GB2172343A - Methods and apparatus for pumping fluids e.g. hand operated bore-well reciprocating pumps - Google Patents

Abstract

A reciprocating pumping system uses rolling lobe diaphragms 34 as sealing means between piston 30 and cylinder 31. Non-return valves (17 not shown) and 16 govern entry of fluid into cylinder 31 and piston 30, respectively, in the conventional manner. Non-return valve 36 permits fluid to flow into chamber 37 between two diaphragms 34 to assist them to maintain their operating shape. In another embodiment, cross-bore 20 and the single, uppermost diaphragm 34 are dispensed with, the fluid passing directly to the outlet by means of a tube connected to the piston bore. The piston is reciprocated by means of a lever. <IMAGE>

Description

SPECIFICATION Methods and apparatus for pumping fluids e.g. hand operated bore-well reciprocating pump This invention relates to methods and apparatus which will cause fluids to be moved from one location to another e.g. bore-well hand operated water pump, by the use of apparatus capable of functioning in but not limited to confined spaces, e.g. a bore-well hole, said apparatus is particularly of use where the distance moved by the reciprocating parts is greater than the bore of the member in which the reciprocating parts operate, which said apparatus will also function if used in a fluid pressurised environment, and/or create pressure within the fluid by the action of moving the fluid if so required.Apparatus will include such component parts of the device which will cause sealing between two reciprocating members caused to reciprocate by a further member called a connecting member, which said member may be linked directly to a further mechanism e.g. manually operated pivoting lever type pump stand, the aforementioned connecting member may be of rigid or flexible construction and said connecting member may also be used as a vessel to direct fluid from one location to another or, if so desired, may be solid and the said fluid will then be directed and contained within a separate member with the solid connecting member contained within.

The apparatus will contain suitably located valves which will allow fluid flow in one direction only and will be located within certain component parts which will co-operate with any or all of the aforementioned components to cause fluid to be directed as re quired. The method of the aforementioned connect ing member which combines the operation of caus ing reciprocating motion and acting as a vessel to direct fluid can be applied to conventional piston seal type pumps to advantage. The arrangement of all aforementioned apparatus and the way they are used to achieve the purpose the invention seeks to show will be apparent from the description set forth later in this specification.

It is well known for water pumps and other devices to provide between a pair of relatively reciprocable members a fluid seal means comprising one or more sealing rings arranged to be supported by and moveable in unison with one of the members and to slide in fluid tight contact over a surface of the other member. It is also known that the inner of the members is caused to reciprocate by means of further connecting member which links to the power source e.g. manually operated pivoting lever type pump stand. It is also known that the aforemen tioned connecting member operates within a hollow member which is attached to the outer member of pump cylinder and which said hollow member conveys the fluid from one location to another.It is also known that the two relatively reciprocating members and other components have valves lo cated within them which co-operate with the recipro cating parts and cause fluid to be moved. The method and the way the aforementioned device will cause water movement will be apparent from the description set forth later in this specification. Whilst such devices are able to provide good operation in certain environments, often they are expensive to manufacture. This arises in part because of the need to provide a smooth concentric surface on one of the members for sliding fluid tight contact by the sealing ring, and in part the need to use selected materials which are resistant to wear and corrosion by the fluid which contacts the device.A further disadvantage particularly when the devise is of a kind operated manually, e.g. a hand operated bore-well water pump, is that energy must be expended non-profitably in overcoming the frictional resistance of the sealing ring so as to cause it to slide over one of the members. Another disadvantage is if the fluid being pumped contains abrasive parts, e.g.

sand; wear on seals and sliding faces will greatly increase and will reduce the effective life of the device.

As an alternative to the use of sealing rings it is appropriate for some applications to consider the use of flexible diaphragms. Annular disc-like diaphragms can be used with success in certain applications and are capable readily of withstanding reversing pressure differentials but they are not capable of allowing a significant degree of relative movement between those members between which they effect a seal. In contrast, rolling lobe type diaphragms are able to permit a greater degree of relative movement but are not well able to withstand reversing pressure differentials. In particular, under conditions of reversing pressure differential a conventional rolling lobe type diaphragm is forced to undergo shape reversal and/or slide over itself in either of which events its useful working life may be restricted.

The present invention seeks to provide methods and apparatus which the aforementioned disadvantages of known pumping devices and sealing means are mitigated and overcome. Rolling lobe diaphragms applied to certain devices are well known, but this present invention seeks to apply them to certain devices, e.g. hand operated water pumps, in ways that have not previously existed. The invention relates particularly to pumping environments where the device is located in a restricted space such as a small bore-well hole, e.g. 100 millimetre inner bore diameter or less, for pumping water to the surface by manual means. It is considered that any conventional liquid or gaseous mediums would be suitable for use in this device such that would not destroy the surrounding components. Fluids having a paste-like consistency may be used.

In accordance with one aspect of the present invention there is provided a seal means for effecting a fluid seal between first and second members one of which extends within the other, these members will be referred to as the piston member and the pump body member. These members are moveable one relative to the other in a reciprocating manner, sail seal means comprising three rolling lobe diaphragms each having a flexible lobe forming portion between inner and outer edge portions each diaphragm having a respective edge portion thereof secured to a respective one of the piston member and pump body member and the lobe forming portions of the respective lower pair of diaphragms being arranged to extend from their associated edge portions in directions which are opposite as considered in the direction in which the members are to reciprocate one relative to the other.The upper diaphragm lobe extending towards the diaphragm lobe below it. A chamber is defined at least in part by the lower pair of said diaphragms and said piston member and pump body member. When the seal means is in use the aforementioned chamber will substantially become filled with some of the fluid being moved and it will be retained within said chamber by means of a one-way valve which has passage through and from the hollow piston member and said valve is located between the lower pair of diaphragm end fixings. In this case the pressure of fluid contained within the said chamber may result from the pressure of the fluid contained within the hollow space of the piston member. Further, the piston member has at its lower portion and within its hollow body a one-way valve which in operation allows fluid up into the hollow body but stops fluid flow in the reverse direction.The one-way valve which allows fluid into the chamber formed by the pair of lower diaphragms is located above the aforementioned inner piston member valve. The top portion of the piston member is solid with the hollow centre hole below extending downwards to the bottom valve; directly below this solid portion and above the top diaphragm inner edge portions is a hole from the hollow centre to the outside face of the piston member. The chamber formed between the top diaphragm lobe and the centre diaphragm lobe can be/is vented through the pump body member.

The reason for this will be apparent from the description set forth later in this specification. The piston member and the pump body member form the members which move relative to each other, the piston member is caused to reciprocate by means of a connecting member which may be of flexible or solid construction and which said connecting member is attached to the upper portion of the piston.

The upper end of the connecting member is linked to a power source, e.g. manually operated pivoting lever type pump stand. The pump body member has a valve located at its lower end, the end extends below the lower diaphragm lobe, which valve will allow fluid into the lower chamber defined by the lobe of the lower diaphragm, the lower valve, the piston member and the valve in the piston member.

The said valve will not allow fluid to flow in the reverse direction downwards out of the pump body member chamber previously described. Attacked to the upper end of the pump body member and above the said diaphragm is a hollow tube the purpose of which is to contain and direct or convey the pumped fluid which has passed through thr piston member and exited at the top portion of said member, and to move said fluid from that location to another, e.g.

the fluid outlet of aforementioned pump stand on the ground surface, acting within said hollow tube is the aforementioned connecting member which causes the piston member to reciprocate.

Afurther embodiment of this invention referring to Figure 2 and Figure 3 provides the means to preload the piston in a downwards direction so that when using flexible materials for the operating rod 14 and pump casing 5 these items will be kept taut.

This is achieved by reducing the diameter of the cylinder 31 over the acting area of the lower two diaphragms 34, thereby the upper diaphragm 34 having a greater projected area will force the piston 30 in a downwards direction when pressures are equai in cavity 40 and the area above the top diaphragm 34. Conversely, the piston 30 can be forced in an upwards direction if the two lower diaphragms 34 function within a larger bore member than the upper diaphragm under identical pressure conditions.

Afurtherembodimentofthe invention provides an alternative seal means between the piston member and the pump body member comprising two rolling lobe diaphragms similar in construction and disposition to the lower pair of diaphragms described in the first embodiment; the attachmentto the relatively reciprocating members is also as previously described. The lower portion of the piston contains two one-way valves and are located and function in similar fashion to the description in the first embodiment.The piston member of this embodiment is hollow through to the top and is joined to a hollow connecting member to which fluid will pass from said inner piston directly, said connecting member now forms a common hollow tube which can be example extend up to a similar mechanism as described in the first embodiment, e.g. a lever operated pump stand, and said connecting member will cause said inner piston to reciprocate and also act as a vessel convey fluid from the piston member to an outlet above the ground surface level connected with the pump stand. The outer pump body is substantially as described in the first embodiment excepting the top portion stops a short distance above the upper diaphragm lobe and is substantially open ended.

A further embodiment of the invention provides a method using a similar connecting member described in the previous embodiment to operate in association with a conventional piston and seal ring type pump devices as generally previously described. This comprises a pump body member in which a piston body member having attached sliding seals reciprocates whereby said seals slide in fluid tight contact with the pump body member. The said piston member is substantially hollow and has attached at its upper portion a hollow connecting member, which hollow portion is connected and continuous with said piston member the hollow connecting member extends from the inner piston member to a power source, e.g. a manually operated pivoting lever type pump stand; further, the hollow connecting member contains fluid being moved through and from the aforementioned piston member, said fluid will exit at the hollow connecting member's upper end portion; further, there is located either within the said piston member hollow body or the lower portion of the hollow connecting member of one-way valve which will allow fluid into the hollow body or the lower portion of the hollow connection member a one-way valve which will allow fluid into the hollow portion of the said members but will not allow fluid flow in the reverse direction. Further said pump body member extends below the piston member and has located at its lower portion a one-way valve which substantially forms a chamber between the said valve, piston member with associated valve and seal and the pump body member, said valve will allow fluid into the aforementioned chamber but will not allow flow in the reverse direction. The top portion of the pump body is substantially open-ended and extends only a short distance above the piston member.The present invention is believed to be particularly suitable for use in pumps such as water pumps of the kind installed at the bottom of a bore-well pump and which by virtue of a reciprocating movement whether caused electrically, manually or by any other means will deliver water to ground surface level.

Embodiments of the present invention as applied to water pumps will now be described by way of examples with reference to the accompanying diagramatic drawings wherein: Figure 1 is a vertical sectional view of a conventional hand operated water pump installed in a bore-well.

Figure 2 is a vertical sectional view of a hand operated pump installation and comprising a pump having seal means in accordance with the first embodiment of the invention, and Figure 3 shows in cross section a larger scale detail of the pump shown in Figure 2.

Figure 4 is a vertical sectional view of a hand operated pump installation and comprises seals and other components in accordance with the third embodiment of the invention, and Figure 5 shows in cross-section a larger scale detail of the pump shown in Figure 4.

Figure 6 is a vertical sectional view of a hand operated pump installation using a piston, seal and pump body of conventional design as Figure 1 but further comprising components in accordance with a fourth embodiment of the present invention.

The conventional bore-well water pump installation shown in Figure 1 comprises a well lining 1 the lower end of which is surrounded by a porous particulate fill 2. The lower end of the lining is formed with a plurality of openings 3 whereby water may permeate from the ground through the fill 2 and enter the bottom of the lining 1 causing water to build up in lining 1 to water level 19 which will vary in height.

Extending from the ground surface level 4 downwards to the bottom of the well lining lisa pump casing 5 formed from a single or a plurality of connected lengths of tube.

The lowest section 7 beneath joint 8 surrounds the pump mechanism, which is described in more detail below, and is of a corrosion resistant type of material.

Above ground level a standpipe unit 9 is attached to the top of the casing 5. The unit 9 has a water outlet spout 10 and a lever 11 pivoted at 12 to the standpipe unit 9. One end 13 of the lever 11 serves as an operating handle and the other end within the body of the standpipe unit 9 is pivotaly at 6 attached to the top of an operating rod 14 which extends down through the casing 5 to the pump mechanism.

The weight of the operating rod 14 and pump mechanism may be counter balanced by means of weights (not shown) attached to the lever 11 or 13 thereby to facilitate ease of operation of the lever.

The conventional pump mechanism provided within the casing 7 comprises a hollow bore piston 15 connected to a lower end of the operating rod 14 and provided with a simple one-way type ball valve 16 within the hollow bore. The valve 16 serves to allow water to flow vertically upwards through the piston and out of the top of the piston at 20, during downwards movement of the piston, but prevents a reversed flow when the piston is lifted bytherod 14 to force water up the casing 5 to outlet spout 10.

The lower end of the pump casing 7 is provided with a second one-way type ball valve 17. This serves to prevent flow of water from the lower end of the casing 7 and below the piston 15 during downward movement of the piston; in consequence water trapped above the valve 17 is forced to flow through the hollow bore piston and through valve 14 for onward flow to the top of the well.

Although not shown in detail the piston 15 is provided with an assembly of sealing rings 18 which during reciprocating movement of the piston are caused to slide in fluid tight contact over a smooth concentric inner surface of the lower casing section 7. The force needed to overcome the frictional resistance to sliding of the sealing rings is provided by the operator of the handle 13.

Figure 2 and 3 shows a water pump embodying a seal means in accordance with the present invention and which obviates the need to provide a lower casing section 7 Figure 1 with a smooth concentric inner surface or to expend energy in overcoming seal sliding friction during the reciprocation movement of the piston, further as there are no sliding parts incorporated within the present invention the presence of abrasive parts within the fluid is no longer detrimental to the device.

In Figure 2 and 3 like numerals to those of Figure 1 are used for parts which correspond. In the water pump construction of Figure 2 and 3 the operating rod 14, which may be of solid orflexible construction, has attached to the lower end thereof a piston 30 of a modified construction compared to piston 15 of Figure 1. The piston 30 is of a smaller relative outer diameter than piston 15 but is provided with a through bore and a one-way valve 16 similarto those of piston 15 but located at the lower end of piston 30. The pump casing 5 may comprise a plurality of connected length of tube or one continuous tube, either alternative may be rigid or flexible. In place of the smooth concentric hard wearing section 7 of Figure 1 is a lower section 31 which may be of plastic, which said section 31 may have an internal surface finish not as smooth or concentric as that required by 7. The lower section 31 can be of a multi-part construction comprising tube portions which provide seating surfaces for the respective outer bead location 33 of three rolling lobe type fabric reinforced rubber diaphragms 34 provided between the casing 31 and piston 30. The component parts of section 31 will be fixed together to form a load bearing continuous member and, if required, a further outer casing member 32 which provides a seating face for tube portions 31.The piston 30 may be formed of a number of portions which will have suitable seating surfaces 35 for location at the respective inner bead location regions of the diaphragms 34, the piston will contain a further one-way valve 36 located above valve 16 and positioned between the diaphragms 34 inner bead locations 35, passage through the valve will join the piston 30 hollow centre section with the chamber 37 formed by the diaphragms 34 and associated parts, the purpose of said valve 36 is to allow fluid to flow from the inner portion of the piston 30 into chamber 37 but to stop fluid flow in the reverse direction.

Casing 31 may have vent or vents 38 located between the lobes of the upper and centre diaphragm 34; the purpose being to allow free flow of air of fluid between the chamber 39 and the outside of casing 31. Chamber 39 is defined by the two upper diaphragms 34, the casing 31 and piston 30. The lower portion of casing 31 has a similar one-way valve 17 to casing 7 Figure 1 and allows fluid into chamber 40 but not in the reverse direction. When the device is installed into the bore-well as shown in Figure 2 the pump lever 13 when caused to reciprocate causes a corresponding reciprocation of the pump piston 30 through member 14 when piston 30 moves upwards water present within well lining 1 is sucked into chamber 40 through open valve 17 by the displacement of piston 30 and the lower diaphragm 34, valve 16 seals off the lower portion of piston 30.When the pump piston 30 is caused to move downward valve 17 closes, valve 16 opens and water flows into and through the hollow body of piston 30 exiting from the top of piston 30 through hole 20 into the casing upper body 31. At this stage of the operation all three diaphragms 34 are partly deformed from their normal operating shapes, which said shapes will be achieved when a suitable positive pressure is exerted within their inner surfaces. The piston 30 continues to reciprocate up and down causing the aforementioned water movement, which said water will begin to enter and rise up pump casing 5, which head of water will thereby cause continuous water below it to become pressurised. The water pressure within chamber 39 will relate to the head of water 19 within the well lining 1.

When piston 30 is on its upstroke water pressure in chamber 40 will also relate to the head of water 19 within the well lining and also the cavitation produced by the aforementioned upwards movement of piston 30. As the water in the pump casing 31 and 5 rises above the well water level 19 a positive internal pressure will be applied inside the top diaphragm 34 which will, with sufficient water pressure, inflate it to a normal operating shape and will remain so whilst there is a sufficient head of water in pump casing 31.

Also, as the water in the pump casing 31 rises above the well water level 19, the water contained within the hollow piston 30 will cause to be pressurised and when the piston 30 is on its upstroke the water within cavities 39 and 40 will be of a lower pressure than inside piston 30 which will cause one-way valve 36 to open and allow pressurised water to flow into the chamber 37. This will continue to happen every time the piston 30 moves upwards so increasing the water level in pump casing 5 till the diaphragms 34 are fully inflated to their normal operating shapes to suit said resulting pressure.On the piston 30 downstroke the pressure in chamber 40 will substantially equal the pressure within chamber 37, when valve 16 is off its sealing seat, then one-way valve 36 will close to stop water flowing out from chamber 37 back into piston 30 thereby ensuring the lower pair of diaphragms 34 remain inflated irrespective of which direction the piston 30 is moving. In contrast to the piston sealing rings 20 in Figure 1 construction, and in order to prevent leakages of water around the outside of the piston between the piston and piston casing the present invention seeks to provide said sealing by means of rolling lobe diaphragms 34 and the means for said diaphragms 34 to be caused to inflate and be kept inflated to their normal operating shapes whilst down the bore-well hole.As said diaphragms 34 roll over the surfaces when caused to move and sealing is obtained by the pressurised contact of the flexible diaphragm sidewalls against the adjacent members, therefore the inner surface of the pump casing 31 and the outer surface of the piston 30 need not be a smooth or concentric a finish as that required by conventional seal type pumps Further, as there is no longer a sliding contact between moving surfaces the presence of any abrasive elements suspended within the fluid will not be detrimental to any of the pump members, and further the resistance to piston movement is considerably reduced related to the high frictional resistance to conventional seals under pressure.

Figure 4 and 5 shows a water pump embodying a seal means in accordance with the present invention which has all the advantages described in the first embodiment shown in Figure 2 and 3 but further includes additional advantages in reiation to the first embodiment and the conventional pumps as previously described in Figure 1. This invention uses one common rigid member to cause both the pump reciprocating movement 14 at Figure 1 and the pump casing 5 at Figure 1 to convey the water.

In Figure 4 and 5 like numerals as those of Figures 1,2 and 3 are used for parts which correspond. In the water pump construction of Figure 4 and 5 only two diaphragms 34 are used and are shown to be located to the piston 30 and pump casing 51 in a similar way to the lower diaphragms 34 of the Figure 2 and 3 in the previous embodiment. The pump casing 51 below the diaphragms 34 is similar also to that pump casing 31 shown in Figure 2 and 3 with valve 17 located within. The pump casing may be formed of a number of component tubes. The upper part of pump casing 51 is substantially open-ended and has vent holes 52 if required. The piston 30 has a similar one-way valve 36 located within its body between the inner diaphragm bead locations with passage through and from the hollow centre of piston 30; the valve 36 operates in a similar way to the valve 36 described in the previous embodiment of Figure 2 and 3. The upper portion of piston 30 is fixed directly to connecting tube 50 which will receive water passing through piston 30. The upper portion of connecting tube 50 is attached to pivot 6 and is caused to reciprocate by the method described in Figure 1; also at the upper portion of connecting tube 50 is an outlet tube 52 which will allow water to exit from the pumping device. Aweight 53 may be fixed within the pump casing 51 at its lowest portion if so desired.When the device is installed into the bore well lining 1 the lower portion of pump casing 51 and weight 53 will sit on the well bottom. The connecting tube 50 is attached to pivot 6 in a suitable position. The well water level is shown at 19 but will vary with every different well. The well water will enter the bottom of the well casing 51 from the well lining through holes 54. In operation lever 13 will be caused to reciprocate causing a corresponding movement of piston 30, when piston 30 is moved downwards some of the water or air trapped in chamber 40 by the closed one-way valve 17 will be forced to lift valve 16 and enter piston 30, when piston 30 moves upwards water is drawn from the well into chamber 40 through valve 17 which will have opened, valve 16 will be closed.As piston 30 continues to be moved up and down water will be moved through piston 30, through and up connecting tube 50 to finally exit at outlet 52. During this period when the pumped water level moves above well water level 19 water pressure will be caused within the piston 30 and one-way valve 36 will open and cause the chamber 37 formed by the diaphragms 34 to receive water which will finally stretch and inflate diaphragms 34to their normal operating shapes. When the piston upstrokes as previously described in Figure 2 and 3 chamber 40 and chamber 39 will contain water or air at a lower pressure than that contained within piston 30.

As previously described fluid entering chamber 37 will be retained when valve 36 closes. If this valve 36 was omitted when the piston 30 moved downward water pressure within the diaphragm chamber 37 would be equal with the water pressure within piston 30 and chamber 40, this would result in the lower diaphragm 34 collapsing from its normal operating shape to its moulded shape and could cause reduced working life for the lower diaphragm 34. The upper diaphragm 34 will always be inflated if there is a sufficient head of water in connecting tube 50, water pressure on the outside of the upper diaphragm 34 will always be that resulting from the well water level 19. This type of pump is preferably for use in wells of 0 - 30 metres water head.

A further embodiment of the invention provides a means for a conventional reciprocating piston pump as described in Figure 1 to convey water and to cause reciprocating movement within one member.

Figure 6 shows a sectional view of a conventional seal type pump combined with aforementioned common member. The piston 60 has seals 20 similar to those shown described in Figure 1, also a one-way valve 16 located within said piston 60. The piston 60 is hollow throughout and connects directly to hollow connecting tube 50 which may be of either solid or flexible construction. The upper portion of connecting member 50 is attached to the surface pump mechanism as described in Figure 4 and 5 and said connecting member has an outlet 52 for water to exit from said connecting member 50. The external pump body 61 is substantially as described in Figure 4 and 5 for pump body 7. The bore of said member will be smooth and concentric; there may be fixed to the lower portion of pump body 61 a weight 53.In operation handle 13, when caused to move, will impart a reciprocating movement to piston 60, which said piston will cause water movement as described in Figure 4 and 5. This type of pump is preferably for use in wells of 0 - 30 meters water head.

Referring to Figure 2 and 3 the operating rod 14 and the pump casing 5 can be made from continuous flexible materials e.g. plastic cord and plastic or rubber hose, which said components will enable the complete below-ground assembly to be withdrawn from the well very easily and by manual means. They are considerably lighter than the matching components of the conventional pump Figure 1, items 14 and 15, which will be made from rigid sections jointed together which causes the pump withdrawal to need assistance from mechanical apparatus. It is known, particularly in developing countries, that spacial lifting equipment and the skills necessary to operate said lifting apparatus are not readily available, therefore the ability to simply manually haul the pumping device up from the well and to accomplish it in a relatively short period of time is a significant advantage.

Claims (25)

1. A seal means for effecting a fluid seal between first and second members one of which extends within the other, these members will be referred to as the piston member and the pump body member.

Said members are moveable one relative to the other in a reciprocating manner, said seal means comprising three rolling lobe diaphragms each having a flexible lobe forming portion between inner and outer edge portions each diaphragm having a respective edge portion thereof secured to a respective one of the first member and second member.

The lobe forming portions of the respective lower pair of diaphragms being arranged to extend from their associated adge portions in directions which are opposite as considered in the direction in which the members are to reciprocate one relative to the other. The upper diaphragm lobe extending towards the diaphragm lobe below it. A chamber is defined at least in part by the lower pair of said diaphragms and said first and second members. A further chamber is defined at least in part by the upper pair of said diaphragms and said first and second members.

2. Seal means according to Claim 1 wherein the lower chamber is caused to be pressurised and kept pressurised.

3. Seal means according to Claim 1 or Claim 2 wherein valve means, such as a one-way valve is provided for flow of fluid into said lower chamber from hollow inner second member as hereinbefore described.

4. Seal means according to any of Claims 1 to 3 wherein a second one-way valve is provided at the lower end of the hollow inner second member and below the aforementioned valve to provide for fluid flow into said member as hereinbefore described.

5. Seal means according to any of Claims 1 to 4 wherein a third one-way valve is provided at the lower end of the outer first member to provide for fluid flow into said member as hereinbefore described.

6. Seal means according to any of Claims 1 to 5 wherein a hole or holes can be provided in the outer first member in the upper chamber between the upper pair of diaphragms.

7. Seal means according to any of Claims 1 to 6 wherein the lower pair of diaphragms may function within an outer first member of different bore size to the same said member containing the upper diaphragm or conversely.

8. Seal means according to any of Claims 1 to 7 wherein either a solid or flexible connecting member may be attacked to said hollow inner second member at its top end which may link said member to a force lever which will cause said hollow inner member to reciprocate as hereinbefore described.

9. Seal means according to any of Claims 1 to 8 wherein the aforementioned flexible connecting member may be contained within either a solid or flexible tube which is attached at its lower end to the top of the outer first member which said tube will convey the aforementioned fluid from the hollow inner second member elsewhere.

10. Seal means according to any of Claims 1 to 9 wherein the aforementioned bore of the outer first member need not of necessity be concentric or of a fine surface finish.

11. A seal means according to Claims 1 to 10 wherein the seal means comprises two rolling diaphragms wherein the lobe forming portions of the respective diaphragms extend away from one another from their respective edge portions as hereinbefore described.

12. A seal means according to Claims 1 to 11 and constructed and arranged substantially as hereinbefore described with reference to Figures 2,3,4 and 5 ofthe accompanying drawings.

13. A reciprocating type fluid pump comprising a piston and casing moveably one relative to the other with a reciprocating motion and between said piston and casing, seal means according to any one of the preceeding claims as hereinbefore described with reference to Figures 2,3,4 and 5 of the accompanying drawings.

14. A seal means substantially as described in Claims 11 to 17 wherein is provided a single tube member which will both cause piston reciprocation and link directly with the hole in the hollow inner second member so as to convey fluid from said piston to another location.

15. A seal means according to Claims 11 to 17 wherein the outer first member is substantially open at its upper end, above the operating area of the top diaphragm.

16. A seal means according to Claims 1 to 17 wherein the inner second member is provided with a through passage for flow of pumped fluid.

17. A reciprocating fluid pump substantially as described in Claims 10 to 15 wherein the seals are conventional seals with suitable piston construction and arranged substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

18. A seal means according to any of the previous Claims wherein the arrangement of the components as substantially described hereinbefore will cause the diaphragms to be permanently inflated and kept inflated to their normal operating shape.

19. A seal means according to any of the previous Claims which when operating under pressure conditions will cause the piston to self-centre thereby avoiding centralising bushes.

20. A seal means according to any of the previous Claims which provides a pumping system with no sliding part to offer frictional resistance as do conventional sliding seals under pressure between sealed faces.

21. A seal means according to any of the previous Claims which uses the pumped fluid to support and resist the diaphragms being deformed by any fluid pressure reversal.

22. Seal means in accordancewith any of the previous Claims which provides a means of relieving pressure on the outside of the rolling lobe diaphragms whilst maintaining a greater pressure within as and when required.

23. A seal means in accordance with any of the previous Claims which provides systems for pumping fluids which will fit into small diameter cavities of less than 100 millimetres.

24. A seal means in accordance with any of the previous Claims which provides a pumping system wherein the piston stroke is greater than the diameter of the pump cylinder.

25. A seal means in accordance with any of the previous Claims which provides a method of supporting the diaphragms under reversing pressure differentials by means which do not require the physical presence of a solid component such as a support spring or former.