by the vertical double arrow (without reference symbol). In addition, the fill level control 3 can also be adjusted in the horizontal direction, indicated by the horizontal curved double arrow (without reference symbol).

A carrying handle 6 is arranged above the measuring and control device 8, 9. This is firmly connected to the container 1 and is positioned in such a way that it protects the components underneath from mechanical damage caused by the suction end 7 of an airless sprayer. The carrying handle 6 is arranged slightly outside the central axis (not shown) of the container 1; since the inlet 2 with the measuring and control device 8, 9 is arranged on the right-hand side in the picture, the center of gravity of the entire device also moves slightly to the right. The carrying handle is therefore arranged in such a way that its gripping surface is above the center of gravity of the container 1.

Downstream of the control device 9, a nozzle 4 is arranged which emits a sharp and directed jet of fresh water W into the interior of the container 1 (dotted area). In this case, the jet is directed approximately towards the center and at the same time downwards in order to prevent water W from splashing out during the cleaning process.

The suction end 7 of an airless sprayer (not shown) extends into the interior of the container 1. This intermittently or continuously draws water W from the container 1 in order to be pumped through the interior of the airless sprayer and thus clean it. This would lead to a continuous drop in the level N unless sufficient Fresh water W would be supplied via inlet 2. Since the inflow rate is greater than the withdrawal rate, the level N can rise again.

The Figure 2 shows the situation after reaching the predetermined value X of the level N. The measuring device 8 shown comprises two wires which protrude towards the bottom of the container 1. As soon as these are in the water W, the resistance between these wires changes, which is easily detectable and leads to the valve being closed by the control device 9. The inlet 2 is thus closed and the jet dries up.

What is not shown is that if the water W is still being removed using the airless sprayer, the level N drops again, which leads to the valve being opened again, etc.

Thus, a device is provided which operates in a simple manner and which nevertheless effectively avoids the disadvantages of the prior art and by means of which an airless sprayer can be cleaned.

The Figure 3 shows an embodiment of the invention with a nozzle level control unit that can be hung. This includes both the inlet 2 and the nozzle 4; also the level control 3, which in turn includes a control device 9 and a measuring device 8. In the present case, this is implemented by a simple pressure cell comprising a membrane (not shown); when the membrane is flushed, a switch is activated, which in turn controls the valve. The pressure cell can also be moved in a vertical direction, indicated by the double arrow (without reference symbol). This makes it very easy to set and read the desired target level. The inlet 2 is designed to be guided over the edge of the container 1 so that the unit can be hung. This means that almost any container, indicated by the handle 10, can be easily combined with the device in order to obtain a device that has a largely identical effect to the cleaning device according to the invention.

Not shown are optional fastening means which should preferably be provided to ensure that the nozzle level control unit does not move undesirably during operation.

In Figure 4 a system comprising the device according to the invention and a recycling device 11 for grey water is shown. The device for cleaning airless sprayers, on the right in the picture, is only shown roughly schematically. Fresh water is fed into the device. Next to the device, also roughly schematically, an airless sprayer 13 is shown in the middle of the picture, the suction end 7 of which extends into the container 1 of the device, where it can be cleaned. The end of the airless sprayer 13 downstream of the high-pressure pump (not shown) is led into the basin of a recycling device 11, which in this case comprises a washstand with a basin. The grey water flowing from this end can be collected there and fed to the recycling device.

All parts of the system, and in particular the cleaning device, are placed on the floor. This means that there is no need to lift the airless sprayer onto a washstand or similar. During the cleaning process, all parts remain in the same place; the transport of fresh and/or grey water known from the state of the art is completely eliminated, which also reduces the risk of tripping over containers lying around.

List of reference symbols

1

container

2

Intake

3

Level control

4

jet

5

Container inner wall

6

Carrying handle

7

Suction

8th

Measuring device

9

Control device

10

handle

11

Reprocessing facility

12

Hose

13

Airless sprayer

W

Fresh water, water

N

level

X

Value

Claims (10)

1. Apparatus for cleaning the internal lines as well as the suction end (7) of airless paint spray devices (13), comprising an upwardly open container (1) for receiving fresh water (W), into which the suction end (7) of the airless paint spray device (13) can be introduced, as well as an inlet (2) which can be connected to a water supply, wherein the container (1) has a level control (3) by means of which the level (N) of the fresh water (W) in the container (1) can be maintained at a predetermined value (X), characterised in that the inlet (2) opens into at least one nozzle (4) which is arranged above the level (N) and increases the speed of the emerging fresh water (W) and by means of which a sharp jet of fresh water (W) can be discharged downwards into the boundary region between the level (N) and the suction end (7) directed onto the water surface for the purpose of forming turbulence in the interior of the container (1), the volume of the container (1) being between 0.5 and 20 litres.
2. Apparatus according to claim 1, wherein the volume of the container (1) is between 1 and 10 litres, and/or wherein the feed rate is between 15 and 25 litres/minute.
3. Apparatus according to claim 1 or 2, wherein the diameter of the container (1) amounts to no more than 30 cm, and/or wherein the level control (3) is arranged to maintain a level (N) of 8 to 15 cm.
4. Apparatus according to claim 1 to 3, wherein the inlet (2) opens into a plurality of nozzles (4).
5. Apparatus according to claim 4, wherein the nozzles (4) are arranged in a vertical and/or circumferential direction on the container inner wall (5).
6. Apparatus according to any of the preceding claims, wherein the at least one nozzle (4) and the level control (3) are connected to each other and are displaceable in the vertical direction.
7. Apparatus according to any of the preceding claims, wherein the same has a carrying grip (6) which is arranged such that it is located above the inlet (2), wherein the carrying grip (6) is firmly connected to the container (1) and is shaped such that its gripping surface lies above the centre of gravity of the container (1).
8. A system for cleaning airless paint spray devices (13), comprising an apparatus according to any one of claims 1 to 7, further comprising a recycling device (11) for treating grey water flowing from the end of the airless paint spray device (13) downstream of the high-pressure pump.
9. Method for cleaning the internal lines and the suction end (7) of airless paint spray devices (13), comprising the following steps:

   - Providing a container (1) for holding fresh water (W);

   - Inserting the suction end (7) of the airless paint spray device (13) into the container (1);

   - Filling the container (1) with fresh water (W) up to a predetermined value (X) of the level (N);

   - Switching on the high-pressure pump of the airless paint spray device (13), so that fresh water (W) is conveyed out of the container (1) and through the airless paint spray device (13), so that the level (N) is reduced;

   - Detecting the reduction of the level (N) by means of a suitable measuring device (8);

   - Opening an inlet (2) of fresh water (W) into the container (1) by means of a control unit (9) connected to the measuring device (8), so that the level (N) rises again;

   - detecting that the predetermined value (X) of the level (N) has been reached and closing the inlet (2);

   so that the level (N) of the fresh water (W) in the container (1) remains essentially constant despite the continuous withdrawal of fresh water (W) by the airless paint spray device (13), characterised in that fresh water (W) is discharged into the interior of the container (1) by means of at least one suitable nozzle (4) arranged downstream of the inlet (2) and above the level (N), forming turbulence, so that a suction end (7) of the airless paint spray device (13) introduced therein is cleaned of liquid residues adhering thereto, and/or sediments which would otherwise settle on the bottom of the container (1) are whirled up and sucked in by the airless paint spray device (13), and/or already contaminated water (W) is diluted and conveyed out of the container (1).
10. Method according to claim 9, wherein the grey water flowing from the end of the airless paint spray device (13) located downstream of the high-pressure pump is fed to a recycling device (11).

Images