Abstract:
A sanitary, live loaded, pass-through fitting apparatus which allows for variable depth insertion of a pass-through object is disclosed. The apparatus is useful for sanitary introduction of a thermowell probe, dip tube, or other objects into a process stream or vessel. The pass-through object is sealed to the fitting at the point of fluid insertion with the seal material under a live load.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation-In-Part of U.S. Nonprovisional application Ser. No. 11/500,693 filed Aug. 9, 2006 which claims priority benefit of U.S. Provisional Application Ser. No. 60/709,061 filed Aug. 17, 2005. The contents of U.S. Ser. No. 60/709,061 and U.S. Ser. No. 11/500,693 are expressly incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates to apparatus and methods to monitor process conditions in a container or chamber or process stream including bioreactors for cell cultures and microbial fermentation, semiconductor fabrication, or any process where microbial contamination or chemical cross contamination is undesirable. 
         [0007]    2. Description of Related Art 
         [0008]    In the related art, thermowells or cylindrical tubes, have been employed to hold sensors used to monitor conditions of process fluids. Typically compression fittings such as in  FIG. 2  are used in combination with thermowells and the like which feature seals located within the interior portion of the fitting, i.e., these fittings seal to the probe or tube away from the process stream but allow for variable insertion depth. An example which describes a variable depth thermowell assembly employing compression fittings is U.S. Pat. No. 4,137,768. A disadvantage of compression seal-based designs ( FIG. 2 ) is that because the seals  1  are positioned away from the insertion point to the process stream, process fluid can become entrapped in a retention zone  2  in the interior portion of the fitting permitting bacterial growth or chemical contamination. In many applications such as biopharmaceutical processes, bacterial or chemical contamination may render the process fluid unacceptable for use. For this reason, compression-type fittings must be disassembled, cleaned, and thoroughly drained before reuse—a time consuming and therefore costly disadvantage. An example of a typical pass-through fitting utilizing compression fittings is depicted in  FIG. 2 . As an alternative to adjustable depth designs, thermowells or dip tubes can be welded and sealed in place to a sanitary fitting at a predetermined length for the insertion depth. This design which avoids the disadvantages of fluid entrapment that occurs with designs employing compression fittings does not allow for variable insertion depth of a probe or tube once it has been manufactured. An example of a typical welded and sealed design is shown in  FIG. 1 . 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The invention relates to a sanitary pass-through fitting apparatus. The apparatus permits variable depth insertion of a cylindrical pass through object such as thermowell or dip tube into a process stream featuring sealing at the point of insertion and therefore confines process fluid to the process side of the apparatus without entrapment areas or cavities that may entrap process fluid and lead to bacterial growth or cross-contamination. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S). 
         [0010]      FIG. 1  Is a side view and partial sectional view of a typical thermowell example from the related art. 
           [0011]      FIG. 2  Is a side view and partial sectional view of a typical industrial thermocouple threaded into sanitary cap. 
           [0012]      FIG. 3  Is a sectional view from the side of an embodiment of the sanitary, live loaded pass through apparatus with cylindrical object in place to illustrate the internal construction. 
           [0013]      FIG. 4  Is a sectional view from the side of another embodiment of the sanitary, live loaded pass through apparatus with cylindrical object in place to illustrate the internal construction. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    An embodiment of a fitting apparatus is shown in  FIG. 3  comprising a fitting body  5 , an upper portion having external threads to accommodate a packing nut  3  with internal threads, and including a packing step  10 , and having a process side with an inclusive angle  6 , terminating at a radius  7 . The term, “process side,” denotes that region of space relative to the fitting body wherein the end face faces process fluid. Thus the expression “the surface of the fitting body on the process side” denotes a surface of the end face of the fitting apparatus that contacts fluid. It should be understood that from the perspective as illustrated in  FIG. 3  “upper” or “above” when applied to an internal component within the apparatus refers to the direction proximal to the packing nut and the terms “lower” or “below” analogously refer to the direction of the process fluid and that these terms are applied in this directional sense even if the device is positioned with horizontal or inverted orientation. An internal cavity  14  is formed when the packing nut and fitting body are engaged. A cylindrical device  1  is passed through the packing nut and fitting internals as shown. Internal components are arranged as shown in a cavity  14  formed within the packing nut and the fitting body, comprising spring washers  2 , upper packing gland  4 , upper packing  13 , lower packing gland  12 , and lower packing  11  such as but not limited to a chevron packing. The packing can be fabricated from polytetrafluoroethylene or other polymers. A lower packing  11  is positioned such that it abuts with and is retained by a packing step  10 . 
         [0015]    Upon tightening the packing nut  3 , an axial load is translated to the spring washers  2 , and to the packing glands  12 ,  4 , and to the packing seals  13 ,  11 . An axial seal is made by the lower packing  11  to the packing step  10  on the lower interior portion of the pass through fitting body. A radial seal  9  is created to the cylindrically shaped pass through object. Because the process side  8  of the pass through fitting body has an inclusive angle  6  terminating in a radius  7  as shown, with the radius being contiguous with the packing step, the lower packing is partially exposed and fluid cannot penetrate upward beyond the plane in which the radial seal lies, i.e., fluid cannot penetrate upward or in the direction of the packing nut beyond the insertion point. The term, radius, denotes the rounded terminus of the end face of the fitting body which forms the orifice ( 25 ) through which the cylindrical object passes. The term, inclusive angle, denotes a concave surface on the process side end face of the fitting body contiguous with the radius, such that the surface formed by the inclusive angle is nonparallel to the plane of the orifice ( 25 ). The insertion point is defined according to its plain meaning within the context of settings involving insertion of a probe protruding into a fluid-filled chamber or process stream—thermowell probes, pass through probes, and various process control probes. It is the point where the pass-through object enters the process stream, the chamber, or the body of fluid. The insertion point according to the embodiment shown in  FIG. 3  is located at the point of seal formed between the pass-through object and the lower packing at the exposed surface of the lower packing. On the process side, only exposed surfaces contact the fluid and these can be easily rinsed, cleaned or drained because entrapment of fluid in the interior portion of the fitting is prevented. The gap ( 16 ) between the radius and pass-through object is of sufficient magnitude that fluid retention is prevented. There are no narrow cavities or crevices permitting infiltration of process fluid into the fitting. Contact between process fluid and apparatus is essentially limited to a continuous surface formed by the exterior portion of the cylindrical object  1 , the partially exposed portion of sealing means  9 , the inclusive angle  6 , and radius  7 . Thus an impenetrable barrier is formed that is essentially or substantially surfacial. 
         [0016]    By loosening and retightening the packing nut  3 , the insertion depth of the cylindrical object  1  can be adjusted to an optimum sensing or sampling point. The spring washers  2  dynamically compensate for wear and thermal cycling of the packing components, aiding in leak tightness of the apparatus. 
         [0017]    The upper packing  13  serves to grip and provide lateral support without damage to a cylindrically shaped pass through object. 
         [0018]    The upper and lower packing glands  4 ,  12  serve to properly load and contain the upper and lower packings. Additional pairs of packings and packing glands may be employed. 
         [0019]    In another embodiment,  FIG. 4 , a single packing gland ( 4 ) is positioned adjacent to the spring washers ( 2 ), a Chevron packing ( 11 ) is positioned on the packing step ( 10 ) and a second Chevron packing ( 13 ) is positioned between packing ( 11 ) and packing gland ( 4 ). The exposed surface of the Chevron packing ( 11 ) is flush with the fitting body. The diameter about the radius is greater than the diameter of the pass-through object so that the gap formed between the pass through object and radius can range from 0.0020-0.0050 inches. With radius diameter of 0.255 in, the optimal gap for high temperature operation is 0.0025 in. This embodiment is suitable for high temperature operation. The point of probe insertion is more accessible for clean in place and steam in place operation than the apparatus shown in  FIG. 3 . 
       Sequence Listing  
       [0020]    Not Applicable