Abstract:
An air sampling tube is provided that provides superior air flow, strength, and manufacturability and couples to an air sampling sensor housing. The sidewall of the tubular section has an axially extending groove. To facilitate installation and inspection, an air sampling tube is provided with a starter cap. An end cap prevents air flow through the distal end of the tube. An air sampling tube is provided that assures proper axial positioning of tubular section apertures through resort to a coupler with a rotationally asymmetric joining element. A modular kit is provided that allows for custom installation without resort to cutting or forming operations in the field.

Description:
FIELD OF THE INVENTION 
     The present invention relates in general to a tube for conveying air between a forced air supply and a housing containing a detector and in particular to a tube assuring correct alignment and providing high efficiency of air flow. 
     BACKGROUND OF THE INVENTION 
     The sampling of air within the air handling system of a structure is essential to the early detection of air quality dangers such as smoke or carbon monoxide. A conventional scheme for air sampling includes a housing containing a duct air quality detector such as a smoke detector, carbon monoxide detector or other types of air quality detectors such as particulate, humidity, or oxygen. A conventional duct detector housing is exposed to air from an air handling system by way of a sampling tube extending into a duct of the air handling system. The duct detector housing includes an exhaust port so as to create air flow through the detector housing. The housing exhaust port is often coupled to the duct being sampled so as to create a return flow of the sampled air back into the air handling system. Conventionally, an air handling tube is custom formed to accommodate duct dimensions relative to the housing. The tube is formed from an extended length of periodically perforated tubing.  FIG. 1  depicts a conventional prior art duct detector housing equipped with conventional air sampling tubes and coupled to an air handling system duct. 
     Conventional air sampling tubes of a needed length are cut from periodically perforated tubing having a length greater than any that is anticipated to be used. This approach is not only wasteful of tubing material, but also requires field work to cut the tubing, and presents logistical problems associated with the transport and handling of tubing having a length of, for example, 5 feet. Alternatively, conventional air sampling tube construction has involved joinder of rotationally a specific sections of pre-apertured tubing as detailed in, for example, prior art  FIG. 1 . Regardless of construction, periodically perforated tubing is prone to hole fouling associated with particulate in the air handling system and in the instance of galvanized steel tubing the hole formation compromises coating protective integrity. The custom nature of assembly of an air sampling tube poses a problem of assuring proper hole directionality about a tube axis. This rotational symmetry increases both installation and inspection effort. 
     Thus, there exists a need for an air sampling tube having a tubular section that is only joined to another component in a unique orientation relative to an aperture in the tubular section. There further exists a need for an air sampling tube that has a tubular extension with an axially extending groove defined by edges where at least one of the edges is enveloped to form an eddy channel adjacent to the groove. Still further, there exists a need for an assembler or inspector to be able to identify the axial position of air intake holes on a tubular section without resort to movement of the air sampling tube. 
     SUMMARY OF THE INVENTION 
     An air sampling tube is provided that provides superior air flow, strength, and manufacturability and couples to an air sampling sensor housing. The tube in simplest form is a tubular section having a sidewall defining a tube interior and tube exterior. The sidewall of the tubular section has an axially extending groove defined by a first edge and a second edge. At least one of the edges is enveloped within the tube interior to form an eddy channel adjacent to the groove. The tubular section is adapted to join to the housing. 
     To facilitate installation and inspection, an air sampling tube is provided that includes a tubular section having a sidewall defining a tube interior and a tube exterior with at least one aperture through the sidewall providing air communication therebetween. A starter piece is provided having a choke partially occluding air flow within the starter piece and having a shaped aperture indicative of the orientation of the at least one aperture. The starter piece is joined intermediate between the tubular section and an air sampling sensor housing. The distal end of the tubular section relative to the housing engages a coupler for receipt of another tubular section or an end cap occluding air flow through the distal end. 
     An air sampling tube is provided that assures proper axial positioning of tubular section apertures and includes a first tubular section having a sidewall defining a tube interior and a tube exterior and at least one aperture providing air communication therebetween. At least one rotationally asymmetric joining element is associated with an end of the first tubular section or a coupler secured to the tubular section end. A component is also provided having a component end with complementary tab or complementary groove to the at least one rotationally asymmetric joining element to only form a complete engagement directly with the first tubular section or the intermediate coupler in a single rotational orientation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art duct detector housing in fluid communication with a conventional air sampling tube; 
         FIG. 2A  is a perspective view of an inventive tube of a tubular section with a symmetric cross section and two eddy channels and mated to a starter section for engaging a duct detector housing; 
         FIG. 2B  is an end view of  FIG. 2A ; 
         FIG. 3  is a perspective view of an alternate tubular section operative in the present invention with an asymmetric cross section and a single eddy channel; 
         FIG. 4A  is an exploded perspective view of an inventive air sampling tube; 
         FIG. 4B  is an end view of a linear coupler shown in  FIG. 4A ; 
         FIG. 4C  is a perspective view of an angled coupler for joining a tubular section to other parts of an inventive tube; 
         FIG. 4D  is a perspective view of a receptacle-like coupler for tubular sections per  FIG. 2B ; 
         FIG. 5A  is a perspective view of a tubular housing starter section; 
         FIG. 5B  is an end view into the bore of a tubular housing starter; and 
         FIG. 5C  is a cross-sectional view of the section of  FIG. 5B  along line A-A. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention has utility as an air sampling tube to draw a continuous aliquot of air from an air handling system to convey the aliquot to a housing containing an air sampling sensor. The present invention can address a number of limitations found in conventional air sampling tubes, and the inventive improvements include assurance of directionality of an air instance aperture within a tubular section of an air sampling tube; superior mechanical strength and air flow characteristics of a tubular section; modular assembly; and a choke allowing for the visual confirmation of aperture directionality without resort to movement of a tubular section of the air sampling tube. Each of these attributes of an inventive tube is operative independent of the others. An additional attribute of an inventive air sampling tube is the ability to provide an assembler with a component kit allowing for customization of the air sampling tube without resort to tools to cut or otherwise modify inventive tube elements to satisfy the geometries of a given air handling system and the relative position of an air sampling sensor housing. 
     Referring now to  FIGS. 2A and 2B , the tubular section of an inventive air sampling tube is shown generally at  10 . The tubular section  10  has a sidewall  12  defining a tube interior  14  and an exterior. A groove  18  provides fluid communication along the sidewall  12  between the exterior and the interior  14  and is not subject to the uneven air uptake within a duct or the debris fouling associated with a conventional tube having a uniformly spaced line of round holes. The groove  18  is bounded by a first edge  20  and a second edge  22 . It is appreciated that the groove  18  need not extend along the entire length of tubular section  10 . Typical widths for a groove  18  are between 0.1 and 2 centimeters. However, it is preferred that the groove extends over the majority of the length of tubular section  10  in uninterrupted form. It has surprisingly been discovered that, unlike conventional periodic apertures, a groove  18  is less prone to fouling than erratically spaced apertures; the fouling associated with dust and other particulate found in an air handling system. In a tubular section  10 , preferably at least one of the first edge  20  or the second edge  22  is enveloped within the tube interior  14  to form an eddy channel  24  adjacent to the groove  18 . As shown in  FIGS. 2A and 2B , eddy channels  24  and  24 ′ are shown being formed in both edges  20  and  22  while an inventive tube is appreciated to be formed with only one such eddy channel. An eddy channel  24  has been formed to more efficiently transmit air through a tubular section  10  relative to a periodically apertured tube or a grooved tube lacking an eddy channel. Additionally, formation of an eddy channel  24  greatly improves the strength of the tubular section  10  relative to a comparable walled circular cross section tube having either periodic apertures or a groove along the length thereof. A tubular section  10  is readily formed from a variety of materials illustratively including steel, aluminum, and copper; thermoplastics such as polyethylene, polyvinylchloride, and polystyrene. It is appreciated that a tubular section  10  is well suited for extrusion formation and is more efficiently produced than forming a tube and then boring periodic apertures therein. Additionally, in instances when a tubular section  10  is formed of steel and anticorrosion coating is applied thereon, the resultant coating is not compromised by subsequent periodic aperture formation. While the tubular section is depicted in the accompanying figures as having a circular cross section, it is appreciated that other shapes such as cross sections that are triangular, rectilinear, and hexagonal are also operative herein. A notched starter cap  60  is coupled to proximal section end  28  to couple the tube  10  to a conventional duct detector housing. The starter  60  is further detailed with respect to  FIGS. 5A-5C . Distal end  27  of tube  10  is amenable to engagement to a joinder, an end cap or other modular kit component. 
       FIG. 3  shows an alternative inventive tubular section depicted generally at  30 . Tubular section  30  is similar to tubular section  10  of  FIGS. 2A and 2B  that is depicted with a single eddy channel and a second edge extending outward to expand the lateral extent of groove. The tubular section  30  is formed of the same materials as detailed with respect to tube  10 . Tubular section  30  has a sidewall  42  defining an interior  34  and an exterior. A groove  38  extends along at least a portion of the length of the tubular section  30  and is bounded by a first edge  40  and a second edge  42 . The first edge  40  is enveloped within the tube interior  34  to form an eddy channel  44  adjacent to the groove  38 . The second edge  43  is extended outward towards the exterior  36  so as to increase the lateral extent of the groove  38  relative to groove  18  for a given tubular section diameter. Optionally, the second edge  42  is likewise enveloped to form a second eddy channel (not shown). The groove  38  provides air communication between tube exterior and the tube interior  34 . Optionally, an aperture  46  is provided proximal to a tubular section end  47  with the aperture  46  adapted to engage a locking tab of another inventive air sampling tube component. A starter cap  60  as detailed with respect to  FIG. 2  is readily modified to mateably engage the distal end  48  of the tube  30 . 
     A tubular section  10  or  30  is readily coupled to a housing containing an air sampling sensor to form an air sampling tube. An inventive air sampling tube is depicted in  FIG. 4A  in exploded perspective view generally at  50 . Air sampling tube  50  has at least one tubular section such as linear section  10  of  FIGS. 2A-2B  or tubular section  30  of  FIG. 3 . For illustrative purposes,  FIG. 4A  depicts two tubular sections:  10  and a like duplicate section  10 ′ detailed with respect to  FIGS. 2A and 2B . However, it is appreciated that one or both of these tubular sections  10  or  10 ′ is readily replaced by a tubular section  30  with an appropriate change in the joinder. 
     An end cap  60  is provided to engage an end of tubular section  10 . The end cap  60  has a protrusion  52  adapted to engage the wall  12  or  42  of tubular section  10  or  30 , respectively. A protrusion  52  preferably inserts within the interior of the tubular section  10  or  30 . Optionally, the protrusion  54  has a protrusion edge adapted to engage an eddy channel  24  of the tubular section  10  or eddy channel  44  of the tubular section  30 . It is noted that the starter cap  60  is only capable of engaging the tubular section in a single orientation and upon engagement precludes air flow via the distal end of the tubular section and instead only provides fluid communication between the exterior and interior of the tubular section  10  by way of the groove  18  (or  38  of tubular section  30 ). The air sampling tube  50  is rendered modular by providing a coupler  58  or  59 . The coupler  58  or  59  has a tubular section proximal end joinder portion  61  and a tubular section distal end joinder portion  63 . The joinder portion  61  forms a semi-cylindrical blade or receptacle complementary to either the proximal end  28  or distal end  27  of tubular section  10 ; or the proximal end  48  or distal end  47  of tubular section  30 . The joinder portion  61  defines a friction fit with the complementary end of the tube section  10  or  30 . Adhesive or fusion is optionally used to secure the coupler and tubular section. Joinder portion  63  is formed as a blade or receptacle per portion  61  to join a second tubular portion. A receptacle-type coupler  58 ′ for joining two tubular portions  30  is depicted in perspective view in  FIG. 4D . The coupler  58  in end view is depicted in  FIG. 4B  and matingly engages a wall  12  or wall  42  of a tubular section. Preferably, securement is through friction fitting, although adhesive or fusion is also operative herein. Coupler  59  operates in the same manner as coupler  58  with the exception that the joinder of two tubular sections occurs at a nonlinear angle. The couplers  58  and  59  are both operative in an inventive air sampling tube, each alone or in combination. The couplers  58  and  59  provide a communicative internal bore between joined tubular sections. A tab  68  is provided on starter  60  thereby rendering the resultant air sampling tube  50  suitable for usage with a housing as detailed in U.S. Pat. No. 7,204,522. Alternatively, the starter piece  60  has a recess adapted to engage a complementary engagement element found within the air sampling sensor housing. The air sampling tube  50  as depicted in  FIG. 4A  is readily provided as a modular kit containing a starter cap  60 , an end cap  29 , multiple tubular sections  10  or  30 , or a combination thereof with the multiple tubular sections being of like or different lengths. With the inclusion in the kit of multiple couplers  58  and  59 , and optionally at least one starter piece such as that depicted at  60  or other starter pieces adapted to engage particular makes and models of housings, an installer is able to quickly form a custom air sampling tube without resort to tools. An inventive air sampling tube  50  is optionally terminated with an end cap  29 . The end cap  29  has a complementary protrusion  31  engaging a tubular section  10  or  30  to provide a friction fit therewith in a similar manner to portion  52  of starter cap  60 . The body  33  of end cap  31  precludes air entry via the distal end into a tubular section  10  or  30  of assembly  50 . An end cap  29  is formed of like materials relative to a tubular section  10  or  30 , and a starter cap  60 . 
       FIGS. 5A-5C  show with detail starter piece  61 . A starter piece  61  optionally includes a choke  82  in the bore that partially occludes air flow within the starter piece interior and is visible from front end  69 . While it is appreciated that the choke  82  occludes air flow between the air sampling tube  50  and the air sampling sensor housing, a choke  82  having a shape indicative of groove position in a tubular section  10  or  30  greatly facilitates inspection and assurance of correct orientation of the air sampling tube. The choke  82  is optionally painted a different color than the remaining portions of the starter piece  61  to further emphasize directionality. As shown in  FIG. 5B , the aperture  84  is arrow shaped within the choke  82  and is intended to point in the direction of the groove  18  with respect to  FIG. 4A . 
     Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference. 
     The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.