GB2211555A

GB2211555A - Pump for raising subterranean water

Info

Publication number: GB2211555A
Application number: GB8724942A
Authority: GB
Inventors: Cecil James Watkins
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-10-24
Filing date: 1987-10-24
Publication date: 1989-07-05
Also published as: GB8724942D0

Abstract

There is described a low-cost solar powered pump for raising subterranean water. In the simplest embodiment (Fig 2) the pump comprises a rigid casing (1) into which an inlet tube (9) extends vertically upwards to terminate at an inlet adjacent the upper wall (4) of the casing (1). A tap (11) at the lower part of the casing allows the water raised to be drawn off. In a preferred embodiment, a pressure relief valve (13, 14, 15, 16) is fitted to the upper part (4) of the casing (1) and a non-return valve (10) is fitted to the inlet. In use, the casing (1) is heated during the day and cooled at night. Excess pressure generated within the casing during the day by expansion of the gases therein is vented off, and the reduction in pressure produced by cooling at night draws water up from below ground to partially fill the casing (1). <IMAGE>

Description

PUMP FOR RAISING SUBTERRANEAN WATER The present invention relates to pumps, and is particularly concerned with pumps for use in raising subterranean water.

In many desert areas, subterranean water is available but the population is unable to afford expensive pumps of the piston type to raise the water to the surface. The present invention provides a low-cost pump which utilises the temperature difference between day and night to raise subterranean water.

According to the present invention, a pump comprises a fixed volume chamber having an inlet opening adapted to allow the ingress of liquids into the chamber and to prevent their egress, and an outlet tap positioned to allow the selective removal of liquids from the chamber. Preferably the chamber includes an inlet fitted with a non-return valve, an outlet tap, and a pressure relief valve, the chamber being so oriented in use that the pressure relief valve is in an upper wall of the chamber and the outlet tap is adjacent the lower extremity of the chamber.

The chamber is preferably cylindrical, having its axis arranged vertically in use, and its inlet at the centre of its base.

The pressure relief valve is advantageously at the centre of the upper end wall, and the outlet tap in the cylindrical side wall adjacent the base.

The non-return valve at the inlet is preferably a ball valve on a conical seat, as is the pressure relief valve. The pressure relief valve may include a manual operating facility so that it can also serve as a vent.

Two embodiments of the invention will now be described in detail, with reference to the accompanying drawings which show central longitudinal sections of the two pumps in their operating positions.

Referring now to figure 1, the pump 1 comprises a cylindrical casing 1 having a tubular sidewall 2, a circular base 3, and a circular top wall 4.

Situated centrally in the base 3 is a non-return valve 5 comprising a cup-like housing 6 containing a ball 7 seated on a conical surface 8. Extending down from the conical surface 8 is a tube 9 leading through the base 3. The housing 6 and tube 9 are secured to the base in an airtight manner such as by soldering, brazing or welding, or by providing screw fasteners and sealing glands.

The ball 7 may be of metal, plastics, or rubber, and is retained in the housing 6 by a bar 10, although other means of retaining the ball are possible. A resilient element such as a helical or leaf spring may be provided to urge ball 7 onto its seat surface 8.

A tap 11 is provided in the sidewall 2 of the casing 1 adjacent the base 3. The tap may be of any convenient type, a conical plug cock being shown in the figure. The tap must be airtight when closed, but must allow water in the casing to flow out when open. The tap 11 may include a vent to allow air in as water flows out. The cock is shown in its closed position in the figure, rotation of the conical plug 12 through 900 about its axis serving to open the cock.

At the upper end of the casing 1, top wall 4 is provided centrally with a pressure relief valve which in the embodiment shown is a ball valve having a housing 13, a ball 14 resting on a conical seat 15, and a vent tube 16 leading out of the casing. Again resilient means may be incorporated to urge ball 14 onto its seat 15 if desired. Housing 13 is secured to the top wall in an airtight manner so that the only communication between the inside of casing 1 and the atmosphere is via the vent tube 16 through the pressure relief valve, via the tube 9 through non-return valve 5, and via the tap 11.

Connected to tube 9 is a pipe 17 which extends into the ground to have its lower end positioned in water-bearing strata. The pipe 17 is simply driven down into the ground, penetration being assisted by a piercing tip 18 fitted to the lower end of pipe 17.

When the required depth is reached, a slight withdrawal of the pipe 17 causes tip 18 to be freed from the end of the pipe, allowing water to enter. Piercing tip 18 also prevents the pipe from becoming blocked during insertion.

In use, once the pipe 17 has been sunk to the required depth and withdrawn to release the tip 18, the casing 1 is mounted to the upper end of pipe 17 using an airtight joint for example by a screw connection incorporating a seal. The casing may be supported by stakes driven into the ground and attached to the casing by brackets, straps or the like, or if a permanent installation is contemplated a masonry pedestal may be erected.

The casing is then left, with cock 11 closed, to heat up in the sun. This causes the air within the casing to expand, increase the pressure within the casing 1, and flow out of the casing via the pressure relief valve by raising ball 14 from seat 15. The pump is left all day to achieve maximum expansion.

As the sun sets, and temperatures drop during the night, the air within the casing cools and contracts, reducing the pressure within the casing Since atmospheric air cannot enter the casing due to the pressure relief valve being closed, the reduced pressure within the casing 1 will draw water up the pipe 17, through the non-return valve 5 and into the casing 1. The water then becomes trapped in the casing, and may be drawn off by a user simply opening the tap 11.

Clearly, each time the temperature cycle between hot daytime and cold night occurs, more water will be drawn up the pipe 17 into the casing 1.

Since the amount of water drawn up will depend on the volume of gas and vapour in the casing 1, it will be advantageous to draw off all the water raised each day through the tap 11, preferably during the morning so that the maximum possible volume of vapour is exposed to high midday temperatures.

Since the device is intended for use in desert areas where repair facilities may be rudimentary, a rugged metal construction is preferred. However, plastics parts or even a plastics casing may be used if light weight is a requirement of the device.

The maximum depth of pipe 17 for drawing water up is clearly about ten metres, depending on the temperature difference experienced by the casing. If the casing is filled with water vapour, steam will fill the casing if temperatures in excess of 100 oC are achieved.

Subsequent condensation of this steam will provide significantly better water-raising capability than the expansion and contraction of atmospheric air.

To avoid loss of water due to a faulty non-return valve at the base of the chamber, this valve may be provided with an upwardly extending inlet tube so that water passes through the valve, up the inlet tube and is discharged into the chamber at a point distant from the base, This will prevent collected water from draining away through a faulty valve.

To provide an extremely low-cost device, it is envisaged that the pressure relief valve and the non-return valve may both be omitted completely, and the device comprise a casing having a tap adjacent its base and an inlet tube leading into the casing to discharge at a point remote from the base, as shown in figure 2.

The pump of figure 2, in which parts corresponding to parts shown in figure 1 are given like reference numbers, is installed in essentially the same way as that of figure 1, but its operation is not automatic. At about midday, the tap is opened to drain any water and to allow the pressure in the casing to equalise with the atmosphere at the hottest time of the day. The tap is then closed, and remains closed until the following morning. The reduced pressure in the casing caused by cooling draws water up the pipe 17 as before, but if the water is not drawn off before the casing is again heated by the sun, the water is unable to escape since it has no access to the only available opening in the casing, the upper end of inlet pipe 9. Thus the expense and fallibility of the non-return valves is completely avoided with only a small operational penalty to be paid of remembering to vent the casing each day at midday.

While two cylindrical embodiments of the invention have been described, it will be appreciated that the invention Is by no means limited to the casing shape or valve types described.

Claims

1. A pump comprising a fixed volume chamber having an inlet opening adapted to allow the ingress of liquids into the chamber and to prevent their egress, and an outlet tap positioned to allow the selective removal of liquids from the chamber.

2. A pump according to Claim 1, wherein the chamber is cylindrical in shape and is oriented with its axis vertical in use, the upper and lower faces of the chamber being circular.

3. A pump according to Claim 1 or Claim 2 wherein the inlet is situated in the upper region of the chamber.

4. A pump according to Claim 1 or Claim 2, wherein the inlet is situated at the lower region of the chamber and incorporates a oneway valve means to allow liquid to flow only into the chamber.

5. A pump according to any preceding Claim, wherein a pressure relief valve is provided in the upper part of the chamber to allow pressurised gases and vapour within the chamber to escape to atmosphere.

6. A pump according to Claim 3 as dependant on Claim 2, wherein an inlet pipe passes vertically upwardly through the lower face of the chamber and terminates adjacent the upper face.

7. A pump according to any preceding Claim, wherein the chamber is adapted to be supported above ground level by detachable legs or stakes.

8. A method of recovering subterranean water comprising the steps of:

1. placing a pipe having open upper and lower ends so that the lower end is in a subterranean reservoir and the upper end is above ground level,

2. attaching the upper end of the pipe in an airtight manner to an inlet of a fixed volume chamber adapted to allow the ingress of liquid into the chamber but to prevent its egress,

3. equalising the pressure within the chamber with atmospheric pressure during the warmer part of the day,

4. sealing the chamber to prevent the ingress of atmospheric air,

5. allowing the chamber to be cooled during the night to draw water up from the reservoir as a result of the decreased pressure within the chamber on cooling, and

6. drawing off water from the chamber by means of a suitably positioned tap.

9. A method according to Claim 8, wherein steps 3 and 4 are carried out automatically by a non-return pressure relief valve.

10. A method according to Claim 8 or Claim 9 wherein the pipe is placed in position by fitting a penetrating point over its lower end, driving the pipe down through the ground to a depth beyond the required-depth, and withdrawing the pipe a short distance to separate the pipe from the penetrating point.

11. A pump for raising subterranean water substantially as described with reference to Figures 1 or 2 of the accompanying drawings.

12. A method of raising subterranean water substantially as herein described.