EP1053077B1 - Abrasive-medium ejector gun - Google Patents

Abstract

The present invention relates to an abrasive-medium ejector gun (1) which has separate inlets for pressurised air, water and the abrasive medium and comprises an outlet opening (17) for the abrasive medium mixed with the pressurised air and water. In order to provide an improved wetting of the abrasive medium, a first mixing device (24) is used for adding water to the pressurised air, while a second mixing device (19) is used for adding the abrasive agent to the water-pressurised air mixture.

Description

The invention relates to a blasting agent injector gun with separate inlets for compressed air, water and blasting media and an outlet for that with compressed air and water mixed blasting media, with a first Mixing device in which water is added to the compressed air and with a second mixing device, in the the compressed air-water mixture the blasting agent is added.

An injector gun is known from DE 90 00 178 U1, at what air and abrasive in the gun are mixed, then this dry air / abrasive mixture water added. It has been found that such Arrangement a complete and reliable Mixing is difficult to achieve.

In US-A-5 099 619 there is a delivery device of moistened abrasive described which in a compressed air flow via a closable Water pipe water is injected into this Water-air mixture is then in a mixing chamber mixed with an abrasive. It is without further possible that the water supply is open, before the air supply is switched on as this can be operated completely independently of one another. It there is therefore a risk that the abrasive will not is only moistened, but by mixing is drenched with a pure stream of water.

Based on this state of the art, the subject of the application lies based on the task of preventing that atomized water enters the gun and wet, instead of moistened abrasive becomes.

This task is done with a blasting agent injector gun of the type described above according to the invention solved in that the compressed air supply and the water supply are closed with closing valves and that an opening device is provided for these closing valves which is the shutoff valve of the water supply only opens when the compressed air supply shut-off valve opens is.

Such an opening device ensures that water is only pumped when there is a flow of compressed air is present, it is therefore impossible that liquid, non-atomized water into the gun entry. It also ensures that propellant flowing through the gun in the suction area the abrasive particle water only in one Contains amount that leads to a very fine atomization leads so that no wet abrasive is released is, but only moistened.

It is favorable if the first mixing device is an injector with the compressed air flow as the blowing agent flow. In such an injector, the water can flow to the compressed air can be added, preferably here Water with mains pressure can be used, i.e. with a pressure of, for example, 6 to 12 bar.

It can also be provided that the second Mixing device an injector with the compressed air / water flow as a blowing agent flow. Such an injector leads to a particularly uniform mixing of the Compressed air / water flow on the one hand with the propellant flow on the other hand, and thus to the desired wrapping effect of the individual abrasive particles.

It is advantageous if the opening device is a Movable actuator comprises, which at an opening movement first the closing valve of the Compressed air supply and then the closing valve of the Water supply opens. Such an actuator ensures that the compressed air supply always comes first is open, and only then the water supply is opened when the compressed air supply is already open is.

It is also advantageous if the opening points of the two closing valves along the opening movement of the actuator are adjustable. Thereby the possibility is given, even with structural Tolerances the sequential Ensure opening of the closing valves. Moreover can with a progressive opening of the closing valve be selected in the compressed air line at what strength of the compressed air flow the water supply should start.

In a preferred embodiment, that the operative connection between the actuating element and the shut-off valve of the water supply optionally and can be switched off, so that the actuating element Water supply shut-off valve during its opening movement either after the closing valve of the compressed air supply opens or keeps it permanently closed. The The user thus has the choice of whether he clicks on the Actuator generate a stream of compressed air wants to be mixed with water, or one completely dry compressed air flow. If he has the water supply wishes, it will only be opened when the compressed air flow is open when there is a water supply is not desired by pressing of the actuator only the closing valve Compressed air supply opened, but not the closing valve the water supply.

It can in particular be provided that Switching the active connection on or off is a movement transmission element is provided that in switched on Condition the movement of the actuating element the shut-off valve transfers the water supply when switched off Condition is positioned so that a such motion transmission is not possible.

A particularly preferred embodiment includes provided that the motion transmission member a is a plunger mounted in a guide, a thrust transmission link when switched on between the actuator and the closing valve the water supply forms.

In particular, the guide with the plunger in the gun between an on and an off Position can be moved. If the Plunger is in the transfer position, he can transmit a pushing motion to the closing valve, if, on the other hand, he moves out of this transfer position is the power transmission between the actuator and shut-off valve of the water supply interrupted, so that even when the actuating element moves no opening of the closing valve Water is supplied.

It is advantageous if the actuating element for Opening the closing valve of the water supply with a Driver on a stop of the closing valve to the system comes and when at the beginning of the opening movement of the Actuator a distance between the driver and Stop exists, which is in the opening movement of the Actuator reduced to the system. Thereby ensures that the shut-off valve of the water supply at the start of the opening movement of the actuating element is not yet opened, but that this Opening only begins when the actuator is already part of its opening motion behind it brought.

In particular, the initial distance of the driver be adjustable from the stop, so that too is selectable when along the opening movement of the actuating element the opening of the closing valve Water is supplied.

In a preferred embodiment it is provided that the driver is mounted in a pistol-fixed guide Ram is, if necessary, with the interposition of a removable plunger a thrust on a valve body of the closing valve of the water supply transfers.

It is advantageous if there is a metering valve in the water supply is arranged so that the user can choose how much the compressed air stream is humidified.

In a further preferred embodiment, that the maximum opening cross section of the Closing valve of the compressed air supply is adjustable. The This gives the user the opportunity to change the strength of the Adjust compressed air flow.

In particular, it can be provided that the opening device the closing valve of the compressed air supply a movable Includes actuator, which at his Opening movement of the closing valve of the compressed air supply opens so that its opening cross-section to the end the opening movement of the actuating element continuously increases, and that the beginning of the opening of the Closing valve along the opening movement of the actuating element is adjustable so that until the end of Opening movement of the actuator a different Opening cross section of the closing valve can be reached is.

This can be achieved in particular in that the Actuating element has a driver on one adjustable stop of the closing valve is present. In a preferred embodiment, this stop be screwed onto a tension rod, which with a valve body of the closing valve of the compressed air supply connected is.

It is advantageous if the stop between two end positions are adjustable, in particular they can End positions in turn can be adjustable.

The provision of these end positions ensures that that the opening of the closing valve of the compressed air supply is not delayed so far that this opening only at the same time or even later than the opening of the Closing valve of the water supply takes place.

For example, an end position can be changed to a Tension rod screwed nut are determined which the Screwing movement of the stop screwed onto the tension rod limited.

Furthermore, it can be provided that a different end position through a threaded plug screwed into the stop is determined to which the tension rod at the Screwing movement of the stop strikes the face.

Basically, the actuator on the gun be of any design, but is advantageous training as a pivot lever.

In this case it is convenient if the swivel lever slidable between two in the gun parallel to each other mounted thrust elements rotatably mounted is and the thrust elements in its pivoting movement in opposite direction shifts and if the Swivel elements the closing elements of the compressed air supply or open the water supply. It then turns out a very space-saving arrangement for the separate feeders provided with closing valves.

In a preferred embodiment, further be provided that metered in the blasting agent supply closable false air opening is arranged, so that the amount of a certain compressed air / water flow dosed blasting media is.

Figur 1:

eine Längsschnittansicht durch eine Injektorpistole;

Figur 2:

eine Teillängsschnittansicht der Pistole der Figur 1 mit verschlossenen Schließventilen für Druckluftzufuhr und Wasserzufuhr;

Figur 3:

eine Ansicht ähnlich Figur 2 mit geöffneten Schließventilen für Druckluftzufuhr und Wasserzufuhr;

Figur 4:

eine Schnittansicht längs Linie 4-4 in Figur 2 und

Figur 5:

eine Schnittansicht längs Linie 5-5 in Figur 2.

The following description of a preferred embodiment of the invention serves in conjunction with the drawing for a more detailed explanation. Show it:

Figure 1:

a longitudinal sectional view through an injector gun;

Figure 2:

a partial longitudinal sectional view of the gun of Figure 1 with closed closing valves for compressed air supply and water supply;

Figure 3:

a view similar to Figure 2 with open closing valves for compressed air supply and water supply;

Figure 4:

a sectional view taken along line 4-4 in Figure 2 and

Figure 5:

a sectional view taken along line 5-5 in Figure 2.

The injector gun 1 shown in the drawing includes a two-shell housing 2 with two down protruding handles 3, 4 at their free ends are connected to one another via a web 5.

A valve block 6 is arranged in the interior of the housing 2, which is a step-widening blind hole 7 has. In this blind hole is on one A ring-shaped valve seat 8 is inserted, the one with a longitudinally displaceable in the blind hole 7 guided valve body 9 cooperates. This valve body 9 is with an operating rod 10 connected by a longitudinal bore 11 at the end the blind hole 7 emerges from the valve block 6 and the inside of the blind hole 7 by one Coil spring 12 is surrounded, which is on the ground the blind bore 7 supporting the valve body 9 seals against the valve seat 8.

The valve body 9 and the valve seat 8 together form a closing valve 13 for a compressed air flow, the via a leading through the front handle 3 Compressed air line 14 in the rear part of the blind hole 7 occurs. The through this compressed air line 14th from a compressed air source, not shown in the drawing Compressed air supplied can be opened Closing valve 13 through the front part of the blind hole 7 flow out.

In this front part of the blind hole 7 is a sleeve-shaped insert 15 inserted from the housing 2 protrudes and there is a tubular extension 16 carries, in which a nozzle body 17 with a narrowing through opening 18 is inserted.

The tubular extension 16 surrounds between the Insert 15 and the nozzle body arranged at a distance from it 17 a cylindrical mixing chamber 19 into which substantially radially a supply line 20 for a Blasting material flows in, for example for sand. On this feed line 20, a sleeve 21 is longitudinally displaceable stored in one position False air opening 22 in the wall of the supply line 20 closes, but releases it in the other position and thus a connection of the interior of the supply line 20 to the environment.

The insert also opens into the mixing chamber 19 15 penetrating and over the end into the mixing chamber 19 protruding pipe section 23, which the Mixing chamber 19 in the longitudinal direction over a large part their length. This pipe section 23 forms one Injector. With the closing valve 13 open compressed air flows through the compressed air line 14 and that Pipe piece 23 and finally passes through the Through opening 18 from the gun. The result trained compressed air flow breaks in the as an injector trained mixing chamber 19 abrasive particles the supply line 20, which deals with the compressed air mix evenly and finally together with this as a homogeneous mixture through the nozzle body 17 escape.

In the blind hole 7 is between the annular Valve seat 8 on the one hand and the end at a distance from it Insert 15, on the other hand, a second mixing chamber 24 trained, in the side of a supply line 25 for Water flows out. Immediately next to the ring-shaped Valve seat 8 is annular in the mixing chamber 24 Insert 26 used, the central opening in Flow direction of the compressed air flow is narrowed, so that thereby also an injector in the area of the mixing chamber 24 is formed, the flow of compressed air sucked water conveyed through the supply line 25 and homogeneous in the area of the following pipe section 23 mixed with the compressed air flow. The water is there nebulized and torn into tiny droplets, so that A blowing agent flow occurs in the area of the mixing chamber 19, which consists of humidified compressed air in which smallest droplets distributed homogeneously in a compressed air stream are.

In the supply line 25 for the water is just before Junction into the mixing chamber 24 in a transverse to the feed line 25 extending conical bore 27 a also conical closing body 28 used, the when fully immersed in the conical hole 27 closes the feed line 25 and pulls it out the supply line from the conical bore 27 25 releases with increasing cross section, the Closing body 28 thus forms a metering valve in the Supply line 25 out. For moving the closing body 28 in the conical bore 27, this is with a Shaft 29 emerging laterally from the housing 2 connected, which in a side threaded bore 30 of Valve block 6 is screwed in and by means of a Twist grip 31 more or less deep in the threaded hole 30 can be screwed. The closing body 28 is opposite the threaded bore 30 through an annular seal 32 sealed in a circumferential groove 33 of the Shaft 29 is inserted (Figure 4).

Parallel to the blind hole 7 is in the valve block 6 another also stepped towards the front expanding blind hole 34 arranged from the in Area of the closed end of the supply line 25 for water leaks. In a higher one Area of the blind hole 34 opens into this in Valve block 6 arranged bore 35, which in turn with an angled bore 36 in the valve block is connected (Figure 4). This Hole 36 is with a water connection 37 on the bottom of the valve block 6 in connection (Figures 1 to 3).

The blind hole 34 is by means of a threaded plug 38 closed and takes a closing valve 39 an annular valve seat 40 and one in the blind hole longitudinally displaceable valve body 41 on. This is achieved by attaching itself to the threaded plug 38 supporting coil spring 42 against the valve seat 40 pressed and can by this by an operating rod 43 are lifted off, which with the valve body 41st is connected in one piece and by a longitudinal bore 44 in the bottom of the blind bore 34 from the valve block 6 protrudes sealed. As long as the valve body 41 sealingly rests on the valve seat 40 Water supply to the mixing chamber 24 is interrupted However, valve body 41 against the action of the coil spring 42 lifted from this valve seat 40, water can from the water connection 37 through the holes 36 and 35 and the blind hole 34 reach the feed line 25 and from there into the mixing chamber 24.

The two closing valves 13 and 39 are actuated via a pivot lever 45, which is inside the housing 2 is pivotally mounted and between the handles 3 and 4 down from the housing 2 protrudes. The pivot bearing 46 is between the longitudinal axes of the blind hole 7 on the one hand and the blind hole 34 on the other hand, the The pivot axis runs perpendicular to these longitudinal axes.

The actuating rod 10 of the valve body 9 passes through the pivot lever 45 with play and protrudes at the rear end the housing 2 out of this. On an external thread 47 this actuating rod 10, a sleeve 48 is screwed on, in the housing 2 in the direction of the actuating rod 10 is slidably mounted and inside of the housing 2 surrounded by a coil spring 49 is, which is on the one hand support discs 50, 51 supported on the housing 2 and on the other hand on the pivot lever 45. This coil spring 49 holds the pivot lever 45 in a front rest position, he can go against the Effect of this coil spring 49 in an open position be pivoted by the stop of the Swivel lever 45 on the housing 2 is limited. At rest can the pivot lever 45 by a define pivotable latch 52, which on the web 5th is mounted between the two handles 3 and 4.

The sleeve 48 surrounds the operating rod 10 also emerges from the housing 2 and expands bowl-like in this area. In this bowl-like extension 53, a threaded plug 54 is screwed in, the Screw-in depth by one on the threaded plug 54 screwed lock nut 55 can be fixed. The cup-shaped extension 53 and the threaded plug 54 surround an interior space 56 into which the end of the operating rod 10 protrudes. Are on this end two nuts 57, 58 screwed on for fixing their position on the operating rod 10 as lock nuts are rotated against each other.

The sleeve 48 forms with its facing the pivot lever 45 Face 59 a stop on which the Swing lever 45 abuts when it is in the open position is pivoted. He takes the sleeve 48 with and moves this out of the housing 2, this at the same time the actuating rod screwed into it 10 takes along and thus the valve body 9 from the valve seat 8 takes off. The sleeve 48 can on the external thread 47 of the operating rod 10 are rotated so that the Position of the sleeve 48 relative to the operating rod 10 is changeable. This has an impact on how strong the valve body 9 at a certain position the pivot lever 45 is lifted off the valve seat 8, by screwing the sleeve 48 and the axial displacement the sleeve 48 on the operating rod 10th the opening cross section of the closing valve 13 varies at a certain position of the pivot lever 45 become. Around the sleeve 48 on the external thread 47 to be able to screw, the outer circumference 60 of the extension 43 preferably knurled or corrugated.

The displacement of the sleeve 48 relative to the operating rod 10 is limited in both directions, however in one direction by hitting the End face 61 of the actuating rod 10 on the threaded plug 54 and in the other direction by striking the nut 58 on the bottom of the cup-shaped extension 53. These stops can be done by screwing the nut 58 and screwing the threaded plug 54 in their Position are changed, but they remain after one Initial setting usually unchanged.

Parallel to the operating rod 10 is in the extension the blind bore 34 is a rod-shaped plunger 62 slidably mounted in the housing 2, with the Swivel lever 45 through a lateral driver 63 is connected and when pivoting the pivot lever 45 is moved in the longitudinal direction, in opposite directions for the direction of displacement of the actuating rod 10.

The plunger 62 has a hat-shaped at its front end Mother 64 who is not on one in the drawing shown external thread of the plunger 62 screwed and is fixed there by means of a lock nut 65 becomes. The mother 64 can have different depths be screwed onto the plunger 62 so that a front driving surface 66 of the mother 64 in her Position along the plunger 62 set differently can be.

A further tappet 68 is located in a guide block 67 mounted longitudinally displaceable, one end 69 of the Driving surface 66 and the other end 70 of the end the actuating rod 43 of the closing valve 39 is opposite. This plunger 68 serves the movement of the plunger 62 to be transmitted to the actuating rod 43. When the plunger 62 is moved by the pivot lever 45 the driver surface 66 lies against the Tappet 68 and also moves this, so that this moves the operating rod 43 and the valve body 41 lifts off the valve seat 40.

The driver surface 66 is positioned so that between a space remains between her and the plunger 68, when the pivot lever 45 is in the rest position (FIG 2).

This leads to the fact that when pivoting the pivot lever 45 from the rest position to the open position initially only the closing valve 13 for the compressed air is opened while the closing valve 39 for the water remains closed. Only after opening the The driving surface reaches the closing valve for the compressed air 66 on the plunger 68 and can now do that Open shut-off valve 39 for the water. It is because of it ensures that the closing valve in every opening 13 for the compressed air before the closing valve 39 is opened for the water, and also when closing the closing valve 39 for the water is first closed and only then the closing valve 13 for the Compressed air. It is therefore excluded that water in liquid form reaches the mixing chamber 19, in the Mixing chamber 19 can only be dry or moistened Intake compressed air.

The content of the inflowing water can be determined using the Rotary handle 31 can be set by the Closing body 28 more or less deep in the conical Hole 27 is inserted, the amount of inflowing Compressed air can be turned by rotating the sleeve 48 on the Male thread 47 can be adjusted, and the amount of Blasted particles can be sucked in through the sleeve 21 are adjusted, the false air openings 22nd closes or opens more or less wide.

Each time the pivot lever 45 is pivoted into the open position is thus moistened in this way Compressed air provided as a blowing agent.

In addition, it is also possible to use the injector gun 1 to operate with dry compressed air, i.e. without supply of water.

This would basically be achievable through complete Screwing the closing body 28 into the conical bore 27, however, is in the described embodiment a special device is provided to the water supply to prevent.

The guide block 67 with the plunger 68 is namely transverse slidable to the longitudinal direction of the plunger 68 on the housing 2 stored and can in the respective end positions of the shift. The postponement takes place through lateral pins 71 opposite end faces of the guide block 67, which protrude laterally from the housing 2 (Figure 5). To determine the guide block 67 in the respective End positions in the guide block 67 is one by one Coil spring 72 loaded ball 73 in a blind hole 74 stored by the coil spring 72 against a transverse wall 75 of the housing 2 on the underside of the guide block 67 is pressed. In this cross wall 75 there are two troughs 76, 77, in which the ball 73 when reaching the respective end positions is inserted so that in the two end positions of the guide block 67 elastic locking fixtures enter. This fixation is by a vigorous Pressure on the side pin 71 can be canceled.

In one end position of the guide block 67 is the Tappet 68 in the manner described with the tappet 62 on the one hand and the operating rod 43 on the other aligned, so can in the manner described Movement of the plunger 62 onto the actuating rod 43 transfer.

In the other end position, however, the plunger is 68 shifted laterally so that the driving surface 66 at Displacement of the plunger 62 this displacement movement can not be transferred to the operating rod 43, the The closing valve 39 therefore remains below the Effect of the coil spring 42 closed. In this Position of the guide block 67 is so when actuated the swivel lever 45 only opens the compressed air supply, no water is added to the blowing agent.

Claims (24)

1. An abrasive-medium injector gun having separate feeds for compressed air (14), water (37) and abrasive medium (20) and an outlet (17) for the abrasive medium mixed with compressed air and water, having a first mixing-device (24) in which water is added to the compressed air, and having a second mixing-device (19) in which the abrasive medium is added to the compressed air and water mixture, characterised in that the compressed-air feed (14) and the water feed (37) are closed by closing valves (13; 39), and in that an opening device (45) for these closing valves is provided, this opening device only opening the closing valve (39) of the water feed (37) when the closing valve (13) of the compressed-air feed (14) is open.
2. A gun according to Claim 1, characterised in that the first mixing-device (24) is an injector with the compressed-air flow as the motive-agent flow.
3. A gun according to Claim 1 or 2, characterised in that the second mixing-device (19) is an injector with the flow of compressed air and water as the motive-agent flow.
4. A gun according to any one of the preceding Claims, characterised in that the opening device comprises a movable actuating element (45) which during an opening motion opens first the closing valve (13) of the compressed-air feed (14) and then the closing valve (39) of the water feed (37).
5. A gun according to Claim 4, characterised in that the opening points of the two closing valves (13, 39) are adjustable along the opening motion of the actuating element (45).
6. A gun according to one of Claims 4 and 5, characterised in that the operative connection (66, 68, 44) between the actuating element (45) and the closing valve (39) of the water feed (37) can be connected and disconnected as desired, so that during its opening motion, the actuating element (45) either opens the closing valve (39) of the water feed (37) after the closing valve (13) of the compressed-air feed (14) or else keeps it permanently closed.
7. A gun according to Claim 6, characterised in that a motion-transmitting member (68) is provided to connect or disconnect the operative connection, which member transmits the motion of the actuating element (45) to the closing valve (39) of the water feed (37) in the connected state, however in the disconnected state is positioned such that motion transmission of this type is not possible.
8. A gun according to Claim 7, characterised in that the motion-transmitting member is a ram (68), displaceably mounted in a guide (67), which in the connected state forms a thrust-transmitting member between the actuating element (45) and the closing valve (39) of the water feed (37).
9. A gun according to Claim 8, characterised in that the guide (67) with the ram (68) is displaceable in the gun (18) between a connected and a disconnected position.
10. A gun according to any one of Claims 4 to 9, characterised in that to open the closing valve (39) of the water feed (37), the actuating element (45) comes to rest against a stop (69) of the closing valve (39) by means of an entrainment means (66), and in that at the start of the opening motion of the actuating element (45) there is a gap between the entrainment means (66) and the stop (69) and this gap decreases during the opening motion of the actuating element (45) until there is contact.
11. A gun according to Claim 10, characterised in that the initial gap between the entrainment means (66) and the stop (69) is adjustable.
12. A gun according to one of Claims 10 and 11, characterised in that the entrainment means is a ram (62, 66), mounted in a guide fast with the gun, which optionally with the interposing of a removable ram (68) transmits thrust to a valve body (41, 44) of the closing valve (39) of the water feed (37).
13. A gun according to any one of the preceding Claims, characterised in that a metering valve (27, 28) is arranged in the water feed (37).
14. A gun according to any one of the preceding Claims, characterised in that the maximum cross-section of opening of the closing valve (13) of the compressed-air feed (14) is adjustable.
15. A gun according to Claim 14, characterised in that the opening device of the closing valve (13) of the compressed-air feed (14) comprises a movable actuating element (45) which during its opening motion opens the closing valve (13) of the compressed-air feed (14) such that its cross-section of opening increases continuously until the end of the opening motion of the actuating element (45), and in that the start of opening of the closing valve (13) is adjustable along the opening motion of the actuating element (45), so that a different cross-section of opening of the closing valve (13) can be achieved by the end of the opening motion of the actuating element.
16. A gun according to Claim 15, characterised in that the actuating element (45) has an entrainment means contacting an adjustable stop (48, 59) of the closing valve (13).
17. A gun according to Claim 16, characterised in that the stop (48, 59) is screwed onto a tension bar (10) connected to a valve body (9) of the closing valve (13) of the compressed-air feed (14).
18. A gun according to one of Claims 16 and 17, characterised in that the stop (48, 59) is adjustable between two end positions.
19. A gun according to Claim 18, characterised in that the end positions are themselves adjustable.
20. A gun according to Claims 17, 18 and 19, characterised in that one end position is determined by a nut (58), screwed onto the tension bar (10), which limits the screwing motion of the stop (48, 59) screwed onto the tension bar (10).
21. A gun according to any one of Claims 17, 18 and 19 and optionally 20, characterised in that one end position is determined by a threaded stopper (54) screwed into the stop (48), the end face of the tension bar (10) striking this threaded stopper (54) during the screwing motion of the stop (48).
22. A gun according to any one of Claims 4 to 21, characterised in that the actuating element is a pivoted lever (45).
23. A gun according to Claim 22, characterised in that the pivoted lever (45) is pivotably mounted between two thrust elements (10, 62) mounted in the gun (1) so as to be displaceable parallel to one another and displaces the thrust elements (10, 62) in opposite directions during its pivot motion, and in that in the process the thrust elements (10, 62) open the closing valves (13 and 39 respectively) of the compressed-air feed and the water feed respectively.
24. A gun according to any one of the preceding Claims, characterised in that a secondary-air opening (22) closable in a metered manner is arranged in the abrasive-medium feed (20).

Images