Abstract:
A rotationally adjustable valve is disclosed whereby the user is able to control the flow of fluids from complete shutoff to maximum flow by rotating the body of the valve, said rotation being axial to the flow of the fluid. Additionally, the user is able to attach high and low pressure test probes directly to the valve, as it is rotatably adjusted, so that additional equipment is not required next to the valve. An embodiment of this invention includes the use of an adjustable Cv disk to set the maximum flow of the valve, rather than just create a simple 180° on/off, very similar to a current 90° ball valve that this device will replace. All of the problems associated with the ball valve have been minimized including creating a linear relationship between the percentage open of the valve and the percentage of maximum flow of the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     There are not any pending applications that cross-reference this application. 
     FIELD OF THE INVENTION 
     The field of this invention is the heating ventilation and cooling (HVAC) industry where fluids are the medium for the heating and cooling. Fluids that are sent from boilers or chillers are routed through piping structures which need to be balanced in terms of pressure and flow in order to even distribute the hot or cold fluids into air handler units which deliver temperature controlled air. In this industry, quarter-turn ball valves are usually used which present a host of problems and restrictions on their location and use. 
     BACKGROUND OF THE INVENTION 
     This device is used in piping system in large HVAC systems where the control of the amount of flow is desired. Currently, most controls that regulate the flow in piping systems are based on the principle shown in the quarter-turn ball valve, where the operator can have complete shutoff or full flow within a 90° turn of the handle. In the field of power assisted actuators, most all of the manufactures design them for the same quarter-turn application as well. Generally in this industry, a full port or more commonly known full bore ball valve is incorporated into the piping structures. This valve has an over-sized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. 
     There are many problems with the basic ball valve involve it&#39;s inability to regulate evenly as the valve is opened or closed. This means that simply opening the ball valve a certain percentage of the total range, say 50% for example, does not equate to 50% of the total flow of the valve. This non-linear relationship between the percentage open and percentage of flow creates problems in setting the flow into a particular section of the piping system. This is because of the shape of the insert being circular. This non-linear problem can be greatly improved with the additional of a parabolic or other characterized insert into the ball opening itself. 
     In the disclosed invention, a venturi tubes is used to calculate pressure differential and thus fluid flow. With a ball valve, to the nature of the throttling or jetting aspects of the ball as it rotates at low percentages of openness, it is very difficult to accurately measure flow anywhere near the valve. This leads to oversizing of the pump and running the pump at a higher pump rate to compensate for the inefficiencies of a ball valve. A venturi is used whenever low pressure loss and high accuracy is desired, and due to the nature of the valve disclosed herein, the length of straight piping is greatly reduced as the pressure differential measuring means are located directly upon the valve as this valve incorporates a venturi. Due to the low pressure loss, a venturi saves the user many dollars and frequently pays for itself in one year of continuous operation by greatly reducing pumping cost. 
     Other problems associated with ball valves is the amount of force necessary to open or especially close the valve when under pressure as the flow of fluid fights against the closing or opening of the valve. Especially when one is trying to barely crack open the valve to let in only a minimal amount of flow. Also, due to the characteristics of the flow opening and exit of the ball itself, at low flow rates, that is a tremendous amount of cavitation and noise exist if the pressure differential is substantial across the ball itself. The critical flow in a ball valve is encountered when delta P (the differential pressure) is 0.15 P, which is far below the usual figure of 50% of absolute inlet pressure. Another issue is the handle to adjust the opening of the ball itself, as it must be located in a position where the user can access it. In piping structures where many pipes are located and space is at a premium, the knuckles of more than one person has been wracked against the piping structure when attempting to access and adjust a ball valve. Where pressures are significant, the size and length of the handle becomes a critical aspect of the operation of the valve and the need for space can drastically increase. 
     The current state of the art can be found to use ceramic disks that have angular segments removed that allow for the flow of fluids. These ceramic disks are used to regulate the flow of fluids in many applications, such as high end water faucets and shower fixtures. U.S. Pat. No. 7,841,362 issued to Kim on Nov. 30, 2012 shows the use of multiple disks in a faucet or water control valve, where temperature and flow are controlled. This disclosure is typical of the faucet style of control valves, where two sources of fluid are mixed and flow is controlled. These valves have the discharge of fluid through a spout which is basically perpendicular to the flow of the fluid. Prior art does exist to detail that ceramic disks can be used to supply and discharge fluids as well as U.S. Pat. No. 7,373,950 issued to Huang on May 20, 2008 demonstrates where a single set of disks control the mixing of hot and cold water from two distinct sources and regulates the outbound flow of water through the same disks. 
     One of the deficiencies of the current state of the industry as well as the prior art is that a valve, that can go to complete shutoff and maximum flow with a 90 degree rotation about the axis of fluid flow, cannot also be capable of measuring the differential pressure between the inlet and outlet of the valve. Current ball valve technology, which through the use of parabolic or other inserts to the ball can approach a more linear relation between the percentage of openness of the ball to the percentage of maximum flow through the valve, does not have the capabilities to have a pre-set Cv in association with the ball valve. 
     Additionally, due to the surfaces upon which the fluids impact upon when the ball valve is turned and due to the close tolerances required to prevent fluids from leaking past the ball portion of the valve, it is imperative that the fluids be free from any hard impurities that can scratch or mar the surface of the ball and that can damage the exposed O-Rings. Furthermore, since the O-Rings are exposed to the fluids on a daily basis, the chance for O-Ring degradation due to reactions with the fluids is greatly enhanced, leading to failure and leakage. To prevent this possible degradation, some manufactures use Teflon seals which facilitate a sealing function as well as creating a surface with less friction than O-rings. 
     Another issue with using ball valves is that the user most still incorporate a venturi and high and low pressure test probes to measure the flow of the fluid. Since cavitation and throttling may occur with the use of a ball valve, the venturi must be location a sufficient distance away from the ball valve in order to more accurately measure the flow. This could cause problems in the reading and adjusting the flow in a particular section of a piping structure. 
     It is an object of this invention to create a device that will enable the user to adjust the flow of fluid in a piping structure where space is at a premium and where accuracy of the fluid flow is critical. 
     It is a further object of this invention to provide the user with a valve whose adjustment is axially relation to the flow of fluid. This axial relationship provides for a more compact unit and which more accurately controls the flow using linearly related flow control disks. 
     It is a further object of this invention to provide a device with which the user can measure the differential pressure as the device is being operated so that flow can be accurately measured at the actual valve as it is being adjusted. It is desirable that the space required for this measurement be compact in nature and close to the body of the valve for the most accurate measurement as well as being compact for the tight spaces that it will likely be experiencing. 
     It is a further object of this invention to provide an embodiment of this device where be a Cv can be set for this valve, through the use of flow control disks, whereby the user has an axially controlled valve with a set maximum Cv, said valve being able to go to complete shutoff. 
     Accordingly, it is the goal of this invention to create an adjustable valve that is axially related to the fluid flow, containing port to determine the actual flow of the fluid, that has the aforementioned characteristics of simplicity, accuracy, adaptability to current uses and safety. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, this application discloses a valve that is adjusted axially along the axis of the flow of fluid. This valve is adjusted by the rotation of the body of the valve where the valve is part of a piping structure. Along with the adjustment portion, there is also the addition of two test ports for high pressure and low pressure measurement, said ports being integral with the rotational member. The valve rotates through 180° from a complete shutoff to maximum flow and back to complete shutoff within the 180°. The valve is able to be rotated simply by hand control and does not need any tool due to the design of the interface between the control disks and the minimal need for 0-rings interference. Furthermore, the valve has a set screw that is attached to an external boss, which is used to lock the valve in place and prevent any unwanted rotation. The valve either has a stop at 180°, so that the user cannot continue past 180° or the valve does not have a stop and allows the user to then complete the rotation for the full 360°. As stated, test ports are integral with the rotating member so that there is an instant feedback of the pressure differential between the high side and the low side of the valve so that one can calculate flow. Since this valve design does not permit increases in cavitation or turbulent flow in the piping system, it is possible to measure the pressure differential at a location that is very close to the actual adjustment means, which is one of the drawbacks with normal ball valves. 
     The valve has two control disks, one stationary and one that is movable and it is the interface between openings on both disks that allow the user to select a particular flow rate. Due to the smoothness of the disks, which are preferably made of ceramic materials, the friction moment is greatly reduced even under high pressure fluid flow. 
     As an embodiment the user can incorporate an adjustable Cv control disk into the valve so that the maximum Cv or maximum flow rate can be established for the valve. This allows the user to set the flow rate and also allows the system to be able to anticipate the maximum flow coming out of the valve. 
     Another embodiment is the addition of a larger Cv control surface which will enable the valve to rotate through up to a total of 300° of rotational movement. This allows a user to more finitely adjust the valve over a larger rotational range and can accommodate higher Cv values. The 300° degrees of rotation is not a limiting factor this invention, but rather a range of motion that will be most suitable for the application in HVAC piping structures. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       In  FIG. 1 , in a view of the valve where the viewer is looking into the test ports of the device. This will be called the upper view. 
       In  FIG. 2 , the view is of the inlet side of the valve with the test ports pointing downwardly. 
       In  FIG. 3 , the view is of the outlet side of the valve with the test ports pointing downwardly. 
       In  FIG. 4 , an upper oblique view of the valve is shown with the outlet of the valve being exposed. 
       In  FIG. 5 , a side profile view of the valve is shown with a cutaway view through the body of the valve is shown detailing the inlet portion of the valve and the first metering section. 
       In  FIG. 6 , a side profile view of the valve is shown with a cutaway view through the body of the valve is shown detailing the regulating means and the outlet portion of the valve. 
       In  FIG. 7  through  FIG. 10 , is a series of views looking at the valve from the inlet side, where the valve has been adjusted to various flow amounts, as shown as a percentage of total flow. One can observe the different regulating means as they interact with one other by the difference in the cross hatching. 
       In  FIG. 11 , a detail of only the outlet portion of the valve is shown along with the primary flow control regulating means. 
       In  FIG. 12 , a detail of only the outlet portion of the valve is shown along with the secondary flow control regulating means, where the primary flow control regulating means has been removed from the view for clarity. 
       In  FIG. 13 , an oblique view of the valve is shown where the outlet portion has been removed and only the primary flow control regulating means is shown. 
       In  FIG. 14 , an oblique view of the valve is shown where the outlet portion has been removed and the primary flow control regulating means is also removed to detail the inner bore of the body of the valve.  FIG. 14A  is showing the optional detents. 
       In  FIG. 15  and  FIG. 15A , the primary flow control disk is shown in a frontal and an oblique view respectively, where the disk is used in an application where the valve is capable of complete shutoff every 180° degrees. 
       In  FIG. 16  and  FIG. 16A , the secondary flow control disk is shown in a frontal and an oblique view respectively, where the disk is used in an application where the valve is capable of complete shutoff every 180° degrees. 
       In  FIG. 17  and  FIG. 17A , the variable Cv or variable flow regulating control disk is shown in a frontal and an oblique view respectively, where the disk is used in an application where the valve is capable of complete shutoff every 180° degrees. 
       In  FIGS. 18 and 18A , the primary flow control disk is shown where the embodiment of having a range of motion greater than 180°. 
       In  FIG. 19  and  FIG. 19A , the variable Cv or variable flow regulating control disk is shown in a frontal and an oblique view respectively, where the disk is used in an where the embodiment of having a range of motion greater than 180°. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention as disclosed in the drawings has the principle use in the HVAC environment but there exists no limiting language to prevent this invention to be practiced in other fields of use. The invention consists of three main elements, inlet section, a body and an outlet portion. This invention is an adjustable valve that is adjusted axially to the flow of the fluid, with the further embodiments of ports that are designed to report differential pressure through the valve and whereby the Cv of the valve can be set and still have the valve go to complete shutoff. 
     In  FIG. 1 , the valve is shown with its three main sections; a central body  100 , an inlet portion  200  and an outlet portion  300 . Shown in this view are differential pressure measurement means, shown as ports  102  for high side pressure and port  103  for low side pressure. It is disclosed that this invention will function without ports  102  and  103  as the measurement of differential pressure across this valve can be done through the use of other independent devices. It can be seen in this  FIG. 1  that high side pressure test port  107  is at the base of high side pressure monitoring port  102 . Similarly, low side pressure test port  106  is located at the base of low-pressure test port  103 . Both ports  102  and  103  are internally adapted, by threads or other means, to accept industry standard pressure probes, which can include those probes that are capable of measuring pressure and temperature. Located between inlet portion  200  and high pressure port  102  is set screw boss  104  therein located on boss  104  is threaded set screw through hole  112 . It is the procedure for the user to adjust the device to the desired flow, and then use the set screw to lock it in place preventing further rotation. Located appurtenant to outlet  300  is angular displacement index  105  which corresponds in 90° increments to major angle indicator  106 . It is the relation of the increments on index  105  to angular displacement guide  310  that is located on outlet portion  300 , so that the user can reference the amount of rotation that has been accomplished through a number of degrees. Guide  310  is located upon the hex-nut  301 . Both outlet hex-nut  301  and inlet hex-nut  201  are shown as hexagonal connecting members, but there is nothing in this application that defines and/or limits the shape or size of either of the flanges. Body  100  is defined as a cylindrical member  101  that can either have a smooth or polygonal exterior surface. Inlet portion  200  and outlet portion  300  defined the two ends of the cylindrical member  101 , where the inlet portion  200  is defined as the proximal end and the outlet portion  300  is defined as the distal portion. 
     It is in  FIG. 2 , that the valve is shown with inlet portion hex-nut  201  facing the observer. As references one can see set screw boss  104  and high pressure test port  102 . In this view primary control disk  113  is seen in its closed position. The opening that defines inner bore  203  is defined as sharing a common central axis to the cylindrical member  101 . Inlet lead-in bevel  206  allows the operator to more accurately insert the connecting member into the body. It is noted that the piping system connection means are located at the distal end of inlet section  200  and outlet portion  300  respectively, are not adapted to any particular piping structure connecting means. In this embodiment of this invention, connection means are internally threaded couplings which have a described hexagonal external interface, which is commonly known in the plumbing industry as inlet hex nut  201  and outlet hex nut  301 , which are located at the distal end of inlet section  200  and outlet portion  300  respectively. This device, though commonly using national pipe thread threads, can be adapted to a piping system by a sweated or swaged joints or any other common plumbing practice joinery. In  FIG. 3  we see the opposite end from  FIG. 2  as hex-nut  301  is shown, and low-pressure port  103  is shown for reference. Secondary control disk  315  is shown and primary control disk  113  is shown as well. It is the relationship between the two that details that is in a closed position as the two control disks are diametrically opposed in their position. Interior bore  303  has a common bore that is coincident to bore  203  and outlet lead in bevel  317  assists the operator in inserting the piping joints.  FIG. 4  is an oblique view of the upper portion of the valve. Reference is made throughout this application as the upper portion of the valve as being that portion containing the high pressure and low pressure ports  102  and  103 .  FIG. 4  details the outlet bore  303  along with lead in bevel  317  along hex-nut  301 . 
       FIG. 5  is a cutaway version of the valve which details the inlet portion as well as the first half of the main body. Lead-in bevel  206  is located about the entrance of bore  203 . Further interiorly located in the center of opening of bore  203  is stepped down region  207  which provides entrance to the venturi  204 . The venturi is a commonly used device in the plumbing industry. The venturi allows for the measurement of the volumetric flow rate of the fluid going through the valve as there is a direct relationship between the high side and the low side pressure difference and the fluid speed through the valve, where fluid flow increases as the cross-sectional area decreases, which is based on Bernoulli&#39;s principles. This step down from bore  203  to the entrance of venturi  204  is shown as rough steps which is common for manufacturing to create a bore pattern using smooth sides and sharp corners as that is the shape of the boring tool. There is nothing that prevents the disclosure of a smoother transition between board  203  and venturi  204 . Venturi wall  209  is a conically described section which terminates at the proximal end of inlet portion  200  along inlet portion termination wall  208 . Inlet portion  200  fits into main body  100  along the common bore between the two parts. Along the interior of inlet portion  200  is snap ring groove  211  which holds snap ring  202 , said snap ring  202  secures the inlet portion  200  onto body  100 . Inlet portion  200  butts against body  100  along the joint between the interior flange wall  210  and body exterior collar  121 . Distal portion  109  of body  101  contains O-ring groove  124 . The O-ring that sits in O-Ring groove  124  is not shown so as to maintain the clarity of the drawing. Venturi  204  terminates into low-pressure sensing ring as part of body  101 . It is seen in  FIG. 5  high-pressure testing port  107  is in direct contact and relations there with circular venturi sensing ring  108  so that the low pressure can be measured. High-pressure port  102  is shown with smooth walls but is designed to adapt to any size and or connection type, including the common NPT thread, that is available on the testing probes. Though desirable to remain located with the valve, the testing probes can be removed and used on other applications. After the fluid passes through sensing ring  108  it is throttled down through throttling area  110  after which the now higher pressure fluid flows into interior channel  111  prior to the fluid de-throttling into primary control disk  113 . The fluid flow through interior channel  111  is at a higher pressure than it was going through the low-pressure sensing ring. It is at the end of channel  111  that low-pressure sensing port  106  is seen on  FIG. 6 . 
       FIG. 6  details the outlet and of the valve. Primary control disk  113  is placed upon O-ring that is compressed upon in O-ring groove  126  by disk  113  as disk  113  is tightly fit and secured into primary disk enclosure  130 , where the purpose of the O-ring is the sealment means that prevents blow-by of the fluids as well as to promote contact with the secondary flow control disk  315  through the compressive and expansive characteristics of a circular sectioned O-Ring. Again the O-ring is excluded for purposes of clarity. Primary control disk  113  has two locating tabs  117  located 180° opposite along the exterior of the primary control disk  113 . Tabs  117  of primary disk  113  are securely located into primary disk securement slots  125  located on body  101  as more clearly seen in  FIGS. 13 and 14 .  FIG. 6  also shows rotation stop  312  which is placed to prevent rotation of the body  100  past a set number of degrees, which in this case would be 180°. The valve uses the rotation stop as a convenience versus a necessity as there is no harm to the valve should the user completely rotate the body 360° except for issues with the differential pressure probes. 
     Outlet portion  300  has centered through it bore  303  which has a common axis with bore  203  and channel  111 , lead-in bevel  317  being centered about bore  303 , which has a similar step down region  305  that has sharp side, again referring to common tooling nomenclature of the industry. Region  305  steps down into central outlet bore  304  which is in fluid communication with secondary control disk  315 . Secondary control disk  315  also has locking flanges  308  which slide into slot  316  which holds disk  315  in place. As with the primary control disk  113 , secondary control disk  315  also is tightly fit and secured into secondary disk enclosure  321  and compresses upon an O-ring that fits into O-ring groove  306 , the O-ring is not shown for purposes of clarity and adapts the characteristics of sealing and compressive resistance as the O-Ring provides to the primary control disk  113 . It can be shown that snap ring  316  sits in groove  302  of the outlet portion  300  and interfaces with body  101  through snap ring channel  119 . This snap ring secures outlet portion  300  into body  100 . Located interiorly from snap ring  316  is O-ring groove  116  which provides additional sealing for outlet portion  300 , as before O-ring is not shown for purposes of clarity. All O-rings used in this device are common O-rings with a circular cross-section that are used in the industry, constructed of a material that does not degrade in the presence of the proposed fluids going through the about. In this case buna-nitrile, silicon or EPDM O-rings can be used, as water is the proposed fluid. Proximal edge  318  of outlet portion  300  butts up against outside flange wall  121  and there is a close fit tolerance between interior bore wall  307  of outlet portion  300  and the interior wall  123  of body  101 . Though it is shown on  FIG. 6  that primary control disk  113  and secondary control disk  315  are not in contact, this is for purposes of clarity of the drawing. In actual application O-rings that are contained in O-ring grooves  126  and  306  will maintain the control disks in constant contact. Furthermore the pressure and flow of the water will push the to do is to gather further preventing any leakage between the deaths The two control disks are ground smooth and have a surface roughness of no greater than 0.2 of a micrometer. 
       FIGS. 7, 8, 9 and 10  show the relationship between the primary and the secondary control disks  113  and  315  respectively. Being viewed from the inlet hex-nut  201  as the valve body rotates one can see how the primary control disk shown with the wavy lines rotates through the stationary secondary control disk shown with the straight lines. 
       FIG. 11  is a view of the outlet portion  300  as can be seen the interior bore wall  307  defines the piece. Snap ring groove  302  a shower and at the proximal and the distal and is defined by termination wall  313 . Primary control disk  113 , though not being part of the outlet portions  300 , is shown for reference only. One can see the tab  117  as well as the defined opening  120 . Shown in this view is rotation stop  312  which can be used if the purchaser of the product wants only 180° rotation or any specified angle as we will see later that the maximum rotation is 300°. The maximum of 300° rotation is not a limiting feature of this invention. The shape of the openings in the secondary disk  315  can be adapted to any finite number of degrees, but it found that in the practicing of this invention in the HVAC industry, approximately 300 degrees of rotation would be the most adaptable to the application of this invention. Rotation more than 330 degrees might cause issues with test probes inserted into the test ports  102  and  103  along with problems associated with the secondary disk  315 . It is important that the user be able to have a positive stop to know when the valve is flowing at its maximum or minimum valves.  FIG. 12  is the same view as  FIG. 11  scans primary control disk  113 . Secondary control disk  315  is shown flush with termination wall  313  as disk  315  is positioned into disk enclosure  321 , where disk enclosure  321  contains O-ring groove  306 . Secondary control disk  315  being held in place by tabs  308  which fit in the slot  316 . As can be observed between  FIG. 11  and  FIG. 12  the opening  120  of primary control desk  113  interfaces with the closed portion of secondary control disk  315 . This would be in the closed state. 
       FIG. 13  is a view of the body and inlet portion distally related to the bore of the body. As can be seen the outlet portion  300  has been removed so that we can observe the inside of body  101 . Primary control disk  113  can be seen with tab  117 .  FIG. 14  shows a view of slot  125  as it is cut into the bore of the body  101 , termination shelf  127  is shown in  FIG. 13  along O-ring groove  116  and snap ring  119 . Rotational stop  118 , interfaces with rotation stop  312 , is located at the proximal edge  121  of body  101 . Rotational stop  118  works in conjunction with rotation stop  312  providing the user a positive stop to know when the user has fully opened or closed the valve. In this particular example rotation stop  312  interfaces with rotational stop  118  and provides the user with an approximate 300° rotation. In other embodiments the rotation stop  312  and rotational stop  118  can limit the user to 180° of rotation. In embodiment of the valve has a tactile feel so that each incremental rotation through guide  105  of the valve can have an indent and detent (dentent  116  is shown in  FIG. 14A  as an optional feature) combination so that the user can feels the rotation and notice that each tactile bump represents a number of degrees. 
       FIGS. 15 and 15A  shows a detail the primary control disk where there are two openings. The primary control disk  113  that has two 90° angular sections or openings in the face of the disk.  FIGS. 16 and 16A  show the matching secondary control disk  315  having two 90° angular sections or openings in the face of the desk.  FIGS. 15 and 16  disclose disks with two 90° circular segments where the radius of the segment is less than the radius of the disk. The radius and chord sections of each of the circular segment on the primary and secondary control disk must be coincident. The segments are cut out of the where the operator has 180° to go between any of the two extremes, such as 180° from shut off to shut off or 180° from full-flow to full flow. There is no limit to the number of angular sections on a particular disk so long as the disk has an equal number of closed sections that will interface with a similar number of sections on the secondary disk so that the valve can completely shut off the flow of fluids through the valve. 
       FIGS. 17 and 17A  show the variable Cv disk  415  that can be used as an embodiment to this device. The Cv is defined by the geometry of the arc&#39;s radius and chord. As can be seen disk  415  works with primary disk  113 , where that the design of disk  415  is unique to a defined Cv or maximum flow. The variable Cv Disk  415  has a crescent shaped arcs where the major arc has a defined diameter based on the diameter of disk and a minor arc of lesser diameter is tangentially placed against first arc, and the surface area of the opening defines the maximum flow. Disk  415  is factory set for example to 5 gallons per minute, so that the maximum flow through the valve is set by the disk  415 . The rotation of this style of desk is 180°. The interface between Cv disk  415  and primary disk  113 , is that disk  113  rotates about the fixed Cv disk regulating flow up to the maximum flow rate as described by the arcs through a rotation of 180°. 
       FIGS. 18 and 19  detail an embodiment where a set of disks selected by the user sets a particular Cv from the factory and the valve can rotate up to 300°. With this increase in angular rotation, a more finite adjustability is introduced into the valve and the design of secondary disk  415 A allows for a more linear relationship between the percentage of the valve opening to the percentage of maximum flow of fluids through the valve. Disk  113 A is similar in function as primary disk  113  and disk  415 A is similar in design and function as secondary disk  415 . The radius of the major arc is less than the radius of the secondary disk  415 A and the minor arc is not tangentially located but is more centrally located and is defined mathematically according to the surface area desired based on the maximum Cv or flow rate required of the valve. The valve body, using rotation stops  118  and  312 , allows the user a finer control of the valve through the entire adjustment range of up to 300°. 
     Another embodiment, not shown on the drawings is the addition of a piezometer ring or averaging annulus ring in place of low pressure sensing ring  108 . This piezometer ring is used when the valve is not located on a length of pipe that is sufficiently for a distance to accurately measure the pressure differential with a regular circular cylindrically shaped venturi sending ring  108 . The concept of the piezometer ring is to create a much finer ability to more accurately sensing the low pressure so that the valve can operate with a higher degree of accuracy. 
     It can be appreciated by those appropriately skilled in the art that changes, modifications or embodiments can be made to this invention without departing from the spirit, principles, theories, ideas or conceptions that have been disclosed in the foregoing. It is herein recognized that the embodiments disclosed by this description of the best mode of practicing this invention, which will be hereafter described in their full breadth in the claims and equivalents thereof.