This invention relates to pumps and, more specifically, to a pump for pumping liquids and solids materials in divided form.

Pumps for pumping liquid are well known in the art and are conventionally driven by a prime mover, such as an electric motor, an internal combustion engine or a compressor, rated to obtain optimum performance of the pump.

In many examples the pump and its prime mover are constructed as a single assembly but in other uses the pump and its prime mover are separate assemblies and, when mobile, are capable of independent transportation to a location for use. With all such prior art arrangements the pump and its associated prime mover are essential to the operation of the pump.

One object of the invention is to provide a pump which does not require a prime mover specific thereto.

A further problem with conventional liquid pumps, in particxαlar diaphragm pumps, is that the pump must be primed before pumping can be initiated. If the pump filter should become blocked the pump must be closed down whilst the filter is cleared and the pump must be re-primed. Such pumps include relatively delicate moving parts and regular maintenance is essential.

One object of the present invention is to provide a pump arrangement which does not have any moving parts.

The pumping of solids materials in finely divided form is also well known in the art and, for example, the pneumatic conveying of finely divided solids is widely practised. There are two basic methods for pneumatic conveying.

In one such method a container charged with divided solids is pressurized whereupon, and when an outlet duct leading from the charged container to a receiving container is opened, the solids material is conveyed to the receiving vessel by the pressure air flows escaping from the charged vessel.

In the other such method the receiving vessel is held at a sub-atmospheric pressure and the divided solids are again conveyed by the air flows from the charged container to the low pressure container.

The pump proposed by the present invention offers a third method for the pneumatic conveying of the divided solids materials.

In many pneumatic conveying systems it is essential for the divided solids materials to be discharged at high velocity and one such arrangement is used in shot blasting.

In a conventional shot blasting arrangement a pressure vessel is charged with shot, the vessel is sealed and pressurized often to a pressure in excess of 3,000 p.s.i. (210.9 kilograms per. square centimetre), and an outlet line from the pressure vessel terminates at a nozzle outlet. When

the line is open to said nozzle outlet the pressurized air from the vessel conveys the divided solids materials along the line and discharges said divided solids at high velocity from the nozzle outlet.

The preser invention seeks to provide a shot blasting arrangement capable of operating without a pressurized vessel for the shot.

According to the present invention there is provided a pump comprising an inlet for flowable material to be pumped an outlet for the flowable material being pumped, and a flow passage for the material being pumped between said inlet and and said outlet, characterised by an air release duct arranged to release pressure air directly into said flow passage and towards said outlet.

Preferably the pump is characterised in that said flowable material inlet, outlet and flow passage lie on a common axis.

In one embodiment •the said air release duct comprises a tubular member and said tubular member enters said flow passage through said flowable material inlet.

In another embodiment said air release duct comprises a tubular member and said tubular member enters said flowable material flow passage through a wall region defining said flow passage.

Preferably part of said air release duct adjacent the air release outlet therefrom is concentric with the axis of the said flow passage.

In one embodiment the flow passage is defined by a tubular element, the flowable material inlet is defined by one end of the said tubular element and the flowable material outlet is defined by the other end of said tubular element.

In another embodiment the flow passage is of an elliptical form and the said inlet and outlet are at opposite ends of said flow passage, concentric with the major axis of the flow passage.

Preferably the pump includes a filter upstream of said flowable material inlet.

In one embodiment the pump includes means for connecting a discharge pipe to the said flowable material outlet.

In one preferred embodiment in accordance with the invention a pump, for pumping a liquid, comprises a tubular casing defining a material flow passage, an opening from said flow passage defining the inlet for the pump, an opening from said flow passage at the other end of the pump defining the outlet for said pump, means presented by said casing for connecting a discharge duct to the outlet end of said casing, an air release duct having a discharge outlet within said flow passage, said air release duct having its regions adjacent said discharge outlet concentric with the axis of said casing and its said discharge outlet opening towards said flow passage outlet, a means for connecting said air release duct to an air pressure line.

In another preferred embodiment a pump, for pumping a solids material in divided form, is characterised by a pump casing defining a flow passage, an opening to said flow passage at one end region of said casing defining the inlet to said flow passage, means for connecting said inlet end of said casing to a divided solids material supply, an opening to said flow passage at the opposite end of said casing defining the outlet from said flow passage, a discharge element extending from said discharge outlet and an air release duct having a discharge outlet in said flow passage, said discharge outlet being concentric with the axis of said flow passage and directed towards said flow passage outlet and means for connecting said air release duct to a pressure air supply.

In one embodiment, the pump according to the invention is used in combination with a divided solids material supply, connected to the inlet to said flow passage via a duct connected to said inlet end of said pump, and a divided solids material receiving vessel connected to said discharge

element .

According to another aspect there is provided a pump according to the present invention in combination with a shot hopper connectable to the inlet to the pump and a shot discharge nozzle open to the outlet from the pump.

It will be appreciated that the pump proposed by the present invention is capable of operating over a wide range of air pressures and the efficiency of the pump in accordance with the invention will be dependent upon the rate and pressure at which the air is released from the air release duct and the pressure in the flowable material to be pumped at the inlet to the pump.

It is well known in the art that many commercial vehicles, and in particular vehicles engaged in the building trade, include compressor means normally 'provided to perform some function associated with the vehicle, and it has been found in practise that the output from such a vehicle compressor is adequate to drive the pump proposed by the invention for most of its intended uses.

It will be appreciated that the pump proposed by the present invention has no moving parts, it can be readily fabricated or moulded or cast, it can be of lightweight or heavy construction, it is relatively inexpensive to manufacture, it requires no maintenance and it requires no priming and is always immediately ready for use.

The invention will now be described further by way of example with reference to the accompanying drawings in which;

Fig. 1 shows, diagrammatically, a longitudinal cross section through a pump in accordance with the invention,

Fig. 2 shows, diagrammatically, a longitudinal cross section through a second embodiment in accordance with the invention.

Fig.3 a pump in accordance with the invention for use with the shot blasting vessel shown in Fig. 3.

Fig. 4 shows, a side view of a shot blasting vessel.

In the example illustrated in Fig. 1 a pump, for pumping liquids, comprises a casing defined by a tubular element 11, of uniform cross-section.

The tubular element 11 has radial flanges 12 and 13 at its opposite ends and an air release duct defined by a tubular element 14, of smaller cross section than the tubular element 11, is entered through the cylindrical wall of tubular element 11, substantially at right angles to the axis of tubular element 11, and is turned through ninety degrees so that at least that part of the element 14 adjacent to the discharge outlet 14a of element 14 is coaxial with the central axis of tubular element 11.

That part of tubular element 14 concentric with the axis of element 11 is retained in such position by rigid webs 15, circumferentially spaced apart about the axis of the element 14 and in planes passing through the said axis of element 11.

That end of the tubular element 11 having the radial flange 12 thereon is intended to be the inlet IE for the pump and, in the illustrated example, a cylindrical filter 16 is secured to the flange 12, as by bolts 17.

That end of the tubular element 14 externally of the tubular element 11 has connection means thereon, in the illustrated example pins 18 defining a bayonet fitting, and by which connection means a pressure air supply pipe (not shown) may be connected to that end of element 14 presenting the pins 18.

That end of the tubular element 11 having the radial flange 13 thereon constitutes the outlet OE for the pump and a discharge duct (not shown) may be connected to the flange 13

to duct away the spent air and entrained water from the outlet end of element 11.

As will be seen from Fig. 1, the webs 15 space the tubular element 14 from the bore of the element 11 thus defining a substantially annular liquid flow passage, broken only by the webs 15, surrounding the outlet end 14a of the duct 14 and extending in the axial direction of the element 11.

The perforations, or screen size, of the apertures in the filter 16 will be such as to prevent solids material, having a larger dimension than the radial width of the fluid channels surrounding the discharge end 14a of the ^' element 14, from entering into and blocking the flow passage.

Thus, the filter 16 prevents blockage of the annular flow passage whilst offering little resistance to the flow of liquid to be pumped through the element 11.

In operation, and for pumping liquids, the pump is lowered into the liquid the tubular element 14 is connected to an air pressure source (not shown) having a pressure greater than the hydrostatic pressure in the liquid in the flow passage defined by element 11, and air is supplied to the element 14. The pressure air flows along element 14 and is released at the discharge end 14a thereof, said air when released from the element 14 flows towards and through the outlet OE and entrains liquid, causing said liquid to flow along the flow passage to the outlet OE, whereupon causing liquid to flow from the inlet IE to the outlet OE.

The efficiency of the pump will be directly related to the size of the pump and the relative sizes of its component parts, the hydrostatic pressure in the liquid within the tubular element 11 and the delivery pressure of the air supplied to the outlet 14a but with a pump of the type defined, working at no more than ten pounds per square inch air pressure greater than the hydrostatic pressure in the liquid in the tubular element 11 and without a discharge duct connected to the outlet end OE, the pump can effect a

"stirring" of a relatively large volume of liquid, most useful for preventing the separation of emulsions, and because the pump can operate at the air pressures delivered by a conventional air generator of a vehicle, for example a road tanker, such a pump can maintain an effective stirring of the bulk liquid contained in the vehicle.

In the example illustrated in Fig. 2 the pump comprises a tubular element 21 with an enlarged bore region 22 at one end defining the flowable material inlet IE to the pump. The end of the element 21 remote from the bore region 22 constitutes the outlet end OE of the pump.

An air release duct 24 is supported coaxially within the element 21 by radial walls 25, the outlet 24a _^ for the duct 23 is spaced upstream from the outlet end 23 of the element 21 and said duct 24 extends through the inlet end of the element 21 and is coπnectable to an air supply source (not shown), for example the pressure outlet duct from a vehicle compressor.

The pump may include a filter (not shown) closing the enlarged bore region 22.

When a discharge duct (not shown) is connected to the outlet end OE of the element 21, by, for example, a jubilee clip, and the pump is dropped into a water filled hole, footing or excavation on a building site and air is supplied to the air duct 24, the air released from the duct 24 flows towards and through the outlet end OE of the element 21 and causing liquid flows in the flow passage from said inlet end 10 to said outlet end OE.

The air and entrained liquid flow through the outlet end OE and along the discharge duct (not shown) to the outlet therefrom.

In practise a pump, having an air supply duct of 1 inch external diameter (bore 0.8 inches), within a tubular element 11 having a bore in the region of Ik" with air at 80 p.s.i. delivered to the supply duct 24 by a construction vehicle compressor, successfully raised air entrained liquid

more than 12ft above the free surface of the water within which the pump was immersed.

The pump may be constructed of metal or rigid plastics material.

Whilst the pump shown in Figs. 1 or 2 and described above will have many general purpose uses particular advantage will be found in building and the like construction or quarrying sites, where rain water or ground water can collect in excavations and must be pumped out regularly to allow work to continue. On such sites one, or a number, of pumps according to the invention may be retained as permanent site equipment and used with any vehicle visiting the site and having a compressor. Alternatively and because of th low costs of the pump proposed by the present inventor, all construction vehicles having a compressor may carry a pump according to the invention as part of its permanent tool kit, for use on any site visited by the vehicle.

As stated above, another usage of advantage is in the bulk storage and/or transportation of liquids and in particular slurries and emulsions where the liquid must be continuously "stirred" to maintain the dispersion of the solids or liquids constituting the discontinuous phase. With such usage the pump proposed by the present invention and lowered into the liquid connected to any pressure air source where upon the pump will operate continuously whilst pressure air is supplied thereto. When the liquid is being transported by a bulk carrier vehicle the pressure air may be supplied by the compressor, which is now almost a standard equipment, of such a carrier.

Fig. 3 shows another pump construction in accordance with the invention, particularly useful for pumping solids materials in finely divided form and most useful for shot blasting processes.

The pump generally comprises a vessel 31 of elliptical form with an inlet 32 and an outlet 33 defined by openings at opposite ends of the vessel 31, concentric with the major axis

of the vessel 31.

A tubular element 34 extends from the inlet 32 and is connectable to a supply source (not shown) for containing finely divided solids material and remote from the vessel 31, via a supply duct 35.

A discharge element 36 extends from the outlet 33 end of the vessel 31, concentric with the outlet 33, and said element 36 tapers, reducing in cross section, from the outlet 33 to a nozzle outlet 37 remote from the vessel 31.

A rigid air release duct, defined by a pipe 38, enters through the wall of the elliptical vessel 31 adjacent the inlet 32 and terminates, within the vessel 31 in a section 39, concentric with the axis of the vessel 31 and extending partially into the tubular element 36, concentric therewith. The outlet 40 from the section 39 is within the tubular element 36 and directed towards the nozzle outlet 37. Externally of the vessel 31 the air pipe 38 has a valve 41, for opening and closing the air flow duct along the pipe 38.

Thus, on the tubular element 34 being open to the divided solids material supply and on pressure air being supplied to the pipe 38 and on the valve 40 being displaced to an open position air flows along air pipe 38, the pressure air is released from the outlet 40 from pipe 38 and flows along the nozzle element 36 to the outlet 37 therefrom. The rapid flow of air along element 36 entrains air from the elliptical flow passage defined by vessel 31, thus reducing the air pressure therein below atmospheric pressure, and generating air flows from the supply divided materials toward and through the flow passage in vessel 31. Such air flows cause displacement of the solids particles along the supply duct

35 to the vessel 31 and as solid material flows along the flow passage in vessel 31 and into the annular passage between the nozzle element 36 and the air supply pipe 38 said particles are entrained by the rapid air flows along element

36 and are discharged from the nozzle outlet 37.

The pump embodiment illustrated in Fig. 3 has proved to

be most effective for pumping shot in a shot blasting process but in an alternative embodiment the nozzle element 36 can be replaced by an outlet duct to a solids material receiving vessel, open to atmosphere and the said pump can act most efficiently for pumping solids divided material from a solids material supply to the solids divided material receiving vessel.

One solids material supply suitable for use with the pump illustrated in Fig. 3, is shown in Fig. 4 and wherein a cylindrical vessel 51, supported with its central axis vertical by four legs 52 (only three of which are shown), includes a sieve or filter 53 in its upper regions and a lid 54, and which lid 54 does not form an air tight seal with the vessel 51.

The lower regions of the cylindrical vessel 51 are closed by a downwardly and inwardly sloping base 55 and a discharge duct 56, depending downwardly from the central regions of the sloping base 55, opens into the lowermost regions of the vessel 51.

The discharge duct 56 includes a manually adjustable valve 57 and, at its lower regions, the duct 56 opens to a horizontal duct 58, comprising the supply duct 35 to the inlet end of a pump in accordance with the invention.

Thus, with the solids materials supply vessel 51 charged with shot, the valve 57 in an open condition, and with pressure air discharging from the pressure air release duct 39 into the element 36, to create a low pressure in the elliptical casing 31 as described hereinbefore, air flows from the vessel 51 down the duct 56 and along the duct 58 (35) to the inlet to the flow passage in the vessel 31 and said air flows carry shot from the vessel 51 into the flow passage in the casing 31. The shot is carried by the air flows in the flow passage into the discharge element 36 and, upon coming into the influence of the high pressure air being discharged along the element 36 shot is entrained by such air flows and directed through the outlet 37 at a speed dependant upon the

flow rate of the air through the outlet 37.

The rate at which shot is delivered to the element 36 can be carefully regulated by manual adjustment of the valve 37.

It has been found and practised that with a shot hopper of the type illustrated in Fig. 4 discharging through a pump of the type shown in Fig. 3 with the pressure air supplied to the air release duct 39 at a pressure between 80 psi and 100 psi a most efficient shot blasting effect can be obtained.

When a solids material in finely divided form, and thereby suseptiblε to compaction, is to be conveyed it has been found advantageous to provid an air bleed into the system, conveniently a small hole or aperture in the lower regions of the hopper 51 adjacent to the discharge outlet therefrom, in the discharge duct 56 or in the horizontal duct 58.

Whilst the present invention has been described by way of example with reference to specific embodiments the invention is not restricted thereto and many modifications and variations, capable of adapting the pump for different uses, will be apparent to persons skilled in the art.