Patent Publication Number: US-7211742-B2

Title: Fire resistant, forced air cooled enclosure for computer digital data storage device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority from U.S. provisional application Ser. No. 60/565,713 filed Apr. 26, 2004. 
    
    
     BACKGROUND AND BRIEF SUMMARY OF INVENTION 
     The present invention relates generally to apparatus for protecting an operable computer digital data storage device from damage and loss of data in a fire. More particularly, the present invention provides for the first time a compact, forced air cooled, fire resistant enclosure for an operable computer digital data storage device. Typical computer digital data storage devices include computer hard drives, optical disk drives, solid state memory devices, tape drives, computers, or any other device which can actively read and write digital data with the intent of storing and retrieving computerized digital data. 
     As digital data storage devices become able to store staggering amounts of data, the loss of a digital data storage device in a fire becomes more and more catastrophic. There is clearly a need to provide a compact, reliable fire resistant enclosure for operating digital data storage devices. 
     The prior art includes a relatively large enclosure for operable digital data storage devices, such as the Engler U.S. Pat. No. 6,158,833, which dissipates heat generated by the digital data storage device through the insulated walls of the container. The Engler design requires a relatively large enclosure since it does not provide any active or fan-driven cooling system. The present invention, in contrast, provides a compact enclosure a fraction of the size of the Engler enclosure. The compact size of the present invention is achieved primarily because of a forced-air cooling system not present in the Engler device. 
     The prior art includes other digital data storage device enclosures with “passive” cooling systems, such as Pihl et al U.S. Pat. No. 5,479,341 which cools by convection through a partially open vent door. This technique is “free convection” because no fan or other active device is used to cause the convection. The Kikinis U.S. Pat. No. 5,623,597 utilizes a rather complex, passive heat exchanger with a rather large heat sink structure. That design requires a cumbersome insulation injection mechanism to fill the heat sink space when a threshold temperature is sensed. 
     The prior art also includes the Kishon et al published U.S. application No. U.S. 2004/0064631 dated Apr. 1, 2004. The Kishon et al device utilizes passive conduction of heat generated by the data storage device through screws to the device cover (see paragraph [0021]). This technique is limited by the relatively low amount of heat transferable through the metal screws. The active, fan-driven cooling provided by the present invention achieves a much greater cooling capacity. 
     The prior art also includes forced air cooling systems for operational digital data storage drives, but not used together with a compact, fire resistant enclosure. 
     The present invention provides a compact fire resistant enclosure having one or more fire resistant movable hatches. In its open position, the movable hatch provides inlet and/or exhaust passage for ambient air. A fan driven cooling system (also referred to as “forced convection”) actively cools the digital data storage device with ambient air. As used herein and in the claims, the word “fan” and the phrase “fan means” are used broadly to include bladed fans, squirrel cage fans, blowers, impellers and other active devices used to cause forced convection currents of air. When a predetermined temperature is sensed, the movable hatch or hatches automatically close. The mechanism for closing the hatch can be, without limitation, a temperature sensitive element such as an eutectic metal, plastic, rubber, chemical, liquid, solid or wax that melts or expands at a specific temperature and causes the hatch to close. The temperature sensitive element can be used together with actuation springs that expand or contract to close the hatch. The temperature sensitive element could also support the top of the enclosure and gravity close the hatch when the element melts. Alternately, the movable hatch or vent door may be electronically closed by a solenoid wherein the solenoid is actuated by a thermocouple or other element when a specific temperature is sensed. Other electronic actuation means or other passive methods (temperature sensitive elements) may also be utilized to automatically close the hatch or vent door. Furthermore, another embodiment is to provide air inlet and exhaust ports or passageways that are automatically closed, either actively (electronic actuation) or passively (temperature sensitive elements), when a specific temperature is sensed. Another variation is to cause the top (or upper wall) of the enclosure to open and close by either being hinged along one edge, for example, or by providing a moving portion of the top (or upper wall) of the enclosure. The “temperature sensitive element” is either an eutectic metal, wax, plastic, rubber, chemical, liquid, solid, electronic sensor or electronic actuator, for example. In addition, multiple data storage devices may be “rack mounted” in a single enclosure. 
     In each of the embodiments described herein, a temperature sensitive element is “activated” in the presence of a threshold temperature. For example, a meltable tab is activated by melting, a solenoid coupled to a temperature sensor is activated by either extending or retracting its arm in response to the temperature sensor, and an evaporative material is activated by expanding in the presence of the threshold temperature. 
     A primary object of the invention is to provide a fire resistant enclosure for an operable digital data storage device having a forced air cooling system capable of cooling large capacity data storage devices. 
     A further object of the invention is to provide a fire resistant enclosure for an operating digital data storage device having an extremely reliable sensing and actuation system with minimum moving parts. 
     A further object of the invention is to provide a fire resistant enclosure for an operable digital data storage device which substantially reduces or eliminates false alarms and the associated damage and mess created by prior art systems in the event of a false alarm. 
     Still another object of the invention is to provide a fire resistant enclosure for one or more operating computer digital data storage devices, which is relatively small in size while simultaneously having a large capacity for cooling the data storage device. 
     Other objects and advantages of the invention will become apparent from the following description and the drawings wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of one embodiment of the invention illustrating the device in use before a fire is sensed; 
         FIG. 2  is a schematic representation of the device shown in  FIG. 1  illustrating the device after fire has been sensed; 
         FIG. 3A  is a schematic representation of the movable hatch and temperature sensitive spacers used in the embodiment shown in  FIGS. 1 and 2 ; 
         FIG. 3B  is a schematic representation of an alternate movable hatch; 
         FIG. 4  is a schematic representation of an alternate movable hatch; 
         FIG. 5  is a perspective, and exploded view, of the components of an alternate embodiment of the invention; 
         FIGS. 6A and 6B  are schematic representations of one embodiment wherein a single, movable hatch is shown held open by meltable tabs in  FIG. 6A  and is shown in its closed position in  FIG. 6B ; 
         FIGS. 7A and 7B  illustrate an embodiment wherein the lid of the enclosure forms a first hatch and a second hatch is formed in the bottom wall, wherein both hatches are held open by meltable spacers as shown in  FIG. 7A , and  FIG. 7B  illustrates the closed position after the meltable elements have melted; 
         FIGS. 8A and 8B  illustrate a further embodiment wherein six separate data storage devices are mounted within the enclosure, meltable tabs hold the hatches in their open position shown in  FIG. 8A , and  FIG. 8B  illustrates the closed position after the tabs have melted; 
         FIGS. 9A and 9B  illustrate a further embodiment wherein six rack mounted data storage devices are mounted within the enclosure and separate inlet and outlet passageways are provided, and  FIG. 9B  illustrates are all hatches are closed after the meltable tabs have melted and the hatches are closed; 
         FIGS. 10A and 10B  show an alternate embodiment wherein a contained evaporative substance causes two hatches to close by the expansion of the evaporative substance as shown in  FIG. 10B ; 
         FIGS. 11A and 11B  illustrate a second embodiment utilizing an evaporative substance to actuate one hatch and utilizing a shape memory material to activate a second hatch,  FIG. 11B  showing the closed position of both hatches; 
         FIGS. 12A and 12B  illustrate an embodiment wherein the lid of the enclosure forms a single, movable hatch which is actuated by a solenoid,  FIG. 12B  showing the closed position after the solenoid has been activated; 
         FIGS. 13A and 13B  illustrate an embodiment utilizing two hatches actuated by two solenoids, wherein  FIG. 13B  illustrates the closed position after the solenoids are actuated; 
         FIGS. 14A and 14B  illustrate an embodiment wherein two hatches having separate solenoids are connected to a single temperature sensor; 
         FIGS. 15A and 15B  illustrate yet another embodiment wherein one hatch is held open by a meltable tab and a second hatch is actuated by a solenoid; 
         FIGS. 16A and 16B  illustrate another embodiment wherein one hatch is held open by a meltable tab, and a second hatch is held in position by a cable and pulley mechanism wherein one of the pulleys is carried by a solenoid and the solenoid upon being activated extends the cable and closes one of the hatches; 
         FIGS. 17A and 17B  illustrate another embodiment wherein five data storage devices are contained within the enclosure and two relatively large hatches are actuated by solenoids; and 
         FIGS. 18A and 18B  illustrate another embodiment wherein relatively large hatches are formed in two of the side walls and are actuated by solenoids. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     As used herein and in the claims, the phrase “fire resistant” refers to an enclosure capable of preventing loss of data from a digital data storage device within the enclosure when subjected to certain high temperature conditions for a specified period of time. 
       FIG. 1  is a schematic representation of one embodiment of the present invention wherein an operational computer digital data storage device  10  is carried inside a fire resistant enclosure shown generally as  20 . The fire resistant enclosure  20  includes a lower or bottom wall  21 , an upper wall  22 , and side walls  23  and  24 . The enclosure also includes solid end walls, not shown in  FIG. 1 . Side walls  23 , 24  each carry a movable hatch  51 , 52 , respectively. The movable hatches  51 , 52  are positioned adjacent openings or passageways  31 , 32  formed in side walls  23 , 24 , respectively. The movable hatches  51  and  52  are shown in their first or open position in  FIG. 1  wherein ambient air may flow through openings or passageways  31  and  32 . Incoming air flows through opening or passageway  32  and is driven by fan  40  as shown by the arrows across digital data storage device  10  and is exhausted as shown by the arrows through exhaust passageway  31 . 
     In the open position illustrated in  FIG. 1 , temperature sensitive spacer elements  71 , 72  are carried by hatches  51 , 52 , respectively. Spacers  71 , 72  are made from either an eutectic metal or wax which is designed to melt at a predetermined temperature such as 300° F. 
     Movable hatches  51  and  52  are held in their open position by springs  61  and  62  which are in turn anchored to upper wall  22  by brackets  65  and  66 . 
     Power for digital data storage device  10  as well as fan  40  enters the enclosure through bottom  21  through a cable  80 . An optional temperature sensitive fuse (not shown) may be utilized to shut off power to digital data storage device  10  and fan  40  when a predetermined temperature, such as 300° F., is sensed. 
     The enclosure  20  also includes a removable segment (not shown in  FIG. 1 ) to allow installation and removal of the data storage device  10 . The preferred removable segment is a removable lid, described below. 
       FIG. 2  illustrates the embodiment of  FIG. 1  when the predetermined temperature has been achieved. The spacers  71  and  72  have melted, and movable hatches  51  and  52  have moved to their closed position by the expansion of springs  61  and  62 . Electrical power to digital data storage device  10  and fan  40  has been interrupted, either by a temperature sensitive fuse blowing or power or data line  80  becoming destroyed by fire. Alternatively, the power or data lines could be made of a small enough gauge as to not create an adequate thermal path for the extreme outside air temperature to damage the internal digital data storage device. In the embodiment shown in  FIGS. 1 and 2 , springs  61 , 62  together with temperature sensitive elements  71 , 72  comprise hatch closure means for closing hatches  51 , 52  automatically when a threshold temperature is reached, signifying the presence of fire. 
     It is significant to note that temperature sensitive spacers  71  and  72  will only become activated and melt when the threshold temperature has been sensed and sustained long enough for spacers  71  and  72  to melt. This feature essentially eliminates false alarms, which are an inherent weakness of some prior art devices. Furthermore, some prior art devices cause the flow of insulation or other material in the event of a false alarm, resulting in a mess to be cleaned up, and related down time. 
       FIG. 3A  illustrates movable hatch  52  and temperature sensitive spacer  72  shown in  FIGS. 1 and 2 . The movable hatch  52  includes a cylindrical body portion  53  which slidably engages opening  32  in side wall  24 , as shown in  FIGS. 1 and 2 . A cap portion  54  is formed as a unitary structure with body  53 . Cap  54  is a circular shaped disc having a flat front face  55  which engages the inner surface of wall  24  when hatch  52  moves to its closed position as shown in  FIG. 2 . The cap is of larger diameter than the body portion  53 . The temperature sensitive element includes tabs  72  which are planar tabs connected to the end  58  of body portion  53  and which extend radially outwardly. This configuration allows cooling air to pass between the temperature sensitive elements  72  and continually cool the data storage device  10 . The body portion  53  and the cap portion  54  are preferably injection molded and filled with fire resistant insulation. The planar tabs  72  hold the hatch in its open position. 
       FIG. 3B  illustrates an alternate hatch design  52   a  which is similar to the hatch design  52  shown in  FIG. 3A , except that planar tabs  72   a  are carried on the cylindrical surface of body  53   a  and extend radially outwardly. 
       FIG. 4  illustrates an alternate configuration of movable hatch  152  and an alternate configuration of opening  132  in side wall  124 . Opening  132  has a frusto-conical shape. Hatch  152  has a body portion  153  of frusto-conical shape which is identical to the shape of opening  132  in side wall  124 . Planar tabs  175  are temperature sensitive. Movable hatch  152  is driven by a spring mounted to a bracket as is shown in  FIG. 1 . The spring and bracket are omitted from  FIG. 4  in the interest of brevity. Alternate shapes and configurations may be utilized for the openings in the side wall and for the movable hatch. For example, the hatch can be positioned in the bottom wall of the enclosure or the top wall. The preferred embodiment utilizes two movable hatches mounted in opposite side walls. 
       FIG. 5  is a perspective and exploded assembly drawing of an alternate embodiment of the invention. A digital storage device  210  is mounted to an internal mounting plate  290 . A fire resistant enclosure base  220  includes bottom wall  221 , side wall  223 , side wall  224  and end walls  225  and  226 . A removable lid  222  is of fire resistant material and is completely removable from the enclosure base  220  to allow insertion and removal of the data storage device  210 . In the embodiment shown in  FIG. 5 , the movable hatches  251  and  252  carrying meltable spacers  271 , 272  are both positioned adjacent openings  231  and  232  in a side wall  223  of the fire resistant enclosure base  220 . Openings  231   a  and  232   a  are formed in internal mounting plate  290  to facilitate mounting of the movable hatches  251  and  252 . Fan  240  is positioned adjacent the inlet opening  232  and drives air into the enclosure and outwardly through exhaust opening  231 . An optional sheet metal outer enclosure  291  is provided to protect fire resistant enclosure base  220  and fire resistant lid  222 . A metallic rear cover  292  is also provided to protect the rear wall  224  of fire resistant enclosure base  220 . An optional plastic bezel  295  is also provided. Springs  261  and  262  urge the movable hatches  251  and  252  against side wall  223 . 
       FIGS. 6A–9B  illustrate alternate embodiments of the invention utilizing a temperature sensitive element which melts at a threshold temperature being used in conjunction with one or more movable hatches. 
       FIG. 6A  illustrates an embodiment including enclosure  320  and a single data storage device  310 . This embodiment utilizes a single movable hatch  351  which is positioned adjacent opening  331  formed in side wall  323  of enclosure  320 . Fan  340  circulates ambient air in the direction shown by the arrows, whereby air flows inwardly above hatch  351 , flows across data storage device  310  and then exhausts around the opposite side of hatch  351 . Alternately, fan  340  could be positioned adjacent the lower edge of opening  331  and blow air inwardly beneath hatch  351  and circulate the air upwardly across data storage device  310  and then outwardly above hatch  351 . 
       FIG. 6B  illustrates the closed position of hatch  351  of  FIG. 6A . Meltable tabs  371  have melted, allowing spring  361  to close hatch  351 . 
       FIGS. 7A and 7B  illustrate an embodiment utilizing enclosure  420  and a single data storage device  410 . In this embodiment, the upper wall or lid  422  of enclosure  420  forms a first hatch which is hinged at pivot point  495  and is held in its open position shown in  FIG. 7A  by a meltable spacer  471 . A second hatch  452  is positioned adjacent opening  431  formed in the bottom wall  421  of enclosure  420 . Hatch  452  is pivoted at pivot point  496  and is held in its open position shown in  FIG. 7A  by meltable spacer  472 . Fan  440  draws air inwardly through opening  431  upwardly across data storage device  410  and upwardly and outwardly beneath raised hatch  451 . 
       FIG. 7B  illustrates how hatch  451  and hatch  452  have closed by gravity when a threshold temperature has been sensed and meltable elements  471  and  472  have melted. 
       FIGS. 8A and 8B  illustrate an embodiment including enclosure  520  wherein six different “rack mounted” data storage devices  510 – 515  are mounted. Enclosure  520  includes side walls  523  and  524  having large passageways  531  and  532  formed therein. Hatches  551  and  552  are mounted adjacent passageways  531  and  532 . Hatches  551  and  552  may be rectangular or arcuate in shape. Hatches  551  and  552  are sufficiently large to allow adequate airflow to cool all six data storage devices  510 – 515 . Four fans  540 – 543  are provided to provide sufficient cooling for the six data storage devices. Because of the relative large size of hatches  551  and  552 , multiple springs are utilized. Hatch  551  is connected by two springs  561   a  and  561   b  to bracket  565 . Similarly springs  562   a  and  562   b  connect hatch  552  to bracket  566 . Two meltable tabs  571   a  and  571   b  hold hatch  551  in its open position. Similarly, meltable tabs  572   a  and  572   b  hold hatch  552  in its open position shown in  FIG. 8A . 
       FIG. 8B  illustrates how hatches  551  and  552  have moved to their closed positions upon the melting of tabs  571   a ,  571   b ,  572   a  and  572   b.    
       FIGS. 9A and 9B  illustrate an embodiment including enclosure  620  and six “rack mounted” data storage devices  610 – 615 . Side wall  623  includes four passageways  631 – 634 . Hatches  651 – 654  are mounted adjacent openings  631 – 634 . Individual fans  640 – 643  are mounted adjacent openings  631 – 634  and by “forced convection” cause ambient air to move across data storage devices  610 – 615 . Side wall  624  has four outlet passageways  635 – 638  through which the cooling air is exhausted as shown by the arrows. Meltable tabs  671  and  672  hold each of the eight hatches shown in  FIG. 9A  in their open position illustrated. Springs  661  hold all eight hatches open. 
       FIG. 9B  illustrates how all eight hatches have closed when the threshold temperature is sensed and the meltable tabs have melted and allowed springs  661  to close all eight hatches  651 – 658 . 
       FIGS. 10A ,  10 B and  11 A,  11 B show alternate embodiments wherein a contained, evaporative substance is utilized to cause the movable hatch or hatches to close upon the sensing of a threshold temperature.  FIG. 10A  illustrates enclosure  720  housing a single data storage device  710 . Side wall  723  and side wall  724  each have a passageway  731  and  732  formed therein. Fan  740  causes air to flow inwardly as shown by the arrows across data storage device  710  and outwardly through passageway  732 . Hatches  751  and  752  are slidably mounted within piston tube  759  which extends generally from a position near inlet passageway  731  to a position near outlet passageway  732 . A housing  790  contains an evaporative substance which expands upon being exposed to a given temperature such as 300° F. 
       FIG. 10B  illustrates that when the threshold temperature is sensed, the evaporative substance in housing  790  is activated and expands into transversely mounted piston  759 , causing hatches  751  and  752  to move outwardly as shown by arrows  759  to seal passageways  731  and  732 . 
       FIGS. 11A and 11B  illustrate a second embodiment wherein an evaporative substance is utilized together with a “shape memory” material to close dual hatches.  FIG. 11A  illustrates enclosure  820  housing a single data storage device  810 . Side walls  823  and  824  have passageways  831 , 832  formed therein, respectively. Fan  840  blows air through inlet passageway  831  across data storage device  810  and outwardly through exit passageway  832 . A first movable hatch  851  is positioned adjacent passageway  831  and is held in place by an expandable bladder  895 . Bladder  895  is connected to bracket  865 . Evaporative substance is contained in housing  890  which is in fluid communication with bladder  895 . When a threshold temperature is sensed, the evaporative fluid from container  890  is activated and expands bladder  895 , closing hatch  851 , as shown in  FIG. 11B . The second hatch  852  is held in position by a “shape memory” spring  862 . Spring  862  holds hatch  852  in its open position shown in  FIG. 11A . Spring  862  reacts to a given threshold temperature, such as 300° F. by moving to its flat position shown in  FIG. 11B  wherein hatch  852  is moved to its closed position in which it forms a seal with passageway  832 . 
       FIGS. 12A through 18B  illustrate alternate embodiments utilizing one or more solenoids as part of the actuation mechanism for one or more hatches. Each solenoid is electrically connected to a temperature sensor and is activated when the threshold temperature is sensed.  FIG. 12A  includes an enclosure  920  housing a single data storage device  910 . The lid  922  of enclosure  920  forms a single movable hatch  951  which is hinged at point  995 . Hatch  951  is held in its open position illustrated in  FIG. 12A  by solenoid  971 . Solenoid  971  is connected to temperature sensor  991 . Fan  940  cools the data storage device  910  as described above. When a threshold temperature is sensed by sensor  991 , solenoid  971  is activated and caused to retract its arm  972 , thereby closing hatch  951 . 
       FIG. 13A  illustrates enclosure  1020  housing a single data storage device  1010 . The lid  1022  of enclosure  1020  forms hatch  1051  and is held in its open position shown in  FIG. 13A  by multiple tabs  1071  and  1072 . A second hatch  1052  is positioned near passageway  1032  formed in side wall  1024 . Solenoid  1072  is mounted to bracket  1065  and holds hatch  1052  in its open position shown in  FIG. 13A . Solenoid  1072  is connected to temperature sensor  1091 . In the open position of hatch  1052 , as shown in  FIG. 13A , solenoid  1072  has its arm in the retracted position. 
       FIG. 13B  illustrates the closed position of enclosure  1020 . After a threshold temperature has been sensed, multiple tabs  1071  and  1072  are “activated” in the sense they have melted and allowed hatch  1051  to close by gravity. Temperature sensor  1091  has caused solenoid  1072  to become activated or energized and move its arm to its extended position wherein hatch  1052  is sealed against opening  1032 . 
       FIGS. 14A and 14B  show an alternate embodiment wherein enclosure  1120  houses a single data storage device  1110 . Side wall  1124  has an inlet passageway  1131  and an outlet passageway  1132  formed therein. First and second hatches  1151  and  1152  are positioned adjacent openings  1131  and  1132 . Solenoids  1171  and  1172  hold hatches  1151  and  1152  in their open position shown in  FIG. 14A . Temperature sensor  1191  is connected to both solenoids  1171  and  1172 .  FIG. 14B  illustrates the closed position wherein sensing element  1191  has sensed the threshold temperature and has energized solenoids  1171  and  1172 , causing them to move their arms  1171   a  and  1172   a  to their extended position wherein hatches  1151  and  1152  are closed. 
       FIG. 15A  illustrates a further embodiment wherein enclosure  1220  houses a single data storage device  1210 . Side wall  1224  has a first passageway  1231  formed therein which forms an inlet passageway for fan  1240 . A first hatch  1251  is hingedly mounted at pivot point  1298  and is held in its open position shown in  FIG. 15A  by meltable tab  1271 . A second, exhaust passageway  1232  is formed in side wall  1223 . A second hatch  1252  is hingedly mounted adjacent opening  1232  and is hinged at pivot point  1299 . In this embodiment, when the threshold temperature is sensed, meltable element  1271  melts and allows first hatch  1251  to be closed by the expansion of spring  1261 . The second hatch  1252  is closed by solenoid  1272  being activated by temperature sensor  1291  causing solenoid arm  1272   a  to extend, thereby closing hatch  1252 . 
       FIG. 16A  shows another embodiment wherein enclosure  1320  houses a single data storage device  1310 . Side wall  1323  has a first opening  1331  formed therein. A first hatch  1351  is hingedly mounted adjacent inlet passageway  1331  and is hingedly mounted at pivot point  1399 . Meltable tab  1371  holds hatch  1351  in its open position shown in  FIG. 16A . A second hatch  1352  is shown pivotally mounted adjacent a second or exhaust passageway  1332  formed in side wall  1324 . Hatch  1352  is held in its open position shown in  FIG. 16A  by a cable  1375  which extends over first pulley  1376 . A second pulley  1377  is carried by solenoid  1371  and is attached to bracket  1365 . Solenoid  1371  is connected to temperature sensor  1391 . 
     When a threshold temperature is reached, as shown in  FIG. 16B , meltable tab  1371  melts allowing spring  1361  to close first hatch  1351 . Solenoid  1371  moves from its retracted position shown in  FIG. 16A  to its extended position in  FIG. 16B  wherein the arm  1371   a  interacting with pulleys  1376  and  1377  causes hatch  1352  to close. 
       FIG. 17A  shows another embodiment wherein enclosure  1420  houses five data storage devices  1410 – 1414 . Side wall  1423  has a first passageway  1431  formed therein and side wall  1424  has a second passageway  1432  formed therein. Movable hatches  1451  and  1452  are hingedly connected at  1451   a  and  1452   a  to side walls  1423  and  1424 , respectively. Solenoids  1471  and  1472  hold hatches  1451  and  1452  in their open position shown in  FIG. 17A . Temperature sensors  1491  and  1492  are connected to solenoids  1471  and  1472 , respectively. 
     As shown in  FIG. 17B , when the threshold temperature is sensed, solenoids  1471  and  1472  move to their retracted positions, thereby closing hatches  1451  and  1452 . 
       FIG. 18A  shows an embodiment wherein enclosure  1520  houses five separate data storage devices  1510 – 1514 . Side wall  1523  has a first passageway  1531  formed therein and side wall  1524  has a second passageway  1532  formed therein. A first hatch  1551  is hinged at point  1551   a  near the top of side wall  1523 . Second hatch  1552  is hinged at point  1552   a  near the bottom of side wall  1524 . Solenoids  1571  and  1572  hold hatches  1551  and  1552  in their open positions shown in  FIG. 18A . When the temperature sensors  1591  and  1592  are exposed to a threshold temperature, they energize solenoids  1571  and  1572  causing those solenoid arms to extent and close hatches  1551  and  1552  as shown in  FIG. 18B . 
     The embodiments shown in  FIGS. 17A ,  17 B and  18 A,  18 B show that the hatches can be hinged near the uppermost portion of the side walls and extend outwardly as shown in  FIG. 17A  or can be hinged at opposite ends of the side walls to form parallel planes in their open position as shown in  FIG. 18A . 
     The foregoing description of the invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teaching. The embodiments were chosen and described to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best use the invention in various embodiments and with various modifications suited to the particular use contemplated. The scope of the invention is to be defined by the following claims.