WO2006013401A1

WO2006013401A1 - A hand-held slurry spraying device

Info

Publication number: WO2006013401A1
Application number: PCT/IB2004/002434
Authority: WO
Inventors: Johan Leonard Human
Original assignee: Dayton, Alan
Priority date: 2004-07-30
Filing date: 2004-07-30
Publication date: 2006-02-09

Abstract

A hand-held slurry spraying device 10 that is adapted for use in spraying cement slurry having a water/cement (WC) ratio of less than 0.45, comprises an open-topped hopper 12 and a discharge pipe 14. The pipe 14 includes an L-shaped pipe section 20 extending from the hopper 12 and has a reduction nozzle 22. The pipe section 20 defines a discharge nozzle 24 and includes a holding formation 26 that leads into the pipe section 20, for holding a gas pipe conveying a propellant gas. The holding formation 26 defines a gas inlet opening 28 in which the gas pipe is located and that is aligned with the discharge nozzle 24, thereby permitting the propellant to enter the discharge pipe directly behind and in alignment with the slurry as it is discharged through the nozzle 24.

Description

AHAND-HELDSLURRYSPRAYING DEVfCE

THIS INVENTION relates to a hand-held slurry spraying device.

FIELD OF INVENTION

It. relates particularly to a hand-held slurry spraying device for spraying cement slurry onto a wall surface.

SUMMARY OF INVENTION

According to the invention there is provided a hand-held slurry spraying device for spraying cement slurry onto a wall surface, the slurry spraying device comprising

an open-topped container for holding the cement slurry, the container defining an outlet opening near a lower end thereof through which cement slurry can be discharged from the container; and a discharge pipe having a substantially L-shaped pipe section that extends from the outlet opening of the container for discharging cement slurry from the container, the pipe section including a discharge nozzle which defines a discharge nozzle inlet opening through which cement slurry can enter the discharge nozzle and a discharge nozzle outlet opening through which cement slurry can be discharged from the discharge nozzle, the pipe section defining a gas inlet opening through which a propellant gas can be introduced into the discharge pipe for propelling cement slurry through the discharge nozzle, the gas inlet opening and the discharge nozzle outlet opening being aligned concentrically.

The container may be in the form of a funnel-shaped hopper for feeding cement slurry into the discharge pipe under the influence of gravity.

The discharge nozzle of the discharge pipe, may have a frusto-conical configuration, with the discharge nozzle outlet opening being eccentrically aligned with the discharge nozzle inlet opening in an arrangement wherein the discharge nozzle outlet opening is disposed operatively lower than the discharge nozzle inlet opening.

The discharge pipe may include a reduction nozzle that is disposed downstream of the discharge nozzle.

The reduction nozzle may have a frusto-conical configuration and may define a reduction nozzle inlet opening and a reduction nozzle outlet opening. The diameter of the reduction nozzle inlet opening may be equal to or less than the diameter of the discharge nozzle outlet opening of the discharge nozzle.

The reduction nozzle may be removably connected to the pipe section of the discharge pipe.

The reduction nozzie outlet opening may be aligned concentrically with the reduction nozzle inlet opening.

In another embodiment of the invention, the reduction nozzle outlet opening may be eccentrically aligned with the reduction nozzle inlet opening in an arrangement wherein the reduction nozzle outlet opening is disposed operatively lower than the reduction nozzle inlet opening.

The gas inlet opening may be configured to receive a gas pipe having a discharge opening, for conveying a propellant gas.

The slurry spraying device may include adjustable holding means for holding the gas pipe in the gas inlet opening in an arrangement wherein the position of the gas pipe can be adjusted relative to the gas inlet opening thereby to adjust the distance of the discharge opening of the gas pipe from the discharge nozzle outlet opening. Further features of the invention are described hereinafter by way of a non-limiting example of the invention, with reference to and as illustrated in the accompanying diagrammatic drawings. In the drawings:

The spraying device may be adapted for use in spraying a cement slurry having a water/cement ("WVC") ratio of less than 0.45.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic side view of a hand-held slurry spraying device in accordance with the invention;

Figure 2 shows a sectional side view of the device of Figure 1 , showing an exploded view of the reduction nozzle;

Figure 3 shows a schematic front view of the device of Figure 1 ;

Figure 4 shows a schematic side view of the device of Figure 1, with the reduction nozzle removed;

Figure 5 shows a schematic front view of the device of Figure 4;

Figure 6 shows a schematic top plan view of the device of Figure 4;

Figure 7 shows a schematic exploded side view of the device of Figure 4;

Figure 8 shows an exploded schematic sectional side view of the end of the pipe section of the discharge pipe and the reduction nozzle of the device of Figure 1, showing in sequence, the manner in which the reduction nozzle is secured to the end of the discharge pipe; Figure 9 shows an exploded schematic sectional side view of the end of the pipe section of the discharge pipe of the spraying device of Figure 4, showing the manner in which another embodiment of a reduction nozzle, is secured to the pipe section of the discharge pipe; and

Figure 10 shows an exploded schematic sectional side view of the end of the pipe section of the discharge apparatus of Figure 4, showing the manner in which yet another embodiment of a reduction nozzle, is secured to the pipe section of the discharge pipe.

DESCRIPTION OF PREFERRED EMBODIMENT

With reference to the drawings, a hand-held slurry spraying device in accordance with the invention is designated generally by the reference numeral 10. The spraying device 10 is specifically adapted for spraying a cement slurry having a WC ratio of less than 0.45. A cement slurry having a WC ratio of less than 0.45 is desirable as drying and curing of the slurry when sprayed onto a wall surface, occurs only via a chemical reaction. Where the WC ratio is greater than 0.45, then in addition to a chemical reaction, evaporation is required for drying and curing plaster deposited on a wall surface. During evaporation, a certain amount of shrinkage takes place which leads to cracking and a reduction in strength. A cement slurry having a WC ratio lower than 0.45 will exhibit increased strength when applied to a wall surface and has a longer lifespan than a cement slurry having a WC ratio higher than 0.45. Further, due to the lower water content, use of a slurry having a WC ratio of less than 0.45 will result in less corrosion of embedded steel for reinforcing, etc. The plastering device 10 is thus dimensioned and configured to spray a cement slurry having a WC ratio of less than 0.45.

The spraying device 10 is of fabricated stainless steel and comprises, broadly, a container in the form of an open-topped hopper 12 and a discharge pipe designated generally by the reference numeral 14. The hopper 12 is funnel-shaped and defines an outlet opening 16 in a base region thereof, through which cement slurry can be discharged from the hopper into the discharge pipe 14. The hopper has a handle 18 by which it can be held, in use.

In use, cement slurry can be introduced by hand using, for example, a trowel, into the hopper, which can then be fed into the discharge pipe 14 under the influence of gravity via the outlet opening 16 in the base of the hopper.

The discharge pipe 14 includes an L-shaped pipe section 20 that extends from the outlet opening 16 of the hopper and a reduction nozzle 22. The pipe section 20 defines a discharge nozzle 24. The pipe section 20 includes adjustable holding means in the form of a holding formation 26 defining an internal passage 27 in which a gas pipe (not shown) for conveying a propellant gas such as air, can be received. The gas pipe is connectable to a supply of air. The holding formation 26 defines a gas inlet opening 28 at the end of the passage, that leads into the pipe section 20.

The holding formation 26 includes a screw 30 which can be releasably screwed onto an outer surface of the gas pipe, in use, for securing the gas pipe within the holding formation. The gas pipe is thus slidably displaceable within the internal passage of the holding formation in an arrangement wherein the position of the gas pipe within the holding formation can be adjusted. Once a desired position has been achieved, it can secured in place by means of the screw 30. Hence, the position of a discharge opening of the gas pipe can be adjusted relative to the reduction nozzle. The reason for this feature will be explained hereinafter.

The discharge nozzle 24 is formed integrally with the pipe section 20 and has a frusto-conical configuration. More particularly, the discharge nozzle has a nozzle inlet opening 32 and a nozzle outlet opening 34. The nozzle outlet opening 34 is eccentrically aligned with the nozzle inlet opening in an arrangement wherein the nozzle outlet opening is disposed operatively lower than the nozzle inlet opening. The nozzle outlet opening 34 of the discharge nozzle 24, is aligned concentrically with the gas inlet opening 28 thereby providing for the propellant to enter the discharge pipe directly behind the slurry and in alignment therewith. In the drawings, axis A passes through the concentrically aligned centres of the nozzle outlet opening 34 and the gas inlet opening 28. This configuration generates a "back" pressure in the discharge pipe, resulting in an increase in the pressure of the propellant gas upstream of the cement slurry for more effectively propelling the slurry from the slurry spraying device. The configuration has the advantage that the device 10 thus requires less air pressure for spraying the cement slurry and thus uses less air. More particularly, the upper wall portion of the discharge nozzle 24 has an angle of taper of 20 degrees when viewed in sectional side view,,

« whereas the lower wall portion thereof extends parallel to axis A.

The reduction nozzle 22 has a cylindrical configuration and is removably connected to the pipe section 20. The internal diameter of the reduction nozzle is less than the diameter of the nozzle outlet opening 34 of the discharge nozzle. The pipe section 20 includes a connector flange 36 defining an external screw- thread formation.. The discharge pipejncludes a sleeve 38 into .which a proximal end of the reduction nozzle 22 can be press-fitted and a collar 42 having an internal screw-thread that can be screwed onto the connector flange 36. As such, the sleeve 38 defines a flange 40 against which the collar 42 can be located for securing the sleeve to the discharge nozzle.

With reference to Figure 8 of the drawings, the manner in which the reduction nozzle 22 is secured to the pipe section 20, is illustrated.

In another embodiment of the invention, the reduction nozzle may be in the form of a convergent nozzle having a frusto-conical configuration. Such a reduction nozzle is shown in Figure 9 of the drawings and designated by the reference numeral 46. In Figure 9 of the drawings, the manner in which the reduction nozzle 46 is removably connected to the discharge pipe 20 is shown. By providing for the removable connection of the reduction nozzle to the discharge pipe, a number of interchangeable reduction nozzles having different dimensions and configurations can be used for cement slurry of differing properties. A generally tapered discharge nozzle is used for cement slurry wherein the sand particle sizes are not generally consistent throughout the cement slurry mixture.

In yet another embodiment of the invention, the reduction nozzle may be in the form of a convergent nozzle having a tapered frusto-conical configuration. Such a reduction nozzle is shown in Figure 10 of the drawings and designated by the reference numeral 52. The manner in which the reduction nozzle is removably connected to the discharge pipe 20, is shown in Figure 10. The reduction nozzle 52 has an inlet nozzle opening 54 and an outlet nozzle opening 56. More particularly, the inlet and outlet nozzle openings are eccentrically aligned with respect to one another, in an arrangement wherein the centre of the outlet nozzle opening 56 is disposed operatively lower than the centre of the inlet nozzle opening 54. As is explained for the discharge nozzle 24, this configuration generates a "back pressure" in the discharge pipe for more effectively propelling the cement slurry from the slurry spraying device. It will be appreciated that both the cylindrical reduction nozzle and the tapered reduction nozzle 46 provide a reduction in the effective diameter of the discharge pipe which results in an increase in the "back pressure" in the discharge pipe when spraying a cement slurry. However, the applicant has found that the best results are achieved using the reduction nozzle 52.

In the embodiment shown in Figure 10, the outlet nozzle opening 56 has a diameter of 24mm. In this example, the diameter of the gas inlet opening 28 is 6mm. As such, the ratio of the nozzle outlet opening 56 of the reduction nozzle 52 with respect to the diameter of the gas inlet opening 28 is 4. The angle of taper of the upper wall portion of the reduction nozzle 52 is 20 degrees when viewed in sectional side view. The angle of taper of the reduction nozzle 52 is thus equivalent to the angle of taper of the discharge nozzle 24. The applicant has found that the best results are achieved when the angles of taper of the discharge and reduction nozzles are the same. Further, the applicant has found that the abovementioned ratio of 4 in respect of the diameter of the nozzle outlet opening 56 relative to the diameter of the gas inlet opening 28 is an optimal ratio for the slurry spraying device 10 using a tapered frusto-conical reduction nozzle such as that shown in Figure 10 of the drawings, wherein the nozzle outlet opening is disposed operatively lower than the nozzle inlet opening.

In use, the position of the gas pipe can be adjusted so as to move the discharge opening thereof closer to or further from the reduction nozzle. The applicant envisages that with a relatively drier slurry (having a lower WC ratio), the discharge opening of the gas pipe will be positioned further away from the discharge nozzle, whereas with a relatively wetter slurry, the discharge opening of the gas pipe will be positioned relatively closer to the discharge nozzle. The slurry spraying device is adapted for use in spraying cement slurry onto a wall surface at a speed of approximately 120m/s. The high delivery speed is achievable due to the concentrically arranged gas inlet opening 28 and nozzle outlet opening 34 of the discharge nozzle, which permits the propellant to exert a direct "in-line" force on the slurry. As such, the gas pipe and the discharge pipe of the device, are configured to deliver 400-600 litres of air per minute at a pressure of 4-5 bar. The relatively high slurry delivery speed achieved by the slurry spraying device is particularly important when spraying the slurry onto porous wall surfaces such as expanded polystyrene (EPS). As the cement slurry hits the surface of the EPS, it penetrates the surface, thereby effectively bonding the cement slurry to the EPS without requiring the use of bonding agents.

Further, the applicant has found that the relatively high delivery speed achieved by the slurry spraying device combined with the fact that the slurry is applied in layers to a wall surface , allows the application of a high density slurry layer to a wall surface.

The slurry spraying device has been designed to apply a high density layer of cement slurry to a wall surface, having strength properties similar to that of concrete that has been vibrated prior to drying. In tests conducted with the slurry spraying device, the applicant has achieved densities in a range between

1900kg/m³ - 2100kg/m³. This is similar to results achieved with Grade 25 MPa concrete. It is well known that there is a direct relationship between the density of cement and its strength. The high density of the slurry when applied to a wall surface is possible because of the relatively low WC ratio of the cement slurry that can be sprayed by the slurry spraying device and because the cement slurry is applied to a wall surface in layers at a relatively high velocity. The configuration of the slurry spraying device causes a relatively large cloud of water vapour to form when spraying cement slurry onto a wall surface. This causes an approximately

10% reduction in the water content of the cement slurry that is applied to the wall surface. This lowering of the WC ratio of the applied cement slurry via evaporation, further enhances the strength and durability of the layer of plaster that is applied to a wall surface.

Claims

1. A hand-held slurry spraying device for spraying cement slurry onto a wall surface, the slurry spraying device comprising

an open-topped container for holding the cement slurry, the container defining an outlet opening near a lower end thereof through which cement slurry can be discharged from the container; and

a discharge pipe having a substantially L-shaped pipe section that extends from the outlet opening of the container for discharging cement slurry from the container, the pipe section including a discharge nozzle which defines a discharge nozzle inlet opening through which cement slurry can enter the discharge nozzle and a discharge nozzle outlet opening through which cement slurry can be discharged from the discharge nozzle, the pipe section defining a gas inlet opening through which a propellant gas can be introduced into the discharge pipe for propelling cement slurry through the discharge nozzle, the gas inlet opening and the discharge nozzle outlet opening being aligned concentrically.

2. A slurry spraying device as claimed in claim 1 , wherein the container is in the form of a funnel-shaped hopper for feeding cement slurry into the discharge pipe under the influence of gravity.

3. A slurry spraying device as claimed in claim 1 dr claim 2, wherein the discharge nozzle of the discharge pipe, has a frusto-conical configuration with the discharge nozzle outlet opening being eccentrically aligned with the discharge nozzle inlet opening in an arrangement wherein the discharge nozzle outlet opening is disposed operatively lower than the discharge nozzle inlet opening.

4. A slurry spraying device as claimed in any one of the preceding claims, wherein the discharge pipe includes a reduction nozzle that is disposed downstream of the discharge nozzle.

5. A slurry spraying device as claimed in claim 4, wherein the reduction nozzle has a frusto-conical configuration and defines a reduction nozzle inlet opening and a reduction nozzle outlet opening.

6. A slurry spraying device as claimed in claimed in claim 5, wherein the diameter of the reduction nozzle inlet opening is equal to or less than the diameter of the discharge nozzle outlet opening.

7. A slurry spraying device as claimed in claim 5 or claim 6, wherein the reduction nozzle is removably connected to the pipe section of the discharge pipe.

8. A slurry spraying device as claimed claim 5, wherein the reduction nozzle outlet opening is aligned concentrically with the reduction nozzle inlet opening.

9. A slurry spraying device as claimed in claim 5, wherein the reduction nozzle outlet opening is eccentrically aligned with the reduction nozzle inlet opening in an arrangement wherein the reduction nozzle outlet opening is disposed operatively lower than the reduction nozzle inlet opening.

10. A slurry spraying device as claimed in any of the preceding claims, wherein the gas inlet opening is configured to receive a gas pipe having a discharge opening, for conveying a propellant gas.

11. A slurry spraying device as claimed in claim 10, which includes adjustable holding means for holding the gas pipe in the gas inlet opening in an arrangement wherein the position of the gas pipe can be adjusted relative to the gas inlet opening thereby to adjust the distance of the discharge opening of the gas pipe from the discharge nozzle outlet opening.

12. A slurry spraying device as claimed in any one of the preceding claims, which is adapted for use in spraying a cement slurry having a WC ratio of less than 0.45.

13. A new slurry spraying apparatus substantially as described in the specification.

14. A slurry spraying device substantially as described in the specification, with reference to and as illustrated in the accompanying diagrammatic drawings.