Abstract:
An aerodynamically smooth air manifold designed for use with an underground shelter located very close to ground zero, including a manifold body; a bottom plate under the manifold body; a manifold cover atop the manifold body; a baffle; an air pipe; a gully surrounding the top outside manifold body; a rolled angle ring surrounding the bottom outside manifold body; a plurality of first fasteners that secure a bottom flange of the air pipe and the bottom plate together; and a plurality of second fasteners that secure the rolled angle ring and the bottom plate together.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to emergency underground shelters, and specifically, to air inlets and air outlets for such shelters. 
       BACKGROUND 
       [0002]    There is a misconception about underground shelters and intruder assaults. It is believed that people will try to break into the main hatch with guns or equipment. The inventor&#39;s experience from Hurricane Hugo and Hurricane Andrew, on the other hand, is that people tried to break into the shelter by assaulting the air manifolds of the shelters. The purpose of such an assault is to force the shelterists out so that the underground shelter may then be taken over by the intruders. Unlike an attack on the hatch, the air manifold attack leaves the shelter intact and usable for the intruders. 
         [0003]    In order for an underground shelter to be inhabitable, air needs to be able to enter the shelter. The conventional method for air entering an underground shelter is a gooseneck  50  or pipe cap  52 , such as those shown in  FIG. 1 . When the gooseneck is subjected to impact from flying debris, its failure mode is to fold over and pinch the air inlet or air outlet pipe, thus blocking the air passage into or out of the shelter. Such air inlets or manifolds should only be used for shelters that have no blast rating. Such air inlets may, for example, be used with a fallout shelter that is not designed to be located at a distance from a detonation where there is any type of blast wind. If the shelter is designed for use during and after a blast and for impact resistance from flying debris, however, such conventional air inlet methods are inadequate, and another aerodynamically designed manifold must be employed. 
         [0004]    Therefore a more robust air manifold designed to resist flying debris and high winds, such as those that may occur at a close distance from a nuclear weapon or tornado, is needed. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention is an air manifold and air manifold system designed for use with underground shelters. 
         [0006]    The air manifold of the present invention includes a manifold body, a bottom plate disposed beneath the manifold body, and a manifold cover disposed on top of the manifold body. The air manifold also includes a baffle. The baffle includes a baffle body and a baffle lip. The baffle body extends downward from and is attached to the bottom of the manifold cover. The baffle lip extends inward at a right angle from the baffle body. The air manifold also includes an air pipe. The air pipe includes a top lip, a bottom flange, and an air pipe body extending between the top lip and bottom flange. The top lip of the air pipe is disposed above the baffle lip and the bottom flange of the air pipe is disposed directly on top of the bottom plate, to which it is secured. The air manifold also includes a blast valve disposed around the air pipe body. The air manifold also includes a gully surrounding the top outside of the manifold body. The gully includes a manifold side where it attaches to the manifold body, an other side opposite from the manifold side, and a floor. The manifold side includes a screen. The screen is preferably a series of round, 3 inch diameter air in push in aluminum screens positioned at regular intervals around the manifold side. A top flange of the blast valve is positioned almost at a level with the top of the screen. The floor of the gully includes drain holes. The gully floor is preferably at or above ground level of the site. In some situations, where the entire manifold is above ground using a berm, this is a given. The air manifold also includes a rolled angle ring, which surrounds the bottom outside of the manifold body. The rolled angle ring is a rolled angle that continues all the way around the manifold body. The rolled angle ring includes a right angle, with an angle ring bottom that is disposed directly upon and is securely attachable to the bottom plate, and an angle ring side that is flush with the manifold body. It is understood that in referring to the rolled angle “ring,” the preferred round shape is being referred to, but that the rolled angle ring may be rectangular or other shaped in non-preferred embodiments where the manifold body is not cylindrical. Finally, the air manifold also includes first fasteners that attach the air pipe bottom flange securely to the bottom plate, and second fasteners that attach the angle ring bottom securely to the bottom plate. The first and second fasteners are preferably V2 inch cap screws or machine bolts. 
         [0007]    The air manifold is preferably made of steel. The steel is preferably carbon steel. Stainless steel underground corrodes more than carbon steel because the corrosion resistance of stainless steel is based on an aerobic environment whereas underground is an anaerobic environment. The air manifold may also be made of fiberglass reinforced plastic (FRP). The air pipe is preferably made of fiberglass, and may be steel epoxy coated. It is preferred that the manifold body, blast valve, air pipe body, baffle, and gully are all cylindrical in shape, with a common center point. The preferred cylindrical shape puts the manifold body in hoop stress, which allows it to resist the high external pressure. In non-preferred embodiments of the present invention, these features may be rectangular or other shaped, rather than cylindrical, but the wall thickness of any of the features would need to be thicker than their cylindrical counterparts, in order to resist the high external pressure that is addressed by their cylindrical counterparts through hoop stress, as discussed above. The preferred cylindrical manifold body is 24 inches in diameter, but may have a lesser or greater diameter. The preferred manifold is also has a depth of approximately 24 inches, but may have a lesser or greater depth. As used herein, “depth” of the manifold refers to the distance between the manifold cover and the bottom plate. Although the manifold cover may be flat, it is preferred that it is convex away from the manifold body, or curved upward from the ground, and that its edges extend slightly out from where the manifold cover sits on top of the manifold body, so that liquid, such as rain, that encounters the manifold cover drains down into the gullies of the air manifold. The convex manifold cover is also advantageous in that, unlike with a flat manifold cover, most debris that falls and rests on the convex manifold cover will not have a glove fit that shuts off the air flow. It is preferred that the air manifold also include a coupling that is connected to a ceiling vent in the top of the underground shelter. This coupling is preferably a 2 inch coupling. It acts as an air outlet manifold. 
         [0008]    The air manifold system of the present invention includes the air manifold of the present invention, as described above, and a lower air pipe. The lower air pipe connects directly to the underground shelter. The lower air pipe includes a flange that is disposed directly below and securable to the bottom plate of the air manifold. The first fasteners that secure the air pipe bottom flange of the air manifold to the bottom plate also secure the lower air pipe&#39;s flange to the bottom plate. In this manner, the bodies of the air pipe of the air manifold and the lower air pipe are aligned. The lower air pipe also includes a seismic joint. This seismic joint allows the system to move with ground movement and vibrations. The lower air pipe, like the air pipe of the air manifold, is also preferably made of fiberglass. 
         [0009]    The air manifold of the present invention is disposed in a hole in the ground at a site where an underground shelter is located. The air manifold includes an edge where the manifold body and manifold cover meet. This edge must be at least 12 inches above the 100 year flood level or storm surge for the site and at least 4 inches above the ground level of the site. Once the air manifold is properly positioned in the hole at the site, the space around the air manifold is filled in with crushed stone at least to the level of the gully floor to facilitate drainage. The hole is filled up all the way to the manifold cover, however. Crushed stone may be used to fill all the way to the manifold cover, but the gradient between the edge and the ground level is preferably filled with soil or other materials on top of the crushed stone in order to make the air manifold less conspicuous. 
         [0010]    The air manifold system is aerodynamically smooth and is designed to resist flying debris from winds up to 350 miles per hour, which can occur at a close distance from a nuclear weapon or a tornado. The preferred air manifold system is capable of moving 1200 cubic feet per minute of air in and out of the underground shelter. 
         [0011]    These aspects of the present invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a side, cut-away view of two prior art air manifolds. 
           [0013]      FIG. 2  is a side, cut-away diagram of the air manifold system of the present invention. 
           [0014]      FIG. 3  is a top view diagram of the air manifold system of the present invention. 
           [0015]      FIG. 4  is a diagram showing the unlikely path that liquid would have to follow in order to get into the air pipe of the air manifold. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Now referring to  FIG. 2 , a side cut-away view of the air manifold system  100  of the present invention is provided. Air manifold system  100  includes air manifold  2  and lower air pipe  32 . Air manifold  2  is preferably has a diameter  75  and a depth  71 , each of approximately 24 inches and is made of steel or FRP. Air manifold  2  includes manifold body  74 , manifold cover  8 , and bottom plate  28 . Manifold body  74  extends between manifold cover  8  and bottom plate  28 , and includes an outside  68 , a top  70 , near the manifold cover  8 , and a bottom  72 , near the bottom plate  28 . An annular space or cavity  80  is formed within these aspects of the manifold body  74 . Within this annular cavity  80 , air manifold  2  also includes baffle  10 , air pipe  6 , and blast valve  4 . Baffle  10  is attached to manifold cover  8  and extends downward therefrom into cavity  80 . Baffle  10  includes baffle body  54  that extends down from manifold cover  8  and baffle lip  56  that extends inward from baffle body  54  at a right angle. Air pipe  6  includes air pipe body  58 , air pipe top lip  18 , and air pipe bottom flange  20 . Air pipe top lip  18  is disposed above baffle lip  56 . Air pipe bottom flange  20  is disposed directly on top of bottom plate  28 . Air pipe bottom flange  20  is securely attachable to bottom plate  28  with first fasteners  42 . First fasteners  42  are preferably ½ inch cap screws or machine bolts. 
         [0017]    Blast valve  4  surrounds air pipe body  58 . Blast valve  4  is preferably a large stainless steel poppet valve with a standard 6 or 8 inch pipe flange on each end with a standard bolt circle pattern. A blast valve is used to protect a shelter from the effects of sudden outside air pressure changes that will cause underpressure or overpressure within the shelter. A nuclear weapon, for example, creates a shock wave, which may produce sudden pressure changes of more than one atmosphere even several miles from the detonation point. After the shock wave passes, a sudden negative pressure follows. If such pressure waves enter a shelter, they will likely do substantial harm to occupants and equipment. If a blast valve is located inside the shelter, the blast valve may be subjected to reflected over or underpressure that is much higher than pressure at the ground surface. The air manifold system  100  allows the blast valve  4  to be secured inside the air manifold  2 . This placement allows the air pipe  6  to remain open normally, but to automatically close when strong pressure is applied in either direction. In addition, the air manifold system  100  allows the blast valve  4  to be inspected by digging down and removing the manifold body  74 . The extension of the bottom plate  28  beyond the width  75  of the air manifold  2  also provides resistance of the system  100  to hydrostatic pressure and negative pressure after a blast or from a tornado. 
         [0018]    Air manifold  2  also includes gully  14  surrounding the outside  68  top  70  of manifold body  74 . Gully  14  includes manifold side  62  where gully  14  is attached to manifold body  74 , other side  64 , and gully floor  66 . Manifold side  62  includes a screen  16 , not visible in this view. Screen  16  is preferably a series of round, 3 inch diameter air in push in aluminum screens positioned at regular intervals around manifold side  62  of gully  14 . Gully floor  66  includes drain holes  22 , also not visible in this view. It is preferred that manifold cover  8  be slightly convex away from the manifold body  74 , or curved upward as shown, and that its edges extend slightly outward past the manifold body  74 , so that liquid that comes in contact with the manifold cover  8  simply drains into the gully  14  and down through the drain holes  22 . 
         [0019]    Air manifold  2  also includes rolled angle ring  30 . Rolled angle ring  30  includes an angle ring bottom  38  and an angle ring side  40 . Angle ring bottom  38  is flush with and securely attachable to bottom plate  28  with second fasteners  43 . Second fasteners  43 , like first fasteners  42 , are preferably ½ inch cap screws or machine bolts. Angle ringside  40  is flush with manifold body  74 . 
         [0020]      FIG. 3  is a top view diagram of air manifold  2  that illustrates the concentricity of cylindrical gully  14  with gully floor  66  and drain holes  22 ; rolled angle ring  30 , with angle ring bottom  38  shown; manifold body  74 ; baffle  10 ; and air pipe  6  secured to bottom plate  28  (shown in  FIG. 2 ) with first fasteners  42 . It is understood that blast valve  4  is also cylindrical and concentric with these features and disposed around air pipe  6 . The preferred cylindrical shape puts manifold body  74  in hoop stress, which allows it to resist the high external pressure. 
         [0021]    Lower air pipe  32  connects to an underground shelter. Lower air pipe  32  includes lower air pipe flange  34  and seismic joint  36 . Lower air pipe flange  34  is disposed directly below and securely attached to bottom plate  28  of air manifold  2 . This connection aligns air pipe  6  and lower air pipe  32 . Lower air pipe  32  is preferably made of fiberglass. The seismic joint  36  allows the air manifold  2  to move with ground movements and vibrations. 
         [0022]    Air manifold  2  also includes pipe coupling  44 . Coupling  44  connects to the ceiling vent in the top of the underground shelter, and functions as an air outlet device. Coupling  44  is preferably 2 inches. 
         [0023]    Air manifold  2  is disposed in a hole in the ground at a site where an underground shelter is located. Edge  12 , where manifold body  74  and manifold cover  8  meet must be at least 12 inches above the 100 year flood level or storm surge for that site. In addition, that edge  12  must be at least 4 inches A above ground level  76  at the site, so that air manifold  2  is bermed on about a 5 degree slope. Once air manifold  2  is properly position in the hole at the site, the space around the air manifold  2  is filled in with crushed stone  24  at least from the level of the gully floor  66 . Crushed stone  24  is used to facilitate drainage from drain holes  22  in gully floor  66 . Local soil is used for the gradient between the gully  14  and ground level  76  to make the site less conspicuous given the site surroundings. 
         [0024]    The air manifold system  100  shown is aerodynamically smooth and is designed to resist flying debris from winds up to 350 miles per hour, which can occur at a close distance from a nuclear weapon or a tornado. The preferred air manifold system  100  is capable of moving 1200 cubic feet per minute of air in and out of the underground shelter with relatively low static pressure. 
         [0025]    There are four basic manners in which an intruder may assault an air manifold of an underground shelter: First, a vehicle may drive over the air manifold and damage it. Second, water, fuel, or other liquid may be poured into the air manifold, and ignited if it is a flammable liquid. Third, the air manifold may be disassembled so that such liquids may be poured into the underground shelter. Finally, the air manifold may be blocked with some type of cloth or plastic. The air manifold system  100  addresses these potential assaults. First, it is strong enough to resist vehicles traveling on top of it and heavy debris coming to rest on it after being moved from high winds. The round manifold body  74  acts like a column when heavy traffic rolls over the cover  8 , which is resisted by the bottom plate  28 , which is resting on the soil. Second, it would be basically impossible for liquid to get into the air pipe  6 . Referring to the dotted line in  FIG. 4 , liquid would have to take the unlikely path of going into gully  14 , getting through screen  16 , which is protected by the overhang of manifold cover  8 , traveling laterally, then up past the baffle lip  56 , then laterally again to get past the air pipe top lip  18 , then up again, and finally down into the air pipe  6 . Rain simply drains out of the drain holes  22  in the gully floor  66 . Third, disassembly could only occur after the air manifold  2  is excavated, which would take great effort and time. Gasoline powered concrete saws, excavators, and cutting torches are real threats that would aid in such disassembly, but few people would have the skills to use these tools, even assuming they were available and operating. Finally, a plastic garbage bag could be placed over the air manifold  2 . To address this threat, the underground shelter with which the air manifold  2  is used is designed with a second non-visible or disguised air manifold  2 . With only one of the air manifolds  2  visible, the idea is that intruders will place the garbage bag over the visible air manifold  2 , but the non-visible air manifold  2  will continue operating so that air into and out of the shelter is not affected. The inventor has encountered this situation in real life when his underground shelters were assaulted during Hurricanes Andrew and Hugo. Defending the air manifolds is the main issue with underground shelters, and no air manifold is impenetrable. In addition to the above discussion, this issue is usually addressed by having an emergency escape hatch that is not visible from the ground, which would allow shelterists to open up a hatch and surprise the intruders, allowing the shelterists to use tear gas, guns, or other weapons to disable the intruders. 
         [0026]    Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions would be readily apparent to those of ordinary skill in the art. Therefore, the spirit and scope of the description should not be limited to the description of the preferred versions contained herein.