US3630642A

US3630642A - Diaphragm pump

Info

Publication number: US3630642A
Application number: US8297A
Authority: US
Inventors: Edmund J Osterman
Original assignee: EI Du Pont de Nemours and Co
Current assignee: ETI EXPLOSIVES TECHNOLOGIES INTE
Priority date: 1970-02-03
Filing date: 1970-02-03
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28
Also published as: ES195226U; CA936042A; FR2078100A5; GB1319718A; JPS5514277B1; DE2105005A1; SE378130B; ES195226Y; BR7100805D0

Abstract

A diaphragm pump having means adapted to utilize the driving fluid of the pump to apply a supplementary force to the pumping diaphragm of the pump thereby providing a total pump discharge pressure which is greater than the pressure of the driving fluid.

Description

I Unlted States Patent l1113,630,642

[72] Inventor Edmund J. Oder-man [56] References Cited WW, UNITED STATES PATENTS [21] P 533,449 2/1395 Erwin 417/393 [22] Flled Feb. 3, 1970 2,186,970 1/1940 l-lambly 417/393 [45] Patented Dec. 28, 1971 [73] Assignee E. I. du Pont de Neruours and Company FOREIGN PATENTS wn m ,])d 165,861 11/1955 Australia 417/395 572,023 9/1945 Great Britain 417/395 541 DIAPHRAGM PUMP 1 31223}??? walk 5 Claims, 2 Drawing Figs. Y Y

417/393, 417/395, 91/329, 91 4 1 ABSTRACT: A diaphragm pump having means adapted to 51 Int. (:1 F0411 3/00, utilize the driving fluid of the P p to pp y a supplementary 041, 43/06 01 15/13 force to the pumping diaphragm of the pump thereby provid- [501 Field of Search 417/245, g a total p p discharge pr ure whi h is gr ter than the 246, 393, 395, 396; 91/232, 329, 411,412, 413, pr ssure fthe d i ing fluid.

L 55 10 4a 69 90 s f -19 FIG.

INVENTOR EDMUND J. OSTERMAN ATTORNEY l DIAPHRAGM rum BACKGROUND OF THE INVENTION This invention relates to diaphragm pumps, more particularly to diaphragm pumps wherein the pump discharge pres sure is higher than the pressure of the driving fluid.

Diaphragm pumps are well known for their utility in pumping thickened or solids-laden liquids as well as for pumping plain water, other liquids, and low-viscosity solutions based on such liquids. Accordingly, diaphragm pumps have found extensive use in pumping out sumps, shafts, pits, and excavations, and generally in handling a great variety of slurries, sludges, and solids-laden liquids. Pneumatically driven diaphragm pumps offer certain further advantages in convenience, effectiveness, portability, and safety, as disclosed in U.S. Pat. No. 2,780,177. This patent describes a single-actiontype pump having two interconnected horizontally disposed diaphragms that operate in an up-and-down motion, and two pneumatically operated valve closures, one each on an intake line and a discharge line, respectively. In another modification of the above-described pump, the cylindrical casing of the pump is mounted in a substantially horizontal position, the diaphragms are disposed vertically on a connecting rod that moves back and forth in a substantially horizontal direction, one side of each diaphragm communicates with an inlet and an outlet port for the liquid to be pumped, and the other side of each diaphragm communicates with an inlet port for compressed air and an outlet port for venting the exhaust air to the atmosphere. A diaphragm pump of this modification is sometimes designated as the double-acting type. Such a pump is described in U.S. Pat. No. 3,338,171.

In the operation of a diaphragm pump of the type just described, the fluid to be pumped is discharged at a pressure no higher than the pressure of the fluid driving the pump. The driving fluid, e.g., compressed air, pushes against one side of the diaphragm with a force equal to its own pressure mul tiplied by the area of the diaphragm. This same force is exerted by the diaphragm pushing against the fluid to be pumped, e.g., water, which is on the side of the diaphragm away from the compressed air, over an area essentially equal to the area that the compressed air is pushing against, and the pressure, or force per unit area, against the fluid to be pumped will be essentially the same as the pressure of the driving fluid, i.e., if compressed air at 50 lb./sq. in. is supplied to a diaphragm pump, the pump will deliver water at a pressure not higher than 50 lb./sq. in. This upper limit on the discharge pressure of a diaphragm pump detracts from its usefulness in many applications where its unique characteristics make it a highly suitable device. In remote locations, for example, in quarries or in road construction, the only conveniently available source of power may be compressed air supplied by a portable air compressor driven by an internal combustion engine. In such remote locations a pneumatically operated diaphragm pump is a highly useful piece of equipment, so long as it is not required to discharge liquids at a pressure near or above the pressure of the available compressed air supply. Pump discharge pressures that are high relative to the pressure of the compressed air supply are required when a fluid is to be raised from one elevation to an elevation considerably higher, when a fluid is to be moved through along, constricted, or tortuous conduit in which fluid friction is high and pressure loss is great, when the fluid to be moved is highly viscous and sluggish, or when a combination of these or similar conditions exist. Even when the required pump discharge pressure is below the pressure of the compressed air supply, the pumping rate, i.e., the capacity of the pump to deliver a volume of fluid in a unit of time, will be directly proportional to the difference between the two pressures. As the required discharge pressure of a diaphragm pump increases, the diaphragm moves progressively more slowly and the delivery rate decreases, until the discharge pressure becomes essentially equal to the compressed air pressure, at which time the pump will stop completely.

In pneumatic, hydraulic, or hydropneumatic pumps, presses, rams, or like devices employing pistons reciprocating within cylinders, it is well known that the discharge or delivery pressure of the driven fluid may be raised many fold over the supply pressure of the driving fluid, by selecting pistons of differing areas, whereby the pressure of the driving fluid is exerted on a piston of large area to create a large force that is transmitted by a connecting rod to an opposed piston of small area and is concentrated in that small area to produce a pressure in the driven fluid higher than that of the driving fluid. The ratio of the two pressures is inversely proportional to the areas of the two pistons. Such devices employing differential pistons are known as hydraulic or pneumatic boosters or intensiflers. One embodiment of an intensifier is disclosed in U.S. Pat. No. 2,336,446. Another embodiment is described in Engineering, I89, 462-3 (I960), Apr. l.

Intensifiers or boosters using pistons close fitting in cylinders are best suited to handling clean fluids, e.g., oil, water, and air. However, when the fluid to be pumped is a sludge or a slurry, is thick or viscous, is laden with solids, or is otherwise of a nature that it could not be pumped by a piston pump, or might be harmful to a piston pump, e.g., by reason of its containing abrasive particles, or might be affected adversely by a piston pump, as by attrition of fragile crystals in a slurry, a diaphragm pump is a highly suitable means for moving such a liquid. This is especially so when the liquid to be pumped is a liquid blasting agent or a liquid containing explosive components. In recent years certain kinds of blasting operations have been carried on by use of water-bearing, slurry-type blasting agents that are pumped from bulk containers such as delivery trucks, or from portable mixing plants, directly into the blast holes. Because such blasting agents usually are thickened and contain considerable amounts of more or less abrasive undissolved solids, a diaphragm pump is well suited for loading these blasting slurries into blast holes. Although these water-bearing, slurry-type blasting agents are relatively insensitive and require an initiator stronger than a conventional blasting cap, they often contain particles of undissolved high explosives as sensitizing agents. Hence, freedom from metal-to-metal contacts, friction, and potential pinch points in pumps is desirable for maximum safety in pumping such explosive compositions. Such safety features can be incorporated into a diaphragm pump and make it a preferred means for pumping these explosive materials.

The water-bearing, slurry-type blasting agents are supplied to the blasting operation usually by either delivery in a tank mounted on a motor truck or by preparation at the site in a mixing plant, also mounted on a motor truck. Either way, however, the supplying means must be self-contained and able to operate in a remote location, e.g., a quarry. The diaphragm pump used to charge the blasting agent into the blast holes is conveniently operated by compressed air supplied by an air compressor carried on a motor truck. Because the water-bearing, slurry-type blasting agents generally are thickened or gelled and do not flow freely and because the delivery conduits or hoses that lead to the blast holes are restricted in cross-sectional area and often are overly long, the discharge or delivery pressure required of the diaphragm pump becomes high relative to the pressure of the compressed air supplied by the air compressor even when the compressor is working at its top pressure limit. Consequently, the speed and efficiency of blast-hole charging are lowered, and it may be necessary to move the supplying unit closer to individual blast holes to shorten the delivery hoses.

Thus, there is a need for a diaphragm pump wherein discharge pressures can be attained which are higher than the pressures of the driving fluids.

SUMMARY OF THE INVENTION According to the present invention there is provided a diaphragm pump having means adapted to utilize the driving fluid of the pump to apply a supplementary force to the pumping diaphragm of the pump thereby providing a total pump discharge pressure which is greater than the pressure of the driving fluid. The supplementary force is conveniently applied to the pumping diaphragm by providing a second diaphragm, a piston, or the like, substantially parallel to the pumping diaphragm and connected thereto by a fixedly attached rigid movable rod or the like. Simultaneously with the application of the driving fluid pressure to the pumping diaphragm, the driving fluid pressure is applied to the second diaphragm, piston, etc., in the same direction, and a force is thereby transmitted via the rigid rod to the pumping diaphragm thus making the total pump discharge pressure greater than the pressure of the driving fluid.

In the preferred embodiments of this invention, air is employed as the driving fluid and the pump comprises a casing having therein a partition dividing the interior of the easing into two separate compartments, a flexible diaphragm spanning and dividing each of the compartments into inner and outer spaces, the former of which adjoin, while the latter are located remotely from the partition, a rigid movable rod or the like interconnecting the diaphragms through the partition, fluid inlet and discharge ports in at least one of the outer spaces, an air control valve chamber and an air-operated con trol valve located within the valve chamber positioned and adapted to admit compressed air alternately to each of the inner spaces and simultaneously to vent compressed air to the atmosphere from the other of the inner spaces through an airexhaust conduit, and thereby to flex the diaphragms simultaneously in like directions. If the pump is single acting, i.e., the fluid to be pumped is pumped through only one of the outer spaces, and accordingly, only one outer space has fluid inlet and discharge ports, then the supplementary force is conveniently applied to the pumping diaphragm by applying air pressure to the outer space without ports so that the pressure in that space varies directly with the pressure in the inner space adjacent the pumping diaphragm. If the pump is double acting, i.e., the fluid to be pumped is pumped alternately through each of the outer spaces, and, accordingly, each outer space has fluid inlet and discharge ports, then the supplementary force is conveniently applied to the pumping diaphragms by utilizing the air to apply pressure to the liquid in the outer spaces alternately so that the pressure in each outer space varies directly with the pressure in the inner space remote therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 represents a pneumatically operated, single-acting diaphragm pump which comprises a casing ll of substantially circular cross section (as seen at right angles to the drawing) that forms a chamber 12 having therein a cylindrical partition 13 dividing the interior of said casing into segregated right and left compartments l4 and 15, respectively; substantially vertically positioned, circular flexible diaphragms 17 and 18 spanning and dividing each of the compartments into

inner spaces

21 and 22, and

outer spaces

19 and 20, the former of which adjoin the partition while the latter are remote from said partition; movable means including rod 23 interconnecting the diaphragms centrally through the partition; liquid inlet port 24 and discharge port 25 positioned substantially 180 apart at the bottom and top, respectively, of outer space 19 and communicating therewith; inlet ball check valve 26 and discharge ball check valve 27, together with

corresponding valve seats

28 and 29 and stops 30 and 31; a conduit 32 providing communication between inner space 21 and outer space 20; a valve chamber 33 formed in said partition, an airoperated control valve 16 located within said valve chamber and adapted to admit compressed air alternately to each of said inner spaces and simultaneously to vent compressed air to atmosphere from the other ofsaid inner spaces through an airexhaust conduit 34 and thereby to flex said diaphragms simultaneously in like directions.

The flexible diaphragms of the pump are centrally interconnected by rigid movable means comprising connecting rod 23 and an inner and an outer

metal clamping disk

35 and 36, respectively, which hold, at peripheral position, the inner edge of each of the centrally perforated flexible diaphragms. Each inner and outer disk is central attached to connecting rod 23 by a centrally located screw 37 entering said connecting rod at an angle of about from the rod's axis.

Compressed air used to operate the pump is supplied through an air filter to diagrammatically shown air control valve 16 which is housed in a portion of the partition which also is provided with air inlet ports (not shown) communicating directly with the air control valve chamber 33 which in turn communicates with inner space 21 and with inner space 22. The valve chamber 33 is also vented (passageways not shown) to the atmosphere through exhaust tube 34. Although various means, including hand-operated air valves, are suitable for controlling the compressed air to effect movement of the diaphragms, the slide valve described in US. Pat. No. 3,07 l ,1 18 has been found to be especially suitable.

In operation, control valve 16 directs compressed air into inner space 22 and against diaphragm l8 and at the same time vents to the atmosphere inner space 21 and outer space 20 (via conduit 32). The compressed air pressure forces flexible diaphragm 18 to move to the left and with it connecting rod 23 and diaphragm l7, creating a suction in outer space 19 that draws the fluid to be pumped through inlet port 24, past inlet ball check valve 26, which is raised off its seat 28 and against the stop 30, and into outer space 19, which has been scaled by discharge ball check valve 27 held on its seat 29 by back pressure from discharge port 25, until outer space 19 is filled by the fluid at the end of the leftward stroke. Air control valve 16 now reverses, venting inner space 22 to the atmosphere through exhaust pipe 34 and directing compressed air into inner space 21 against diaphragm l7 and through conduit 32 into outer space 20 against diaphragm l8. Diaphragms l7 and I8 and connecting rod 23 move to the right and diaphragm l7 pushes the fluid in outer space 19 against inlet ball check valve 26 forcing it into its seat 28 to seal inlet port 24 and simultaneously against discharge ball check valve 27 raising it offits seat 29 and against the stop 31. Fluid moves through discharge port 25 under the force created by air pressure against both diaphragms 17 and I8 cooperatively acting by means of connecting rod 23, so that the pressure of fluid at discharge port 25 is substantially twice the pressure of the compressed air supplied to air control valve 16. When diaphragms I7 and 18 and connecting rod 23 complete the rightward stroke, air control valve 16 reverses, and the cycle is repeated.

FIG. 2 represents a pneumatically operated double-acting diaphragm pump 40 comprising interconnected pump 41 and pumping apparatus 42 which comprise casings 43 and 44 of substantially circular cross sections (as seen at right angles to the drawing) that form chambers 45 and 46, respectively, having therein cylindrical partitions 47 and 48, respectively, dividing the interior of casing 43 into segregated right and left compartments 49 and 50 and casing 44 into segregated right and left compartments 51 and 52, respectively; substantially vertically positioned, circular flexible diaphragms 53, 54, 55 and 56 spanning and dividing each of the compartments into inner spaces 57, 58, 59 and 60 and outer spaces 61, 62, 63 and 64, inner spaces 57 and 58 adjoining partition 47 and inner spaces 59 and 60 adjoining partition 48, while outer spaces 61 and 62 are remote from partition 47 and outer spaces 63 and 64 are remote from partition 48; movable means including rod 65 interconnecting diaphragms S3 and 54 centrally through partition 47 and rod 66 interconnecting diaphragms 55 and 56 centrally through partition 48, fluid inlet ports 67, 68, 69 and 70 and discharge ports 71, 72, 73 and 74 positioned substantially apart at the bottom and top, respectively of each of outer spaces 61, 62,63 and 64 and communicating therewith, with inlet ports 67 and 68 in communication with discharge ports 73 and 74, respectively; inlet ball check valves 75 and 76, discharge ball check valves 77 and 78 and ball check valves 79 and 80 which act as inlet valves for pump 41 and discharge valves for pumping apparatus 42, together with corresponding valve seats 81, 82, 83, 84, 85 and 86 and stops 87, 88, 89, 90, 91 and 92; conduits 93 and 94 providing communication between inner spaces 58 and 59 and 57 and 60, respectively; a valve chamber 95 formed in partition 47, an airoperated control valve 96 located within said valve chamber and adapted to admit compressed air alternately to each of inner spaces 57 (and 60 via conduit 94); and 58 (and 59 via conduit 93) and simultaneously to vent compressed air to atmosphere from the other of said inner spaces through air-exhaust conduit 97 and thereby to flex diaphragms 53 and 54 simultaneously in opposite directions from diaphragms 55 and 56. The diaphragms are centrally interconnected by rigid movable means and the compressed air is supplied and vented with means as in the pump of FIG. 1.

Fluid inlet ports

69 and 70 communicate with each other at and with inlet manifold 98, and fluid discharge ports 71 and 72 communicate with each other at and with discharge manifold 99.

In operation, control valve 96 vents to the atmosphere through exhaust conduit 97

inner spaces

57 and 60 and directs compressed air into

inner spaces

58 and 59, moving

diaphragms

55 and 56 and connecting rod 66 to the right and diaphragms 53 and 54and connecting rod 65 to the left, creating a suction in outer space 64 that draws fluid from inlet manifold 98 past inlet ball check valve 76, which is raised off its seat 84 and against the stop 90, and into outer space 64, which has been scaled by ball check valve 80 held on its seat 86 by the pressure in outside space 62 caused by the leftward movement of diaphragm 54 and simultaneously pushes fluid in outer space 63 (drawn in by previous stroke) against inlet ball check valve 75 forcing it onto its seat 83, against ball check valve 79 raising it off its seat 85 and against stop 91, and into outer space 61, until the end of the stroke when

outer spaces

61 and 64 are filled with the fluid to be pumped. Air control valve 96 now reverses, venting to the atmosphere through exhaust conduit 97

inner spaces

58 and 59 and directs compressed air into

inner spaces

57 and 60, moving diaphragms 55 and S6 and connecting rod 66 to the left and

diaphragms

53 and 54 and connecting rod 65 to the right. These movements simultaneously draw fluid from inlet manifold 98 past inlet ball check valve 75 raised off its seat 83 and against stop 89 and into outer space 63, push the fluid in outer space 64 against inlet ball check 76 forcing it onto its seat 84, against ball check valve 80 raising it off its seat 86 and against stop 92, into outer space 62 which has been scaled by back pressure from discharge manifold 99 forcing discharge ball check valve 78 onto its seat 82, and against diaphragm 54, and push the fluid in outer space 61 against ball check valve 79 forcing it onto its seat 85, against discharge ball check valve 77 raising it off its seat 81 and against stop 87, past discharge ball check valve 77, and into discharge manifold 99. The total force moving the fluid from outer space 61 into discharge manifold 99 is the force of the compressed air in inner space 60 acting on diaphragm 56 and transmitted by means of the fluid in

outer spaces

64 and 62 pushing against diaphragm 54 and via connecting rod 65 against diaphragm 53 added to the force of the compressed air in inner space 57 acting directly on diaphragm 53, making the pressure of the fluid in discharge manifold 99 substantially twice the pressure of the compressed air. At the end of the rightward stroke of

diaphragms

53 and 54 and connecting rod 65, air control valve 96 reverses, and the cycle is repeated, with the fluid in outer space 62 being forced on the next stroke against discharge ball check valve 78 lifting it off its seat 82 and against stop 88 and into discharge manifold 99.

The materials of construction are not specifically limiting or critical for the improved pump of the present invention. The pump casing, partition, valves, clamping disks, and connecting means therefore may be made of any conventional metal having adequate strength, e.g., aluminum. A stainless steel alloy, such as type 304 stainless steel, which is resistant to corrosion by acidic slurry blasting agents or other corrosive liquids being pumped, is preferred for all parts of the pump which come in contact with the corrosive liquid. Centrally perforated diaphragms having molded beads at the inner and outer peripheries are illustrated in the drawing, but unperforated diaphragms may be used. The diaphragms generally are constructed of flexible and resilient polymeric materials reinforced by embedded fibrous materials or structures. Reinforced molded neoprene diaphragms are preferred in a pump of the present invention, but are not critical to the operation thereof. In general, the material chosen for said diaphragms will be compatible with and will have long service life when in contact with the fluid being pumped. While ball check valves are illustrated in the drawing, any other suitable valves can be used, such as, for example, flapper valves or guillotine valves. When ball check valves are used, the balls preferably are made of neoprene. However, any long-lived resilient polymeric material may be used in place of neoprene. Ball check valves, having metal-to-metal seals, of course, are not suitable from the safety standpoint when the fluid being pumped is an explosive or contains an explosive ingredient. Ball check valves may be made of any compatible metal if nonexplosive, noncorrosive, and nonhazardous materials, for example food products, are being pumped.

While specific embodiments of the pump of this invention have been illustrated in detail, they are not meant to limit the scope of this invention in any way, for other embodiments will be obvious to those skilled in the art. For example, while the drawings illustrate substantially horizontal pumps with substantially vertically disposed diaphragms, these are not critical features of this invention. Similarly, while fluid inlet and discharge ports are shown which are substantially l from each other, this also is not a critical feature of this invention.

Advantages gained by use of the improved diaphragm pumps of the present invention are further illustrated by the following examples, which, however, are not to be interpreted as limiting in any way the scope of the present invention.

EXAMPLE 1 A single-acting diaphragm pump of FIG. 1 is used to pump water. When compressed air at a pressure of 90 lb./sq. in. is supplied to the pump, the water is discharged through a hose connected to the fluid discharge port at a pressure of I50 lb./sq. in. and at a rate of 14 gaL/min. When the discharge hose is closed off, the dead end" pressure is I75 lb./sq. in.

EXAMPLE 2 A double-acting diaphragm pump of FIG. 2 is used to pump water. When compressed air at 90 lb./sq. in. is supplied to the pump, the water is pumped through a hose connected to the discharge manifold at a discharge pressure of l50l65 lb./sq. in., the pressure varying as the pumping rate is changed.

EXAMPLE 3 A double-acting diaphragm pump of FIG. 2 is used to pump a water gel explosive composition through I00 ft. of l-in. ID hose at a rate of 30-35 lb./min. The air pressure supplied to the pump is 90 lb./sq. in. and the discharge pressure of the pumped fluid is l45l 50 lb./sq. in.

EXAMPLE 4 A single-acting diaphragm pump of FIG. 1 is used to pump several water gel explosive compositions, having different viscosities, through l5 ft. of l-in, ID hose and 8 ft. of %-in. aluminum pipe at rates of l5-70 lb./min., the rate depending on the viscosity of the composition. The air pressure supplied to the pump is 90 lb./sq. in., and the discharge pressure of the pumped fluids varies from 1 10 to lb./sq. in.

What is claimed is:

1. A diaphragm pump comprising a casing having therein a partition dividing the interior of said casing into two separate compartments, a flexible diaphragm spanning and dividing each of said compartments into inner and outer spaces, the

former of which adjoin, while the latter are located remotely from said partition, fixedly attached rigid movable means interconnecting said diaphragms through said partition, valved fluid inlet and discharge ports in at least one of said outer spaces, an air control valve chamber and an air-operated control valve located within said valve chamber positioned and adapted to admit compressed air alternately to each of said inner spaces and simultaneously to vent compressed air to the atmosphere from the other of said inner spaces through an airexhaust conduit and thereby to flex said diaphragms simultaneously in like directions, and means adapted to utilize said compressed air to apply pressure to the outer space side of a diaphragm which is remote from the outer space having said ports so that the pressure therein varies directly with the pressure in the inner space which is adjacent to said outer space having said ports thereby supplementing the force exerted by the compressed air in said inner space on the diaphragm adjacent thereto via said rigid movable means.

2. A pump of claim 1 wherein only one of said outer spaces has said ports therein and said means adapted to utilize said compressed air comprises a conduit connecting the outer space not having said ports with the inner space remote therefrom.

3. A pump of claim 1 wherein each of said outer spaces has said ports therein and said means adapted to utilize said compressed air comprises a pumping apparatus which comprises a casing having therein a partition dividing the interior of said casing into two separate compartments, a flexible diaphragm spanning and dividing each of said compartments into inner and outer spaces, the former of which adjoin, while the latter are located remotely from said partition, fixedly attached rigid movable means interconnecting said diaphragms through said partition, valved fluid inlet and discharge ports in each of said outer spaces and communicating therewith, one of said fluid discharge ports of said pumping apparatus being in communication with one of said fluid inlet ports of said pump and the other fluid discharge port of said pumping apparatus being in communication with the other of said fluid inlet ports of said pump, and two conduits, one conduit connecting an inside space of said pumping apparatus with the inside space of said pump which is adjacent the outside space of said pump the fluid inlet port of which is in communication with the fluid discharge port of the outside space of said pumping apparatus remote from said inside space of said pumping apparatus, and the other conduit connecting the other inside space of said pumping apparatus with the other inside space of said pump.

4. A pump of claim 2 wherein said diaphragms are positioned substantially vertically and, said fluid inlet and discharge ports are positioned substantially from each other at the bottom and top, respectively, of said outer space and are valved with ball check valves.

5. A pump of claim 3 wherein said diaphragms are positioned substantially vertically and, said fluid inlet and discharge ports are positioned substantially 180 from each other at the bottom and top, respectively, of each of said outer spaces and are valved with ball check valves.

* i t l I

Claims

1. A diaphragm pump comprising a casing having therein a partition dividing the interior of said casing into two separate compartments, a flexible diaphragm spanning and dividing each of said compartments into inner and outer spaces, the former of which adjoin, while the latter are located remotely from said partition, fixedly attached rigid movable means interconnecting said diaphragms through said partition, valved fluid inlet and discharge ports in at least one of said outer spaces, an air control valve chamber and an air-operated control valve located within said valve chamber positioned and adapted to admit compressed air alternately to each of said inner spaces and simultaneously to vent compressed air to the atmosphere from the other of said inner spaces through an air-exhaust conduit and thereby to flex said diaphragms simultaneously in like directions, and means adapted to utilize said compressed air to apply pressure to the outer space side of a diaphragm which is remote from the outer space having said ports so that the pressure therein varies directly with the pressure in the inner space which is adjacent to said outer space having said ports thereby supplementing the force exerted by the compressed air in said inner space on the diaphragm adjacent thereto via said rigid movable means.

4. A pump of claim 2 wherein said diaphragms are positioned substantially vertically and, said fluid inlet and discharge ports are positioned substantially 180* from each other at the bottom and top, respectively, of said outer space and are valved with ball-check valves.

5. A pump of claim 3 wherein said diaphragms are positioned substantially vertically and, said fluid inlet and discharge ports are positioned substantially 180* from each other at the bottom and top, respectively, of each of said outer spaces and are valved with ball check valves.