Patent Abstract:
A pump for ultra-pure fluids comprises a flexible diaphragm separating a fluid chamber from an air chamber. The diaphragm creates an airtight seal between the fluid chamber and the air chamber when a self-centering and trapezoidal shaped wedge compressively forces the diaphragm into a trapezoidal shaped perimeter cavity surrounding the chambers. Any leak from the fluid chamber into the air chamber is detected by a fiber optic system comprising two optical fibers that are disposed at an angle that is calculated to enable light to pass between the fibers only in the presence of a liquid having a predetermined index of refraction. The fiber optic system can also be used to determine the stroke of the pump by disposing the fiber optic lines at an angle calculated to reflect light off of the oscillating diaphragm when the diaphragm arrives at a predetermined location.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/642,426, entitled FREE-DIAPHRAGM PUMP, filed Aug. 21, 2000, abandoned, which is a continuation of U.S. patent application Ser. No. 09/166,490, entitled FREE-DIAPHRAGM PUMP, filed Oct. 5, 1998, which has issued as U.S. Pat. No. 6,106,246. Each of the aforementioned applications is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     This invention relates to components for operation in ultra-pure environments and, more particularly, to novel systems and methods for providing long-lived pumps that are metal-free, ultra-pure, non-reactive, etc. for providing environments for hot, reactive or pure, liquids at elevated temperatures, with respect to ambient. 
     2. The Relevant Technology 
     Non-reactivity is a critical function in systems managing, transporting, or relying upon fluids. Fluids include gases and liquids. Many industrial processes rely on liquids, that may damage, weaken, leach, or otherwise interact with metals, elastomeric polymers, and other common materials. 
     One industry that has suffered with the limited technology available to provide high purity and temperature is the semiconductor processing industry. For example, hot, de-ionized water is used in numerous processes. Impurities are measured in parts per billion. Some materials may be hot acids used in etching and cleaning processes. Transporting, holding, heating, and other procedures for managing ultra-pure water, acids, and the like, are problematic in several ways. 
     For example, pumps have traditionally been made of metal. Metals are commonly used in the support structures of the pumps. Regardless of the “stainlessness” of a metal, the purity requirements are not met by any known metals. 
     Polymers are often used for sealing members but may leach, react, degrade, or otherwise contaminate liquids. Moreover, polymers are typically not dimensionally stable. Polymers creep, stretch, yield, and otherwise become unreliable. Polymers (plastics, elastomers) respond to load, pressure, time, chemical environment, and, if any system failure occurs, may destroy any hope of reliability and “failing clean,” failing to function yet leaving no contamination possible. Failures in the sealings may arise by creep or yielding of polymers. Leaks or other failures may expose materials during any failure. Accordingly, seals do not achieve perfect protection. The ability to avoid failures completely ranges from extremely difficult to impossible. Failures can be catastrophic if a system will not “fail clean.” 
     Contaminants in trace amounts which exceed allowable limits may destroy a batch of product. Physical destruction is not required. Rendering a silicon wafer, or other high purity substrate material, unusable due to contaminant reaction with a surface can waste product output. Down time for decontamination may be even more costly in actual lost production. 
     What is needed is a fluid handling system that is clean to extremely high standards. All materials that may potentially contact contained fluids, even in the event of failures, should be pure and non-reactive. Materials should tolerate temperatures in the range of 1 degree Celsius to 180 degrees Celsius. In some acids, temperatures may range from 100 degrees Celsius to 180 degrees Celsius. 
     Thus, stability over a broad range of temperatures, reliability in service, long life under exposure to extreme of temperatures, pressure, and reactive agents, and the like must all be tolerated. Repeatability of designs, and reliable repeatability over the lifetime of all installed apparatus in the system are very desirable. Currently, the most reliable pump mechanisms still depend on elastomeric seals and metal structural supports. Pumps do not have sufficient life and do not “fail clean” in service. Upon failure, metals and elastomers are then exposed and are reactive. Thus, pumps still fail to maintain purity in failure or to operate reliably over many millions of cycles. 
     What is needed is a reliable, failclean, pump that operates over 10-50 million cycles, and that maintains purity, even in failure. Long term durability at elevated temperatures, pressures, and reactivities, without the threat of catastrophe at failure, is needed. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the foregoing, it is a primary object of the present invention to provide a clean, high temperature, non-reactive, repeatable, producible, reproducible, low-cost, dimensionally stable, long-lived pump. 
     It is an object of the invention to provide a pump that will tolerate conventional manufacturing processes while providing suitable reliability and low-cost operation and maintenance for routine installations. 
     It is an object of the invention to provide a pump construction that can rely on readily available materials and readily available manufacturing processes at standard a manufacturing tolerances in order to maintain costs while providing reliability over tens of millions of cycles. 
     It is an object of the invention to provide reliable sealing in a pump, long-lived diaphragms at low cost, and a simple reliable mounting assembly that will support a fluid handling system and which will fail clean in the event of any failure. 
     Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, an apparatus and method are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention. In certain embodiments an apparatus and method in accordance with the present invention may include a body and heads holding diaphragms with an associated adaptive seal. A union ring on each head may be provided, to connect to the body and to hold the diaphragm securely. 
     A pump may be assembled with threads. A union-type connector may hold the body and a head together. In one apparatus and method in accordance with the invention, a polymeric, preferably a fluoropolymer and non-reactive film, may form a diaphragm. The diaphragm maintains a single, substantially constant thickness without the need for changes in cross-section in order to accommodate mounting. The diaphragm may be contoured to fit a chamber so as to match the chamber wall at each end of a stroke. Accordingly, the diaphragm is fully supported when the pump is dead-headed, or backed up in a flooded or shut off position. 
     As a practical matter, no inflection point is required in the diaphragm during any unconstrained or unattatched point of its traverse. Hardware contact on the diaphragm is not substantial enough to cause overstressing, secondary creep, yielding or the like in the diaphragm. 
     The diaphragm is extremely reliable such that it becomes non-limiting in the life of the pump. Components close to the diaphragm use tight tolerances, closely matched angles, and short gaps between components. The configuration of the components provides for little unsupported material which reduces the stress within the material. No other loading is applied to the diaphragm. In the event of an air system failure, in an air-actuated pump, the high pressure applied to the diaphragm will be supported by the backing material on a chamber head or piston head. Likewise, since no buckling is required in the diaphragm, there is no change of direction and no inflection point within the chamber during operation. As a result, the life of the pump is greatly extended. 
     In one embodiment, the frame may be installed using a trapezoidal seal shim that produces a sharp angle bend, preferably less than or equal to 70 degrees. Thus, the diaphragms may be locked into trapezoidal slots, and held in place by trapezoidal shims, all comprising the same class of material, and preferably the exact chemically consistence or chemically identical material. Accordingly, the pump diaphragms limit any need for rim or compression seals, clamps, flanges, elastomeric seals, metals, and the like. 
     In one embodiment, the trapezoid may be irregular. One side may have a 70 degree angle, 20 degrees less than a right angle, and the other side may be a right angle. In another embodiment the trapezoid is regular and has a 70 degree angle, 20 degrees away from normal or perpendicular. The seal formed in a regular trapezoid becomes self centering. 
     The diaphragm is retained using no elastomeric materials, no rims, no metals, no flanges, no through-holes, and the like. Furthermore, the diaphragm is subjected to equalized loads. Prior art systems dealing with elastomeric materials will not fail clean. Moreover, creep is a factor in all fluoropolymers. However, geometries that can creep are adapted to conform to the seal, forming a tight mechanically adhesive load between the shim, the diaphragm, and the receiver slot for the shim. 
     A design after this mode prevents creation of diaphragm flange material that would pull in and increase diaphragm arc length. Increasing the diaphragm arc length tends to cause buckling or diaphragm roll at the point of flexure or the point of maximum flexure near the outer most confines of the chamber in which the diaphragm is located. Thus, even thin films of less than or equal to 30 thousands inch may be operated without buckling. Therefore, folding of the diaphragm and premature rupture of the diaphragm is avoided. 
     In one embodiment, a union nut is used to secure the head of the pump to the pump body or pump frame. A union nut is a slip ring having an aperture allowing the head to protrude there through away from the pump frame or pump body. The head may thus be registered, and the nut is fully free to slip circumferentially while loading the head longitudinally along the access of the driving rod between the pistons and diaphragms of the pump. 
     A non-reactive material, preferably a polypropylene is used to construct the entire nut. The nut applies a load to a cantilevered edge or lip of the head. Accordingly, primary creep is allowed to occur and loaded out. Thereafter, the head maintains sufficient spring properties, along with sufficient deflection under such spring properties, to maintain the minimum required loading of the head against the pump body at all times of service. 
     Moreover, the creep losses of thread materials and of the cantilevered head combine to permit less deflection than that required to maintain the spring loads in spite of continuing secondary creep. Therefore, head loading is maintained. The seal surface remains loaded and sealing. Pneumatic loading on the heads during actuation of the pump diaphragms is ineffective to cause excessive creep and unload the heads. Moreover, weeping, releasing chemicals, is eliminated. Moreover, compliant elastomeric seals are not required to act as energizers. Again, such a sealing system provides for a “fail-clean” failure in the event of any potential failure. 
     In one embodiment, the heads of the pump may be provided with leak detectors. The leak detectors may be sealed away from the fluid of the pump by a window. The window is constructed of “non-reactive” material that allows light to transmit. 
     In one embodiment, a thin diaphragm may be formed of polytetrafluoretheyne. In one embodiment, an anisotropic polymer is used. Moreover, in one embodiment, an expanded PTFE may be used. 
     Other plastics such as PFA may be used. Nevertheless, PTFE has been shown to be most effective. Moreover, by forming the diaphragm of PTFE, an amorphous fluoropolymer, a flexible diaphragm making a mechanically hermetic seal with the pump body and head (trapezoidal slot and shim) is so effective in practice that in certain circumstances minimal to no loading of the seal is required after a certain period of operational time. 
     Creep is ever present with fluoropolymers. Accordingly, threads creeping is typical when in tension and shrinking when in compression. Creep and shrinking presents a continuing problem in the use of fluorocarbons. In one embodiment, an entire pump may be assembled, with the lip on the edge of a head retained in an engagement portion of a slip ring or union nut threaded to the body of the pump. 
     Accordingly, creep will ensue in all components, the body, the cantilevered head portion and the slip ring or union nut. However, heat soaking and below ambient cooling under load may remove primary creep. Thereafter, the nut or union nut may be retightened on each end of the pump, maintaining dimensions within tolerances required for loading. Thus, secondary creep occurring after a heat soak and cooling cycle and loading of primary creep, is insufficient to unload the cantilevered member of the head, and thus maintains the head against the body in sealing relation. 
     A pump made in accordance with the invention improves operations substantially by including no metallic parts and no elastomeric parts. That is, an apparatus in accordance with the invention, is intended to “fail clean.” To fail clean signifies that a failure of any component within the pump, including any sealing component, results in no contamination of any liquids by reactive materials. Reactive materials include elastomeric polymers such as Neoprene™, Viton™, Nitrile, FKM, EPDM and the like. Other reactive materials include virtually all metals. Although some metals are considered non reactive, the requirements for the purity of liquids used in the semi-conductor processing industry is so strict that even “nonreactive” metals must be considered reactive in so far that the invention is concerned. 
     Thus, valves in the apparatus made in accordance with the invention contain no reactive components. Two types of strike valves or end-of-stroke valves are contemplated. In one embodiment, a short-stroke valve or poppet valve may operate at the end of a stroke of a diaphragm. The diaphragm, upon reaching the limits of the displacement permitted by a head portion of the operating cavity, contacts the head dome or cavity. Accordingly, a protrusion or post on a poppet valve is contacted by the diaphragm. The poppet valve opens a channel (air channel) to communicate with the now-evacuated head chamber over the diaphragm. The poppet valve, it&#39;s actuator with a post integrally formed therewith, and a seat securable, such as threadable, to the head, may be provided. 
     In another embodiment, a long valve may be adapted to access the end of a stroke of a diaphragm or piston retreating away from the head and toward the body of a pump in accordance with the invention. A long-stroke, pilot valve may be designed to operate as a spool. Accordingly, a shank or shaft of the long-valve may be provided with a bumper maintained in contact with a diaphragm, such as against a diaphragm over an underlying piston head driving and being driven by the diaphragm. 
     The spool shaft, shank, tang, etc. thus extends into the chamber until the piston and diaphragm are halted by stops. Thereafter, chamber pressure may bleed through ports in the pilot valve to shift operation of the pump, by reversing the stroke. The spools may be designed as known in the art to use the main shaft, having a circumferentially extending channel, with cylindrical bearings passing over ports. Accordingly, bearings may selectively expose ports to circumferential channels, thus altering a position of the spool and subsequent channeling of flows between ports in a main housing surrounding the spool. 
     In one embodiment, only machined surfaces of nonreactive materials act as sealing surfaces. Additional wear may occur due to a lack of hardness, durability, abrasive-resistance, and the like. Nevertheless, nonreactive polymers maintain low core frictions with one another in certain embodiments. Moreover, any particulates from galling, wear, abrasion, fretting, and the like will nevertheless remain nonreactive. Accordingly, filters and traps within flow lines may typically remove such particulates, and the presence of such particulates will not cause leaching of contaminating ions into pumped fluids. 
     In one embodiment, no elastomeric seals are used in any valve, including principal check valves checking against back flows into the double chambers of the pump. Machined surfaces serve as sealing surfaces, and relief or clearance is provided in each circumstance where needed in order to maintain loads, tolerate secondary creep, following heat soaking primary creep out, such that loading and deflection requirements for sealing are maintained. 
     Metal springs are used in certain devices. Likewise, elastomeric seals, such as face seals or “O” rings and the like are often used in prior art systems to form seals. Downtime, lost processing batches, and the like are very expensive propositions. Accordingly, a fail clean system made in accordance with the invention relies on no metal springs, no metal washers, no metal retainers, and no metal of any kind. The fail clean system further does not rely on reactive, or organic materials exposed to operating fluids (gases, air) nor the transferred fluids (DI water, acids, hot acids, etc.). Any possible contact between the air chamber, or the liquid chamber in the pump (of which the pump has two of each, typically) eliminates all contact even in the air chamber with metals and elastomers. 
     In one embodiment of an apparatus and method in accordance with the invention, a base mounting system may be used for integrating a controller with a pump. Air controllers may be external and may be remote from a pump. However, mounting a pump is often problematic. Accordingly, a base is provided in which fluid conduits of the pump are formed to become the legs connecting a pump for mechanical support to a base. Meanwhile, the entire air controller mechanism may be formed in the base. Alternatively, the base may simply pass air through the pump from an external controller, depending on a users selection. 
     Several types of air control systems exist. A recirculating air system does not use high pressure. A high duty cycle is typical. Duty cycles bordering on 100 percent over many days may exist. Such a recirculating control system may operate non-stop indefinitely. An external control apparatus relies on a third party to connect a speed control to a pump installation. The third-party speed control dictates the amount of air flow to actuate a pump. Accordingly, reducing volume or pressure of incoming, driving air can be used to decrease the speed of operation of the pump. Thus, decreased displacement may be obtained directly by an external control. 
     A third type of control module may be a distribution unit. A distribution unit may operate under control of controlling mechanisms within the base. However, as a distribution unit, a pump in accordance with the invention may be dead-headed against a closed line. Thus, the entire pressure of the pump may be brought to bare against the pump and conduit system. A modular air pump may be made externally removable. However, a mount in accordance with the invention may be used for either recirculating air, external air vented to atmosphere after actuation of a cycle of the pump operation, or a distribution unit in which air is recirculated but the pump may be dead-headed against a closed line. A mount may provide a platform adapted to a universal pump. Adapted to different bases for control schemes. 
     By providing the opportunity for an external air system to mount to the base, the air logic transfer passages may be connected to the pump body directly from the external control system without the use of elastomeric seals. The base is symmetric about its air logic porting. One may note that externally controlled systems theoretically produce no contaminates that could be received into a system. Nevertheless, the pump in accordance with the invention is provided with rapid discharge of all controlling air overboard. 
     The air logic system is isolated, on the one hand, from the pump, on the other hand, the air logic and air connection system is easily removable and serviceable. Moreover, a clamping block may be inserted laterally into the base, to be locked against the base, maintaining the pump in position. The logic and connection system are easily serviceable in such a package, especially when provided with quick-release capability. Likewise, fluid systems need not be opened in order to conduct air system repairs or service. Since the material in the lines and the pump chambers for liquid is ultra pure, elimination of any possible contact of elastomers, metals, or the like. 
     A spool valve actuated by a pilot valve detecting the end of a stroke of a diaphragm may be implemented to control the speed and the return of a piston driving or being driven by a diaphragm. However, spool valves may be somewhat treacherous. Spool valves typically receive a signal from one line, and they try to equilibrate that signal at some point. For example, at the end of a stroke, the pilot valve cannot move, and air ported through the pilot valve accumulates in a location. As the pressure in a specific location rises, it may act in an axial direction (transversely with respect to an axis of the driving shaft on the pistons) to shift the position of the spool or shuttle. Stabilizing shifting pressure at a specific location has traditionally been difficult. 
     A detent or bias mechanism may be implemented in accordance with the invention. Previous diaphragms have typically been frameloaded. For example, in flange-mounted diaphragms, a widely varying range of pressures results in shifting a spool or shuttle. Overcoming friction and the like may provide unreliable forces. In an apparatus and method in accordance with the invention, a snap disk is positioned to a collar and shaft of a spool. A disk is maintained in a cavity restricting the diameter thereof. Nevertheless, longitudinally, with respect to the shuttle or spool, the detent is free to move. 
     The detent is free to move axially, with respect to the spool or shuttle within a gap freely. However, the detent must break over a center in order to change position between a first biased position deflected in a first direction and a second biased position deflected in a second opposite direction axially with respect to the spool. Moreover, the detent may be made of a particularly stiff material rather than a softer, more flexible elastomeric material. The effect of the more rigid, stiff, radially-constrained, axially-free bias detent is to provide a strict, digital motion of the spool at a narrowly repeatable pressure change. 
     In keeping with a virtually absolute prohibition against a metallic or otherwise reactive materials in the air path and the liquid path of a pump in accordance with the invention, a rapid exhaust valve is provided. Again, rather than common elastomeric materials, a thin, comparatively rigid, stiff film is provided. A disk of the film may be on the order of less than 0.010 inches in thickness. The dump valve or quick exhaust valve is included to divert rather than return controlled air. 
     For example, a circulating air control is returned to a prime mover. However, external control systems use ambient air, that is discharged after one use. Thus, a plastic disk is provided that deflects to permit passage of air around it&#39;s exterior perimeter and yet to close down against a port at near the center thereof and on the opposite side thereof in response to an airflow in the opposite direction. Thus, a very rapid dump around the exterior parameter of the disk may be conducted, yet no back flow into the lines can occur at any significant rate or total amount. 
     In one embodiment, a chamber holds the disk. The disk is supported on a grid on one side with fluted walls providing a standoff distance between the outer most radius of the disk and the outer most radius of the containing chamber. Accordingly, air may pass around the disk. The disk is mounted to press against a face of a port occupying an area very near the center of the disk on one side. During venting, air may pass out of the port against the disk, deflecting the disk and passing around the outermost circumference of the disk. By contrast, any pressure of air against the disk from an opposite side nearly forces the entire disk back against the port, sealing the port off against backflow. 
     A leak detection scheme may rely on fiber optics. In one embodiment, the leak detectors may include a body containing fiber optic lines disposed at an angle calculated to produce reflection of a beam from one fiber optic line to a receiving, second, fiber optic line, only in the presence of liquids. The difference in refractive indices of air and liquids common to processing in the semiconductor industry is sufficient to detect the presence of liquids in the air chamber actuating the piston. 
     In one embodiment, the fiber optic lines may be sealed against liquids for direct contact with the chamber of the pump. In another embodiment, a separate window may be provided having a very thin thickness, and formed of a material that is likewise non-metallic, high purity, non-electrical, nonreactive, and sealed. In such an embodiment, an acrylic fiber may be used. Acrylic fibers will absorb more deflection during handling. 
     By contrast, fiber optics may tend to break when mishandled, such as by being bent on too tight a radius. It is important to protect operators from being sprayed by exhaust or by controller exhaust when an external controller is used to operate a pump in accordance with the invention. In such an environment, a chamber filled with fluid, may be evacuated by the continuing operation of an external controller, unresponsive to the leak. In one presently preferred embodiment, a window completely seals the chamber from the leak detector, as an acrylic, fiber optic line may be used. 
     The double-line design is superior to prior art systems and other technologies wherein fiber optic lines are laid side-by-side in order to cooperatively send and receive a beam. The difficulty with such embodiments often includes an inability to define a digital location at which reflected light intensity indicates either a liquid is present or that an end of stroke of the pump has been reached. By using off-axis orientations between the sending and receiving fibers, the index of refraction or the presence of a film layer creates a dramatic, even digital demarcation between a desired condition and an undesired condition. 
     In one embodiment, a leak detector may be located near an outer circumference of a chamber in which a diaphragm is operating. In such an embodiment, another leak detector may be positioned centrally or elsewhere within an air chamber in order to identify an end of a stroke by the pump. Accordingly, an external controller may use a fiber optic detector for the end of the stroke of the diaphragm of the pump. 
     For example, as in parallel lines that become retroreflective, a pre-determined angle may be established between two, separate, cooperative fiber optic lines. The difficulty of establishing a value or trigger lever for the reflected light from a sending fiber to a receiving fiber is eliminated by the construction in accordance with the invention. Rather, the range of distance within which a diaphragm positioned to reflect light from the sending fiber to the receiving fiber may be adjusted within a very narrow range. The narrowness of the range is sufficiently precise to be effective for operational functionality of the pump. 
     The signal corresponding to the reflection of light quickly decays to a minimal value far from that corresponding to a trigger position. Whenever the diaphragm moves away from a specific location designed for the sensor. Thus, a detector in accordance with the invention provides a digital signal rather than an analog signal, for all practical purposes with respect to detecting the end of stroke for controlling the operation of the pump. 
     These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a front quarter perspective view of a pump in accordance with the invention; 
     FIG. 2 is a sectioned, perspective view of one embodiment of a pump in accordance with the invention; 
     FIG. 3A is a sectioned, side, view of a portion of the pump illustrated in FIG. 3; 
     FIG. 4 is a sectioned, side, elevation view of one embodiment of a pump in accordance with the invention; 
     FIG. 5 is a sectioned, perspective view of a long, end-of-stroke, control valve for operation in an apparatus in accordance with the invention; 
     FIG. 6 is a partially sectioned side, elevation view of a valve for use as a pilot or end-of-stroke valve detecting proximity of a diaphragm to the head, in contrast to the valve of FIG. 5 for detecting proximity of the diaphragm to the body of a pump in accordance with the invention; 
     FIG. 7 is a sectioned, perspective view of a leak detection mechanism for implementation in an apparatus in accordance with the invention; 
     FIG. 8 a sectioned side elevation view (end with respect to the pump) of a spool valve for the air control in the base of an apparatus in accordance with the invention; 
     FIG. 9 is a perspective view, partially-exploded, of a base for implementation with an apparatus in accordance with the invention; 
     FIGS. 10-11 are a perspective and elevation, respectively, sectioned views, of a quick-release, high-volume, air-exhaust valve for use with an externally controlled air supply for an apparatus in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in FIGS. 1 through 11, is not intended to limit the scope of the invention. The scope of the invention is as broad as claimed herein. The illustrations are merely representative of certain, presently preferred embodiments of the invention. Those embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
     Referring to FIG. 1, an apparatus  10  for pumping a transfer fluid such as hot, de-ionized water, etching acids, or the like may be formed of components manufactured of exclusively of nonreactive, non-contaminating materials. In one embodiment, an apparatus  10  may be oriented to have a longitudinal direction  11   a,  a lateral direction  11   b,  a transverse direction  11   c,  and a circumferential direction  11   d.  The apparatus  10  comprises a pump  12  and a supporting apparatus  14 , such as a controller  14  or base  14 . In one embodiment, the controller  14  and base  14  may be integrated into a single component. As a practical matter, a controller  14  may be separate, distinct, remote, and external with respect to a pump  12 . Also, a base  14  may be manufactured to attach securely to a body  16  of a pump  12 . However, in one presently preferred embodiment, the pump  12  is integrated into a controller/base  14  all integrated into a monolithic unit. Thus, installation, control, integrity, valving, porting, fluid communications, and the like may be factory-integrated for an improved reliability. Moreover, contamination may be reduced, and the opportunities to damage or alter equipment upon installation are reduced. Moreover, the sealing technologies appropriate for operating with such nonreactive materials as fluoroplastics, creep-prone materials, may be implemented in the manufacturing assembly of the entire apparatus  10  as a pump  12  and controller/base  14  with accompanying interconnection. 
     The body  16  of the pump  12  may be referred to also as a frame. In one embodiment of an apparatus  10  in accordance with the invention, the body  16  replaces external frames, through-bolts, metallic connections, and the like. As a result, the apparatus  10  results in a very compact envelope having the features of reliable design, creep-insensitivity, durability, extremely long life, fail clean operation, and completely sealed fluid paths. The life of the apparatus  10  may exceed 10 million cycles. As a practical matter, units may be designed to exceed 20 million cycles, 30 million cycles, 40 million cycles, 50 million cycles, and 100 million cycles of the pump with no operational failure of any component. This is particularly important with respect to moveable components within the apparatus  10 . 
     The pump  10  may be configured to contain two chambers  18 . With reference to FIG. 2, the chambers  18   a ,  18   b , are shown. The chambers  18   a ,  18   b  are simply specific instances of a generic chamber  18 . Hereinafter, trailing alphabetical references refer to specific instances of those items to which leading reference numerals refer. 
     Referring again to FIG.  1  and also referring generally to FIGS. 2-4, the pump  12 , may be manufactured to have slip rings  20  or union rings  20 . As a practical matter, alignment of the heads  22  with the frame  16  or body  16  is problematic in many designs of prior art pumps. Various notches, alignment marks, pins, and the like may be used to align the heads  22  with the frame  16  or body  16 . However, once aligned, each of the heads  22  may remain aligned with the body  16 , uninfluenced by the slip rings  20  as to alignment in a circumferential direction  11   d.    
     The slip rings  20  move circumferentially  11   d  with respect to the heads  22 . Accordingly, the heads  22  remain fixed with respect to the body  16  in a circumferential direction  11   d.  By contrast, the slip rings  20 , in rotating in a circumferential direction  11   d  may thread onto the body  16 , drawing the heads  22  longitudinally  11   a  closer in a sealing relationship with the body  16 . The slip rings  20  may thus be tightened to any particular loading, particular for heat soaking to relieve primary creep. In one embodiment, the slip rings  20  may be tightened to a design load tolerated by threads associated therewith, in order to seal the heads  22  against the body  16 . Thereafter, the pump  12  may be heat soaked in order to accelerate primary creep. Thereafter, the slip rings  20  may be tightened with no circumferential  11   d  displacement of the heads  22 . Accordingly, tightening the slip rings  20  against the body  16  at a load and displacement effective to render the apparatus  10  subject only to secondary creep is easily trackable. 
     Ports  24   a ,  24   b  may form an inlet  24   a , and outlet  24   b,  respectively. Within the body  16  may be many suitable arrangements of check valves providing biasing of flows through the pump, preventing backflow. Double, serial check valves may provide a rectifier for the fluid flow from the inlet  24   a , through the chambers  22 , to the outlet  24   b.    
     In one embodiment, an aperture  26  may be formed in one end of the head  22 . A retainer  28  may be provided to thread or otherwise fasten to the aperture  26 , securing a pilot  30  or end-of-stroke detector  30 . The pilot  30  may be configured to detect the end of a stroke of the pump  12  for operation of a piston near the detector  30  or remote from the detector  30 . The pilot  30  may be used to signal the controller  14  in order to switch the direction of an operating fluid driving the pump  12 . According to the flows of operating fluids into the pump  12 , the transfer fluid being conducted through the inlet  24   a  and outlet  24   b  may be appropriately driven and directed through the pump  12 . 
     In one embodiment, a retainer  32  may fit an aperture  33  in the base  14 . The retainer  32  may capture the components of the controller  14  within the base  14 . Accordingly, an aperture  33  may be adapted to extend an appropriate distance as needed in order to support the proper valving, porting, control mechanisms, and the like of the controller/base  14 . 
     In one presently preferred embodiment, mounts  34  connecting the base  14  to the pump  12  may actually integrate fittings. Thus, the mounts  34  or line fittings  34  may extend from the base  14  to the pump  12  for conducting fluids thereto. In one presently preferred embodiment, the mounts  34  are the basic lines  34  conducting operating fluid from the controller/base  14  into the heads  22  for driving the pump  16 . In one presently preferred embodiment, certain portions of the controller/base  14  may be disposed within a pedestal  36 . Moreover, the pedestal  36  may be adapted to fit against the frame  16  or body  16  of the pump  12 . Accordingly, the pedestal  36  may assist in the mounts  34  in supporting the pump  12  and restricting the motion thereof. 
     Referring again to FIG. 2, and continuing to refer generally to FIGS. 1-4, a latch block  38  may be provided for securing the controller/base  14  onto a support surface. The latch block  38  may be configured to engage the base  14  in any of a variety of methods for secure and convenient mounting. 
     A leak detector  40  may be provided in the heads  22 . In one embodiment, a leak detector  40  may also be used as an end-of-stroke detector  30 . The pilot  30  or end-of-stroke detector  30  of FIG. 1, in one embodiment, may be a pneumatic and mechanical apparatus. In the embodiment of the detector  40 , an optical detection mechanism may be implemented to detect the end of a stroke of the pump  12 . 
     A pilot  30 , illustrated in FIG. 2 as a short version for detecting an end of a stroke near the head  22 , as opposed to the detector  30  or pilot  30  of FIG. 1, adapted to detect an end of stroke remote from the head and close to the body  16 , may be captured by a retainer  42 . Similarly, a leak detector  40  may be captured by a retainer  44 . The body  46  of the pilot  30  may thus be secured by sealing, wedging, threading, or the like into the head  22 . As a practical matter, certain pressurization of materials within the head, may form all sealing surfaces with respect to the body  46 . Accordingly, the retainer  42  may apply a force to the body  46 , forming a seal and maintaining loads on the seal. In another embodiment, the body  46  may be threaded directly into the head and forming a seal therewith. 
     A mount  48  for a leak detector  40  may be positioned within the head  22 . In one embodiment, the mount  48  may be threadedly engaged into the head  22 . By contrast, the actuator  50  of the pilot  30  is free to move longitudinally  11   a  with respect to the pump  12  and head  22 . 
     The mount  48  of the leak detector  40  may be fabricated to include or support a window  52 . In one embodiment, the window  52  is adapted to be formed of a material identical to that of the head  22 . Accordingly, material compatibilities, creep, sealing, and the like may all be accommodated readily between the materials of the head  22  and mount  48 . Meanwhile, the mount  48  can be machined to formed a very thin window  52  adaptable to be translucent or transparent to light. Thus, a reflective beam from and returning to the leak detector  40  may pass through the window  52  into the chamber  18 , and back to the leak detector  40  for pickup or reception. 
     A cavity  54  or slot  54  may be provided within the leak detector  40  in order to accommodate passage of electronic or fiber optic lines. In one embodiment fiber optics are used up to the window  52 . Accordingly, the slot  54  may be used to adapt fiber optic lines to fit with their accompanying sheathings through the retainer  44  to the required proximity to the window  52 . A channel  56  may be provided through the retainer  44  in order to conduct such lines to a proper control center for interpretation and actuation with respect to any signal detected by the leak detector  40 . In one embodiment, profiles may be maintained in a minimum envelope by providing tool holes  58  adapted for rotating circumferentially  11   d  the retainers  42 ,  44 . As a practical matter, substantial force may be developed by application of circumferential  11   d  loads on metal prongs adapted to the tool holes  58 . Thus, less material, a cleaner profile, less chance of damage, and the like may be provided by use of the tool holes  58  to operate the retainers  42 ,  44 . 
     Referring to FIGS. 3-4, and continuing to refer generally to FIGS. 1-2, as well, diaphragms  60  may be disposed within the chambers  18  of the pump  12 . The diaphragm  60  may be any isolation medium which is used to separate fluids such as drive fluids from working fluids. In one embodiment, a driver  62 , or plate  62  may be thought of as a piston  62  for communicating force or pressure between corresponding diaphragms  60   a,    60   b.  An aperture  63  may be formed in driver  62  or piston  62  in order to accommodate a shaft  64  operably connecting the drivers  62   a ,  62   b . The shaft  64  may travel through a barrel  65  formed in the body  16  of the pump  12 . The barrel  65  may be received, as illustrated, in order to minimize stress, and permit natural alignment of the drivers  62 , shafts  64 , and surfaces of the barrel  65  in the frame  16 . 
     A recess  66  may be provided in the body  16  as a cavity  66  for receiving each of the drivers  62 . In one embodiment, the recess  66  permits improved support of the diaphragms  60  in operation. More particularly, the recess  66  permits the minimization of any gaps between the body  16  and the driver  62  from leaving unsupported any substantial area of the diaphragm  60 . For example a contoured surface  68  formed in the head  22  may support the diaphragm  60  along its entire operational area. Similarly, a contoured surface  70  of the body  16  may be adapted to transition smoothly and snugly from the driver  62 . Accordingly, the diaphragm  60   b  positioned against the body  16  and the driver  62   b  may be completely supported even against the dead headed load, a stalled line, or a backflow in a line from which the pump has been shut down. Thus, whether position against the contoured surface  68  of the head  22  or against the contoured surfaces  70  of the body  16  and  71  of the drivers  62 , the diaphragm  60  is completely supported. 
     In one embodiment, as shown in FIG. 3, the driver  62  may be configured with a collection chamber  67  for fluid. The collection chamber  67  accumulates fluids as the driver  62  approaches against the body  16 . The driver  62  is further configured with a relief passage  69  for venting the collection chamber  67 , thus avoiding pressure buildup. Otherwise pressure buildup may distort components and reduce pump life. 
     An edge  72  or curvature  72  at an edge of a the body  16  may be smoothly transitioned to reduce or eliminate sources of stress concentrations in the diaphragms  60  in operation. For example, the curves  72  in the body  16 , and curves  74  in the heads  22 , provide for flexure of the diaphragm  60  in either longitudinal  11   a  without production of stress concentrations and without stretching or folding of the diaphragm  60 . In one presently preferred embodiment, all edges or corners of the body  16 , driver  62 , and head  22  of a pump  12  in accordance with the invention, are adapted to have curvatures  72 ,  74  and clearances configured together to provide minimization of stress with virtual elimination of strain within the diaphragms  60 . Thus, unsupported spans are minimized by appropriate selection on clearance between components, such as between the driver  62  and body  16  with appropriate curvatures further reducing the probability of stress concentrations occurring. 
     In one presently preferred embodiment, a head  22  may be fabricated to have a cantilever  76 . A cantilever, may be thought of as a flange, but does not operate as a flange, as that term is typically used. No through holes are appropriate in one presently preferred embodiment of a cantilever  76 . Rather, the cantilever  76  merely forms a plate  76  or skirt  76  extending radially  11   b,    11   c  away from the chamber  18  formed by the head  22  and body  16 . Cantilever  76  is preferably never in contact with the body  16 . 
     Referring to FIG. 3A, a driver  78  is shown which comprises a wedge  80  which is adaptable to fit into the cavity  82  of the body  16  for gripping and sealing the diaphragm  60  between the driver  78  and the body  16 . The driver  78  may be contiguous and integral with the wedge  80 . However, in another embodiment, the wedge  80  may be a separate ring having a trapezoidal cross-section. The trapezoid may be regular or irregular. In one presently preferred embodiment, the trapezoidal cross-section of the wedge  80  is exactly symmetrical in order to provide self-centering and equalization of loading. Thus, loading applied by the engagement portion  84  of the slip ring  20   a , which is transferred from the driver  78  of the head  22  to the wedge  80 , may be immediately transferred evenly by the wedge  80  to the diaphragm  60  and to the walls  83  of the cavity  82  in the body  16 . 
     In one presently preferred embodiment, the wedge  80  may be a separate, distinct, and freely movable piece, with respect to radial (the plane of the lateral  1   b  and transverse  11   c  directions) motions. Thus, no binding may occur to interfere with the wedge  80  evenly distributing forces into the cavity  82  of the body  16 . In one presently preferred embodiment, an engagement portion  84  of the slip ring  20  or the union nut  20  may threadedly engage the body  16 . Accordingly, the turning of the slip ring  20  may draw the head  22 , and particularly the cantilever  76  toward the body  16  longitudinally  11   a.  The lip  86  of the slip ring  20  engages the cantilever  76  to drive the cantilever  76  in the longitudinal direction  11   a.  Accordingly, the driver  78 , preferably integral to the cantilever  76  and head  22  drives the wedge  80  longitudinally  11   a  into the cavity  82 . 
     Continuing to refer to FIG.  3 A and generally to FIGS. 1-4, the wedge  80  may form a half angle  87  of approximately 15 degrees or a full angle  88  of approximately 30 degrees with respect to an axis  89 . An axis  89  may be an axis of symmetry  89 . However, in one embodiment, the wedge  80  is an irregular trapezoid having only one side tapered with a half-angle  87 . However, in one presently preferred embodiment, the wedge  80  has been found to be operationally superior with a symmetric form  88 . 
     Referring to FIG.  3  and generally to FIGS. 1-4, operation of the diaphragms  60  is controlled by a flow of operating fluid, such as air from the controller/base  14  into the chambers  18  toward the heads  22 . Accordingly, the chambers  18  pass a transfer fluid being pumped into and out of the chamber  18  between the diaphragms  60  and the body  16 . The flow of air in the controller  14  is effected by a shuttle valve  90  or spool valve  90  triggered by the pilot  30 . 
     Sealing the chamber  18  into two portions  17 ,  19  is effected by the diaphragm  60  in conjunction with the wedge  80 . The portion  17  is formed by the diaphragm  60  in the head  22 . The portion  19  or chamber  19 , is formed by the body  16  and the diaphragm  60 . The volume of the respective chambers  17 ,  19  or portions  17 ,  19  of the chamber  18  fluctuate. Thus, each  17 ,  19 , in turn, occupies the majority of the chamber  18 . The seal is effected by the force applied by the driver  80  of the head  22  against the wedge  80 , pinning or capturing the diaphragm  60  between the wedge  80  and the surface  83  of the cavity  82 . 
     The wedge  80  has been found so effective that a calendered fluoropolymer in a fluorocarbon body  16  and head  22  had been found to form a seal that is dramatically integral even after removal of any loading on the wedge  80 . Thus, a mechanical, but intimate bond, gas-tight is created between the wedge  80 , the diaphragm  60 , and the surface  83  of the cavity  82  in the body  16 . Due to the presence of the cantilever  76 , loading is maintained. Nevertheless, the sealing effect is superior, and requires no metallic, elastomeric, or other reactive components at any location in order maintain the loads and the seals effective to seal the pump  12 . 
     Referring to FIG. 5, and generally to FIGS. 1-6, a pilot  30  may be formed to have an element  92  adapted to be inserted in a head  22  under a retainer  42 . The element  92  may form a body  92  containing a piston  94 . The piston  94  may operate similarly to a spool. A shaft  96  may provide both alignment and sealing functions. 
     In one embodiment, a chamber  98  may be formed in the element  92  for containing a fluid. A vent  100  may be provided between the vented portion  102  or vented chamber  102 , that is contiguous with the chamber  98 , except for the presence of the piston  94 . Thus, the piston  94  and a bearing surface  104  or sealing surface  104  may form the vented chamber  102 . 
     The sealing for the fluid flows is provided by the piston  94  against the element  92 , and the shaft  96  against the sealing surface  104 . Relief  106 ,  108  may be provided as appropriate. Thus, manufacturing tolerances may be provided, while binding is eliminated. For example, fastening may tend to warp and bind components. 
     In one embodiment, the shaft  96  may be provided with a bumper  110  adapted to make contact with a diaphragm  60  against a face  71  of a piston  62 . The bumper  110  may be adapted to fit a hollow portion  112  of the shaft  96 . A shank  114  may fit into an aperture  116  in the hollow portion  112  of the shaft  96 . Accordingly, the bumper  110  may be secured thereby to travel securely with the shaft  96 . Thus, the bumper  110  may provide stress distribution, abrasion resistance, and the like so as to minimize any deleterious affect by the shaft  96  on the diaphragm  60 . The shafts  96  may thereby follow the diaphragm  60  and piston  62  for detecting the end of the stroke of the piston  62  at the body  16 , rather than at the head  22 . 
     Threads  118 ,  119  may be formed in the element  92  or body  92  of the pilot  30  of FIG. 5. A shoulder  120  may be adapted to stop the element  92  at an appropriate location in the head  22 . In one embodiment, a face  122  may abut a corresponding base in the head  22 . The wall  124  of the element  92  may be secured within a retainer  42  as illustrated in FIG. 1. A face  126  may be driven or loaded by the retainer  42  thereagainst. 
     In operation, a passage  128  is formed between the element  92  and the head  22 . The passage  128  conducts fluid, as with a spool valve. Likewise, a passage  130  provides communication of the operating fluid (e.g. air) between the chamber  102  and a low-pressure area. Thus, the chamber  98  may be loaded with chamber pressure of the pump  12 , until the piston  94  passes a port  100  into the channel  130 . Thereupon, the pressure in the chamber  98  may be vented throughout the port  100 , indicating that the end of a stroke has been reached. 
     Referring to FIG. 6, and continuing to refer generally to refer to FIGS. 1-5, an element  132  of a short pilot  30  is illustrated. The pilot  30  may include an actuator  50  provided with a standoff  134  or post  134  extending into the chamber  18  associated with a head  22 . The posts  136  and actuator  50  are preferably made from a material, as all materials within the pump  12  and base/controller  14  that are nonreactive, chemically compatible with one another, and non-contaminating, in order to be fail-clean in the event of any failure of the apparatus  10 . 
     The post  134  may be provided with a face  136  adapted to contact a diaphragm  60  when the diaphragm  60  approaches or contacts the surface  68  of a head  22 . In one embodiment, the diaphragm  60  may push the face  136  of the post  134  flush with the surface  68  of the head  22 . Accordingly, the actuator  50  is freed to move the actual poppet  140  portion or valve portion  140  away from the seat  142 , exposing and opening the cavity  144  to pass operating fluid there through. The operating fluid (e.g. air) passes from the chamber  18  through the passage  144  between the poppet  140  and the seat  142 , to be discharged through the vents  146  in the sides of the actuator  50 . 
     A threaded portion  148  of a body  46  may secure an insert portion  150  within the head  22 . The face  152  may preferably be positioned near the contoured portion  68  of the head  22 . In one embodiment, the face  152  may be substantially flush therewith. In any event, the face  136  of the post  134  may protrude sufficiently to permit complete opening of the cavity  144  by movement of the post  134  by the diaphragm  60  and piston  42 . 
     In one embodiment, the body  46  may be provided with a shoulder  154  and relief  156  to assure clean and complete engagement by the head. The shoulder  154  may be straight or tapered with respect to the head. The shoulder  154  will maintain a virtually gas-tight seal with the head  22 . 
     Referring to FIG. 7, a leak detector  40  may be formed to have a channel  54  or cavity  54  adapted to receive fiber optic lines. In one embodiment, a clearance  158  may be provided between the head  22  and the mount  48 , assuring intimate access of the leak detector  40  to the window  160 . The thickness  161  of the window  160  may be selected to render the window  160  transparent or translucent with respect to the quantity, wave length, and intensity of light required by the leak detector  40 . The leak detector  40  is optical in nature. Accordingly, a face  162  may be formed at one end of the body  164  for fitting against the windows  160 . A clearance  166  may be provided on an opposite side of the window  160 . 
     In one embodiment, pin tool holes  168  may be provided. Remaining material supports against stresses and distortions in the mount  48 . Thus, the apparatus provides for assembly and dimensional stability in the window  166 . 
     A seal clearance  170  may be provided at the front of a passage  172  adapted to receive a fiber  173 . The fiber  173  may be glass or polymeric. In one presently preferred embodiment, the fiber  173  may be an acrylic plastic. Glass tends to be particularly brittle and not well adapted to handling. Thus, a clearance  170  may be provided for sealing the passage  172  with a nonreactive material. As a practical matter, the window  160  already provides a seal. Thus, the sealing clearance  170  is optional. 
     A face  174  or shoulder  174  is provided in one embodiment to restrict and position a sheath  175  surrounding a fiber  173 . In one embodiment, a fiber  173  is stripped of a sheath  175  for a distance sufficient to extend through the channel  172 . Accordingly, the passage  176  accommodates the entire sheath  175 , while the shoulder  174  positions the end of the sheath  175 , thereby permitting the fiber optic line  173  to extend toward the window  160 . 
     In one embodiment, a slot  178  may be formed in the leak detector  40 . The slot  178  is adapted to receive the sheath  175  and contained line  173  from both the channels  172  (only one is shown). The sheath  175  or leads  175  may then traverse from the slot  178  to be gathered into a channel  54  passing out of the leak detector  40 . The slot  178  has a primary effect of permitting the channels  172  to be positioned at a half angle  184  or full angle  186  of a center line  188 . Thus, the slot  178  provides adequate room for the turning required by the sheath  175  without damage to the fibers  173  or lines  173  of fiber optic material. Accordingly, the sheath  175  may then be routed throughout the channel  54 , exiting the leak detector  40 . 
     In one embodiment, a load  180  may be applied by a retainer  44  engaging the head  22 . The load  180  may be applied directly by the head  182  of the leak detector  40 . Thus, end of a contact may be maintained between the face  162  and the mount  48  and particularly the window  160 . 
     In operation one of the lines  173  may conduct a light beam to the window  160 . The light may be directed by the change in the index of refraction between the material in the line  173 , the window  160 , and air in the clearance  166  or the cavity  17  (chamber  17  of the chamber  18 ). Thus, light directed from a line  173  is reflected back to the receiving fiber, in the presence of air. In the presence of a liquid, however, such as may occur during a leak caused by diaphragm or seal failure, the clearance  166  may become filled with a liquid. Accordingly, the index of refraction for light passing from the line  173  through the window  160 , and into the liquid  160  may be used to determine the angle  186  between the channels  172  and the lines  173 . The presence of liquid in the clearance  166  disburses the incoming light, thereby changing the index of refraction of the light reflected through clearance  166 , which is detected by the leak detector  40 . Thus, the leak detector  40  detects any change in the index of refraction which may be caused by a liquid or a gas leaking into the clearance  166 . In one embodiment, the window  160  may be positioned near to the diaphragm  60 . In such an embodiment, a reflection of light from the diaphragm proximate the window  160  may be detected by a line  173  receiving from a corresponding line  173  eliminating the diaphragm  60 . 
     The leak detector  40  may operate as an end-of-stroke detector  30 . However, the optical signals from the lines  173  must be converted into some kind of mechanical actuation to control the flow of air or other motive fluid or driving fluid into the chamber  17  for driving the diaphragm  60 . 
     Referring to FIG. 8, a spool valve  90  may be provided with a bias  190  or a bias element  190  for rendering a digital response from the spool valve  90  or shuttle valve  90 . In one embodiment, a bias force  191  is provided by the bias element  190  depending on the orientation thereof. The bias  190  is captured by a head  192  or nut  192  secured to a shaft  193 , capturing the bias  192  flexibly therebetween. 
     A chamber  194  adapted for ready movement by the bias  190  is provided by the retainer  32  and a fitting  206 . The chamber  194  permits free motion of the bias  190  in a longitudinal direction with respect to the shuttle valve  90 . A chamber  196  is formed for receiving the head  192  of the shuttle  90 . In one embodiment, a thickness  198  of a gap  200  formed to receive a bias  190  between the retainer  32  and fitting  206  may be critical. Forming a flange in place of the bias  190  provides residual stresses and restraints on deflection thereof. 
     Clearance is made to accommodate positioning of the bias  190  against a far corner  202  or a near corner  204 , with respect to the spool valve  90  or shuttle valve  90 . Thus, the bias  190  may be constrained in a radial direction  199   b,  while being completely free in an axial direction  199   a,  so long as the bias force  191  has been overcome. Thus, the bias  190  operates like the bottom of a traditional oil can. 
     Nevertheless, the constraint in a radial direction  199   b  by the fitting  206  in no way restricts the positioning of the bias  190  in either corner  202 ,  204 . Thus, the bias  190  is free to flip in an axial direction  199   a  upon achievement of sufficient bias force  191 . Thus, the bias  190  renders the shuttle  90  a digital valve rather than a proportional valve. Proportional valving has been found to be unreliable, and not sufficiently precise for reliable operation of the pump  12 . 
     By contrast, the bias  190  by being formed of a stiff, comparatively rigid, yet flexible, nonreactive, fail-clean material, such as a chlorofluorocarbon formed in a comparatively strong, stiff sheet, has been found to be effective to provide a digital operation of the spool valve  90  within a narrowly designed range of bias floats  191 . The proper provision of a cap  198  that does not constrain the motion of the bias  190  and head  192  in an axial direction  199   a  has been found to be effective to provide such a digital positioning function. 
     Otherwise, the spool  210  of the spool valve  90  may otherwise operate as understood in the art. The seals  212 , generally, and specifically each of the seals  213 ,  214 ,  216 ,  218 ,  219  operate to direct fluid into a variety of conduits  220  or channels  220 . The channels  220  and specifically the channels  221 ,  222 ,  224 ,  226 ,  228  direct working fluid the operating fluid controlling the movement of the diaphragm in the head  22  of the pump  12  as heretofore described. Porting the working fluid (e.g. air) to the proper diaphragm  60 , or chamber  17 , in order to drive a diaphragm  60 , may be accommodated by the respective channel  220 , in response to a seal  212  directing the operating fluid from one port  230  to another  230 . Specifically, each of the ports  231 ,  232 ,  234 ,  236 ,  238  is opened, closed, and transferred between the respective channels  240 ,  242 ,  244  as a seal  212  is passed thereover or thereby longitudinally  199   a.    
     A driving fluid may be passed in through a channel  240 , and onto one of the channels  220 . A channel  220  connected to a port  230  may then transfer fluid into a channel  242 ,  244  selected according to the longitudinal  199   a  position of the spool  210 . Thus, a particular seal  212  may direct communication of fluid from one port  230  to another  230  by way of one of the channels  242 ,  244  extending circumferentially about the spool  210 . 
     In one embodiment, the spool  210  may be formed of a ceramic material. Accordingly, no elastomeric seals are formed anywhere in the apparatus  10 . Rather, each of the materials from which the spool  210 , head  192 , bias  190 , fitting  206 , retainer  32 , and base  14  are formed may be selected from nonreactive, durable non-contaminating, fail-clean materials such as chlorofluorocarbons. 
     Referring to FIGS. 9-11, a dump valve  250  or fast-relief, exhaust valve  250  may be formed to operate in the base  14  of an apparatus  10  in accordance with the invention. In one embodiment, an insert  252  may be adapted with a muffler  254  to fit into the base  14 . The muffler  254  may be provided with multiple ports  256  for dumping large amounts of operating fluid (e.g. air) from a non-recirculating, external driver or controller, after discharge thereof, from the chamber  17  of the pump  12 . The post  258  may serve to actuate and align operation of the valve  253 . 
     A disk  260  provides a principal seal  260  for the valve  250 . For example, operative fluid may be provided to or from the spool cavity  262 . Ports  264  and a support post  266  or cross  266  may be formed to pass operating fluid from the cavity  262 , while supporting the structural mechanics of the base  14  and the operation of the disk  260 . A channel  268  may similarly be disposed throughout the interior of the insert  252 . The channel  268  may communicate through a port  270  in the insert  252 . 
     The port  270  may form an aperture having a flat face  275  adapted to support the disk  260  therein. When the disk  260  is forced by a flow against the disk  260  to contact the flat face  275  the aperture  270  may be effectively closed by the disk  260 . The cross  274  supports the flat face  275 , providing ports  270  there through while supporting the disk  260  against failure in an axial direction  199   a.    
     A channel  276  conducts working fluid away from the disk  260 , by passing the fluid from the channel  262 , through the ports  264  drilled eccentrically with respect to the channel  262 , and accessing a cavity  277  on one side  280   a  of the disk  260 . Clearances  278  provide passage for fluid around the perimeter  281  of the disk  260 . Accordingly, area in one direction may pass freely around the disk  260 , accessing the chamber  276  by way of the clearance  278 , which may be fluted to position the disks  260  effectively while still providing passage of fluid. Thus, fluid may pass through a suitable porting mechanism to the port  282  into a chamber  284 , for discharge throughout the ports  256  throughout the muffler  254 . By contrast, the disk  260  may also be biased to seal against the flat faced  275 , closing the ports  270  against passage of loads. 
     The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Technology Classification (CPC): 5