Abstract:
An apparatus for training canines to detect complex hazardous substances from an odor mixture developed from at least two separated material components having at least two separated odors respectively. The training apparatus has a chamber base unit having at least two vial wells configured to hold separate containers of the material components and a chamber top unit having a first side facing the chamber base and a second side opposite the first side. The first side of the chamber top unit and the chamber base unit define a primary vapor mixing chamber in fluid communication with the vial wells. A mechanical seal between the chamber top and the chamber base seals the primary vapor mixing chamber. A passageway extends through the chamber top unit connecting the primary vapor mixing chamber to the second side of the chamber top unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional under 35 USC 119(e) of, and claims the benefit of U.S. provisional application Ser. No. 62/095,946, the entire disclosure of which is incorporated herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    This disclosure relates to detection of explosives and other multi-component substances. More particularly, the disclosure describes an apparatus for training scent detecting working dogs to detect explosives and other materials. 
         [0004]    2. Related Technology 
         [0005]    Scent detecting dogs are routinely trained to detect certain substances, such as drugs or explosives, by using samples of the actual substance of interest. In some instances, the explosive or substance is made up two or more elements combined (each element having separate and distinct odors) which are mixed to produce the compound. However, the use of samples of the actual explosive mixtures raises numerous safety issues. Attempts to train scent detecting dogs using pseudoscents, inert substances, or individual components of a normally mixed/combined compound have not been very effective. The Department of Defense does not use pseudoscents or mimics. U.S. Pat. No. 9,049,845 to Albuquerque, the entirety of which is incorporated by reference herein, discloses an apparatus useful for training dogs to detect complex hazardous substances by mixing the vapors within the device, while keeping the elements separated. 
       BRIEF SUMMARY 
       [0006]    An apparatus for training canines to detect complex hazardous substances from an odor mixture developed from at least two separated material components. In one aspect, the apparatus includes a chamber base unit having at least two vial wells configured to hold the separated material components and a chamber top unit having a first side facing the chamber base and a second side opposite the first side. The first side of the chamber top unit and the chamber base unit define a primary vapor mixing chamber in fluid communication with the vial wells. A mechanical seal between the chamber top unit and the chamber base unit. The chamber top has a passageway extending from the primary vapor mixing chamber to the second side of the chamber top and allowing vapors to diffuse from the vial wells to the second side of the chamber top. 
         [0007]    An apparatus can include a chamber base unit having at least two vial wells configured to hold the separated material components and a chamber top unit having a first side facing the chamber base and a second side opposite the first side, the first side of the chamber top unit and the chamber base unit defining a primary vapor mixing chamber in fluid communication with the vial wells, and the chamber top having a passageway extending from the primary vapor mixing chamber to the second side of the chamber top and allowing vapors to diffuse from the vial wells to the second side of the chamber top. The apparatus also includes a tube configured to be positioned within the passageway with a first end extending into the primary vapor mixing chamber, and further includes a flow restrictor having a first end with a diameter configured to fit within the passageway, and having a cap with a wider diameter at a second opposite end that extends radially outward past the circular upper edge of the passageway. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1A  is an illustration of an exemplary mixed odor delivery device. 
           [0009]      FIG. 1B  is a cross sectional view of the mixed odor delivery device. 
           [0010]      FIG. 1C  is a cross sectional view of the mixed odor delivery device in operation. 
           [0011]      FIG. 1D  is a cross sectional view of the mixed odor delivery device with a flow restrictor having longer legs, adapted to allow more vapor diffusion. 
           [0012]      FIG. 2A and 2B  illustrate the base component of the mixed odor delivery device of  FIG. 1A-1C . 
           [0013]      FIG. 3A-3E  illustrate the upper component of the mixed odor delivery device of  FIG. 1A-1C . 
           [0014]      FIG. 4A and 4B  show a lid component of the mixed odor delivery device. 
           [0015]      FIG. 5  shows an insert component of a mixed odor delivery device. 
           [0016]      FIG. 6A-6C  show a restrictor plug component of a mixed odor delivery device. 
           [0017]      FIG. 7A and 7B  illustrate a mixed odor deliver device with active air flow and a water jacket for heating or cooling. 
           [0018]      FIG. 8A and 8B  show vapor distribution at the outlet of a mixed odor delivery device with and without a flow restrictor, respectively. 
       
    
    
     DETAILED DESCRIPTION 
     1. Overview 
       [0019]    The systems described herein are intended to safely present the odor of hazardous explosive mixtures for canine training by keeping the mixture components separated and allowing only the vapors to mix. 
         [0020]    An example of a mixture is a binary explosive mixture that includes an oxidizer and a fuel mixture. Examples of oxiders are ammonium nitrate (AN) and potassium chlorate (KClO4). Examples of fuels are sugar, aluminum powder (Al), and fuel oil (FO). The components usually have legal uses, but when mixed create explosives. Some explosives has a low vapor pressure, which can present a challenge for detection. For example, the vapor pressure of ammonium nitrate and aluminum powder explosive mixture is 2.2×10 −6  mmHg at 25 degrees C., which is very low compared to the vapor pressure of TNT (2.0×10 −4  mmHg). 
       2. Examples 
       [0021]      FIG. 1A-1D  illustrate a mixed odor delivery device  100  that includes a chamber base  200 , a chamber top  300 , a lid  400 , an insert  350 , and a flow restrictor  330 . 
         [0022]    The device  100  provides for mixing the vapors of the explosive components, and presents a reproducible, efficient, homogeneous vapor distribution to the canine. 
         [0023]    The system holds several removable jars or vials  180  in place, separated from each other so that the liquid or solid substances within the jars or vials do not mix. The vapor from each jar or vial disperses into a surrounding mixing chamber, and travels through a narrow passageway to a second mixing chamber. When a lid or other cover is in place over the vapor outlet of the second chamber, the vapors mix further, and their concentration increase. When the lid or other cover is removed, a vapor plume that includes the mixed vapors is exposed to the exterior environment. This allows the canines to be trained to detect the particular mixed vapors, without mixing the liquid or solid components themselves. 
         [0024]    Turning next to  FIG. 2A and 2B , the chamber base unit  200  is shown in more detail. The chamber base unit  200  is a structure with a top surface  204  that includes several vial wells  220 ,  222 ,  224 ,  226 , which are recesses in which removable jars or vials can be positioned. In this example, the chamber base unit  200  is rectangular or square in cross section, with four sides  206 ,  208 ,  210 ,  212 . As seen in  FIG. 2B , the chamber base unit  200  bottom surface can have inwardly extending metal threaded inserts that, with corresponding screws or bolts, can be used to attach the base of the device to another structure. 
         [0025]    The four vial wells  220 ,  222 ,  224 ,  226  allow up to four components to be stored in jars or vials within the vial wells. It can be suitable to include fewer or more than four vial wells. 
         [0026]    As seen in  FIG. 2A , the vial wells  220 ,  222 ,  224 ,  226  can be arranged at approximately same radial distance from a central point  240  that is aligned directly below the passageway  342  though the top unit  300 . 
         [0027]    The jars or vials  180 , as shown in  FIG. 1C , can have lids with holes through the lids to allow the vapor to escape the jar or vial. The size of the holes in the vial lids can be selected to provide a different concentration of each odor. The jars or vials can alternatively have no lids, or solid lids that intended to be completely removed when the jars or vials are placed in the base component  100 . It can also be suitable to include a number of lids with different sizes and numbers of holes in the lids, to control the amount of vapor that diffuses from each of the vials, in order to vary the relative proportions of vapors in the mixture. The jars or vials  180  can have sides that extend above the top of the vial wells, so that the jars or vials can be manually inserted into and removed from the vial wells without spilling the contents. 
         [0028]      FIG. 3A  shows the upper face of the chamber top unit  300  with the insert  350  and flow restrictor  330  in place.  FIG. 3B  shows the upper face of the chamber top unit  300  with the insert in position but without the flow restrictor.  FIG. 3C  shows the upper face of the chamber top unit  300  without the insert and without the flow restrictor.  FIG. 3D  shows the lower surface of the chamber top unit  300  with an insert in place, and  FIG. 3E  shows the lower surface of the chamber top unit without the insert in place. 
         [0029]    As seen in  FIG. 1B , chamber top unit  300  has a lower surface  318  that fits matingly on a ledge or shoulder in the top surface of the chamber base  200 . Closure latches  102 ,  104 ,  106 ,  108  are positioned on two opposite sides of the device to clamp the chamber top unit  300  and the chamber base unit  200  together. The chamber top unit  300  has a recessed surface  360  on the underside facing the chamber base unit  200 , so that a lower, primary vapor mixing chamber  110  is formed between the top  300  and the base  200  in which the vapors from the substances in the vials can mix. 
         [0030]    The vapor mixing chamber  110  is identified as primary because it is the first space in which the vapors can mix encountered by the vapors diffusing from the vials in the vial wells. 
         [0031]    A groove  228  extends completely around the outer perimeter of the base unit  200 , for holding an o-ring  230  or other gasket. A tight o-ring seal is formed between the chamber top unit  300  and the base unit  200  when the latches are locked in place. In this example, each closure latch is a surface-mounted drawbolt closure latch. Other types of closure hardware may also be suitable in some applications. 
         [0032]    The o-ring groove  228  is positioned radially outward of the mixing chamber  110  formed between the base unit  200  and the top unit  300 . When the closure latches is are secured, the sealing surfaces of the base unit  200  and the top unit  300  are urged together, compressing the o-ring  230  in its groove, and preventing vapors from leaking from between the top unit and the base unit. 
         [0033]    The opposite surface of the chamber top  300  has a recessed area  320  with outer sidewalls  323  and a bottom surface  324 . The sidewalls and bottom surfaces of the recessed area  320 , together with the lid  400 , form a secondary vapor mixing chamber  120 . A shoulder or ledge  321  is formed along the outer circumferential edge of the recessed area, shaped to receive and support the lid  400 . 
         [0034]    A centrally located vertical passageway  342  extending through the chamber top unit  300  joins the two mixing chambers. A cylindrical protrusion  340  extends upward from the bottom surface  324  of the top unit  300  surrounds the passageway  342 . The top surface  341  of the cylindrical protrusion  340  forms one surface of an adjustably sized flow gap  130 , as discussed in later paragraphs. 
         [0035]    The secondary vapor mixing chamber  120  is designated as secondary in order to distinguish it from the primary mixing chamber  110  positioned on the opposite side of the chamber top unit, rather than to characterize any degree of vapor mixing that occurs in the respective mixing chambers. It is noted that the vapors can also mix within the passageway  342  that extends through the chamber top  300  and connects the primary and secondary mixing chambers. 
         [0036]      FIG. 4A and 4B  illustrate an optional lid  400 . In this example, the lid  400  is positioned at the top surface of the chamber top unit  300 , covering the recess in the chamber top. The recess in the chamber top unit  300  and the lid  400  define the secondary mixing chamber. The lid  400  fits partially within the chamber top unit  300 , supported on a shoulder or ledge  321 . 
         [0037]    In this example, the lid  400  is held in place by magnetic catches  410 ,  412 ,  414 ,  416  positioned on the surface  402  of the lid that faces toward the chamber top unit  300 , together with magnetic catches  310 ,  312 ,  314 ,  316  located at the corners of the chamber top unit  300 . The magnetic catches  310 - 316  are positioned on the ledge or shoulder area  321 . When the system is not in use, for example, during storage or transportation, the lid  400  can protect the interior from damage or contamination. During operation, after the vials are place in the vial wells, the lid  400  can be kept in place to allow the vapors to mix and accumulate in the upper mixing chamber  120 . The lid can then be removed by the handler when ready to present the mixed vapor to the canine. 
         [0038]    In other alternatives, the system  100  can include other structures for protecting the interior of the system and/or for allowing the mixed vapors to accumulate in the upper chamber. For example, a lid can be attached with a hinge or other connector, or can be removably attached with clips, clamps, screws, or other mechanical fasteners. It may also be suitable to have the lid fit completely over the chamber top unit  300 , rather than to be positioned on a shoulder or ledge within a recess on the top of the chamber top unit as shown in  FIG. 1B . In some applications in which it is not desired to allow the vapor to accumulate to a higher concentration, it may also be suitable to have no lid or cover for the chamber top unit  300 . 
         [0039]      FIG. 5  illustrates an insert  350 , shown here as a hollow cylindrical tube that fits within the cylindrical passageway  342  through the chamber top unit  300 . As seen in  FIG. 5 , the insert has a substantially constant inner diameter. A portion of the insert has a substantially constant outer diameter, with one end of the insert having a lip  352  with a wider outer diameter. 
         [0040]    When the system is assembled as shown in  FIG. 1B and 3B , the lip  352  rests on a shoulder  344  formed in the cylindrical passageway  342 , preventing the insert from being pushed all the way through the passageway from above. The shoulder  344  extends around the entire circumference of the passageway. Other types of stops may also be suitable. 
         [0041]    When the insert  350  is positioned in the passageway  342 , the shoulder  344  keeps the far end of the insert positioned so it extends beyond the bottom of the passageway  342  at a desired distance below the recessed bottom surface  360  of the chamber top unit  300 , as seen in  FIG. 3D . Depending on the size of the vials, the insert&#39;s opposite end  354  may extend beyond the top of the vials  180 , as shown in  FIG. 1B and 1C . 
         [0042]    In this example, the insert  350  has an outer diameter that allows it to be held in place by friction within the passageway, with a fit that is loose enough to allow the insert to be manually removed by pushing the insert upward from below. Other types of attachments may also be suitable. 
         [0043]    The inner diameter can be chosen to ensure a sufficient amount of odor reaches the canine nose while still minimizing excess odor entering the environment. The extension of the insert  350  beyond the passageway  342  and into the primary mixing chamber can ensure substantial mixing of the component odors prior to reaching the secondary chamber. It may also be suitable to provide a kit of a number of different inserts, each with a different inner diameter and/or length. A particular insert can be selected that provides a desired concentration of mixed vapor to the upper chamber for a particular application. An insert with a narrower hollow center will decrease the total vapor concentration output. Removal of the insert would discourage complete mixing of the odor components. 
         [0044]      FIG. 6A, 6B, and 6C  illustrate a flow restrictor  330 . The flow restrictor  330  works in conjunction with the insert  350  to pass the vapors from the lower, primary vapor mixing chamber  110  to the upper, secondary vapor mixing chamber  120 . 
         [0045]    The flow restrictor  330  has a generally cylindrical solid cap  332  at one end. A lower portion  334  has a smaller diameter than the cap portion, and is sized to fit within the passageway. The flow restrictor&#39;s lower portion  334  has several curved vertical surfaces  338  at its outer diameter. In this example, the vertical surfaces  338  are shaped to match the curvature of the inside cylindrical surface of the passageway  342  through the top unit  300 . The flow restrictor  330  can be sized so that it is held in place by friction between the vertical surfaces of the flow restrictor and the inner cylindrical surface of the passageway through the chamber top unit. The fit between the flow restrictor  330  and the chamber top  300  is such that the flow restrictor can be removed by manually pulling the upper part upward, or by manually pushing the insert  350  upward to dislodge the flow restrictor  330 . Other types of attachments may also be suitable. 
         [0046]    Between each of the vertical surfaces  338  is a recessed contoured surface  337  that extends from the lower planar surface  335  of the flow restrictor to the solid cap portion  332 . As seen in  FIG. 6D , the recessed contoured surfaces  337  curve inward from the outermost diameter of the lower portion  334  to form several vertical flow conduits  339  between the flow restrictor and the inner cylindrical diameter  343  of the passageway  342 . Three legs  336  extend downward beyond a the flow restrictor&#39;s lower planar surface  335 . 
         [0047]    The flow restrictor  330  can be positioned in the passageway so the legs  336  rest on the upper end of the insert  350  or on a shoulder  344  of the passageway  342 , leaving a space  150  under the flow restrictor&#39;s lower planar surface  335  through which the vapors can pass from hollow center of the cylindrical insert into the vertical flow conduits  160 . 
         [0048]    The height of the lower portion of the flow restrictor  330  is such that a gap  130  is formed between the lower surface  331  of the cap portion  332  and the upper surface  341  of the cylindrical protrusion  340  on the chamber top unit  300 . In this example, the gap  130  is cylindrical in shape and extends radially outward without obstruction. In this example, the cap portion  332  of the flow restrictor  330  is held in position by the legs and/or friction between the lower portion and the passageway, so in the gap region  130 , there is no obstruction to radially outward diffusion of the mixed vapors from the vertical flow conduits  160  into the secondary vapor mixing chamber  120 . 
         [0049]    The length of the legs  336  controls the size of the space  150 , which limits the diffusion of the odors, allowing a given concentration of mixed odor to reach the secondary chamber. In one embodiment, the device includes several restrictor plugs  330 , each of which has a different leg length, so that using a particular one of the restrictor plugs provides a desired amount of total odor concentration output. The handler can select and use the appropriate restrictor plug for a particular application.  FIG. 1B  illustrates the device  100  with a flow restrictor  330  with shorter legs, and  FIG. 1D  illustrates the device  100  with a flow restrictor  330 ′ with longer legs. The resulting space  150 ′ and gap  130 ′ in  FIG. 1D  are larger than the corresponding space  150  and gap  130  in  FIG. 1B , allowing a higher odor concentration output. 
         [0050]    Referring again to  FIG. 1C , the mixed vapors escape from the vials and mix in the chamber  110  formed between the top unit and the base unit. The partially mixed vapors diffuse under the lower edge of the insert and into the central hollow region extending through the insert, diffuse upward through the insert, then are redirected outward by the bottom surface of the flow restrictor in the space  150 . The vapors then diffuse upward in the flow conduits  160  formed between the sides of the flow restrictor and the inner cylindrical diameter  343  of the passageway  342  through the top unit  300 . The vapors then are directed radially outward in the gap  130  and into the second mixing chamber  120  by the bottom of the cap portion of the flow restrictor. 
         [0051]    In one example, the outer dimensions of the mixed odor delivery device  100  are approximately 5 inches by five inches by 4 ½ inches tall. The mixing chamber  110  formed in the underside of the chamber top is about 3 inches wide at its narrowest point, about 4 ¾ inches across at its widest diagonal direction, and about ½ inch deep. Each vial well is approximately 1 ⅜ inch deep and 1 3/16 inches in diameter. The upper mixing chamber  120  has dimensions of about 4 inches by 4 inches by 1 ⅛ inch deep. The insert  350  shown in  FIG. 5  has an outer diameter of about ¾ inches, is approximately one inch in length, and has an inside diameter of about ½ inch. The resulting overall internal volume of the device  100  is about 32 cubic inches. Smaller or larger devices can also be suitable, depending on the particular application. 
         [0052]    In some applications, the components of the system can be formed of polyvinyl chloride (PVC). PVC readily adsorbs volatile vapors, thus limiting the vapor concentration at the outlet and minimizing dispersion into the environment. Alternatively, polytetrafluoroethylene (PTFE) or a polymer with similar material and chemical properties may be suitable. PTFE resists adsorption of volatile materials. Both PVC and PTFE are easily cleaned, so that little or no odor residue will affect subsequent uses of the system. In the example discussed above, the chamber base unit, top unit, lid, and cap are formed of PVC, and the insert is formed of PTFE. When formed of PTFE and PVC, the system weighs less than 5 pounds, is rugged and compact for transportation. 
         [0053]    In this example, each of the chamber base, top, lid, and cap can be formed of a single piece of material. In this embodiment, the only seams are the clamped o-ring seal between the chamber base and top units and the magnetic seal between the chamber top unit and the lid. The density and thickness of the components that surround the vapor further reduces the loss of vapors to the environment. 
         [0054]    The system can be used to train canines for detecting scents of materials other than explosives. As one example, the system can be used to train canines to detect an illegal drug in the presence of a distractor (e.g., orange peels). 
         [0055]    The device  100  can also be configured with a water jacket in the base unit  200  and/or top unit for heating or chilling the device and the substances in the vials or jars. 
         [0056]    It may also be suitable to use the device without vials or jars in the vial recesses, by placing the substances directly in the recesses. If the substances to be tested are liquid, a sorbent pad or cloth can be soaked in a liquid and the pad or cloth can be placed in the vial well or a vial, to avoid spills due to canines knocking the device over. 
         [0057]    In other embodiments, the chamber top unit is formed of a single piece that takes the place of the chamber top unit, the insert, and the flow restrictor. However, such a device will not allow adjustment by swapping out the flow restrictor piece. 
         [0058]    It may also be suitable in some circumstances to use the device with just the chamber base unit and the chamber top unit, without the insert, flow restrictor, and lid. However, the relatively wide passageway  342  will allow the vapor to diffuse rapidly, with little mixing of the odors, creating a non-symmetric odor distribution. 
         [0059]      FIG. 7A and 7B  illustrates an active sampling mixed odor delivery device  700 . This device includes a chamber base unit  710  with vial wells, a chamber top unit  720  that includes an integral lid, a passageway through the top unit that allows vapor to diffuse between the mixing chambers, and an o-ring seal system  780  with closure latch components  790 ,  792 ,  794 ,  796 . In this system, air from an outside source is pumped into an inlet  750  and passes into the air spaces in the base  710 . As the air moves through the primary vapor mixing chamber in the chamber base unit  710 , it is pumped upward through a passageway  740  in the top unit  720 . A port  730  for a vapor retrieval line is positioned in the top surface of the top unit  720 , with the vapor retrieval line carrying the vapors to a sensor or instrument. 
         [0060]    In this example, a water jacket can be located with inlet and outlet ports for chilling or heating the device, the inlet air, and the odor components. Here, an inlet port  750  in the chamber base allows water to flow through an internal fluid conduit in the chamber base  710 . The conduit in the chamber base mates to an internal fluid conduit in the chamber top unit  720 . An o-ring seal  754  prevents leakage from the fluid conduits into the mixing chamber by compressing the o-ring in a groove when the closure latches are closed. The outlet port  752  in the top unit  720  allows the liquid to exit from the device. 
         [0061]      FIG. 8A and 8B  show the modeled vapor distribution profile of a vapor plume created by the device shown in  FIG. 1A-1C  above. Circular lines  801 - 808  are drawn over a top view of the device  100  to illustrate the vapor distribution profile. The modeled relative vapor distribution profile shown in  FIG. 8A  assumes a sample vial with a 2 gram sample of dinitrotoluene (DNT) was placed in one of the vial wells, and a period of 30 minutes was allowed to elapse. The unitless vapor concentrations range from 1.8 to 1.2 along the circular lines  801  through  808 . The outline of the flow restrictor cap  332  is shown as a dotted line.  FIG. 8B  shows the results of modeling the device  100  performance without the flow restrictor. The outline of the passageway  342  through the chamber top  300  is shown as a dotted line. Circular lines  811 - 818  are drawn over a top view of the device  100  to illustrate the vapor distribution profile Both figures illustrate a symmetrical distribution of odor, which indicates that odor components would be well mixed by the device. The numbers shown on the figures indicate a unitless odor concentration in each region. By comparing  FIG. 8A and 8B , is seen that the system with the restrictor plug greatly lowers the odor concentration and more uniformly diffuses the mixed odors across the surface area. 
       3.Conclusions 
       [0062]    The system described and claimed has several beneficial aspects. The devices  100  and  700  each have a much smaller overall internal volume than the system shown in U.S. Pat. No. 9,049,845. The smaller volume results in less dilution of the vapor in air, with a resulting higher vapor concentration in the vapor plume at the outlet thus requiring a lower mass of training material. The system described herein also provides minimal odor loss by permeation to the environment, because the materials allows absorption of the explosive components. As described above, the system is formed of materials that are easily cleaned of any odorants, and the system is rugged and easy to use and transport. The adjustable flow restriction provides a controllable vapor concentration. 
         [0063]    The Detailed Description of the Exemplary Embodiments has revealed the general nature of the present disclosure that others can, by applying knowledge of those skilled in relevant art(s), readily modify and/or adapt for various applications such exemplary embodiments, without undue experimentation, without departing from the spirit and scope of the disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and plurality of equivalents of the exemplary embodiments based upon the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.