Abstract:
A device is disclosed for sterilizing objects, such as objects used during medical and dental procedures. A high velocity dry hot air sterilization device integrating a closed, sealed air handling system with a closed, sealed sterilization chamber is described. The sterilization device includes a chamber which carries a sealed instrument container. The sterilization device includes an air handling system for heating and adding velocity to the air which is delivered to the instrument container. The instrument container is configured to allow rapidly flowing hot air to enter from and exhaust to the closed air handling system within the high velocity dry hot air sterilization device without any infiltration of external air to the instrument container or to the high velocity dry hot air sterilizer&#39;s closed air handling system during the sterilization cycle, thereby preventing infiltration of microbial contaminants to the sterilization device or instrument container during or after sterilization.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 13/427,662, filed on Mar. 22, 2012, the entire contents of which is incorporated by reference herein. This application claims priority from U.S. application Ser. No. 61/811,278, the entire contents of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present disclosure describes an apparatus and process for sterilization of items, most notably surgical instruments, used in medical, dental, veterinary, or other patient-care markets. The invention relates, more particularly to an improved high velocity dry heat sterilization device to prohibit the introduction of microbial contaminants to the sterilization chamber during the entire sterilization cycle and to ensure such items once sterilized, remain sterile when removed from the high velocity dry heat sterilization device. 
     There are three distinct types of dry heat sterilizers: (1) Static hot air sterilizers in which air convection is generated solely by gravity as hot air rises and cooler air descends; (2) Mechanical convection sterilizers in which air is moved by blowers to uniformly distribute the heated air and equally transfer heat throughout the load; and (3) High velocity hot air sterilizers in which air is moved at a high rate, such as at 2500 feet per minute, with the flowing air serving as the heat transfer medium. Both static air and mechanical convection sterilizers require minimally one hour (at 340° F.) or two hours (at 320° F.) to achieve sterilization whereas the high velocity hot air sterilizer can sterilize in six to twelve minutes (at 375° F.), depending on instrument type or packaging. 
     A high velocity hot air sterilization device has been disclosed by Cox et al. in U.S. Pat. Nos. 4,824,644; 4,894,207; 4,923,681; and 4,975,245. This device was designed and marketed for use in the dental and orthodontic markets to rapidly sterilize small instruments without instrument corrosion. The Cox High Velocity Hot Air Sterilization Device accommodates wrapped or unwrapped instruments which are placed into a wire mesh, open basket and held for pre-designated times at 375° F. as prescribed under the U.S. Food and Drug Administration 510(k) notification (K8726643A and K881371). Upon completion of the sterilization cycle, the basket containing the instruments is removed from the sterilizer. In this system described by Cox et al., unwrapped instruments are subjected to potential microbial contamination from environmental sources during the sterilization process and upon removal from the sterilizer since the sterilizer allows outside air to circulate within the sterilization chamber during the sterilization cycle and because the trays are subjected to outside air following removal from the sterilizer. For dental procedures this practice is acceptable since sterilization of dental instruments has placed emphasis on obtaining complete kill of microorganisms originating from previous patients with no concern regarding contamination from microbial contaminants having environmental origin. Other high velocity hot air sterilization devices by Allen and Sildve (U.S. Pat. No. 4,935,604) and Goldman (U.S. Pat. No. 6,039,926) also operate in a similar fashion that allows unwrapped instruments to be subjected to environmental microbial contaminants. 
     Existing high velocity hot air sterilization devices do not address the introduction of environmental microbial contaminants during the sterilization process or afterward as detrimental to dental patient care. Most orthodontic and dental procedures are topical and are performed in an oral environment already containing high microbial concentrations and contaminants of environmental origin play no role in disease transmission from instruments. All high velocity hot air sterilization devices directly allow outside air into the air handling system by means of fans, louvered vents, or unclosed or unsealed plenums before, during, and after the sterilization cycle. In these systems any instrument or device that is not wrapped, packaged, or pouched is subjected to microbial contamination from continually introduced outside air during the sterilization cycle that has not received the prescribed time and temperature requirements necessary to ensure microbial inactivation. Upon completion of the sterilization cycle, unwrapped instruments are directly subjected to potential environmental microbial contaminants upon the opening of the sterilization chamber and their removal. No unwrapped instrument protection is afforded with existing high velocity, hot air sterilization devices. 
     For use in critical-care environments including dental surgical, hospital surgical, ambulatory or outpatient surgical, and veterinary surgical procedures, patient contact items must be devoid of all viable microbial contaminants to avoid infection or disease transmission. No microbial contaminants can be introduced during the sterilization process, nor can they be introduced after the sterilization process. For unwrapped or directly exposed instruments, any air introduced to the sterilization chamber after the initiation of the sterilization cycle must be subjected to the identical sterilization parameters of designated time and temperature as the instruments being sterilized. This requirement precludes the introduction of any outside air to the air handling system and hence the sterilization chamber, once the sterilization cycle has been initiated; this requirement is not followed by the prior art high velocity hot air sterilizers. 
     High velocity, hot air sterilization technology has the potential to meet the sterilization requirements of the critical-care medical environment as a standard sterilization technology for heat-resistant instruments or devices. However, the original design of high velocity hot air sterilizers has also limited its usefulness due to the sterilizer&#39;s inability to accommodate closed instrument containers that could assure internal sterilization parameters are achieved within an instrument container for instrument sterilization and yet maintain the sterility of those instruments from environmental microbial contamination once the instrument container was removed from the sterilizer chamber. 
     Although wrapping instruments had been a primary mechanism of maintaining instrument sterilization using wet steam heat, static dry heat, high velocity hot air, radiation, and chemical agents in the past, emphasis has shifted to the use of closed containers for sterilizing larger quantities of instruments and providing subsequent protection from environmental microbial contaminants. With the increased use of closed container systems in critical-care medical environments, the use of closed containers in dental practices has also become the preferred way to protect and store sterilized dental instruments. 
     Closed containers allowing migration of the sterilizing agent into the container for instrument sterilization have been developed to accommodate specific sterilizing agents. The design of the container and/or its portal design must be congruent with the attributes of the sterilizing agent and must not interfere with the influx of the sterilizing agent. Accordingly the container design must assure the protection of the sterilized instruments from microbial agent contamination from the point of the container&#39;s removal from the sterilizer until the container is opened for instrument use within the sterile field. 
     Closed containers have been designed to incorporate top and bottom perforations protected by a microbial filtering material permeable to gas or vapor sterilants, but impermeable to microorganisms. These perforations may be static, remaining continuously open and filtered. An example of such a container is described in U.S. Pat. No. 4,551,311 issued Nov. 5, 1985 to Lorenz and entitled “Sterilizer Container.” 
     Another design incorporates open side vents (U.S. Patent Application Publication No.: US 2003/0211023 A1; Su-Syin Wu and Charles Howlett; “Instrument Sterilization Container Having Improved Diffusion”) to allow gas or vapor sterilants into the container. Protection from microbial contaminants is accomplished through the incorporation of internal or external microbial filters by wrapping the instruments or wrapping the entire container. 
     The container may also be of a non-static design, providing an automatic opening and shutting mechanism. For steam sterilization the pressure differential between the inside and outside of the container triggers an automatic opening and closing of a pressure-sensitive valve (U.S. Pat. No. 5,352,416 issued Oct. 4, 1994 to Wagner and entitled “Valve Arrangement for a Sterilization Container”). 
     High velocity hot air sterilizers employ rapidly flowing hot air over the surface of an article to affect microbial kill. Hot air influx into the container at a sufficient rate is therefore necessitated to achieve sterilization in the prescribed time-temperature profile. Any barrier to that necessitated rate of airflow will significantly impact sterilization conditions. Research has demonstrated that container perforation coupled with fabric filtration will disturb the high velocity influx of hot air into the instrument container and have significant impact on the conditions necessary to achieve reliable instrument sterilization. Sterilization conditions cannot be achieved within an instrument container employing high velocity hot air as the sterilant when using air filtration devices designed to prevent the influx of microbial contaminants. Existing instrument containers that employ perforations in the top, sides, and/or bottom of the container also require fabric filtration to mitigate microbial contaminants and thus, prohibit the necessary conditions required for instrument sterilization by high velocity hot air. Existing instrument containers that utilize pressure valves were specifically designed for pressurized wet steam sterilizers and do not function under the non-pressurized treatment conditions employed in high velocity dry heat sterilization. Static, open vent designs still require instrument or container wrapping. 
     A need exists in the art for a high velocity hot air sterilizer that provides and maintains sterile conditions within the high velocity hot air sterilizer&#39;s air handling system and sterilization chamber during the complete sterilization cycle. A need also exists in the art for a high velocity hot air sterilizer that provides the capability to sterilize medical instruments within an instrument container that allows re-distribution of sterile air during the sterilization cycle, yet can be closed and sealed before removal from the high velocity hot air sterilizer upon the completion of the sterilization cycle to assure instrument sterility to point of use. 
     SUMMARY OF THE INVENTION 
     The present disclosure describes a high velocity hot air sterilization device for sterilizing medical, dental, or veterinary instruments or other objects used in critical-care environments. The sterilization device described herein is an improvement over prior devices because the sterilization device described herein (1) incorporates a closed and sealed recirculating air handling system and sterilization chamber during the course of the sterilization cycle and (2) provides the capacity within the high velocity hot air sterilization device to sterilize instruments within an instrument container that allows the parameters necessary of high velocity hot air sterilization, yet can be closed and sealed to prevent instrument contamination once the container is removed from the sterilization device. 
     More specifically, the disclosure describes a sterilization device having: (1) the ability to sterilize trays or racks of instruments and objects within an instrument container or in an open basket configuration, wrapped or unwrapped and ensure such are not subject to any outside air entering the sterilization chamber and all aspects of the sterilizer&#39;s air handling system during the course of the sterilization cycle; (2) the ability to generate and supply high velocity hot air to instruments, objects, or instrument containers therein said high velocity hot air sterilizer device being configured to deliver to the sterilization chamber only high velocity hot air that undergoes the identical sterilization parameters of time and temperature prescribed by the U.S. Food and Drug Administration (FDA) for the sterilization of instruments; (3) the ability to maintain the sterilization chamber&#39;s sterilized environment by ensuring all sterilizer doors, air handling plenums, vents, and other potential air infiltration areas are sealed to prevent the flow of external air into the air handling system or sterilization chamber during the sterilization cycle; and (4) the ability to accommodate instrument containers which allow the sterilization parameters of high velocity hot air sterilization be fulfilled and yet not allow the infiltration of environmental microbial contaminants once removed from the sterilizer. 
     The present disclosure describes the instrument container as either being positionable within the high velocity hot air sterilization device or external to the sterilization device and matable therewith to receive high velocity hot air from the high velocity hot air sterilization device. As described herein, the container is configured to uniformly distribute the air within the container, and exhaust the air back to the closed air handling system of the high velocity hot air sterilization device for subsequent, continuous recharging of heat and air velocity and re-distribution to the instrument container during the course of the sterilization cycle. The instrument container is configured to accept and exhaust sterilizing air during the sterilization cycle. The container is also configured to close to the influx of environmental microbial agents prior to its removal from the high velocity hot air sterilizer upon completion of the sterilization cycle to assure instrument sterility until time and place of use. 
     Thus, the present invention relates to a high velocity hot air sterilization device for sterilizing medical, dental, veterinary instruments, or other objects requiring total sterility of such instruments or objects by providing during the course of the sterilization cycle a closed and sealed, recirculating air handling system and sterilization chamber which disallows the influx, intrusion, or infiltration of outside contaminated air to come into contact with aforementioned instruments or objects. 
     The high velocity hot air sterilization device consists of an air handling system comprised of (1) a recirculating fan with associated plenum, (2) an electric heating coil or similar device (3) a hot air supply plenum, (4) a sterilization chamber, and (5) a return air plenum. The air handling system is completely sealed and closed to the infiltration of outside air once the sterilization cycle is initiated. Air contained in the air handling system is brought to the prescribed air velocity by means of the recirculating fan. The high velocity air is subsequently directed over the electric heating coil to bring that air to the prescribed temperature. The heated, high velocity air is then directed to the sterilization chamber via the hot air supply plenum where it is uniformly distributed throughout the sterilization chamber; the sterilization chamber is a space suitable for holding the instruments to be sterilized. In the preferred embodiment, the instrument container is the sterilization chamber. In another instance the sterilization chamber, containing a basket or tray which holds instruments, is integral to the sterilizer. 
     Air from the sterilization chamber is subsequently directed into the return air plenum which then directs the air to the recirculating fan which recycles the air through the aforementioned system. Hot, high velocity air is continuously recirculated through the air handling system during the complete sterilization cycle to maintain the air temperature and air velocity conditions required to sterilize instruments and objects. At no time during the sterilization cycle is outside air allowed to enter or infiltrate any subset of the air handling system or sterilization chamber. 
     Preferably, the high velocity hot air sterilizer, sterilization chamber, and all its subparts are comprised of materials able to withstand the rigors presented by the temperatures utilized in high velocity hot air sterilization (375 degrees F. or higher). Preferably, these materials include stainless steel, aluminum, high temperature resistant thermoplastic and thermosetting polymers, ceramics, silicone, and nylon fabric plastics. 
     Preferably, the high velocity hot air sterilizer contains the mechanism to heat the air to its required temperature, to give the heated air its required velocity, to deliver the high velocity hot air to the sterilization chamber, and to continuously re-circulate the air to maintain the prescribed air velocity and temperature required throughout the complete sterilization cycle. 
     Preferably, the high velocity hot air sterilizer and associated air handling system are sealed, closed and retains positive pressure relative to the outside environment to preclude the infiltration of external, non-sterile air into the sterilizer&#39;s air handling system during the sterilization cycle. 
     Preferably, the high velocity hot air sterilizer contains thermocouples, an air flow velocity meter, and a timer integrated with a controller to properly monitor, maintain, and record desired temperatures, airflow velocity, and sterilization cycle times, respectively, to ensure proper sterilization conditions. 
     Preferably, the high velocity hot air sterilizer contains pressure gauges and transmitters integrated with a controller to properly monitor and maintain positive air pressure in the air handling system to preclude the infiltration of external air in the event of inadequate positive air pressure. 
     The aforementioned monitoring devices are integrated with a controller. The fans and heaters described herein are also integrated with the controller. The controller is a microcontroller based system with high-resolution ADCs (analog-to-digital converter) to read the monitoring devices input data such as temperature, pressure and air flow and provide control of the output devices such as the blowers, heaters and alarms. The controller is also integrated with an input system, such as a touch screen, keyboard, or other suitable input system, to allow a user to change settings, run a sterilization cycle, or otherwise control the hot air sterilization system. In addition, the controller will also provide operating instructions and system status information for the user through a display system such as a LCD or LED display. 
     Preferably, the high velocity hot air sterilizer contains a cooling cavity surrounding the sterilization chamber in which its contained air remains separated and segregated from the sterilizer chamber and its associated air handling system. 
     Preferably, the high velocity, hot air sterilizer has a locking mechanism on the sterilizer door to maintain an airtight door seal during the sterilization process. 
     Preferably, the instrument container is positioned into the high velocity, hot air sterilizer by its placement onto a sliding tray, which guides the instrument container into and out of the high velocity hot air sterilizer and assures the proper alignment and positioning of the high velocity hot air sterilizer&#39;s hot air supply and exhaust portals with corresponding air supply and exhaust portals of the instrument container. 
     The instrument container includes moveable covers which cover the hot air supply and exhaust portals of the container prior to the container being removed from the high velocity hot air sterilizer. The moveable covers are structured such that the high velocity hot air sterilizer cannot be opened unless the movable covers are in the closed position. The high velocity hot air sterilizer has a locking mechanism to ensure the moveable covers over the instrument container are covered, sealed and latched. The moveable covers may consist of both internal covers and external covers. 
     The instrument container internal covers can be sealed over the instrument container&#39;s internal hot supply air and spent exhaust air portals prior to the container&#39;s removal from the high velocity, hot air sterilizer. 
     The instrument container external covers can be sealed over the instrument container&#39;s external hot supply air and spent exhaust air portals subsequent to the container&#39;s removal from the high velocity hot air sterilizer. 
     Preferably, the instrument container has internal plenums that circulate the hot air within the container and direct it for uniform distribution throughout the instrument container. 
     Preferably, the internal plenum within the instrument container also creates an air exhaust flow where captured spent air is pulled to the exhaust portal for return to the high velocity hot air sterilizer for re-heating and re-circulation back to the instrument container via strategically placed, spaced, and oriented vents. 
     Preferably, the instrument container&#39;s design is configured to accept multiple layers of instruments and to accept instruments that are uncovered on perforated trays or in baskets or are wrapped or pouched. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of this invention has been chosen wherein: 
         FIG. 1  is a perspective view of the recirculating high velocity hot air sterilizer with enclosed instrument container; 
         FIG. 2  is a cross-sectional side view of the recirculating high velocity hot air sterilizer, with the door in the closed position, and holding the instrument container; 
         FIG. 3  is a cross-sectional front view through the recirculating high velocity hot air sterilizer depicting the air supply portal and the air exhaust portal; 
         FIG. 4  is a cross-sectional top view of the recirculating high velocity hot air sterilizer, with the door in the closed position with the enclosed instrument container depicting the air handling plenum, the circulating fan, the circulating fan motor, and the cooling fan; 
         FIG. 5A  is a cross-sectional side view depicting the instrument container partially inserted into the heating chamber; 
         FIG. 5B  is a cross-sectional side view depicting the instrument container fully inserted into the heating chamber; 
         FIG. 6A  is an isometric view of the instrument container with the lid removed and depicting the air supply and air exhaust valves in the open position; 
         FIG. 6B  is an isometric view of the instrument container with the lid removed and depicting the air supply and air exhaust valves in the closed position; 
         FIG. 6C  is an isometric view from below of the instrument container with the lid removed and depicting the instrument container guide slot, the air supply access portal and the air exhaust access portal; 
         FIG. 7  is a cross-sectional side view of an instrument container&#39;s valve plate in the open configuration; 
         FIG. 8  is a cross-sectional side view of an instrument container&#39;s valve plate in the closed configuration; 
         FIG. 9  is an isometric view depicting the air supply access portal and air exhaust access portal within the rear wall of the heating chamber; 
         FIG. 10  is an isometric view depicting the basket/tray sterilization configuration for the high velocity hot air sterilizer; 
         FIG. 11  is a cross-sectional view through the high velocity hot air sterilizer containing the removable basket/tray, with the door in closed position, taken along line  2  of  FIG. 10 ; 
         FIG. 12  is a cross-sectional view through the high velocity hot air sterilizer taken along line  3  of  FIG. 10 ; and 
         FIG. 13  is a cross-sectional view through the high velocity hot air sterilizer, with the door in closed position, taken along line  4  of  FIG. 10 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present disclosure describes a device suitable for prohibiting the introduction of microbial contaminants to a sterilization chamber of a high velocity dry heat sterilization device during an entire sterilization cycle and for ensuring such items, once sterilized, remain sterile when removed from the high velocity dry heat sterilization device. The preferred and described embodiment of the present invention is described below based on the accompanying drawings. 
     Referring to  FIG. 1 , a high velocity hot air sterilizer  100  is provided which is suitable for receiving an instrument container  200 . The instrument container  200  is designed to receive, uniformly distribute, return, and recirculate high velocity hot air from the high velocity hot air sterilizer  100  to sterilize and depyrogenate wrapped and unwrapped medical and dental instruments in a containerized environment. As will be described, the high velocity hot air sterilizer  100  and the instrument container  200  have incorporated therein various structural features which provide for a closed and sealed, recirculating air handling system during the sterilization cycle that is impervious to the influx of external air and microbial contaminants during the course of the sterilization cycle and which provide the uniform circulation of high velocity hot air throughout the instrument container  200  to the held instruments and devices. 
     Referring to  FIGS. 1 and 2 , the high velocity hot air sterilizer  100  includes an outer housing  101 , preferably formed from metal, which surrounds a heating chamber  109 . The heating chamber  109  is accessed for instrument container  200  insertion and removal via a door  103  and through a rectangular opening  110  formed in the outer housing  101 . The door  103  is hingedly attached to the rectangular opening  110  and is movable between an open position and a closed position. Although it is preferred that the door  103  be hinged horizontally, a vertical hinged configuration is also envisioned. Internal to the heating chamber  109  is a sliding rack  104  which carries an instrument container tray  105 . The sliding rack  104  is mounted in the heating chamber  109  and is movable between a contracted position and an extended position. The extended positioned is defined by the sliding rack  104  cantilevered over the open sterilizer door  103  for ease and proper insertion of an instrument container  200  onto the instrument container tray  105 . The contracted position is defined by the sliding rack  104  and instrument container tray  105  contracted within the heating chamber  109  such that the instrument container  200  is in the proper position to align the instrument container  200  within the heating chamber  109  to begin sterilization, as is described in greater detail below. With the sliding rack  104  in the contracted position, the sterilizer door  103  is moved to the closed position and is locked into place by turning a locking door handle  107  which activates a door lock  122 , thereby sealing a door gasket  106  tightly against the sterilizer door rim  102  until the completion of the sterilization cycle to prevent outside air from entering the heating chamber  109 . 
     Referring to  FIGS. 2, 3 and 4 , the heating chamber  109  is defined by a heating chamber wall  114  which defines a back, sides, top, and bottom of the heating chamber  109  and is constructed such as to preclude entry of outside air to the heating chamber  109 , thereby allowing the heating chamber  109  and the associated air handling system to remain airtight when the door  103  is in the closed position during a sterilization cycle. Encompassing the exterior of the heating chamber wall  114  is an insulating jacket structure consisting of an outer insulation wall  111  and an inner insulation wall  113  with an insulating material  112  situated between the inner insulation wall  113  and outer insulation wall  111 . The insulating jacket structure serves two purposes. The first purpose is to minimize heat loss from the heating chamber  109  during the sterilization cycle. The second purpose is to provide a heat barrier between the heating chamber  109  and the metal outer housing  101  of the high velocity hot air sterilizer  100 . 
     Referring to  FIG. 4 , the high velocity hot air sterilizer  100  includes an air handling system which includes a circulating fan  115 , an electric heating element  132 , an air flow monitor  130 , an air pressure monitor  131 , and an air handling plenum  123 . The air handling system directs and monitors supply air to the instrument container  200  and receives exhaust air from the instrument container  200 . The air handling system is located adjacent the rear outside heating chamber wall  114 . The air handling plenum  123  is a chamber which houses the electrical heating element  132  and the fan  115 . 
     Referring to  FIG. 3 , a pair of openings are formed through the back wall of the heating chamber  109  to the air handling plenum  123 . One of the openings serves as an air supply portal  126  which allows hot high velocity air to flow from the air handling system of the high velocity hot air sterilizer  100  into the instrument container  200 . The other of the openings serves as an air exhaust portal  118  which allows air to exhaust from the instrument container  200  to the air handling system of the high velocity hot air sterilizer  100  where the air is re-heated and brought back to velocity before recirculation back to the instrument container  200 . The air handling plenum  123  is air-tight and does not allow air infiltration or exfiltration except through the air supply portal  126  and the air exhaust portal  118 . Together, the air supply portal  126  and the air exhaust portal  118  serves as an air handling portal which allows air to enter and leave the air handling plenum  123 ; in the preferred embodiment, the air handling portal includes a pair of openings, though a single opening is envisioned. 
     Referring to  FIG. 4 , an insulation barrier surrounds the heating chamber wall  114  and includes an outer insulation wall  111  and an inner insulation wall  113  between which is enclosed insulating material  112 . As shown in  FIGS. 3 and 4 , the insulation barrier forms a five-sided barrier within the hot air sterilizer  100  and serves to insulate the contents of the heating chamber wall  114 . The sixth side of the insulation barrier defines an opening through which the instrument container  200  is insertable within the insulation barrier. The locking door  103 , when in the closed position, and the heating chamber wall  114  together define the heating chamber  109 . The locking door  103 , when in the closed position, forms a sealed interface with the heating chamber wall  114  to prevent air from entering the heating chamber  109 . 
     The air handling system is positioned at the rear of the heating chamber  109  and within the heating chamber wall  114 . The air handling system is primarily defined by the air handling plenum  123  which defines a pair of adjacent chambers at the rear of the heating chamber  109 , as best illustrated in  FIG. 4 . The first chamber of the air handling plenum  123  includes the circulating fan  115  which is driven by the circulating motor  124 . As shown in  FIG. 4 , the circulating motor is positioned outside of the heating chamber  109 . The circulating motor is joined to the fan  115  by a drive element, such as a shaft, which passes through the heating chamber  109  wall  114  and the insulation barrier, but is sealed to prevent air transfer to the heating chamber  109 . The second chamber of the air handling plenum  123  contains the heating element  132 , the air flow monitor  130  and the air pressure monitor  131 . The systems within the second chamber of the air handling plenum  123  are discussed in greater detail herein. The first chamber and the second chamber include an opening therebetween for freely communicating air between the first chamber and the second chamber. 
     A cooling cavity  121 , as shown in  FIGS. 2, 3 and 4 , is formed within the hot air sterilizer  100  and surrounds at least the rear, top and bottom of the heating chamber  109 . The cooling cavity  121  serves to insulate the metal outer housing  101  from escaped heat emanating from the heating chamber  109  or air handling plenum  123  and uses outside air recirculating through the cooling cavity by aid of a cooling fan  120  which draws outside air into the cooling cavity  121  where it is subsequently vented by the aid of passive cooling vents  119  at the sides of the high velocity hot air sterilizer  100 . All air within the cooling cavity  121  remains segregated from the heating chamber  109 . 
     Rubber feet/spacers  125  are located on both the exterior back and exterior bottom of the metal outer housing  101  and serve to provide ventilation space between the high velocity hot air sterilizer  100  and the wall or tabletop or other object which the high velocity hot air sterilizer  100  is positioned near during use. 
     Referring to  FIGS. 5A and 5B , the high velocity hot air sterilizer  100  includes a sliding rack  104  and instrument container tray  105  which guides the instrument container  200  to the proper placement within the high velocity hot air sterilizer  100  for the engagement of the air supply portal  126  with the air supply valve plate  208  and the engagement of the air exhaust portal  118  with the air exhaust valve plate  214 . The high velocity hot air sterilizer  100  includes a push bar  117  which is joined to a chain drive  136  which serves to ensure that the container  200  is fully inserted in the heating chamber  109 . The container  200  includes a container guide slot  206  on the underside of the container. To assure that the instrument container  200  is fully inserted to the rear of heating chamber  109  and fully engaged with the air supply portal  126  ( FIGS. 3,4, and 9 ) and air exhaust portal  118  ( FIGS. 3,4, and 9 ) of the high velocity hot air sterilizer  100 , the chain drive  136  with attached push bar  117  is engaged into and along the container guide slot  206  and driven by a stepper motor  116  which is activated by closing and the locking the door  103 .  FIG. 5A  depicts the instrument container  200  partially inserted into the heating chamber  109  with the push bar  117  not yet engaged into the container guide slot  206 .  FIG. 5B  depicts the instrument container  200  fully inserted into the heating chamber  109  with the push bar  117  fully engaged into and along the container guide slot  206 . During insertion of the container  200  into the heating chamber  109 , the push bar  117  is driven by the chain drive into the container guide slot  206  until the push bar  117  becomes engaged with the container guide slot terminal end  207 , at which point the push bar  117  pushes the instrument container  200  to the rear of the heating chamber  109 , this position is defined as the fully inserted position. With the instrument container  200  in the fully inserted position, the rear face of the instrument container  200  contacts a pressure switch  127 , which is carried on the rear wall of the heating chamber wall  114 . The pressure switch  127  turns off the stepper motor  116 , locking the instrument container  200  in the fully inserted position. As shown in  FIG. 2 , vertical pressure rollers  137  are mounted on the upper interior surface of heating chamber wall  114  and provide guidance to assure that the instrument container  200  does not elevate during the transit to the fully inserted position. One or more valve posts  135  protrude from the interior rear heating chamber wall  114  ( FIGS. 5A and 9 ). With the instrument container  200  in the fully inserted position, the valve posts  135  contact the air supply valve plate  208  ( FIGS. 6A and 7 ) and the air exhaust valve plate  214  ( FIGS. 6A and 7 ) of the instrument container  200  to fully open both the air supply valve plate  208  ( FIGS. 6A and 7 ) and air exhaust valve plate  214  ( FIGS. 6A and 7 ) to allow proper airflow to and from the instrument container  200 . The air supply valve plate  208  and the air exhaust valve plate  214  are spring-loaded such that when the valve posts  135  do not contact the air supply valve plate  208  and the air exhaust valve plate  214 , the air supply valve plate  208  and the air exhaust valve plate  214  revert to the closed and sealed position, thereby preventing air from entering the instrument container  200 . With the door  103  in the closed position, the instrument container  200  is moved to and is held in the fully inserted position, thereby ensuring that when the door  103  is the closed position, the instrument container  200  is only capable of exchanging air with the air handling plenum  123 . With the instrument container  200  in the fully inserted position, the air handling portal and the container portal are held in sealed contact, and are an opening through which air is exchanged between the instrument container  200  and the air handling plenum  123 , further, the instrument storage chamber and the air handling plenum together define air-tight space which does not exchange air with the surroundings. 
     Referring to  FIGS. 5A and 6C , the instrument container  200  is configured to accept and exhaust air provided from the high velocity hot air sterilizer  100  to sterilize medical and dental instruments, yet have the ability to prevent the influx of environmental microbial contaminants once the instrument container  200  is removed from heating chamber  109 . The instrument container  200  has the basic elements of any typical container used in the sterilization of medical or dental instruments: the container includes a sealable latchable, microbial impervious lid  202 ; four sides  203 , a bottom  204 , and lifting handles  205  with all construction and components having the ability to withstand the rigor of physical use and materials, preferably aluminum, stainless steel or similar material capable of withstanding temperatures of 375° F. to 420° F., which temperature range is the preferred temperature range of the air during the sterilization cycles described herein. Together, the four sides  203  and the bottom  204  define a surrounding wall which defines an instrument storage chamber within the instrument container  200 ; the surrounding wall is solid and air-tight except for the air-supply access portal  216  and the air-exhaust access portal  217 . Together, the air supply access portal  216  and the air exhaust access portal  217  serve as a container portal which allows air to enter and exit the instrument container  200 ; in the preferred embodiment, the container portal includes a pair of openings, though a single opening is envisioned. The surrounding wall also defines an open top (as shown in  FIG. 6A ) through which instruments may be inserted in and removed from the instrument storage chamber. The lid  202  (as shown in  FIGS. 5A and 5B ) forms an air-tight seal with the surrounding wall to prevent air from entering of leaving the instrument container  200  through the open top when the lid is in place. The lid  202  is removably and sealably mounted to the instrument container  200  to cover and seal the open top. With the lid in place, air is only able to enter and exit the instrument container  200  through the container portal—air is unable to pass through the surrounding wall, the lid  202 , or the interface between the lid  202  and the surrounding wall. The vertical pressure rollers  137  preferably contact the lid  202 , as shown in  FIG. 2 , and serve to hold the container  200  in a preferred orientation within the high velocity hot air sterilizer  100 . 
     For successful sterilization of medical and dental instruments by high velocity hot air, it is necessary that the instrument container  200  receives supplied hot air at a high velocity, preferably 1500 to 3000 feet per minute, without the encumbrances of filters or other devices that reduce air velocity. Referring to  FIGS. 6A and 7 , an air supply valve plate  208  and an air exhaust valve plate  214  are viewed in the open position allowing direct, unencumbered high velocity hot air to enter the instrument container  200  via the air supply access portal  216  and exit the instrument container  200  via the air exhaust access portal  217 . No filters are used with the instrument container  200  or the high velocity hot air sterilizer  100 . Filters are unnecessary since the air is segregated within the instrument container  200  and the air handling system. 
     Referring to  FIGS. 6C and 7 , with the instrument container  200  in the fully inserted position, the fixed posts  135  extend from the heating chamber wall  114  and protrude through the air supply access portal  216  and air exhaust access portal  217  to contact and push the air supply valve plate  208  and the air exhaust valve plate  214 , respectively, along compression-spring guideposts  211  to the open position. The compression spring-loaded guideposts  211  are attached to, and extend inwardly from, the rear interior instrument container wall  201  and protrude through the four corners of the air supply valve plate  208  and the air exhaust valve plate  214 . During the traverse of the air supply valve plate  208  and the air exhaust valve plate  214  to the open position, the compression spring-loaded guideposts  211  maintain the position of the air supply valve plate  208  and the air exhaust valve plate  214  parallel to the rear interior instrument container wall  201 . 
     Referring to  FIGS. 7 and 9 , a first air portal gasket  134  circumscribes the air supply portal  126  providing a sealed perimeter between the air supply portal  126  and the air exhaust access portal  217 . A second air portal gasket  134  circumscribes the air exhaust portal  118  providing a sealed perimeter between the air exhaust portal  118  and the air supply access portal  216 . Each of the portal gaskets  134  nest within respective portal gasket contours  215  which surround the respective air supply access portal  216  and air exhaust access portal  217 . 
     Referring to  FIGS. 6A and 7 , with the air supply valve plate  208  in the open position, high velocity hot air enters the instrument container  200  only from the air handling plenum  123  during the sterilization cycle. One or more air diversion plenums  213 ,  220 ,  221  are provided within instrument container  200  to direct the air flow within the instrument container  200 . In one embodiment (as illustrated in  FIG. 6A ) a first air diversion plenum  213  is positioned adjacent the air supply access portal  216 , a second air diversion plenum  220  is positioned adjacent the air exhaust access portal  217 , and a third air diversion plenum  221  is spaced along the wall from the first air diversion plenum  213 . Preferably, the first air diversion plenum  213  and the second air diversion plenum  220  are oriented in opposing directions to encourage air circulation throughout the instrument container  200 . The third air diversion plenum  221  is positioned on the wall adjacent the first air diversion plenum  213  to circulate air throughout the instrument container  200 . In one embodiment, the third air diversion plenum  221  is perforated to help diffuse the air. Supply air entering the instrument container  200  is prevented from directly diverting to the air exhaust portal  118  by a separator air stream barrier  212  which is preferably defined by the intersection of the terminus of the first air diversion plenum  213  and the terminus of the second air diversion plenum  220 . During the course of the sterilization cycle, the supply air is cooled during the heat transfer process and air is constantly exhausted from the instrument container  200  by way of the second air diversion plenum  220  to the air exhaust portal  118  where the spent air is discharged to the air handling system of the high velocity hot air sterilizer  100  to re-heat the air with the electric heating element  132  and to increase the velocity of the air for recirculation with the fan  115 . 
     Upon completion of the sterilization cycle and before the door  103  is opened, the instrument container  200  is separated from the back heating chamber wall  114  by the automatic reversal of the stepper motor  116 , moving the chain drive with attached push bar  117  to the front of the high velocity hot air sterilizer  100 , relieving the pressure exerted to the rear of the heating chamber  109  and allowing the valve compression springs  210  to push the air supply valve plate  208  and the air exhaust valve plate  214  back to the closed position and uncoupling the instrument container  200  from the air supply portal  126  and air exhaust portal  118  and extracting the fixed posts  135  from the air supply access portal  216  and air exhaust access portal  217 . Referring to  FIGS. 6B and 6C , an air supply valve plate  208  and an air exhaust valve plate  214  are viewed in the closed position over the air supply access portal  216  and air exhaust access portal  217 , respectively. In the closed position the air supply valve plate  208  and the air exhaust valve plate  214  are held securely against the air supply access portal  216  and air exhaust access portal  217 , respectively, by pressure exerted from the compression springs  210  which are located on the interior wall side of the air supply valve plate  208  and the air exhaust valve plate  214 . The air supply valve plate  208  and the air exhaust valve plate  214  have an exterior attached valve gasket  209  ( FIG. 7 ) which is compressed tightly against the air supply access portal  216  and air exhaust access portal  217 , respectively, by the compression springs  210  to provide a sealed and air-tight perimeter when in the closed configuration. 
     Referring to  FIG. 6C , access portal protective covers  218  provide protection to the air supply access portal  216 , the air supply valve plate  208 , the air exhaust access portal  217 , and the air exhaust valve plate  214  from accidental damage or intrusion and act as a secondary barrier to environmental microbial contaminants. The access portal protective covers  218  are movable along protective cover rails  219 . Following removal of the instrument container  200  upon completion of the sterilization cycle from the heating chamber  109 , the access portal protective covers  218  are manually moved across the air supply access portal  216  and air exhaust access portal  217  by sliding the access portal protective covers  218  along the protective cover rails  219 . In an alternative embodiment, the access portal protective covers  218  are opened and closed by mechanical action during insertion and removal of the instrument container  200 . 
     Referring to  FIGS. 2, 3, and 4 , hot air is generated and circulated to and through the instrument container  200  by the air handling system, which consists of a circulating fan  115 , an electric heating element  132 , and an air handling plenum  123 . The circulating fan  115  brings the air to a velocity necessary to achieve rapid sterilization as monitored by an air flow monitor  130  located in the air handling plenum  123  just downstream from the from the circulating fan  115  and the electric heating element  132  near the entrance to the air supply portal  126 . Air is blown over the electric heating element  132  to raise the temperature of the air to the desired temperature necessary for microbial kill at the required sterilization times. The electric heating element  132  is thermostatically controlled by two thermocouple monitors, an air supply thermocouple  128  and an air exhaust thermocouple  129 , to maintain the air within the heating chamber  109  within a desired temperature range. The air supply thermocouple  128  is located within the air supply portal  126  to monitor the temperature of the air as the air is directly supplied to the instrument container  200 . Air discharged from the instrument container  200  is monitored by the air exhaust thermocouple  125  located at the air exhaust portal  118 . To ensure the sterilization cycle initiates with air in the instrument container  200  at the proper sterilization temperature, both the air exhaust thermocouple  128  and air supply thermocouple  129  must be at the desired temperature to achieve sterilization before the sterilization cycle is activated. 
     Heated high velocity air circulates from the air handling plenum  123  which directs the air into the instrument container  200  via the air supply portal  126  and the open air supply valve plate  208  ( FIG. 6A ) for uniform distribution throughout the instrument container  200  as assisted by internal air diversion plenums  213 . As hot high velocity air is supplied to the instrument container  200 , a portion of the air is returned to the circulating fan  115  and electric heating element  132  by way of the open air exhaust valve plate  214  and the air exhaust portal  118 . This continuous process continues throughout the sterilization cycle, keeping the sterilant air at its designated temperature and velocity during the whole of the sterilization cycle without influx of any outside microbiological contaminants to jeopardize the sterilization process. The air handling system remains closed and sealed, creating a slightly positive air pressure to preclude the influx of air into the air handling system if a seal were to fail. The slight positive air pressure differential is monitored with an air pressure monitor  131  located at the entrance of the air supply portal  126  to ensure the air handling system retains a positive pressure. If the air pressure becomes negative, this negative pressure will be measured by the air pressure monitor  131 , and the air pressure monitor  131  will provide an electronic signal which will be used to terminate the sterilization cycle. As apparent to those skilled in the art, the air handling system can also be designed to deliver and exhaust air not only from the sides of the instrument container  200 , but also from the top and bottom, separately or in conjunction to assure airflow requirements and heat distribution necessary to sterilize the contained instruments. 
     An alternative embodiment is provided in  FIGS. 10-13 . A high velocity hot air sterilizer  300  is provided which includes various structural features which provide for a closed and sealed, recirculating air handling system and a sterilization chamber  302  that prevents the influx of external air and microbial contaminants during the course of the sterilization cycle and which provides for uniform circulation of high velocity hot air throughout the sterilization chamber  302  and through an instrument basket/perforated tray  328  to sterilize and depyrogenate wrapped and unwrapped medical and dental instruments and devices, providing sterilization parameters of time and temperature as prescribed by the U.S. Food and Drug Administration (FDA). 
     Referring to  FIGS. 10 and 11 , the high velocity hot air sterilizer  300  includes a metal outer housing  301  which surrounds the sterilization chamber  302 . The sterilization chamber  302  is accessed for instrument basket or perforated tray  328  insertion and removal via a door  303 . Although it is preferred that the door  303  be hinged horizontally by means of a bottom hinge  310  (as illustrated), the door may be hinged along any of the sides of the door  303 . Internal to the sterilization chamber  302  is a sliding rack  304 , which is movable on sliders between an extended position and a contracted position. In the extended position, the sliding rack  304  cantilevers over the open sterilizer door  303  for ease and proper insertion of the perforated tray  328 . Returning the sliding rack  304  to the contracted position places the instrument basket or perforated tray  328  directly over a supply air plate  305  containing elongated air slots  306  designed to uniformly distribute discharged, hot high velocity air to all areas of the sterilization chamber  302 , as described in greater detail below. 
     Referring to  FIGS. 12 and 13 , the sterilization chamber  302  is defined by a sterilization chamber wall  315  which encompasses the back, sides, top, and bottom of the sterilization chamber  302 . The sterilization chamber wall  315  is partitioned to the rear of the sterilization chamber  302  by a secondary common wall  319  to separate a circulating fan  316 , an electric heating element  317 , and a supply air duct  318  from the sterilization chamber  302 . Contained within the secondary common wall  319  is a return air portal  120  which serves to exhaust air from the sterilization chamber  302  for re-heating and recirculation through the air handling system to the sterilization chamber  302 . 
     The front of the sterilization chamber  302  is open to the front of the high velocity hot air sterilizer  300  as defined by a rectangular opening  311 . Prior to the initiation of the sterilization cycle, the door  303  is closed and remains locked in place until the completion of the sterilization cycle by a locking door handle  309 . Once the door  303  is closed, the gasket  308  is pressed against the outside perimeter of the rectangular opening  311  to ensure a tight air seal to prevent outside air from entering the sterilization chamber  302 . The sterilization chamber wall  315  that surrounds five of the six sides of the sterilization chamber  302  is constructed such as to preclude entry of outside air to allow the sterilization chamber  302  and the associated air handling system to remain airtight when the door  303  in the sealed, closed position during a sterilization cycle. 
     Encompassing the sterilization chamber wall  315  of the sterilization chamber  302  is an insulating jacket structure consisting of an outer insulation wall  312  and an inner insulation wall  314  with an insulating material  313  contained between the inner wall  314  and outer wall  312 . The insulating jacket structure serves two purposes. The first is to ensure little or no heat loss from the sterilization chamber  302  during the sterilization cycle. The second is to provide a heat barrier between the sterilization chamber  302  and the metal outer housing  301  of the high velocity hot air sterilizer  300 . A cooling cavity  323  is created between the outer insulation wall  312  and the interior surface of the metal outer housing  301 . A cooling fan  322  draws in external outside air that is circulated through the cooling cavity  323  and exhausted through cooling vents  321  located at the back and sides of the high velocity hot air sterilizer  300 . All air within the cooling cavity  323  remains segregated from the sterilization chamber  302 , circulating fan  316 , and air supply duct  318  by the sterilization chamber wall  315 . 
     Referring to  FIGS. 11, 12, and 13 , hot air is generated and circulated to and through the sterilization chamber  302  by the air handling system, which consists of a circulating fan  316 , an electric heating element  317 , the supply air duct  318 , the supply air plate  305 , and an exhaust air portal  320 . A circulating fan  316  brings the air to a velocity necessary to achieve rapid sterilization as monitored by an air velocity monitor  326  located at the furthest distance from the circulating fan  316  at the front of the sterilization chamber  302  under the supply air plate  305 . Air is blown over the electric heating element  317  to raise the temperature of the air to the desired temperature necessary for microbial kill at the required sterilization times. The electric heating element  317  is thermostatically controlled to maintain the air within the sterilization chamber  302  at a constant and desired temperature by two thermocouple monitors, an air supply thermocouple  324  and an air exhaust thermocouple  325 . The air supply thermocouple  324  is located underneath the supply air plate  305  at the front of the sterilization chamber  302  to monitor the temperature of the air as the air is directly supplied to the sterilization chamber  302 . Air discharged from the sterilization chamber  302  is monitored by the air exhaust thermocouple  325  located in the return air portal  320  at the upper rear of the sterilization chamber  302 . To ensure the sterilization cycle initiates with air in the sterilization chamber  302  at the proper temperature, both the air exhaust thermocouple  325  and air supply thermocouple  324  must be at the proper temperature to achieve sterilization before the sterilization cycle is activated. 
     Heated high velocity air circulates through the supply air duct  318  which directs the air along, underneath, and through the supply air plate  305  via elongated air slots  306  into the sterilization chamber  302  for uniform distribution throughout the sterilization chamber  302  as assisted by the corrugated upper deflection plate  307  and the back deflection plate  329 . As hot air is supplied to the sterilization chamber  302 , a portion of the air is returned to the circulating fan  316  and electric heating element  317  by way of an exhaust air portal  320  located in the secondary common wall  319 . This continuous process continues throughout the sterilization cycle, keeping the sterilant air at its designated temperature and velocity during the whole of the sterilization cycle without influx of any outside microbiological contaminants to jeopardize the sterilization process. The air handling system remains closed and sealed, creating a slightly positive air pressure to preclude the influx of air into the air handling system if a seal were to fail. The slight positive pressure air differential is monitored with an air pressure monitor  327  located in the rear upper corner of the sterilization chamber  302  to ensure the air handling system retains a positive pressure. If the air pressure becomes negative, this negative pressure will be measured by the air pressure monitor  327 , and the air pressure monitor  327  will provide an electronic signal which will be used to terminate the sterilization cycle. As apparent to those skilled in the art, the air handling system can also be designed to deliver air not only from the bottom of the sterilization chamber  302 , but also from the top and sides as required, separately or in conjunction to assure airflow requirements and heat distribution necessary to sterilize the contained instruments. 
     In one embodiment, the high velocity hot air sterilizer  100  includes an air handling portal which is formed in an external wall of the hot air sterilizer  100  which mates with the container portal of the container  200 , such that by placing the container  200  in locked attachment against the high velocity hot air sterilizer  100 , the instrument storage chamber of the container  200  and the air handling plenum  123  of the high velocity hot air sterilizer  100  together define an air-tight space. In such embodiment, the high velocity hot air sterilizer  100  and the instrument container  200  include the same interface as described above, but the instrument container  200  is not carried within the high velocity hot air sterilizer  100 , but instead is attached externally to the high velocity hot air sterilizer  100 . 
     It is understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects. No specific limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Modifications may be made to the disclosed subject matter as set forth in the following claims.