WO2002033296A2

WO2002033296A2 - Pneumatically actuated membrane valve assembly

Info

Publication number: WO2002033296A2
Application number: PCT/US2001/045601
Authority: WO
Inventors: Michael Ferrill; James Shannon; Hossain Saneii
Original assignee: Advanced Chemtech, Inc. (A Kentucky Corporation)
Priority date: 2000-10-19
Filing date: 2001-10-19
Publication date: 2002-04-25
Also published as: WO2002033296A3

Abstract

A valve assembly (10) is described comprising a valve body (12) and a manifold body (14) that overlays the valve body (12). In its simplest form,a pair of ports (22, 24) opens to the upper surface of the valve body (12) adjacent one another for ingress and egress of a fluid. The paired openings define a valve seat area (26) on the upper surface of the valve body (12). A flexible membrane (28) overlays the valve seat area (26) and is actuated by air pressure for movement between a closed position sealing the port openings (22, 24) and an open position allowing fluid communication between the port opening pair (22, 24). Conventional valves such as solenoid valves are provided to control the flow of air to the membrane sheet (28). Ancillary equipment such as the solenoid valves, is isolated from the fluids flowing through the valve body (12) to reduce maintenance and increase the useful life of the ancillary equipment.

Description

PNEUMATICALLY ACTUATED MEMBRANE VALVE ASSEMBLY

Field of the Invention

This invention relates to valve assemblies and more particularly to pneumatically actuated membrane valve manifold assemblies

Background of the Invention A critical component of process systems are valve assemblies that are relied on to control the flow of fluids in a process or to supply the proper amount of a fluid in a chemical reaction and the like. For example, in automated chemical synthesis equipment as many as 192 valves may be employed in the reactant delivery system and for carrying out the various aspects of the synthesis, such as washing, flushing reaction wells, recovering reaction products and the like. Similarly valves and valve assemblies are critical components in other manufacturing processes, such as semi conductor manufacture.

Valve assemblies required an actuating mechanism to open and close the valve. Such actuating mechanisms may be a mechanical linkage or mechanical/electrical or pneumatic solenoid operated valves. In either case the valve assembly and the associated actuating mechanism require a substantial amount of space. Conventional valves are used for such applications as automated chemical synthesis in which reaction blocks containing as many as 96 reaction wells where, as stated above, as many as 192 valves are required to control fluid flow to the reaction wells. However, the large number of conventional valves requires a relatively large space in the robotic apparatus. In addition, conventional valves are subject to wear and can damage the valve seats of the reaction block or be damaged themselves, especially when subjected to harsh chemical conditions. The use of conventional valves in such an application can result in a substantial amount of time-consuming and expensive maintenance. Accordingly, valves are not normally directly associated with the reaction blocks in automated chemical synthesis thus requiring a complexity of lines and eliminating the automation of certain types of reactions which require that the reaction well be sealed, such as reactions that are carried out under pressure or reflux operations. Summary of the Invention

Accordingly, it is an object of this invention to provide a low-cost, easily maintained valve assembly.

Another object of the invention is to provide a valve assembly that is pneumatically actuated.

Yet another object is to provide a valve assembly that can be configured as a simplified manifold.

Still yet another object of the invention is to provide a valve assembly the is resistant to harsh chemical conditions thereby increasing the useful life of the assembly and reducing maintenance costs and losses due to equipment downtime

These and other objects and advantages of the invention are provided by a valve assembly comprising a valve body and a manifold body that overlies the valve body. The valve body includes at least one membrane valve that comprises a pair of ports formed by passages that open to the upper surface of the valve body adjacent one another. One passage is in fluid communication with a source of fluid to be controlled through the valve and the othe passage being in fluid communication with a destination container for receiving the fluid. The portion of the upper surface of the valve body around the ports defines a valve seat area. A flexible membrane sheet overlays the valve seat area for movement between a closed position sealing the port openings and an open position allowing fluid communication between the ports. As assembled, the manifold body serves to secure the membrane sheet against the upper face of the valve body. A control duct in the manifold body communicates with a source of fluid pressure and opens to the lower face of the manifold body in general alignment with the valve seat area of the valve body. A gas tight seal is provided by a sealing member that is disposed between the membrane sheet and the manifold body. The sealing member has an opening in alignment with the control duct opening and the portion of the membrane sheet overlying the valve seat area provides pneumatic access to the membrane sheet for moving the it into the sealing position over the port opening pairs. Release of the pneumatic pressure allows the membrane sheet to return to its normally open position. Control of the pneumatic fluid actuating the membrane valve is preferably carried out by conventional valves that are isolated from exposure to corrosive chemicals.

The valve assembly can be scaled in size and connected by suitable lines to a reaction well for fluid communication therewith. In another embodiment, the valve assembly comprises a plurality of membrane operated valves that can be scaled down in it in size to provide the central valve control and manifold system for automated synthesis apparatus.

Brief Description of the Drawings

FIG. 1 is a side view in section and exploded illustrating the preferred embodiment of the valve assembly of the present invention;

FIG. 2 is a side sectional view of the valve assembly of FIG. 1 illustrating the valve in the close position; and

FIG. 3 is a side sectional view of the valve assembly of FIG. 1 illustrating the valve in the open position.

FIG. 4 is an exploded perspective view of another embodiment of the valve manifold assembly of the invention; FIG. 5 is a top plan view of the intermediate plate of the assembly of FIG. 4;

FIG. 6 is a bottom plan view of the intermediate plate of the assembly of FIG. 4; FIG. 7 is a top plan view of the valve body of the assembly of FIG. 4; FIG. 8 is a side section view of the valve/manifold assembly of FIG. 1 as viewed along line 8-8 of the valve body of FIG. 7; FIG. 9 is a side section view of the valve/manifold assembly as viewed along line 9-9 of the valve body of FIG. 7;

FIG. 10 is a top plan view of the upper face of the valve body of FIG. 1; FIG. 11 is a top plan view of the base plate of the assembly of FIG. 4; and FIG. 12 is an end elevation partially in section of the valve manifold assembly of FIG. 4, as assembled, illustrating the assembly in fluid communication with a reaction vessel.

Description of the Preferred Embodiment

As illustrated in FIG. 1, the valve assembly designed in accordance with the invention and designated generally as 10 comprises a valve body 12 and a manifold body 14 that overlies the valve body in the assembled condition. The manifold body 14 is secured by suitable conventional means, such as by bolts (not shown) that extend through the manifold body and that are received in threaded sockets (not shown) in the valve body 12 . The valve body 12 includes an inlet passage 16 and an outlet passagelδ, both of which open to the upper surface 20 of the valve body to define an inlet port 22 and an outlet port 24, respectively. The inlet port 22 and the outlet port 24 open to the upper surface 20 of the valve body 12 immediately adjacent one another and the area of the valve body upper surface immediately surrounding the openings comprises a valve seat area 26. As illustrated the valve seat area 26 is flush with the remaining portion of the upper surface 20 of the valve body 12 , however, the valve seat area may be machined so that the inlet port 22 and the outlet port 24 are located slightly below the valve body upper surface.

A membrane sheet 28 overlies the upper surface 20 of the valve body 12 and covers the valve seat area 26. The membrane sheet 28 is flexible for movement between a closed position in which the inlet port 22 and the outlet port 24 are sealed by the membrane sheet and an open position in which fluid communication exists between the inlet port 22 and the outlet port. For ease of manufacture, the membrane sheet 28 covers the entire upper surface 20 of the valve body 12 and secured by the clamping action of the manifold body 14 on the valve body. However, rather than using a membrane sheet 28 to overlie the upper surface 20, it is within the scope of the invention to provide a small membrane disk or section to overlie only that portion of the upper surface 20 comprising the valve seat area 26. One method for securing a small membrane sheet is to provide a raised annulus 42 (FIG. 6) on the lower surface 36 of the manifold body 14 surrounding a control port 38 that opens to the lower surface of the manifold body. As the manifold body 14 is clamped against the valve body 12 the annulus 42 secures the membrane Overlying the membrane sheet 28 is a sealing member 30 which provides a gas tight seal between the valve body 12 and the manifold body 14 . The sealing member 30 is perforated in the area overlying the valve seat area 26 to provide an opening 32 for fluid communication between the membrane sheet 28 in the area of the valve seat area 26 and the manifold body 14. The opening 32 defines a relief space, illustrated in FIG. 2 and 3, for receiving a portion of the membrane sheet 28 when in the valve is in the open position.

The control duct 34 in the manifold body 14 communicates with a source (not shown) of pneumatic pressure and it opens to the lower surface 36 of the manifold body 14 to define the control port 38. The control port 38 is aligned with the valve seat area 26 in the valve body 12 for fluid communication with the portion of the membrane sheet 28 overlying the valve seat area 24. The membrane sheet 28 is moved to its closed position sealing the ports 22 and 24 by directing pressure to the control port 38 to create a differential pressure across the membrane sheet. The flexible membrane sheet 28 is forced tightly against the inlet and outlet port openings, 22 and 24, to seal them to prevent fluid communication there between. Removing the fluid pressure at control port 38 allows the flexible membrane sheet 28 to open in response to pressure asserted by the flow of fluid between the inlet port 22 and the outlet port 24.

Referring to FIG. 2, the membrane sheet 28 is shown in its closed position. The control port 38 is pressurized to force the flexible membrane sheet 28 against the valve seat area 26 to seal the inlet port 22 and the outlet port 24. FIG. 3 illustrates the valve in the open position when the control port 38 is depressurized. In the absence of pressure, the membrane sheet 28 can be lifted away from the inlet port 22 and the outlet port 24 and fluid communication there between is restored. The opening 32 in the sealing member 30 provides the space into which the portion of the membrane sheet 28 over the valve seat area 26 is lifted by the force of the fluid flowing through the inlet port 22 and the outlet port. When lifted into the relief space, the membrane sheet 28 defines a chamber for fluid flow from the inlet port 22 to the outlet for and prevents fluid contact with the sealing member.

The membrane sheet 28 is formed of a material which is both flexible and inert with respect of fluids being controlled by the valve assembly. For chemical synthesis operations the preferred membrane sheet material is Teflon®. The Teflon® membrane sheet 28 is formed by skiving thin sheets from a Teflon block. Although the thickness of the membrane sheet 28 can vary depending on the application and fluid pressures to be encountered, good results are achieved with a membrane sheet thickness on the order of 0.002 inches. Similarly, it is highly preferred that the valve body 12 also be formed of Teflon®, particularly where the valve assembly 10 is to be employed in chemical synthesis where exposure to highly corrosive chemicals is likely.

The amount of pressure applied at the control port 38 is determined by the pressure of the fluid flow through the valve body 12 . Free flow of fluid (and thus the valve is open) from the inlet port 22 to the outlet port 24 will occur as long as the ratio of control port 38 pressure to the pressure at the inlet port and the outlet port is 0.59:1.00 or less. Thus it can be seen that some pressure may be applied at the control port 38 without causing the valve to close or otherwise limit the flow of fluid through the valve body 12 .

The valve assembly can be scaled to fit a particular fluid control system such as the single valve assembly illustrated in FIGS. 1 , 2 and 3 or can be employed as a series or combination of valve assemblies for serving as a valve manifold system for more complex operations, such as controlling fluid flow for automated chemical synthesizers. In such an application, a valve assembly having a plurality of valves can be integrally formed as part of a reaction block having a corresponding plurality of reaction wells or as explained and illustrated in connection with FIGS. 4-12, can be separate from, but in fluid communication with, a reaction vessel for automated synthesis protocols.

Referring to FIG. 4, a valve/ manifold assembly 50 designed to control the distribution of fluids to a number of separate reaction vessels comprises a valve block 52 having a plurality of membrane valves defined by a set of inlet ports 54 and outlet ports 56 opening on its upper surface (FIG. 10) for each membrane valve. Each set of inlet ports 54 and outlet ports 56 and the area surrounding the ports defines a valve seat 58 as described above in connection with FIG. 1. The assembly 50 further includes a manifold body assembly consisting of a pneumatic valve mounting plate 60, an intermediate plate 62 and a base 64.

A gasket sheet 66 is disposed between the pneumatic valve mounting plate 60 and the intermediate plate 62 and a second gasket sheet 67 is disposed between the valve block 52 and the base 64 to provide a pressure tight seal between those members. A chemically resistant sheet 68, preferably a Teflon® sheet overlies the upper face of the base 64 to protect the gasket sheet 66 from the effects of chemicals introduced to the valve block 52. In the alternative, the gasket sheet 66 can be provided with a layer of chemically resistant material that is bonded onto the surface of the gasket facing the base. A flexible chemically resistant membrane sheet 70, preferably a Teflon® sheet skived from a block of Teflon® as described above, overlies the upper face of the valve block 52 and a third gasket sheet 71 is disposed between the membrane sheet and the intermediate plate 62. For purposes of description reference to the chemically resistant membrane sheet 70 includes reference to the third gasket sheet 71 since the pressure fluid acts against the third gasket sheet to cause the chemically resistant membrane sheet to seal the ports 54 and 56 of a valve.

Conventional solenoid operated pneumatic valves 72 are mounted on the upper surface of the pneumatic valve mounting plate 60 for controlling the flow of pressure fluid that actuates the opening and closing of the membrane sheet 70 at selected inlet ports 54 and outlet ports 56. The two longitudinal sides of the valve block 52 are provided with openings 74 for the egress of fluids that are distributed by the manifold/valve assembly 50 to reaction vessels. It will be understood that each valve of the assembly 50 can be placed in fluid communication with a corresponding reaction vessel. However, depending the number and or quantity of reaction product desired not every valve of the valve block 52 need be utilized and during such a reaction protocol the unsed valves will not be in fluid communication with a reaction vessel.

Longitudinal adapter blocks 76 having threaded apertures 78 are secured to the longitudinal sides of the valve block 52 . The apertures 78 are aligned with the openings 74 in the valve block 52 and fittings 80 are threadibly received in the apertures for connection of each valve to lines(not shown) that are in fluid communication with corresponding reaction vessels. Similarly, supply ports 82 (shown in FIG. 12) for conducting fluids to and from the valve block 52 from a source (not shown) open at one transverse end of the valve block 52 and a transverse adapter block 84 with threaded apertures 78 is provided for receiving fittings 80 for connection to lines (not shown) from the source of such fluids . The assembly 50 is supported by a bracket 86 and a pair of risers (one riser 88 shown). A plurality of passages 90 corresponding in size and location are provided in each component to define in the assembled condition bolt passages through which extend bolts 92 for securely clamping the components of the assembly 50 together.

Referring to FIGS. 5 and 6, the upper (FIG. 5) and the lower (FIG.6) surface of the intermediate plate 62 are shown. The upper surface is provided with a series of grooves 94 that communicate with through-running ports 100 (FIG. 12) in the pneumatic valve mounting plate 60. A pair of conduits 102 open at each transverse end of the pneumatic valve mounting plate 60 for the ingress and egress of pressure fluid. When assembled the grooves 94 cooperate with the lower face of the pneumatic valve mounting plate 60 to define a chamber for the pressure fluid. A through-running duct 104 opens at each end of the grooves 94 to open to the lower face of the intermediate plate 62 in alignment with the valve seat 58 of an underlying valve. Each of the grooves is in fluid communication with the valve seat 58 of two valves.

In the embodiment shown in FIG. 6, the lower face of the intermediate plate 62 is provided with raised annular members 106 that surround each opening of the ducts 104 in the lower face. The annular members 106 extend down from the lower face of the intermediate plate 62 to clamp the membrane sheet 70 at the periphery of the valve seat 58 to further insure that there is no leakage of fluid to adjacent valves. The annular members 106 also, in cooperation with the upper face of the valve block 52, define a valve chamber 108 (most clearly shown in FIGS. 8 and 9)to confine the flow of fluid between the inlet port 22 and the outlet port 24 of a valve. In the embodiment shown each of the grooves 94 serves to distribute pressure fluid to two membrane valves, however, it can be seen that the grooves can be formed to serve only a single membrane valve.

As shown in FIG. 10 the upper surface of the valve block 52 is provided with a series of paired openings with one opening defining an outlet port 56 and the other opening of the pair defining an inlet port 54 of the valve. Referring to FIG. 7, a first groove 110 and a second groove 112 are formed in the lower surface of the valve block 52 . The first groove 110 and the second groove 112 communicate with the supply ports 82 in the transverse end of the valve block 52 . In the assembled condition the first groove 110 and the second groove 112 cooperate with corresponding first and second grooves, 114 and 116 respectively, in the base 64 (FIG. 7) to define a first supply channel 118 and a second supply channel 120 (FIGS. 8, 9 and 12) for the ingress and egress of reactant fluids and inert gases to and from the valve block 52 . The first supply channel 118 can communicate with a liquid or gaseous reagent for selective transfer to a reaction vessel while the second supply channel 120 can communicate with a source of an inert gas to maintain an inert atmosphere in the reaction vessel if desired and for providing the pressure to move the contents of the reaction vessel out of the vessel. As shown in FIG. 9 a fitting 80 in the supply port 82 is adapted for connection to a line for leading in a fluid that is conveyed to the second supply channel 120 through lines 122 and 124. As mentioned above, each of the grooves 94 in the upper surface of the intermediate plate 62 communicates with the inlet port 54 and outlet port 56 of two of the membrane valves, one valve controlling flow from the first supply channel 118 and the second valve controlling the flow from the second supply channel 120

Laterals 126 communicate between the groove 110 and 114 that form the first supply channel 118 and the openings 74 in the longitudinal walls of the valve block 52. Similarly, laterals 128 communicate between the groove 112 and 116 that form the second supply channel 120 and the openings 74. As is most clearly shown in FIG. 8 an inlet passage 130 communicates between the first supply channel 118 and the inlet port 54 of each valve. Similarly inlet passages (not shown) communicate between the second supply channel 120 and the inlet ports 54 of the valves controlling fluid flow from the second supply channel in the same manner as illustrated in FIG. 8 in connection with the first supply channel 118. An outlet passage 132 communicates between the adjacent outlet port 56 of each of the valves and a corresponding lateral for leading fluid to the respective opening. The outlet passages from the valves controlling fluid flow from the second supply channel 120 are arranged in the same manner. As mentioned above, the annular members 106 on the lower face of the intermediate plate 62 act against the gasket and membrane sheet 70 and the upper surface of the valve surrounding paired inlet port 54 and outlet port 56 of each valve to define a valve chamber. The surface of the valve block 52 immediately surrounding the inlet port 54 and the outlet port 56 of each valve defines a valve seat 58 . Although not critical to the functioning of the valve, the valve seat 58 areas may slightly countersunk to enlarge the valve chamber and to insure that, when sealed, the possibility of leakage of fluid around the membrane to adjacent valves is minimized.

The operation of the valve/manifold assembly 50 is best described in conjunction with FIG. 12 in which the first supply channel 118 communicates with a source of a liquid reagent and the second supply channel 120 communicates with a source of an inert gas. Means such as a conventional pump and valve (not shown) are provided to initiate and terminate the flow of reactant liquid through the first supply channel. Conventionally the inert gas will be supplied from a cylinder in which the pressurized gas is contained.

Solenoid operated 3 -way pneumatic valves are mounted on the upper surface of the pneumatic valve mounting plate 60 over each elongated groove 94. A pressurized fluid such as compressed air is caused to flow through the conduits 102 and the valves are positioned to feed the compressed air through the through-running ports 100 so that pressure is normally applied to the membrane sheet 70 to seal the inlet ports 54 and outlet ports 56 of the valves. The flow of liquid reactants 133 to a reaction vessel 134 is initiated by circulating the reactant from its source through the first supply channel 118. The pneumatic valve 72 controlling the membrane valves for the reaction vessel 134 is positioned to cut off the flow of air to the membrane sheet 70 overlying the valve seats 58 for the valves to be opened thus relieving the pressure on the membrane sheet and allowing fluid to flow from the first supply channel 118 through the inlet passage 130 and inlet port 54 to the outlet port 56 and outlet passage 132 to the reaction vessel 134 through a line 136. When the desired quantity of liquid has been transferred to the reaction vessel 134, the pneumatic valve 72 is repositioned to direct air pressure to the membrane sheet 70 to reseal the inlet ports 54 and outlet ports 56. Once the liquid has been distributed the circulation of reagent through the first supply channel 118 is terminated and the flow of inert gas through the second supply channel 120 is initiated. In manner described above, pressure is relieved on the membrane sheet 70 as described above to open the valve allowing the inert gas to flow from the second supply channel 120 to form a layer 138 of inert gas over the liquid 133. The valves are resealed as described above and the flow of inert gas through the second supply channel 120 is terminated. With the valves resealed it will be understood that the inert gas pressure can be maintained in the reaction vessel if the reaction vessel is properly sealed thus allowing reactions to be carried out under pressure. It will be seen that the valves operate in the same manner as described for the valve illustrated in FIG. 1, 2 and 3. Pairs of valves are provided for each of the reaction wells connected to the valve/manifold assembly 50 and as stated above reactions can be carried out under pressure. Likewise an inert atmosphere can be maintained in the reaction wells permitting reactions which must be carried out under an inert atmosphere to be performed by automated chemical synthesis equipment. Such operations cannot be carried out using conventional reaction blocks. In addition, it will be seen that a different liquid reagent can be circulated through the first supply channel 118 and the second supply channel 120 so that two different reagents can be controllably introduced by the manifold/valve assembly of the invention to a plurality of reaction vessels.

From the foregoing it can be seen that the pneumatically operated solenoid valves are isolated from contact by corrosive chemicals that can shorten the useful life of the pneumatic valves and substantially add to the cost of operating conventional apparatus due to valve replacement costs as well as laboratory time lost while the apparatus is not operating. In addition the valve/manifold assembly is easy to maintain and the gasket sheet and membrane sheet can be readily replaced at a minimum of cost.

As will be understood by those skilled in the art, various arrangements which lie within the spirit and scope of the invention other than those described in detail in the specification will occur to those persons skilled in the art. It is therefor to be understood that the invention is to be limited only by the claims appended hereto.

Having defined our invention we claim:

Claims

1. A pneumatically actuated valve assembly comprising: . a valve body defining an upper face; an inlet passage in said valve body for fluid communication with a source of fluid being controlled by said valve body; an outlet passage for fluid communication with a destination container for receiving said fluid; an inlet port opening in said upper face of said valve body to provide fluid communication between said inlet port and said upper face of said valve body; an outlet port opening in said upper face of said valve body to provide fluid communication between said outlet port and said upper face of said valve body; a valve seat consisting of a portion of said upper face of said valve body surrounding said inlet and said outlet port openings; a manifold body defining a lower face in juxtaposition to said upper face of said valve body; a valve actuating duct opening on said lower face of said manifold body , said duct opening being aligned with said valve seat, said duct being in fluid communication with a source of fluid under pressure; a flexible sheet defining an inner and an outer surface disposed between said valve body and said manifold body overlaying said valve seat, said flexible sheet being movable between an open position to allow fluid communication between said inlet port opening and said outlet port opening and a closed position to seal said inlet port opening and said outlet port opening responsive to a force provided by said fluid under pressure acting against said flexible sheet through said valve actuating duct in said manifold body.

2. The pneumatically actuated valve assembly of claim 1 further including valve apparatus for controlling the flow of fluid under pressure to said valve actuating duct for activating and deactivating said valve.

3. The pneumatically actuated valve assembly of claim 2 wherein said valve apparatus consists of a solenoid operated three way valve, said solenoid valve being disposed between said valve actuating duct and a source of fluid under pressure.

4. The pneumatically actuated valve assembly of claim 1 wherein said flexible sheet is comprised of a material that is chemically inert with respect to the fluid being controlled by said valve assembly.

5. The pneumatically actuated valve assembly of claim 4 wherein said flexible sheet comprises a polytetrafluoroethylene polymer.

6. The pneumatically actuated valve assembly of claim 1 further including a sealing member between said manifold body and the outer surface of said flexible sheet, said sealing member being open at said valve seat to define a relief area in cooperation with the lower face of said manifold body into which a portion of said flexible sheet overlaying said valve seat can be lifted when said valve is in the open.

7. The pneumatically actuated valve assembly of claim 1 wherein said valve seat, and said flexible sheet cooperate to define a flow chamber for said fluid flowing between said inlet port and said outlet port when said flexible sheet overlaying said valve seat is in the open position.

8. The pneumatically actuated valve assembly of claim 1 comprising a plurality of said valve bodies, each of said valve bodies being in fluid communication with a corresponding destination vessel.

9. The pneumatically actuated valve assembly of claim 2 wherein said flexible sheet comprises a barrier between fluids flowing through inlet and said outlet port and said valve apparatus whereby said valve apparatus is isolated from contact by said fluid.

10. A valve/ manifold assembly to control the distribution of fluids to a plurality of separate reaction vessels, said assembly comprising: a valve body having an upper surface and a lower surface and including at least a pair of valves, each said valve including an inlet passage opening on the upper surface of said valve block to define an inlet port and an outlet passage opening on the upper surface of said valve block adjacent said inlet port to define an outlet port, at least one supply channel communicating with said inlet passage and a source of fluid being distributed, each said outlet passage communicating with a lateral passage for egress of the fluid being distributed to a corresponding destination container ; a manifold assembly having a lower face juxtaposed on the upper surface of said valve block, said manifold assembly being in fluid communication with a source of fluid pressure and further including a corresponding control duct opening on the lower face of said manifold assembly for fluid communication with each respective one of said valves; and a flexible sheet disposed between said manifold assembly and said valve body to overlie said inlet port and said outlet port of said valves, said flexible sheet being operable in response to fluid pressure from a corresponding control duct of said manifold assembly to seal said inlet port and said outlet port of said valve ;

11. The valve/ manifold assembly of claim 10 wherein the area of the upper surface of said valve body adjacent said inlet and out let port of each said valve defines a valve seat.

12. The valve/ manifold assembly of claim 11 further including an annular member formed on the lower face of said manifold assembly surrounding the opening of each control duct, said annular members acting against said flexible sheet overlying each said valve seat to clamp said flexible sheet at the periphery of said valve seat.

13. The valve/ manifold assembly of claim 10 wherein said manifold assembly comprises a pneumatic valve mounting plate and an intermediate plate, said intermediate plate defining the lower surface of the valve/ manifold assembly juxtaposed on the upper surface of said valve body and containing said corresponding control ducts;

14. The valve/ manifold assembly of claim 13 wherein said pneumatic valve mounting plate is in fluid communication with a source of pressure fluid and with said corresponding control ducts in said intermediate plate.