Abstract:
A cold smoke generating device includes an air source that may include a hollow flexible collapsible container having an expandable and compressible cavity for accepting air and air-borne reagent therein. The collapsible container is fluidly connected with a narrow flexible extension that includes an elongated cavity or chamber. Isolated and/or free reagents are disposed within the chamber of the narrow flexible extension. These reagents are capable of reacting with each other, with atmospheric air, or with other gases and fluids to generate a visible aerosol when expelled into the surrounding air.

Description:
The present application is a continuation application of U.S. patent Ser. No. 10/926,517 filed on Aug. 25, 2004 now abandoned. 

   The present invention did not receive any federal research and development funding. 
   FIELD OF THE INVENTION 
   The invention generally relates to a cold smoke generating device and more particularly to a device which comprises a hollow flexible collapsible container having an expandable and compressible cavity for accepting air and air-borne reagent therein. The collapsible container is fluidly connected with a narrow flexible extension that comprises an elongated cavity or chamber. Isolated and/or free reagents are disposed within said chamber of the narrow flexible extension. These reagents are capable of reacting with each other, with atmospheric air, or with other gases and fluids to generate a visible aerosol. This aerosol may be easily dispersed or expelled from the chamber by exerting a force or pressure onto an exterior of an expanded container causing air located therein to be forced from the container, into an end of the chamber, across the reagents to be expelled through an open end of the chamber. The process is begun by exposing a reduced pressure interior of the chamber to an atmospheric pressure by removing an end of the chamber. This creates an enriched blending of air with reagent to promote an air quality having a greater percentage of reagent to produce stronger more visible vapor or smoke streams. 
   BACKGROUND OF THE INVENTION 
   Portable, compact smoke generators are widely used for marking a direction and velocity of current air currents or gas flow. They are used to generate a continuous stream of fumes when used with an air supply pump or to produce a small cloud of smoke when used with stroke-type hand pumps. 
   Conventional smoke generators, commonly called ventilation smoke tubes, operate by passing air over a bed of granular sorbent material impregnated with a substance that reacts with the moisture in the air resulting in dense smoke. One such use of these generators is testing the fitting of respiratory protection equipment, in accordance with OSHA Respiratory Protection Standard 29 CFR 1910.134. 
   A major drawback of the known art is the use or presence of highly reactive substances that are harmful and must be carefully handled to prevent personal injury or property damage. Typically, the substances are impregnated in carrier materials and sealed glass tubes that include breakable tips. The carrier material is retained in place by mesh-cups and plugs. The process of manufacturing known smoke generators involves many difficult technological steps which result in more costly generators. 
   Another problem associated with the current smoke generators is the slow reaction between the active reagent and surrounding materials which limits the shelf life of the tubes. Use of glass in the prior art devices presents a hazard to both the user and the generator itself. Edges of broken glass are hazardous when the tube is used in close proximity with humans (such as in the air tight fitting tests for respirators). The use of such glass tubes requires frequent changes of a rubber bulb used widely as a pump because glass particles tend to destroy or limit the life of the pump. The whole construction is bulky and is unsafe. 
   McConnaughey, U.S. Pat. No. 3,658,719, teaches a smoke generating tube constructed with two reagents that are contained within separate glass ampoules. Each ampoule is enclosed within a perforated envelope of polyethylene tubing. The ampoules have to be broken together to produce smoke. The perforations within each envelope are small in dimension so that transfer of the volatile acid is substantially by diffusion. That is, there is no significant convection flow of gases through the envelope. The above mentioned problems and drawbacks apply to this device. Moreover, it is very difficult to break the glass containers to activate the tube. 
   SUMMARY OF THE INVENTION 
   The present invention is a cold smoke generating device that comprises a collapsible container having a cavity for accepting air therein. The collapsible container is fluidly connected with a flexible extension having a chamber that contains one or more ampoules comprised of breakable or crushable material. One or more reagents are included in the ampoule(s) for chemically reacting to produce a visible vapor or smoke. 
   The chamber may be provided at a reduced pressure and include a removable tip that hermetically seals the chamber. During use, the ampoule is broken to release the reagents. The tip is then removed causing atmospheric pressure to force air into the collapsible container by passing it across the reagent. The collapsible container fills with enriched vaporous air and may be collapsed to cause the enriched vapors to pass through the chamber and across the reagent to be expelled from the removed tip into the surrounding air to generate a vapor or aerosol. 
   It is an object of the present invention to provide a smoke generating tube which is simple to manufacture, safe to use and has a long shelf life. 
   Another objective of the invention is to apply contemporary materials and use their features to provide a completely sealed ready-to-use self-contained smoke generator that alleviates the need for a separate pump unit and mountable glass tube construction. The present invention incorporates the features of a pump and smoke generator into one unit which is easy hermetically assembled together. 
   According to the present invention, a collapsible hollow plastic container is connected fluidly with an elongated flexible hollow plastic extension. The flexible hollow plastic extension preferably includes a generally round cross-section shape that may include a cylindrical, conical, ogival or any such combinational shape. One or more ampoules comprising crushable material such as crystalline polystyrene, acrylic, glass, or the like are disposed within an interior cavity of the flexible hollow extension. 
   Each ampoule is filled with reagent or a plurality of reagents that react to produce a vapor or smoke. Each ampoule has at least one weakened region in the sidewall thereof to aid in breakage of the ampoule and release of a stored substance, such as a reagent. Typically the ampoule includes a region across the longitudinal axis which is mechanically less sound or rigid than the other areas of the ampoule structure. This region may be of smaller diameter than other regions of the sidewall comprising the ampoule, a mechanical scratch, notch or the like. The purpose of this mechanically weakened place is to allow easy breakage of the ampoule when the surrounded container is bent or twisted. The ampoules are immobilized and held in place within the interior of the flexible hollow plastic extension by means of at least one chemically-resistant plug. The plug may comprise felt, such as polypropylene or polyester felt, semi or fully sintered low or high porous plastic materials that exhibit low aerodynamic resistance characteristics. 
   In one embodiment, the collapsible container is fully collapsed and hermetically sealed to one end of the elongated extension when stored. The other end of the elongated extension that retains the ampoules is sealed with a removable end. The system is under moderate vacuum and has minimum volume. That is to say, the interior of the collapsible container and the elongated extension is exposed to a vacuum. By simply bending the flexible container, the inserted ampoule or plurality of ampoules breaks and the contents spread into the plug material. To activate the smoke generator, the interiors of the collapsible container and extension are exposed to atmospheric air by opening the sealed end of the flexible extension. Typically this is achieved by removing the sealed end seal by cutting or tearing off the end. Atmospheric air fills the container and extension to fully expand the sidewalls of the collapsible container to its nominal volume. The container then may be partially or fully collapsed to expel reagent laden air from within the smoke generating tube. 
   When the collapsible container is squeezed, the air passes through the plugs, evaporates part of the reagent and mixes it within the chamber directly before the air is expelled from the removed end. Depending upon the type of reagents used, the vapors react together and/or with the air (preferably with normally present water content in the air) to generate an aerosol visible as smoke. Single compound reagents such as titanium tetrachloride and/or tin tetrachloride can be used to fill a single ampoule. Both of these reagents evaporate at over 100° C. (212° F.) and can be stored safely in ampoules. Their vapors when coming into contact with air, immediately forms aerosols exhibiting good visibility qualities. Less irritating fumes can be generated. by using two or more ampoules filed with acid and base reagents. As one skilled in the art will notice, the collapsible container serves as a portable source of air flow. Other sources, such as a hand pump, electric pump, blower or pressurized cylinder air supply, can be used provided the average air flow is within the same air flow range as with the original collapsible container. 
   The air stream mixes the vapors by the mechanism of molecular diffusion and turbulence caused by the internal structure of the tube. The result is emitting an agent that reacts with humidity content in air to form a very visible aerosol. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated on the accompanying drawings where  FIG. 1A  through E shows the schematic of the smoke generating device in different stages of action. 
       FIG. 1A  depicts a view of a device of the present invention and in a stored shape. The interior of the collapsed hollow container is under reduced pressure conditions. An ampoule within the elongated extension is intact. A plug is disposed within a chamber of a flexible extension 
       FIG. 1B  represents the first phase of activation of the smoke generating device wherein the ampoule is broken to release reagents stored therein by stressing or flexing the extension. Next, the sealed end of the extension is opened. 
       FIG. 1C  shows the expansion of the collapsible hollow container by atmospheric pressure being drawn in through an open end of the flexible extension. The air is drawn in and passes through the reagent soaking into the porous plugs. 
       FIG. 1D  renders the collapsible hollow container and the flexible extension full of air enriched with reagent vapors. 
       FIG. 1E  illustrates the phase of smoke generation where the enriched air passes again through the reagent impregnated plugs, to increase its concentration of the reagent before it is emitted into the surrounding air where it generates a strong cloud of aerosol. 
       FIG. 2  shows an inactive device prior to use and containing an ampoule with two mechanically weakened points along its main or longitudinal axis. Plugs are disposed within the flexible extension at opposite ends of the ampoule. The ampoule is secured at one end for aiding in breakage of the ampoule. 
       FIG. 3  represents a variant for easy ampoule breaking and comprises a short, sharp and hard tube surrounding a weakened tip of the ampoule. 
       FIG. 4A  depicts an elevation view for a gas tight joint between the collapsible container and flexible extension. 
       FIG. 4B  is a cross section view of  FIG. 4A . 
       FIG. 4C  shows the gas tight joint of  FIG. 4A  in a partial cross section view and having an end attached to the flexible extension. 
       FIG. 5  is an elevation view showing the flexible extension in cross section and depicting another embodiment of the invention. This embodiment includes a tube as in  FIG. 3 . However, the ampoule includes notched sections for facilitating the breakage thereof. The ampoule in this embodiment may include a plurality of regions that are segregated to include multiple reagent that react with one another upon breaking of the ampoule. Felt plugs may provided at either end of the ampoule for absorbing reagent. 
       FIG. 6A  is a partial cross section view of the device showing a broken ampoule and having the content of ampoule soaked onto the walls of the collapsible container cavity. 
       FIG. 6B  is a bulb-type collapsible container and showing a gas tight joint for joining the container to a flexible extension. 
       FIG. 6C  shows a different embodiment of the invention wherein an end of the flexible extension includes a cap connected to a conduit that connects the flexible extension to a depressible bulb-type collapsible container 
       FIG. 7  shows a plurality of ampoules disposed within the flexible extension. A removable end cap is included at an end of the flexible extension. 
       FIG. 8  is a partial cross section view of another embodiment of the invention. The flexible extension includes a removable end cap. Plugs are longitudinally disposed along an exterior of the ampoule. 
       FIG. 9  is a partial cross section view of another embodiment of the invention showing the flexible extension with a removable end cap. Plugs are disposed within the chamber of the extension at opposite ends of the ampoule. 
       FIG. 10A  shows smoke generating devices with marked line of separation between the collapsible and elongated flexible containers. 
       FIG. 10B  shows a variety of flexible elongated extensions separated from the collapsible container and used with an alternative source of air flow. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   For one skilled in the art, the illustrated invention is self-explanatory and the features and advantages are self-explanatory as well. As seen on the drawings  FIG. 1A  to E, the device  1  comprises a collapsible hollow container  22  is in fluid connection with one end of the flexible elongated extension  32  defined by a sidewall  39 . The other end of the flexible extension  32  is sealed with tip  34  (or hermetical cap  38  shown on  FIG. 3  and  FIGS. 7-9 ). The flexible extension  32  includes an elongated chamber  37  for accommodating an ampoule  42 . A plug  52  is disposed within chamber  37  between ampoule  42  and tip  34 . A gas tight joint  62  connects the flexible extension  32  to the collapsible container  22 . 
   In this embodiment, at least one ampoule  42  is filled with reagent. The ampoule includes a cavity  43  defined by ampoule sidewall  45 . The ampoule sidewall  45  typically comprises crushable materials such as crystalline polystyrene, polymethylmetacrylate (acrylic), glass etc. In this embodiment, the ampoule  42  has along its longitudinal axis at least one place mechanically or structurally weakened area  47  that may comprise a thin sidewall region. This may be achieved by notching or scratching the sidewall  45  of the ampoule  42 . 
   In  FIG. 1A , the collapsible container  22  is shown fully collapsed to develop a partial vacuum confined, within the interior of the collapsible container  22  and chamber  37 . In  FIG. 1B , the device  1  is activated after crushing or breaking ampoule  42  to release its contents by flexing or bending the sidewall  39  of the flexible elongated container  32  in a direction of Arrow A. Next, the tip  34  is cut or removed from extension  32 . Air from the surrounding atmosphere passes through the released reagent that spills from the broken ampoule  42 . The reagent typically soaks into the plugs  52  that may comprise a porous felt or sintered porous material. 
     FIG. 1C  shows the device  1  the moments following the removal of tip  34 . Atmospheric air, depicted by arrows C, is sucked through the chamber  37  and into the collapsible container  22  to expand the container  22  in the direction of arrow B. This air is enriched to some level with vapors from the broken ampoule  42  with reagent and the sintered plug  54 . In  FIG. 1D , the flexible extension  32  fills with air enriched to some level with vapors of the reagent. This position illustrates the device ready to release the generated smoke. 
     FIG. 1E  illustrates the phase of smoke generation where the air passes the plugs for a second time to absorb more vapors from the reagent to increase the content of the reagent vapors within the air. The enriched air is released to the environment where it reacts with the moisture normally present in the air even if the absolute humidity is low. As a result of this immediate reaction, a smoke from fine aerosol particles is generated. More than one ampoule  42  may be included within the chamber  37 . Each ampoule  42  has at least one mechanically weakened point such as a smaller diameter, a thinner wall, a notch or a surface pre-scored scratch. 
   In  FIG. 2 , the device  1  is shown inactivated and having an ampoule with two weakening diameters along the main axis. In this embodiment, notches  70 A and  70 B, include a region of the ampoule sidewall  45  that has a smaller diameter and an area that is less resistive to compressive, tension or other shear forces. In this embodiment, sintered plugs  52 A and  52 B are provided within chamber  37  near opposite ends of ampoule  42 . A holder  71  secures ampoule  42  so that it may be easily broken by flexing the sidewalls  39  that define chamber  37 . 
     FIG. 3  depicts an alternative method for easily breaking the ampoule  42 . In this embodiment, the ampoule  42  includes a tip  48  and a shoulder  49 . The tip  48  is disposed within a cylindrical tube  72  as shown. The cylindrical tube  72  is arranged within the chamber  37  along with the ampoule  42 . The cylindrical tube  72  includes a sharp cut diameter and is comprised of a hard material (preferably glass) for receiving a weakened edge or tip of the ampoule. When the sidewalls  39  are flexed, the hard tube  72  easily breaks the tip  48  of the ampoule  42  and facilitates further crushing. This embodiment includes a removable cap. 
   Turning now to  FIG. 4A through 4C , the connection between the collapsible hollow container  22  and the flexible extension  32  must be hermetic. To facilitate this connection and to support the content of the tension from moving into collapsible container  22 , a specially designed click-lock connector  62  has two joining surfaces allowing hermetically tight connection. The connector  62  comprises an internal extension  63  that extends into chamber  37 . An external extension  64  defines a seat  65  for accommodating an end of extension  32 . A lip  40  may be included on an exterior of the sidewall  39  for locking the extension  32  onto the collapsible container  22 . 
   In  FIG. 5 , another embodiment for easily breaking the ampoule  42  includes a combination of previously mentioned embodiments. In this embodiment, the ampoule  42  includes two weakened regions or notches  70 A and  70 B. One end of the ampoule  42  comprises a tip  48  that extends into a hardened cylindrical tube  72 . An opposite end of the ampoule  42  is secured within chamber  37  by holder  71 . The ampoule is easily broken by flexing extension  32 . 
   The device shown in  FIG. 6A , does not include a plug disposed between the ampoule  42  and connector  62 . This allows the content  80  to flow onto the interior of the walls of the collapsible container  22  decreasing the aerodynamic resistance of the assembly. This variant is convenient one if pre-assembled containers are intended as initial device. In  FIG. 6B , a bulb type collapsible container  22  is shown. In use, the container  22  is squeezed by the operator to expel air from within the container  22 . A connector  62  is connected at an end of the container  22  for mating with an end of a flexible extension. In  FIG. 6C , plugs  54  are disposed within chamber  37  at opposite ends of the ampoule. An end of the flexible extension is sealed by a cap  38  that connects to a collapsible container  22  via conduit  85 . 
   The example illustrated in  FIG. 7  shows the use of more than one ampoule  42 A and  42 B, similar to  FIG. 5  into the elongated container. This is the case when two or more reagents have to a produce substance capable of reacting with the air once they exit the chamber  37 . In this embodiment, a removable end cap  38  hermetically seals an end of chamber  37  until removed. Plugs  52  are disposed at opposite ends of the chamber  37 . A first hollow tube  72 A receives a tip of ampoule  42 . A second hollow tube  72 B receives a second tip of ampoule  42 A at one end and a tip of ampoule  42 B at an opposite end thereof. 
   In  FIG. 8 , plugs  54  are disposed longitudinally along an exterior of ampoule  42  within chamber  37 . Flexible extension  32  may include a flared region as shown for accommodating the plugs  54  and ampoule  42 . In  FIG. 9 , plugs  54  are disposed at opposite ends of ampoule  42 , as shown. 
   The variety of flexible elongated extensions separated from the collapsible container can easily be used with any alternative source of air flow as can be recognized in  FIGS. 10A and 10B . Such sources can be: a hand pump, electric pump, electric blower, gas pressurized canister or the like, provided the air flow through the elongated extension with broken ampoule is moderately similar to the one received with the collapsible container.