US3858358A

US3858358A - High pressure liquid and abrasive cleaning apparatus

Info

Publication number: US3858358A
Application number: US320279A
Authority: US
Inventors: John E Stachowiak; John B Goss
Original assignee: AMERICAN AERO IND
Current assignee: AMERICAN AERO IND; AMERICAN AERO INDUSTRIES Inc; Butterworth Jetting Systems Inc
Priority date: 1973-01-02
Filing date: 1973-01-02
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07

Abstract

A high pressure cleaning apparatus including a blasting nozzle for separately directing a liquid and gas-abrasive mixture outwardly toward an object being cleaned; and, pumping apparatus for pumping liquid and a gas-abrasive mixture to the blasting nozzle, the blasting nozzle including mixing means for mixing the liquid with the gas-abrasive mixture outwardly of the nozzle for propelling the gas-abrasive mixture at high velocity and pressure. Control means operable at the nozzle are provided for controlling the flow of liquid and gas-abrasive mixture to the nozzle.

Description

States Patent 11 1 1111 3,858,358 Staehowiak et al. 1 Jan. 7, 1975 [54] HIGH PRESSURE LIQUID AND ABRASIVE 2,696,049 12/1954 Black 1. 5l/8 X CLEANING APPARATUS 3,201,901 8/1965 Pauli 51/12 [75] Inventors: John E. Stachowiak; John B. Goss, FOREIGN PATENTS OR APPLICATIONS both of Houston, Tex. 969,564 5/1950 France 51/11 [73] Assrgnee: 32555321111210 Industries, llnc., Primary Examiner Donald G. y

Assistant ExaminerMarc R. Davidson [22] Filed: Jan. 2, 1973 [21] Appl. No.: 320,279 ABSTRACT A high pressure cleaning apparatus including a blasting nozzle for separately directing a liquid and gas- [52] [1.3. CI. 51/8, Sl/ll, 51/12 abrasive mixture outwardly toward an Object being 13/02 cleaned; and, p p g apparatus for p p g quid e 0 ea c and a gas-abrasive mixture to the blasting nozzle, the blasting nozzle including mixing means for mixing the [56] References cued liquid with the gas-abrasive mixture outwardly of the UNITED STATES PATENTS nozzle for propelling the gas-abrasive mixture at high 1,814,616 7/1931 Boesger 51/12 velocity and pressure. Control means operable at the LUCC nozzle are provided for controlling {he flow of 2,325,517 7/1943 Howard 5l/l1 and gas abrasive mixture to the nozzle. 2,387,193 10/1945 Swenarton 5l/l1 X 2,641,087 6/1953 Greiser 51/12 4 Claims, 4 Drawing Figures Patnted Jan. 7, 1975 2 Sheets-Sheet l Patented Jan. 7, 1975 3,858,358

2 Sheets-Sheet 2 HIGH PRESSURE LIQUID AND ABRASIVE CLEANING APPARATUS BACKGROUND OF THE INVENTION The field of this invention is high pressure cleaning apparatus.

A disadvantage of sand-blasting equipment that provides a blasting stream of air and sand is the undesirable dispersion of sand and dust from the object being cleaned into the atmosphere in the vicinity of the equipment. Some nozzles for blasting equipment mix water and sand inside the nozzle to provide a blasting stream containing water for at least partly preventing dispersion of the sand and abrasive dust. For example, see US. Pat. Nos. 2,290,979 and 2,325,517. One of the disadvantages of such nozzles is the tendency of the nozzles to wear excessively due to the passage through the nozzle of the sand and water mixture.

SUMMARY OF THE INVENTION It is an object of this invention to provide a new and improved high pressure, water-abrasive cleaning apparatus which provides a high velocity, high pressure blasting stream that cleans an object faster and more efficiently without polluting the atmosphere with abrasive dust. The high pressure cleaning apparatus of the preferred embodiment of this invention includes a blasting gun having a blasting nozzle mounted thereon for separately directing outwardly therefrom a low velocity stream of an air-abrasive mixture and a high velocity stream of water. Peripheral water nozzles are mounted in the blasting nozzle in position to converge streams of water into a central stream of air-abrasive mixture so that the high velocity, high pressure water stream propels the air-abrasive mixture to the object being cleaned. The high pressure cleaning apparatus includes pumping means for pumping water at a high pressure and an air-abrasive mixture at a low pressure.

The blasting gun is connected by hoses to the pumping apparatus such that the blasting gun may be freely moved about and electric control means are mounted with the blasting gun for remotely operating the pumping apparatus. The electric control means includes means for reducing the water supplied to the nozzle to a minimal flow and means for shutting off the flow of air-abrasive.

A corrosion-inhibitor fluid supply is connected with the pumping apparatus and is controlled by the electric control means such that corrosion-inhibitor can be injected into the high pressure water for coating the blasted object after such object has been cleaned.

The peripheral water nozzles include both long and short range sets of water nozzles that direct the water into convergence with the air-abrasive mixture. The long range peripheral water nozzles have axes which intersect the axis of the central nozzle at an angle which is less than the angle of intersection of the axes of the short range water nozzles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of the high pressure, water abrasive cleaning apparatus of the preferred embodiment of this invention;

FIG. 2 is a side view in section of the blasting nozzle of this invention illustrating the angular disposition of the short range peripheral water nozzles;

FIG. 3 is a front view of the blasting nozzle; and

FIG. 4 is a side view of the blasting nozzle illustrating schematically the angular disposition of the long range set of peripheral water nozzles.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the letter H generally designates a high pressure, water-abrasive cleaning apparatus for providing a high velocity blasting stream 10 for the impact cleaning of an object. The high pressure cleaning apparatus includes a blasting gun 11 having blasting nozzle 12 mounted thereon for directing separate streams of an air-abrasive mixture and water outwardly of the nozzle. The blasting gun 11 includes a handle 11a and a shoulder brace 11b which allows the operator to firmly grip and control the blasting gun during use. Electrical control means 14 including trigger switches 14a and 14b are mounted onto the blasting gun at the handle 11a.

The blasting gun 11 includes a water conduit He that is attached to the nozzle 12 and an air-abrasive conduit 11d also attached to the nozzle 12. The conduits are supported by bracket portion lie so that the entire blasting gun can be moved as a unit. The handle 11a is actually mounted onto the water conduit 110.

The blasting gun 11 is connected by

flexible hoses

15 and 16 to a pumping station generally designated by the number 20. The pumping station includes a water pump 21 which is driven by engine 22 as illustrated schematically in FIG. 1. A water supply tank 23 is connected through pipe 24 to the intake of the water pump 21; and, pipeline 25 is attached to the exhaust of the water pump 21 and is connected to flexible hose 16 by coupling 2511. An air compressor 26 is connected by pipeline 27 to an air receiver 28. The air receiver 28 is connected by a pipe 29 to an abrasive hopper 30 containing the abrasive to be utilized herein. A pipe 31 is connected to the pipe 29 and also to outlet 30a of the abrasive hopper 30 through outlet pipe 31a. The pipe 31 is attached to flexible hose 15 by coupling 31b. An instrument air line 32 is attached to the air receiver 28 and extends toa pressure responsive valve 33 mounted in the pipe 31. The instrument air line 32 is also connected to a pressure responsive valve 34 which is mounted in the outlet pipe 30a. As schematically represented in FIG. 1, both the air compressor 26 and the water pump 21 are driven by engine 22. The term pipe as used herein includes any tube or line capable of carrying air-abrasive or water.

A pipe 35 is attached to the air compressor output pipe 27 and extends to and is connected with a corrosion inhibitor tank 36. An outlet pipe 24a is attached to the corrosion-inhibitor tank and extends into connection with the inlet of the water pump intake 21. In the embodiment of the invention shown, the corrosioninhibitor line 24a is attached to the water supply line 24 by any suitable coupling at 24b. An air pressure regulator valve 37 is mounted in pipe 35 and cooperates with an air pressure cap 37a attached to the corrosioninhibitor tank 36 to control the pressure in the corrosion-inhibitor tank 36. A metering valve 38 is mounted in the corrosion-inhibitor outlet pipe 24a in order to provide an adjustment for the amount of corrosioninhibitor that is metered or injected into the intake of the water pump 21.

The electric control means 14 is mounted onto the blasting gun 11 and extends into electrical connection with various elements in the power station through supply line 40. Referring to the electrical schematic portion of FIG. 1 for the electric control circuit 14, a battery 41 is connected by conductor line 41a to both the trigger-mounted switches 14a and 14b. The switch 14a is mounted in conductor line 42 which extends into connection with a solenoid-operated inhibitor valve 43 mounted in pipe 24a. The solenoid-operated valve 43 is movable between an open position designated as 43a and a closed position designated as 43b. The switch 14b is mounted in conductor line 44 which terminates in electrical connection with conductor line 45. The conductor line 45 is electrically connected to a solenoidoperated valve 45 that is movable between an open position designated as 46a and a closed position designated as 46b. The conductor line 45 is electrically connected to a throttle solenoid 47, which through throttle linkage 22a controls the speed of the engine 22. The solenoid 47 is of conventional construction and includes stem 47a that is pivotally connected to throttle linkage 22a. The closing of switch 14b causes actuator solenoid 47 to move stem 47a and linkage 22a to the position illustrated in FIG. 1, which is a high speed operation position. The opening of switch 14b causes the solenoid 47 to move the throttle linkage 22a to an open or idle position.

The water pump 21 is a high pressure water pump that pumps water through pipe and flexible hose 16 to the water conduit 11c and outwardly through the nozzle 12 at a high pressure and a high velocity as measured outside of the nozzle. The air compressor 26, however, provides a relatively low pressure to the air receiver 28, abrasive hopper and pipe 31 for the purpose of delivering an air-abrasive mixture to the blasting gun conduit 11d and nozzle 12. With the

valves

33 and 34 opened by air pressure through instrument air line 32, air pressure is delivered into the top 30b of the abrasive tank 30 and also into the pipe 31 past outlet line 31a of the abrasive tank. The providing of a feed pressure at the top 30b of the abrasive tank and the providing of air flow through line 31 causes the air in line 31 to mix with abrasive from out of line 31a to provide an air-abrasive mixture which is pumped by the -20 to 100 p.s.i.

The nozzle 12 for the blasting gun 11 is provided for directing the air-abrasive mixture separately from the high pressure water while providing a resultant blasting stream 10 of air-abrasive and water for impact cleaning without polluting the atmosphere. The nozzle 12 includes a body 12a having a central opening 12aa therein. The central opening l2aa includes a threaded portion 12b which is adapted to receive coupler 11f for the air-abrasive conduit 11d. A center nozzle 50 includes tungsten inserts 50a that are mounted in recesses 12c in the opening 12aa for projecting outwardly the air-abrasive mixture at a low pressure. The axis of the center nozzle 50 is illustrated by line 50b. A threaded hole 12d is machined in the nozzle body 12a below the center nozzle 50 and the water conduit 11c is threadly mounted therein. The nozzle body 12a includes a horizontal passage 12f which extends through the hole 12d and vertical passages 12g and 12h which extend upwardly to a top horizontal passage 121'. An intermediate horizontal passage 12j is positioned between the lower horizontal passage 12f and top hori-. zontal passage 121' in fluid communication with the vertical passages. The

horizontal passages

12f, 12j, and 121' are in fluid communication with the vertical passages 12g and 12h to provide a network of passages in fluid communication with hole 12d so that water may be distributed through the nozzle body 12a.

A set of short range water nozzles 52 are positioned at 90 intervals about the periphery of the center nozzle 50. Referring to FIG. 2, each of the short range water nozzles includes a threaded nozzle portion 52a which threadedly mounts the nozzle in a drilled opening 12k in the nozzle body 12. The drilled opening 12k and the water nozzle 52 have a common axis which is represented by line 53. The axes 53 of the short range water nozzles converge to intersect the axis 50b of the center nozzle 50 at a common point 10a. The angle of intersection designated as 54 between the axes 53 of the short range water nozzles 52 and the axis of the center nozzle 50 is preferably 2 /z. The included angle 55 formed by the intersection of the axes 53 of the short range water nozzles is preferably 5. Each of the drilled openings 12k are in fluid communication with the nozzle

body water passages

12f, 12g, 12h, 121', and 12] such that high pressure water can be directed through such passages and outwardly of the water nozzle body 12a.

The short range water nozzle 52 thus directs streams of water at high pressures outwardly along axes 53 in a conical pattern into convergence at 10a with the stream of air-abrasive directed outwardly of the center nozzle 50. The water streams from nozzles 52 converge with the air-abrasive stream a distance d from the nozzle 12. The pressure and velocity of the air-abrasive mixture directed outwardly of the center nozzle 50 is quite low as compared to the pressure and velocity of the water directed outwardly of the peripherally located water nozzles 52. The significantly higher pressure, velocity and momentum of water directed outwardly along the axis 53 mixes the air-abrasive mixture with the water and such that the air-abrasive mixture is propelled with the water at the substantially higher velocity and pressure of the water. In this manner, an airabrasive mixture and water are mixed to form a blasting stream 10 of high pressure and velocity for cleaning objects. One of the advantages of the nozzle 12 that directs an air-abrasive mixture outwardly separately from the water is that the center nozzle 50 is subjected to much less abrasive wear. At the same time, the resultant blasting stream 10 travels at a very high velocity and pressure in order to provide highly efficient impact cleaning while minimizing dissemination of the abrasive as a dust into the atmosphere.

Referring to FIGS. 3 and 4, a set of long-range nozzles 56 are mounted in drilled openings 12! in nozzle body 12a peripherally of the center nozzle 50. The long-range water nozzles 56 are positioned between the short-range water nozzles 52 such that the long-range water nozzles 56 are positioned at about the center nozzle 50. The drilled openings 12! extend into fluid communication with the nozzle body passages such as 12g and 12h in a manner similar to the drilled openings 12k for the short-range water nozzles 52. The axis 56a of each of long-range water nozzles 56 converges into intersection with the axis 50b of the center nozzle 50 at a distance dd from the nozzle body 12a. The angle 57 between the axis 56a of the water nozzle 56 and the axis 50b of the center nozzle 50 is preferably 1. Thus the angle 58 between axes of the water nozzles 56 is preferably 2. The point of convergence b of the axes 56a of the long-range water nozzles 56 is at a distance dd, which is greater than the distance d for the shortrange water nozzles 52. In utilizing the blasting nozzle 12, either the long-range water nozzles 56 or the shortrange water nozzles 52 are used while the other set is plugged off by any suitable means such as plugs which are the same as the nozzles except that they are solid and have no nozzle opening. Thus, the blasting nozzle 12 is capable of providing a short-range blasting stream that is effective to a minimal distance d or a long-range blasting stream effective to a minimal distance dd.

Various types of abrasives can be used in the highpressure, water-abrasive cleaning apparatus H of the preferred embodiment of this invention. For example, sand, manufactured grit, slag, glass beads or shot can be utilized simply by loading any of these abrasives in the abrasive hopper 30. One of the advantages of this invention is that of a smaller supply of abrasive as compared to more conventional blasters for cleaning comparable objects. Thereafter, the nozzle 12 of the blasting gun 11 is adjusted for either short-range operation to a distance of at least d or long-range operation to a distance of dd. As previously described, the short-range water nozzles 52 are utilized alone simply by substituting plugs for the long-range nozzles 56. Conversely, the long-range nozzles 56 can be utilized alone simply by substituting plugs for the short-range nozzles 52. After the nozzle range has been chosen and the nozzle adjustments have been made for the particular job, the apparatus H is ready to be used. Prior to use, the operator first moves the blasting gun 11 to the desired position. The blasting gun 11 is easily moved due to the

flexible hoses

15 and 16 which are used to connect the blasting gun 11 with the pumping station 20, which can be located at a point remote from the blasting gun 11.

After the operator is properly positioned with the blasting gun 11, the blasting gun is placed against the body so that the shoulder brace 11b is placed against the operator's shoulder and the operator has one hand on the handle 11a. The operator then closes the switch 14b. The closing of the switch 14b provides electrical power from the battery 41 to the throttle solenoid 47, the solenoid stem moving the linkage 22a to the operating position shown thereby increasing power to both the water pump 21 and the air compressor 26. The air valve solenoid 46 is moved to the open position 46a at the same time that the throttle solenoid 47 is activated. After the compressor 26 and pump 21 are driven to operating pressures by engine 22, air passes through line 32 to open the pressure-

responsive valves

33 and 34.

After the high pressure water pump 21 has attained operating pressure, water is pumped under high pressure from the water supply line 24, through line 25, flexible hose 16, water conduit 11c and through the nozzle 12. The water is pumped through the nozzle valve passages such as 123 and 12h and outwardly through either the long-range water nozzles 56 or the short-range water nozzles 52. In either event, the water is pumped outwardly in a generally conical pattern at a very high pressure and converges into the stream of air-abrasive. After the air compressor 26 has arrived at operating pressure, air is provided under pressure through the air receiver 28 to

lines

29 and 31. Air is provided through line 29 into the top 30b of the abrasive hopper 30 in order to provide a feed pressure onto the abrasive within the hopper 30.. Since the

valves

33 and 34 are open, air pressure is provided through the line 31 past the outlet line 31a of the hopper such that abrasive is carried with the air through the flexible hose 15, air-abrasive conduit 11d and into the nozzle 12. The air-abrasive mixture passes through the abrasive conduit 11d and outwardly through the center nozzle 50 along the axis 50b into intersection with the water directed outwardly from the water nozzles such as 52. The pressure of the air-abrasive mixture is quite low, it need only be sufficient to move the abrasive at a constant pressure and flow rate and direct the air-abrasive mixture outwardly through the nozzle 50. However, as previously mentioned, the pressure of the water being directed outwardly through the water nozzles such as 52 is extremely high, such as between about 3,000 psi. to about 10,000 psi. The intersecting of the streams of water from the peripherally located water nozzles such as 52 with the air-abrasive mixture directed outwardly of the center nozzle 50 causes a mixing of the water with the air-abrasive mixture and the propelling of the air-abrasive mixture with the water towards the object being cleaned at very high pressure and velocity. By utilizing the nozzle 12 of this invention, the air-abrasive mixture is passed outwardly of the nozzle prior to it being mixed with the water from the high pressure nozzles such as 52. Thus, the internal components such as the center nozzle 50 of the blasting nozzle 12 are not subjected to the abrasive at a high pressure. This causes the center nozzle portions to last for a substantially longer time than if the abrasive were pumped outwardly of the nozzle at a higher pressure. Further, the resultant stream 10 is a mixture of air-abrasive and water such that the abrasive is not disseminated into the atmosphere after impact with the object being cleaned. Further, the propelling of the air-abrasive mixture by the water from the peripherally located nozzles such as 52 provides a resultant blasting stream 10 having a very high velocity and pressure for very effective cleaning. For example, the velocity of the air-abrasive mixture and the water in the resultant stream may be approximately 800 feet per second to 1,250 feet per second or more, which is an extremely effective velocity for such impact cleaning.

When the operator desires to stop blasting, the operator opens the switch 14b (which may be a spring loaded switch which automatically moves to the open position upon release) thereby causing throttle solenoid stem 47a to move linkage 22a to the idling position shown in broken lines. Reduction of the engine speed to an idle reduces the water flow from water pump 21 to the nozzle 12 to a minimum which is usually a trickle. Simultaneously, with the reducing of water flow to a minimum, solenoid operated valve 46 is moved to the closed position 46b by the opening of switch 14b. The closing of solenoid operated valve 46 shuts off air pressure to

valves

33 and 34 thereby closing the valves and shutting off the flow of air in line 29 and abrasive in line 31a, which shuts off the flow of airabrasive mixture to the nozzle 12. In this manner, the electric control means 14 operates simultaneously to shut off all flow of gas-abrasive mixture to the nozzle 12 and to reduce water flow to a minimum.

It is occasionally desirable to provide a coating of corrosion-inhibitor to the object which has been blasted clean. The apparatus H of this invention can provide such corrosioninhibitor in the following manner. After the engine 22 has been returned to idling speed, the switch 14a is opened by the operator thereby opening solenoid valve 43 and moving such valve to the open position. With the valve 43 in the open position designated at 430, corrosion-inhibitor is forced outwardly through the line 24a due to the constant, residual pressure in the inhibitor tank 36, which is maintained by pressure cap 37a and the pressure regulator 37. The corrosion-inhibitor passes through the metering valve 38 and into the intake for the pump 21 and thus is pumped outwardly with water through the peripherally located water nozzles such as 52 in the blasting nozzle 12. The metering valve 38 may be utilized to adjust the amount of corrosion-inhibitor which is injected into the pump 21. Generally, the corrosioninhibitor is used only with the engine 22 at an idling speed and water flow through pump 21 is minimal in order to conserve volume. However, it is noted that the corrosion-inhibitor can also be used with the switch 14b open and the engine 22, the pump 21 and the air compressor 26 at full operating pressure.

The apparatus H of this invention has been disclosed in the preferred embodiment as including a particular air compressor 26, air receiver 28 and hopper 30, with the associated controls for operation at the gun 11; it is also within the scope of this invention to use a conventional abrasive supply with the remainder of the apparatus H.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

For example, the apparatus H of this invention has been described as being utilized with water and air. It should be understood that other liquid besides water can be used, and further, that a gas other than air can be utilized, if suitable for such service. Further, the nozzle sets 52 and 56 have been described very precisely in terms of their angular relationship with respect to the nozzle 50. Notwithstanding, it is within the scope of this invention to provide nozzle sets at various angular positions such that the distance of effectiveness of the nozzle is adjustable over a wide range.

We claim:

1. A liquid-abrasive cleaning apparatus, comprising:

a blasting nozzle for separately directing liquid and a gas-abrasive mixture exclusive of any liquid outwardly toward an object for cleaning same;

a liquid supply connected with said nozzle and liquid pump means for pumping said liquid outwardly of said blasting nozzle at a high blast pressure;

a gas supply and an abrasive supply connected with said nozzle, and compressor means for mixing abrasive with gas and for pumping a gas-abrasive mixture outwardly of said blasting nozzle at a lower pressure than said high blast pressure; and

said blasting nozzle including a central, low pressure, nozzle portion in fluid communication with said gas-abrasive mixture, said gas-abrasive mixture being directed outwardly of said central nozzle portion in a low-velocity stream; and

said blasting nozzle further including a plurality of circumferentially spaced, high pressure nozzle portions positioned about said central nozzle portion, each of said circumferentially spaced nozzle being in fluid communication with said high pressure liquid and directing outwardly, separately from said gas-abrasive mixture, high velocity liquid toward said low-velocity, gas-abrasive stream whereby said gas-abrasive mixture is propelled to said object with said high-velocity blasting water.

2. The structure set forth in claim 1, wherein:

each of said circumferentially spaced nozzle portions has an axis which intersects the axis of said central nozzle portion at an acute angle.

3. The structure set forth in claim 1, wherein said circumferentially spaced nozzle portions include:

a first set of circumferentially spaced nozzles having axes which intersect the axis of said central nozzle at a first angle; and

a second set of circumferentially spaced nozzles having axes which intersect the axis of said central nozzle at a second angle.

4. A water-abrasive cleaning device, comprising:

a blasting nozzle for separately directing water and an air-abrasive mixture exclusive of any liquid outwardly toward an object for cleaning same, said blasting nozzle being adapted for connection to a supply of low pressure, air-abrasive mixture supply and to a high pressure water supply;

said blasting nozzle includes a central, low pressure, nozzle portion in communication with said low pressure air-abrasive mixture supply, said airabrasive mixture being directly outwardly of said nozzle in a low-velocity stream; and

said blasting nozzle further including a plurality of circumferentially spaced, high pressure nozzle portions positioned about said central nozzle portion, being in communication with said high pressure water supply and directing high velocity water toward said low-velocity, air-abrasive stream whereby said air-abrasive mixture is propelled to said object with said high-velocity blasting water.

Claims

1. A liquid-abrasive cleaning apparatus, comprising: a blasting nozzle for separately directing liquid and a gasabrasive mixture exclusive of any liquid outwardly toward an object for cleaning same; a liquid supply connected with said nozzle and liquid pump means for pumping said liquid outwardly of said blasting nozzle at a high blast pressure; a gas supply and an abrasive supply connected with said nozzle, and compressor means for mixing abrasive with gas and for pumping a gas-abrasive mixture outwardly of said blasting nozzle at a lower pressure than said high blast pressure; and said blasting nozzle including a central, low pressure, nozzle portion in fluid communication with said gas-abrasive mixture, said gas-abrasive mixture being directed outwardly of said central nozzle portion in a low-velocity stream; and said blasting nozzle further including a plurality of circumferentially spaced, high pressure nozzle portions positioned about said central nozzle portion, each of said circumferentially spaced nozzle being in fluid communication with said high pressure liquid and directing outwardly, separately from said gas-abrasive mixture, high velocity liquid toward said low-velocity, gas-abrasive stream whereby said gasabrasive mixture is propelled to said object with said highvelocity blasting water.

2. The structure set forth in claim 1, wherein: each of said circumferentially spaced nozzle portions has an axis which intersects the axis of said central nozzle portion at an acute angle.

3. The structure set forth in claim 1, wherein said circumferentially spaced nozzle portions include: a first set of circumferentially spaced nozzles having axes which intersect the axis of said central nozzle at a first angle; and a second set of circumferentially spaced nozzles having axes which intersect the axis of said central nozzle at a second angle.

4. A water-abrasive cleaning device, comprising: a blasting nozzle for separately directing water and an air-abrasive mixture exclusive of any liquid outwardly toward an object for cleaning same, said blasting nozzle being adapted for connection to a supply of low pressure, air-abrasive mixture supply and to a high pressure water supply; said blasting nozzle includes a central, low pressure, nozzle portion in communication with said low pressure air-abrasive mixture supply, said air-abrasive mixture being directly outwardly of said nozzle in a low-velocity stream; and said blasting nozzle further including a pluralIty of circumferentially spaced, high pressure nozzle portions positioned about said central nozzle portion, being in communication with said high pressure water supply and directing high velocity water toward said low-velocity, air-abrasive stream whereby said air-abrasive mixture is propelled to said object with said high-velocity blasting water.