Abstract:
Disclosed is a high temperature insertion type flow element and mounting extension assembly for a gas flow measuring device. Designed to overcome the drawbacks associated with compensating for differential thermal expansion between the element and the duct wall, the element consists of an otherwise conventional insertion type flow element, that incorporates the use of a mounting extension assembly and an expansion fitting. The mounting extension positions the element head in an offset manner from the gas duct, placing the element head in a position away from any insulating materials encasing the duct, allowing for convenient access to the instrumentation and cleaning ports. The expansion fitting stabilizes the element tubes within the duct while absorbing any differential thermal expansion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to insertion type gas flow meters and, more particularly, to a high temperature insertion type flow element with a mounting extension. 
     2. Description of the Related Art 
     The instrumentation and process control industry has recognized the use of the Pitot tube as a reliable device for measuring the volumetric flow of both liquids and gasses for many years. The Pitot tube operates based upon the principal that when a fixed probe is inserted into piping or duct work containing a moving fluid, the total pressure sensed by the probe is the sum of the static pressure exerted by the fluid, whether in motion or at rest, and the dynamic pressure equivalent to the kinetic energy of the fluid in motion. Conventional Pitot tube arrangements provide measurement of both the static and total pressure of the flowing fluid, the difference between which is the dynamic pressure. This differential pressure, i.e. the dynamic pressure, is directly related to and can be used to calculate the linear flow rate within the piping or duct work. The volumetric flow rate of the fluid is determined by multiplying the linear flow rate by the cross-sectional area of the conduit. 
     The Pitot tube is particularly useful in measuring gas flows in pipes or ducts with a large cross-sectional area because a Pitot tube causes negligible pressure loss within the conduit. In application, it is well known that flow rates, and thus dynamic pressures, within a conduit are not uniform. Affected by variables such as the Reynolds number of the particular gas and turbulence caused by wall surface roughness, dampers, elbows and other fittings, the flow rate/dynamic pressure is generally higher toward the center of the conduit and lower towards the outer extremes. This phenomenon is described in terms of a velocity profile, wherein a vector representation of the linear velocities at various points within the conduit defines a characteristic profile curve. The dynamic nature of the velocity profile precludes accurate measurement with a single Pitot tube. Rather, an accurate measurement of the flow within the conduit is obtained by placing Pitot tubes at various positions on a cross-sectional plane, sampling the dynamic pressure at various points across the velocity profile, averaging them, and using the result to calculate a volumetric flow rate. 
     A popular type of Pitot tube arrangement is that of the insertion type flow elements. Typical insertion type flow elements consist of a dynamic pressure sensing Pitot tube and a static pressure sensing Pitot tube connected to an element head having connections that allow for connecting the individual tubes to instrumentation devices. Depending upon the size of the duct, any number of elements can be inserted, traversing the interior cross-section of the duct at varying locations so as to account for the flow profile within the duct. The individual dynamic and static pressures are then joined at a common header or manifold so that an overall differential pressure can be determined. Use of the insertion type flow element is advantageous in that the element is suited for insertion through a duct wall and thus requires minimal installation efforts. Depending upon variables such as the size of the duct, temperature and velocity of the gasses passing therethrough, the insertion type flow element is fit with outboard support wherein it is anchored to the duct wall both at the element head end and at the opposite end of the Pitot tubes. In high temperature applications, however, a vast majority of insertion type flow element installations are of the type having an outboard support. While the insertion type flow element provides accurate measurements and ease of installation, its use does give way to some persistent problems that have, until now, gone unsolved. 
     One particular problem can occur in airflow applications in which particulate concentrations are heavy. In such applications Pitot tubes can become clogged, creating inaccuracies in flow measurement wherein the element senses an erroneous gas flow. In these applications, there is a need to frequently clean clogged tubes in order to maintain an accurate gas flow measurement. Typically, the element must be taken out of service for cleaning, which is labor intensive, time consuming and, thus, extremely undesirable. An adequate solution for this problem has yet to be addressed in the industry. 
     Another particular problem occurs in applications where the flow rate of hot gasses are measured, wherein thermal expansion causes a differential expansion between the Pitot tubes and the duct wall. When this occurs, the expansion of the Pitot tubes in the longitudinal direction is greater than that of the cross-sectional expansion of the duct wall. Being that the element is typically fit with outboard support, as a result, the Pitot tubes either fail themselves or the welded bead holding them in place fails. The present invention is directed toward a high temperature mounting extension for use in conjunction with an insertion type Pitot tube flow element having an outboard support that incorporates high temperature packing that allows for thermal differential expansion that remedies the above mentioned problems associated with conventional installation practices. 
     A search of the prior art produced the following inventions related to Pitot tube gas flow measuring devices: 
     U.S. Pat. No. 1,250,238, issued in the name of Spitzglass; 
     U.S. Pat. No. 3,685,355, issued in the name of DeBaun; 
     U.S. Pat. No. 4,297,900, issued in the name of Brandt, Jr.; 
     U.S. Pat. No. 4,344,330, issued in the name of Renken et al.; 
     U.S. Pat. No. 4,602,514, issued in the name of Kurrle et al.; 
     U.S. Pat. No. 4,750,370, issued in the name of Ossyra; 
     U.S. Pat. No. 5,481,925, issued in the name of Woodbury; and 
     U.S. Pat. No. 5,483,839, issued in the name of Meunier. 
     While all of these patents describe devices incorporating the use of a Pitot tube device to determine the volumetric flow rate of gasses in a conduit or the like, none of them address the specific problems associated with tube cleaning or differential thermal expansion in an insertion type flow element. 
     Also, of considerable relevance is U.S. Pat. No. 5,736,651, issued in the name of Bowers, the present inventor. In this patent, disclosed is a high temperature gas flow sensing element wherein a frame structure supports a Pitot tube array that spans its interior cross-section. The internal dimensions of the frame are the same as that of the conduit in which the gas flow is to be measured. Inserted in line with the conduit, the gasses in the conduit flow through the element, thus producing a flow measurement. The Bowers flow sensing element incorporates the use of exterior access ports to allow for cleaning of the Pitot tubes without removing the element. Additionally, pliable, high temperature packing material is used to secure the Pitot tubes within the element while permitting them to expand and contract. While many solutions to the problems associated with high temperature flow measurement are incorporated into this invention, the disclosure does not address the specific problems encountered when dealing with an insertion type element. As such, the present invention is sufficiently novel and non-obvious so as to distinguish it from the prior art, including the present inventor&#39;s own prior art. 
     SUMMARY OF THE INVENTION 
     Briefly described according to the preferred embodiment of the present invention, disclosed is a high temperature insertion type flow element and mounting extension assembly for a gas flow measuring device. Designed to overcome the drawbacks associated with compensating for differential thermal expansion between the element and the duct wall, the element consists of an otherwise conventional insertion type flow element, having dynamic and static pressure sensing Pitot tubes, that incorporates the use of a mounting extension assembly at the element head end and an expansion fitting at the end opposite the element head. The flow element is secured to an existing gas duct by boring a hole in the duct sidewall and inserting the element such that the Pitot tubes span the interior cross-section thereof. Using conventional fastening means such as bolt-type fasteners or welding, the mounting extension and the expansion fitting are secured to opposite exterior surfaces of the duct. The mounting extension positions the element head in an offset manner from the gas duct, placing the element head in a position away from any insulating materials encasing the duct, allowing for convenient access to the instrumentation and cleaning ports. The expansion fitting stabilizes the Pitot tubes within the duct while absorbing any differential thermal expansion. The flow element is designed and installed so as to cause a minimal amount of disturbance to the flow within the duct. 
     Therefore, it is an object of the invention to provide a high temperature insertion type flow element and mounting extension that provides accurate flow measurement of high temperature gasses within a duct. 
     It is another object of the invention to provide a high temperature insertion type flow element and mounting extension that allows for differential thermal expansion between the Pitot tubes and the duct wall. 
     It is another object of the invention to provide a high temperature insertion type flow element and mounting extension that positions the element head away from the insulation packing often found on the exterior surface of high temperature duct work, providing convenient access to the instrumentation and cleaning ports thereof. 
     It is another object of the invention to provide a high temperature insertion type flow element and mounting extension wherein a minimal amount of disturbance is caused to the gas flow within the duct work. 
     Finally, it is an object of the invention to provide a high temperature insertion type flow element and mounting extension used in ducts of varying size and cross-sectional shape. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 LIST OF REFERENCE NUMBERS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 20 
                 High Temperature Flow 
               
               
                   
                   
                 Element 
               
               
                   
                 21 
                 Element Head 
               
               
                   
                 22 
                 Mounting Extension 
               
               
                   
                 23 
                 Element Tubes 
               
               
                   
                 24 
                 Outboard Support 
               
               
                   
                 25 
                 Instrumentation Ports 
               
               
                   
                 26 
                 Cleaning Ports 
               
               
                   
                 30 
                 Outboard Support Fitting 
               
               
                   
                 31 
                 Outboard Access Port 
               
               
                   
                 32 
                 Outboard Support Plate 
               
               
                   
                 35 
                 Tubular Housing 
               
               
                   
                 36 
                 Element Head Support 
               
               
                   
                   
                 Flange 
               
               
                   
                 37 
                 Mounting Extension Support 
               
               
                   
                   
                 Flange 
               
               
                   
                 38 
                 Element Tube Aperture 
               
               
                   
                 39 
                 Second Element Tube 
               
               
                   
                   
                 Aperture 
               
               
                   
                 40 
                 Fastener Apertures 
               
               
                   
                 44 
                 Element Head Mounting Plate 
               
               
                   
                 45 
                 Welded Bead 
               
               
                   
                 46 
                 Element Tube Apertures 
               
               
                   
                 50 
                 Element Head Gasket 
               
               
                   
                 51 
                 Extension Housing Sealing 
               
               
                   
                   
                 Plate 
               
               
                   
                 52 
                 Extension Housing Sealing 
               
               
                   
                   
                 Gasket 
               
               
                   
                 60 
                 Compression Fitting 
               
               
                   
                 61 
                 Cap 
               
               
                   
                 65 
                 Element Tube Support 
               
               
                   
                   
                 Bracket 
               
               
                   
                 66 
                 Cross-Member 
               
               
                   
                 67 
                 Anchoring Rod 
               
               
                   
                 70 
                 High-Temperature Packing 
               
               
                   
                 71 
                 Compression Sleeve 
               
               
                   
                 72 
                 Compression Cap 
               
               
                   
                 80 
                 Duct 
               
               
                   
                 81 
                 Duct Walls 
               
               
                   
                 82 
                 Insertion Apertures 
               
               
                   
                 85 
                 Insulating Materials 
               
               
                   
                   
               
             
          
         
       
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings, in which like elements are identified with like symbols, and in which: 
     FIG. 1 is a perspective view of the high temperature insertion type flow element and mounting extension, according to the preferred embodiment of the present invention; 
     FIG. 2 a  is a horizontal plan view of the high temperature insertion type flow element and mounting extension with outboard access ports and supports, according to the preferred embodiment of the present invention; 
     FIG. 2 b  is a horizontal plan view of the high temperature insertion type flow element and mounting extension with outboard end supports, according to the preferred embodiment of the present invention; 
     FIG. 3 a  is side view of the mounting extension portion of the high temperature insertion type flow element and mounting extension with outboard end supports, according to the preferred embodiment of the present invention; 
     FIG. 3 b  is left end view of the mounting extension portion of the high temperature insertion type flow element and mounting extension with outboard end supports, according to the preferred embodiment of the present invention; 
     FIG. 3 c  is right end view of the mounting extension portion of the high temperature insertion type flow element and mounting extension with outboard end supports, according to the preferred embodiment of the present invention; 
     FIG. 4 is an exploded perspective view of the high temperature insertion type flow element and mounting extension, according to the preferred embodiment of the present invention; 
     FIG. 5 is a horizontal view of the high temperature insertion type flow element and mounting extension depicting the installation of the element head/mounting extension combination, according to the preferred embodiment of the present invention; 
     FIG. 6 is a horizontal plan view of the high temperature insertion type flow element and mounting extension depicting the installation of the element head/mounting extension combination, according to the preferred embodiment of the present invention; 
     FIG. 7 is a horizontal sectional view of the high temperature insertion type flow element and mounting extension depicting the installation of the element head/mounting extension combination, according to the preferred embodiment of the present invention; 
     FIG. 8 is a horizontal plan view of the outboard access port and support for use with the high temperature insertion type flow element and mounting extension as depicted in FIG. 2 a,  according to the preferred embodiment of the present invention; 
     FIG. 9 is a horizontal plan view of the outboard end support for use with the high temperature insertion type flow element and mounting extension as depicted in FIG. 2 b,  according to the preferred embodiment of the present invention; 
     FIG. 10 is a horizontal sectional view of the outboard support for use with the high temperature insertion type flow element and mounting extension as depicted in FIGS. 8 and 9, according to the preferred embodiment of the present invention; 
     FIG. 11 is a horizontal plan view depicting the installation of the high temperature insertion type flow element and mounting extension with outboard access ports and supports as shown in FIG. 2 a,  according to the preferred embodiment of the present invention; and 
     FIG. 12 is a horizontal plan view depicting the installation of the high temperature insertion type flow element and mounting extension with outboard support as shown in FIG. 2 b,  according to the preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. Detailed Description of the Figures 
     Referring now to FIG. 1, depicted is the high temperature insertion type flow element and mounting extension, hereinafter high temperature flow element  20 , according to the preferred embodiment of the present invention. The high temperature flow element  20  consists, in general of four parts: an element head  21 , a mounting extension  22 , element tubes  23  and an outboard support  24 . The element head  21  serves a manifold-type function, having instrumentation ports  25  to which instrumentation devices (not shown) are attached and cleaning ports  26  through which the element tubes can be accessed for cleaning and maintenance purposes. The mounting extension  22  allows the element head  21  to be mounted to a duct (not shown in FIG. 1) in an offset rather than abutting manner, so as to provide easy access to the element head  21  and not causing interference with the duct&#39;s insulating materials. The element tubes  23  span the interior cross-section of the duct and provide a differential measurement of the static and dynamic pressures within the duct. The outboard support  24  stabilizes the element tubes  23  within the duct, preventing vibration, and incorporating a design that serves to absorb differential expansion between the duct walls and the element tubes  23 . 
     Referring now to FIGS. 2 a  and  2   b,  depicted is the high temperature flow element  20  having slight variations in the design and function of the outboard support  24 . In FIG. 2 a,  the outboard support  24  consists of an outboard support fitting  30  and an outboard access port  31  for each element tube  23 . The outboard support fitting secures the element tubes  23  to an outboard support plate  32  that is secured to the exterior surface of the duct wall (not shown in FIG. 2 a  or  2   b ) via conventional fastening means. The outboard access port  31  allows for cleaning and maintenance of the element tubes  23  from the end opposite the mounting extension  22  and element head  21 . In FIG. 2 b,  the outboard support  24  consists of a single outboard support fitting  30 , that stabilizes both of the element tubes  23 , securing them to the outboard support plate  32 . In both configurations, the outboard support fitting  30  consists of an expansion fitting designed to absorb the differential expansion between the element tubes  23  and the duct sidewall. Therefore, the differences in the configuration of the high temperature flow element  20  depicted in FIGS. 2 a  and  2   b  are not material to the operation of the present invention in terms of providing support for the element tubes  23  and absorbing differential expansion. The design and operation of the outboard support  24  and the outboard support fittings  30  will be discussed in further detail herein below. 
     Referring now to FIGS. 3 a,    3   b,  and  3   c,  depicted is the mounting extension  22  portion of the high temperature flow element  20 , according to the preferred embodiment of the present invention. The mounting extension consists of a tubular housing  35  having a rectangular cross section. An element head support flange  36  and a mounting extension support flange  37  are mounted at opposite ends of the tubular housing  35 , oriented perpendicular to its longitudinal axis. 
     The element head support flange  36  provides a flat, rectangular surface upon which to mount the element head  21  and includes a rectangular first element tube aperture  38  bored therethrough. Although various conventional fastening means could be used to accomplish the fastening of the element head  21  to the element head support flange  36 , in the preferred embodiment, the element head  21  is welded to an element head mounting plate (not shown in these Figures) having a rectangular shape that mates with that of the element head support flange  36 . The element head support flange  36  includes a series of fastener apertures  40  that allow for securing the element head  21  to the mounting extension  22  via the element head mounting plate  36 , using conventional threaded fasteners (not shown in these Figures). 
     The mounting extension support flange  37  provides a means by which to secure the mounting extension  22  and, thus, the high temperature flow element  20  to the exterior surface of a duct wall. The mounting extension support flange includes a rectangular second element tube aperture  39  bored therethrough. For purposes explained in further detail herein below, the rectangular dimensions of the second element tube aperture  39  are smaller than the rectangular dimensions of the first element tube aperture  38 . As is the case with the element head support flange  36 , various conventional fastening means could be used to accomplish the fastening of the mounting extension  22  to the duct wall. In the preferred embodiment, the mounting extension support flange  37  is welded to the duct wall, so as to provide a secure fit with an air-tight seal. Nevertheless, the mounting extension support flange  37  is optionally fit with a series of fastener apertures  40  that allow for securing the mounting extension  22  via conventional threaded fasteners. 
     Referring now to FIGS. 4-7, depicted is the assembly of the element head  21 , the mounting extension  22  and the element tubes  23  of the high temperature flow element  20 , according to the preferred embodiment of the present invention. In the preferred embodiment, the element head is secured to the element head mounting plate  44  using a welded bead  45 . The element tubes are passed through element tube apertures  46  and secured to the element head  21  via a welded bead or other suitable fastening means. An element head gasket  50  is then slid over the element tubes  23 , followed by an extension housing sealing plate  51  and an extension housing sealing gasket  52 . The element head gasket  50 , extension housing sealing plate  51  and the extension housing sealing gasket  52  also incorporate element tube apertures  46  that allow the passage of the element tubes  23  therethrough. 
     The purpose of the extension housing sealing plate  51  and the extension housing sealing gasket is to form an airtight seal between the extension housing  22  and the interior cavity of the duct to which it is attached. The seal prevents turbulence that would occur as a result of gasses flowing past an open element housing, producing errors in the flow measurement capabilities of the high temperature flow element  20 . The element head gasket  50  and the extension housing sealing gasket  52  are constructed of an insulating material that prevents thermal losses through the mounting extension. The rectangular dimensions of the extension housing sealing plate  51  and the extension housing sealing gasket  52  are such that they pass freely through the first element tube aperture  38 , but not through the second element tube aperture  39 . Thus, an interference fit is formed between the interior surface of the mounting extension support flange  37  and the extension housing sealing plate  51 /extension housing sealing gasket  52 . The extension housing sealing plate  51  is welded to the element tubes  23  at a position such that, when the element head mounting plate  44  is fastened to the element head support flange  36 , the extension housing sealing gasket  52  is sandwiched between the extension housing sealing plate  51  and the interior surface of the mounting extension support flange  37 , creating an insulated air-tight seal. 
     Referring now to FIG. 8, depicted is the outboard support  24  for use with the high temperature flow element  20  as depicted in FIG. 2 a,  according to the preferred embodiment of the present invention. The outboard support  24  consists of an outboard support fitting  30 , an outboard access port  31 , and an outboard support plate  32 . The outboard support fitting  30  is a modified compression type fitting that replaces the compression ferrule typically found in such a fitting with a high-temperature packing (not shown in FIG. 8) that forms a tight seal while allowing the element tube  23  to slide therein, thus absorbing thermal expansion. The compression fitting incorporated into the design of the outboard support fitting  30  will be discussed in further detail herein below. The outboard support fitting  30  secures the element tubes  23  to the outboard support plate  32  that is secured to the exterior surface of the duct wall via conventional fastening means. The outboard access port  31  consists of a conventional compression fitting  60  that is secured to the element tube and a cap  61  that seals the outboard access port  31 . In situations where a high concentration of particulate matter in the measured gasses tends to clog the element tubes  23 , removal of the cap  61  allows for cleaning and maintenance of the element tubes  23 . 
     Referring now to FIG. 9, depicted is the outboard support  24  for use with the high temperature flow element  20  as depicted in FIG. 2 b,  according to the preferred embodiment of the present invention. The outboard support  24  consists of an outboard support fitting  30 , an outboard support plate  32  and a element tube support bracket  65 . The element tube support bracket  65  consists of a cross-member  66  that spans between the ends of the element tubes  23  and is connected thereto via a welded bead  45  or other conventional fastening means. The cross-member  66  is connected to an anchoring rod  67  that is connected to the outboard support fitting  30 . The outboard support fitting  30  is a modified compression type fitting that replaces the compression ferrule typically found in such a fitting with a high-temperature packing (not shown in FIG. 9) that forms a tight seal while allowing the anchoring rod  67  to slide therein, thus absorbing the thermal expansion of the element tubes  23 . The compression fitting incorporated into the design of the outboard support fitting  30  will be discussed in further detail herein below. The outboard support fitting  30  secures the element tube support bracket  65  and, thus, the element tubes  23  to the outboard support plate  32  that is secured to the exterior surface of the duct wall via conventional fastening means. 
     Referring now to FIG. 10, depicted is a sectional view of the outboard support  24  showing the internal construction of the outboard support fitting  30 , according to the preferred embodiment of the present invention. As previously stated, the construction of the outboard support fitting  30  consists of a modified compression fitting that allows for the thermal expansion of the element tubes  23  or anchoring rod  67 , depending upon the style of the outboard support  24 . As is shown, a high-temperature packing  70  replaces the compression ferrule. While it is envisioned that a ribbon packing or packing ring made of any pliable material resistant to high temperatures can be used to construct the high-temperature packing  70 , in the preferred embodiment, a GRAPHOIL (tm) packing material, as manufactured by U-CAR (tm), or similar and equivalent material has been found to be successful in permanently “sealing” the element tubes  23 , thereby assuring a high pressure seal such that the outboard support fitting  30  retains its integrity and remains leak-free even under conditions of extreme temperature or extreme temperature gradient cycling. The element tube  23  is passed through a compression sleeve  71  and a compression cap  72  threadably fastened to the compression sleeve  71 . The element tube  23  is encased with the high-temperature packing  70  between the compression sleeve  71  and the compression cap  72 . As the compression cap  72  is tightened, the high-temperature packing  70  is compressed within the outboard support fitting  30 , both sealing and securing the element tube  23  therein. The high-temperature packing  70  remains pliable, forming a seal around the element tubes  23 , while still permitting the lateral motion encountered when thermal differential expansion occurs. 
     2. Operation of the Preferred Embodiment 
     In accordance with a preferred embodiment of the present invention, as shown in FIGS. 11 and 12, the high temperature flow element  20  is used in the following manner. The high temperature flow element  20  is installed in a duct  80 , securing it to opposing duct walls  81 . Insertion apertures  82  are cut in the duct walls  81 , allowing the element tubes  23  to pass freely therethrough. Once in place within the duct  80 , the high temperature flow element is secured therein by attaching the mounting extension support flange  37  and the outboard support plate  32  to the duct walls  81  via a welded bead  45  or other conventional fastening means, forming an airtight seal. As described herein above the outboard support fittings  30 , extension housing sealing plate  51  and the extension housing sealing gasket  52  serve to complete the sealing of the high temperature flow element  20  within the duct  80 . Installed in the aforementioned manner, the instrumentation ports  25  are connected to instrumentation equipment, thus providing a differential pressure reading that can be used to calculate a gas flow rate within the duct  80 . When the element tubes  23  need cleaned, access is provided via the cleaning ports  26  or the outboard access ports  31 , depending upon the specific configuration of the outboard support  24 . The inclusion of the cleaning ports  26  as an integrated feature of the element head drastically cuts the costs associated with conventional cleaning methods. The mounting extension  22  places the element head  21 , the instrumentation ports  25  and the cleaning ports  26  in a position outside of any insulating materials  85  encasing the duct  80 , providing unobstructed access. 
     While the preferred embodiments of the invention have been shown, illustrated, and described, it will be apparent to those skilled in this field that various modifications may be made in these embodiments without departing from the spirit of the present invention. By way of example, while two variations of the outboard support  24  have been described herein above, it is envisioned that a variety of configurations incorporating the design of the outboard support fitting  30  would be equally effective. Furthermore, applications are envisioned wherein the advantages of the integrated cleaning port head would be of beneficial use while the mounting extension is not expressly required. It is for this reason that the scope of the invention is set forth in and is to be limited only by the following claims.