Abstract:
Fire prevention and suppression system is provided for computer cabinets and fire-hazardous containers. The equipment of the system provides low-oxygen environments at standard atmospheric pressure. The system employs an oxygen-extraction apparatus that supplies oxygen-depleted air inside an enclosed area communicating with the device. A fire-extinguishing composition is provided for continuous use in computer cabinets and fire-hazardous containers, consisting of oxygen-depleted air having oxygen content below 12%.

Description:
RELATED APPLICATIONS 
     This invention is related to preceding U.S. Pat. No. 5,799,652 issued Sept. 1, 1998, U.S. Pat. No. 5,887,439 issued Mar. 30, 1999, U.S. Pat. No. 5,924,419 of Jul. 20, 1999 and is continuation in part of the U.S. patent application Ser. No. 09/551,026 filed on Apr. 17, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a process and equipment for providing low-oxygen (hypoxic) environments inside a computer cabinet or container with combustible or explosive material in order to prevent or suppress fire before it starts. 
     The demand in reliable fire prevention and suppression systems for industrial applications has been always very high and is growing extensively, especially with the explosive development of Internet, computerized equipment and communication systems. The invented Fire Prevention And Suppression System can be used in any possible application where a non-occupied environment requires protection from fire hazard or explosion. 
     DESCRIPTION OF THE PRIOR ART 
     At the present time there are no products on the market that would allow to prevent fire from igniting inside computer cabinets or other industrial enclosures containing inflammable or explosive materials. A computer or server produces a lot of heat inside its enclosure or cabinet, mainly due to friction and overheating of electronic components. At any time a malfunction of an electronic component or short circuit may cause fire and extensive damage. A spark inside a fuel container at gas station or tanker may cause immediate explosion. All current fire prevention and suppression systems are design in order to suppress fire after it starts, which might be too late. Current fire suppression systems are destructive for computerized equipment and cannot guarantee that fire will not start. 
     There are millions of powerful computers around the world, owned by large corporations, banks, communication companies, military and government agencies, many of them loosing millions of dollars in just one such fire. 
     There is no prior art on fire protection systems build inside a computer cabinet or fire hazardous container. The process and equipment described in this invention can guarantee that no fire will be able to start inside such computer cabinet or container having internal atmosphere with oxygen content under 10%. 
     The invention described in this document will prevent huge financial and environmental losses from industrial fires and will save many lives of fire fighters and general public. 
     SUMMARY OF THE INVENTION 
     A principal object of this invention is to provide a method for producing a fire safe hypoxic environment inside a computer cabinet or container with combustible, inflammable or explosive materials. 
     Further object of the present invention is the provision of an oxygen-depletion process and an apparatus for producing a low-oxygen environment inside a computer cabinet or industrial container, such equipment employing molecular-sieve adsorption or membrane-separation technologies. 
     A still further object of the invention is to provide a fire-retarding oxygen-depleted environment inside a computer room or industrial facility at standard, slightly reduced or increased atmospheric pressure and having oxygen content fewer than 10%. 
     Another object of this invention is to establish fire safe hypoxic environments inside computer cabinets or containers with combustible, inflammable or explosive materials by providing constant ventilation of such enclosures with oxygen-depleted air in order to remove heat and/or explosive fumes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the most preferred embodiment of the fire safe computer cabinet. 
     FIG. 2 illustrates schematically a working principle of the invented hypoxic fire prevention and suppression system employing hypoxic generator in extraction mode. 
     FIG. 3 illustrates schematically an alternative working principle of the invented hypoxic fire prevention and suppression system employing hypoxic generator in supply mode. 
     FIG. 4 presents a schematic view of a working principle of hypoxic generator employing nitrogen adsorbing molecular-sieve material and Pressure-swing adsorption technology. 
     FIG. 5 presents a schematic view of a working principle of hypoxic generator employing oxygen adsorbing molecular-sieve material and Pressure-swing adsorption technology. 
     FIG. 6 shows schematically working principle of hypoxic generator employing Membrane air-separation technology. 
     FIG. 7 illustrates a schematic view of an industrial container filled with highly inflammable fluid. 
    
    
     DESCRIPTION OF THE INVENTION 
     It is well known that combustion process requires oxygen, therefore the goal of this invention is to provide an extreme hypoxic normbaric environment inside a computer cabinet or any container in order to eliminate fire hazard completely. 
     This invention is based on a discovery made by the inventor during research with the Hypoxic Room System made by Hypoxico Inc. in New York. It was discovered that a normbaric hypoxic environment provides a different effect on ignition and combustion process than hypobaric or natural altitude environments with the same partial pressure of oxygen. For example, gasoline or any gas lighter would ignite and bum on an altitude of 19,000′ (5,800 m) in the air having partial pressure of oxygen at 2.99″ (76 mm) of mercury. 
     However, if we create a corresponding normbaric hypoxic environment with the same partial pressure of oxygen at 2.99″ or 76 mm of mercury, we will find that gasoline will not burn or even ignite. Any attempt to ignite it would fail because even a gaslighter or gas torch would not ignite in this environment. It means that normbaric environments with corresponding oxygen content of 10% are absolutely safe against any fire hazard. 
     This invention provides reliable and inexpensive process and equipment for producing such fire-retarding environment inside a computer cabinet or container with fire hazardous material. 
     FIG. 1 shows the most preferred embodiment of the fire safe computer cabinet system  10  consisting of cabinet enclosure  11  having (in this case clear) door  18  and air intake openings  16  and filled with computer equipment or components  17 , further having hypoxic generator  12  mounted on the top of the cabinet enclosure  11 . 
     FIG. 2 shows schematically a working principle of the invented hypoxic fire prevention and suppression system  10  employing hypoxic generator in extraction mode. 
     The fire safe computer cabinet system  10  consists of a computer rack or cabinet enclosure  11  filled with computer devices or components and hypoxic generator  12  mounted directly on cabinet enclosure  11  and having air intake  13  and outlets  14  and  15 . Computer cabinet  11  does not have to be absolutely airtight—it has multiple openings or holes  16 , preferably in its lower portion. Openings  16  are shown schematically for better understanding of air circulation inside cabinet  11 . In reality there is no need for special openings because air will always be able to enter cabinet through gaps around the door or through semi-airtight enclosure. 
     Hypoxic generator  12  draws air from the cabinet  11  through the intake  13  and extracts a part of oxygen from it allowing oxygen depleted air back into cabinet  11  through outlet  14 . Oxygen-enriched gas mixture is disposed into atmosphere through disposal outlet  15 . This process creates a slightly negative pressure inside cabinet  11  that works as a driving force for intaking fresh air through the openings  16 , in order to equalize atmospheric pressures inside and outside of cabinet  11 . Therefore semi-airtight cabinet  11  and even holes  16  in it are absolutely necessary functional components of this fire-retarding system. 
     Hypoxic generator starts working when door  18  is closed. At the beginning, the oxygen-enriched gas being removed from the system through disposal outlet  15  has a little higher oxygen content (about 30%) than ambient air entering cabinet  11  through holes  16  (20.94% at sea level). It means that oxygen content inside cabinet  11  will start dropping to a certain level below 10%. At the same time the oxygen content in the disposal fraction will also decrease to about ambient air level. The higher oxygen content in the disposal fraction, the lower will be the oxygen content inside cabinet  11 . The lowest possible oxygen content inside cabinet  11  will be about 4.5%. Most important in the invented system is that it does not affect air composition in the room where the system  10  is installed. After oxygen content in cabinet  11  drops to desired level, the system  10  becomes balanced and will extract composition with oxygen content close to ambient air. 
     When oxygen content inside cabinet  11  drops below 7%, which will be detected by oxygen transducer  19  installed inside cabinet  11 , hypoxic generator  12  turns off in order to save energy. When, after some time, oxygen content inside cabinet  11  reaches about 12%, transducer  19  will turn on hypoxic generator  12  again, and so further in cycles. Expensive oxygen transducer  19  is optional and can be replaced by a simple timer, which can turn on and off hypoxic generator  12  in preset intervals of time. 
     An air-cooling device  20  is installed in order to reduce temperature inside cabinet  11 . The device  20  consists of thermoelectric module having cold sink plate  22  inside cabinet  11  and heat sink  21  outside cabinet  11 . Big advantage of thermoelectric modules is the absence of refrigerant or any moving parts. Working principle of a thermoelectric cooler is well known and such devices are available on the market. Suitable device with high-performance thermoelectric module and high-fin-density cold sink and heat sink can be bought from TE Technology Inc. in Michigan, U.S.A. 
     It is advisable to direct the gas flow from outlet  14  against the cold sink  22  of the cooler  20  in order to provide better circulation of cold gas mixture inside cabinet  11  and better cooling of electronic components  17 . Cooler  20  can be equipped with a simple thermostat that will control temperature inside cabinet  11  and save energy by turning off the cooler  20  when desired low temperature is reached. 
     FIG. 3 illustrates schematically an alternative working principle of the invented hypoxic fire prevention and suppression system  30  employing hypoxic generator  32  in supply mode. This embodiment does not change anything in design of cabinet  11  and all other components. The only difference is in configuration of hypoxic generator  32  that is the same as generator  12 , but connected different way to cabinet  11 . 
     Hypoxic generator  32  takes in ambient air through intake  33  and separates it into oxygen-depleted fraction being transmitted inside cabinet  11  through outlet  34  and oxygen-enriched fraction being disposed into atmosphere through disposal outlet  35 . This way cabinet  11  becomes constantly ventilated with low-oxygen gas mixture. Hypoxic generator shown below on FIG. 4 will be available in 2001 from Hypoxico Inc. in New York. It can provide oxygen-depleted air with any oxygen concentration in the range from 5% to 10%, which can be exactly preset at the factory. 
     The oxygen-depleted air entering cabinet  11  through outlet  34  is directed against cold sink  22  of the thermoelectric cooler  20  and sinks further down to the bottom of cabinet  11 . In this embodiment openings  16  are moved to the higher position in order to exhaust warm gas mixture instead of cool one at the bottom of cabinet. This way, an effective air circulation inside cabinet  11  is assured, providing better cooling of computer components  17 . The invented system  30  is entirely safe because disposal fraction having only slightly increased oxygen content of about 30% is instantly dissociated in the surrounding atmosphere. The system  30  does not affect air composition in surrounding atmosphere in any way because the oxygen amount in both fractions exiting the system is equivalent to the amount of oxygen in the air entering the system. Constant ventilation of the internal environment allows to remove heat from cabinet  11 . This embodiment is most suitable for fire-hazardous containers because constant ventilation will allow removing of explosive fumes. 
     All parts of the systems  10  and  30  are shown schematically, in order to provide better understanding of the working principle. For instance, thermoelectric cooler  20  could be build in the air supply line before outlet  14  or  34 , or hypoxic generator could be a free-standing unit connected with cabinet  11  through air conduits. Computer rack enclosure  11  can be computer cabinet or container with fire-hazardous materials. Transducer or timer  19  and cooler  20  are optional in some applications. 
     Other oxygen-extraction devices employing molecular-sieve adsorption, membrane-separation or other technologies can be used instead on hypoxic generator  12  or  32  in the invented system. However, it is highly recommended to use reliable hypoxic generators specially designed by Hypoxico Inc. in New York. 
     FIG. 4 presents a schematic view of a working principle of hypoxic generator HYP-10/PSA/Z employing Pressure-swing adsorption technology, which will be available from Hypoxico Inc. in New York in 2001. This hypoxic generator  40  produces about 10 liters per minute of hypoxic air with preset oxygen content in the product between 5% and 10%. Miniature hypoxic generators producing 0.5 to 5 liters per minute will be available for smaller cabinets as well. All these generators employ molecular-sieve materials, mainly synthetic zeolites that adsorb nitrogen and allow oxygen to pass through the adsorbing material. 
     Compressor  41  draws ambient air through intake filter  42  and pressurizes it to about 15 psi or 1 bar. Further compressed air is chilled in air cooler  43  and transmitted through high-efficiency air filter  44  into distribution valve  45  mounted on manifold  46 . 
       3  elongated containers  47  with molecular sieve material are mounted on manifold  46  the way that pressurized air is selectively and in cycles delivered into each container  47  allowing to pressurize them for several seconds at about 15 psi or 1 bar. Number of containers  47  may vary from 1 to 12 or more and they can be pressurized individually or in groups. On the other end all containers are interconnected with a collecting tank  48  having release valve  49 . 
     Under pressure molecular sieve material in containers  47  allows oxygen-enriched fraction to pass through into tank  48 , adsorbing remaining air gases, including mostly nitrogen and water vapors. Oxygen-enriched fraction is disposed into atmosphere through release valve  49  and disposal outlet  50 . Distribution valve  45  continuously in cycling manner redirects the flow of compressed air from one container to two others. After several seconds of pressurization the molecular sieve material in container A becomes saturated with nitrogen-enriched fraction. At this time distribution valve  45  takes first position by opening container A for depressurization and redirects the flow of compressed air into containers B and C. 
     The nitrogen-enriched fraction from container A is transmitted inside manifold  46  into product outlet  51  having recycling loop  52 . Part of nitrogen-rich product is transmitted through recycling loop  52  back into compressor intake  42 . This allows significantly increasing efficiency of the hypoxic generator  40  without increasing working pressure, power consumption and weight. Low working pressure allows extending compressor life up to 5 years or more without any maintenance. Recycling loop  52  is only active for generators in supply mode as shown in embodiment  30  and is closed in generators working in extraction mode as shown on FIG.  2 . 
     During the depressurization cycle of container A, a small amount of oxygen-enriched fraction being kept in tank  48  under minimal pressure by valve  49  is released back into container A, purging it from contaminating nitrogen. 
     Second position of distribution valve  45  sets containers C and A under pressure, depressurizing container B and transmitting its content into product outlet  51 . 
     Third and last position of distribution valve  45  opens container C for depressurization and directs compressed air into containers A and B. 
     There is large selection of suitable distribution valves available on the market: from mechanical and electric to solenoid and air-piloted, both linear and rotary types. For this reason, working principles of these devices will be not explained in this work further. It is not difficult for those skilled in the art to find suitable valve and manifold for any number of containers  47  or their groups. 
     FIG. 5 presents a schematic view of an alternative working principle of hypoxic generator  60  employing the same Pressure-swing adsorption technology, but different adsorbent that adsorbs oxygen and allows nitrogen to pass through the adsorbing material. Carbon molecular-sieve material (CMSO 2 ) has tiny hollow traps in its porous structure called “bottlenecks” that allow oxygen molecules to get in under pressure. Most of oxygen molecules being “trapped” inside such “bottlenecks” cannot find their way out in their chaotic movements. This technology is well known to those skilled in the art and is used in nitrogen generators. 
     Most of the components of the generator  60  are the same as in embodiment  40  and their working principle will not be described again. The only difference in this embodiment is that product and disposal outlets replace each other. 
     Compressed air pressurizes selectively containers  64  with oxygen adsorbing molecular-sieve material that allows nitrogen-enriched fraction to pass through into product outlet  61  via collecting tank  48  and release valve  49 . A part of the product is returned back into system  60  through recycling conduit.  62 . Oxygen-enriched adsorbat is released into atmosphere through disposal outlet  63 . 
     Hypoxic generators  12  and  32  may also employ oxygen-enrichment membrane  70  that is schematically shown on FIG.  6 . Usually such membranes are made as elongated container filled with synthetic hollow fibers that permit oxygen under pressure through their walls and allow nitrogen-enriched fraction to pass through the hollow fibers. 
     Compressed air enters membrane  70  through inlet  71  and is separated there into oxygen-enriched permeate being disposed through outlet  73  and hypoxic product delivered via product release valve  72 . 
     FIG. 7 shows another embodiment  80  of the invented Fire Prevention and Suppression System. A fire-hazardous industrial container  81  contains highly inflammable liquid (alcohol, acetone, gasoline, kerosene, liquid gas, paint, etc.) or dry fire-hazardous and explosive materials. Container  81  can be any industrial container, including stationary and mobile fuel tanks, sea tankers and cargo ships, underground fuel tanks at gas stations, dip and quench tanks, spray and coatings containers, spill containment dikes, storage enclosures and cabinets and other containers with fire hazardous materials and compositions. 
     Hypoxic generator  83  can be installed directly on container  81  like shown in embodiments  10  and  30  or at remote location, as shown on FIG.  7 . It is advisable for such cases to use hypoxic generator in supply mode as shown in embodiment  30 . 
     Hypoxic generator  83  supplies oxygen-depleted air into tank  81  having a hatch or entry  82  and/or vent  85 . Heavy nitrogen rich product covers surface of the inflammable liquid and fills the rest of the container  81  replacing explosive vapors being expelled from container  81  through vent  85  or ventilation hole in hatch  82 . Waste gas containing enriched-oxygen fraction is disposed from generator  83  into atmosphere. 
     Such fire-retarding environment can be kept inside tank  81  permanently by supplying nitrogen rich product in necessary intervals—after fire safe environment with the lowest oxygen content is established, generator  83  can be shut down and turned on again by a timing device. 
     The invented technology should be applied for ventilating underground communication tunnels, mining facilities, munitions and missile bunkers, underground military installations and other facilities in order to remove explosive gases and replace them with fire safe hypoxic air.