Patent Abstract:
A method for turning off fluid flow through a valve. The method includes: movably disposing a member in an interior of a housing between a first position in which an inlet and an outlet are in fluid communication with each other and a second position blocking the fluid flow; restraining the member in the first position when a fluid temperature in the interior or an ambient temperature outside the housing is below a threshold temperature; and releasing the restraint such that the member is capable of moving to the second position when the fluid temperature or the ambient temperature is above the threshold temperature; wherein the releasing comprises changing the shape of an actuator from a first shape restraining the member to a second shape releasing the restraint upon a change in the fluid temperature or the ambient temperature from below the threshold temperature to above the threshold temperature.

Full Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    The present disclosure relates generally to a safety valve for gaseous and/or liquid fuel or other chemical lines, and more particularly, to a self-contained safety valve for gaseous or liquid fuel or other hazardous chemical lines which automatically closes the flow of gaseous or liquid fuel or other hazardous chemical when the surrounding temperature or the temperature of the gaseous or liquid fuel or other chemical substances passing through the valve rise above a predetermined threshold temperature. 
         [0003]    2. Prior Art 
         [0004]    There are currently devices known in the art for shutting the flow of gas such as natural gas or liquid fuel in homes or in commercial buildings in case of fire that operate based on an external and powered sensor to monitor the temperature and then command certain actuation device such as an electrically powered solenoid to actuate a valve or cause it to actuate a valve to close the flow of said gaseous or liquid fuel. 
         [0005]    The currently available methods and devices are complex, expensive, generally require external power (either battery or line power) and the externally actuated valves require sealing of moving parts, which are prone to wear, and when made out of plastics are subject of aging and hardening and cracking, and thereby leakage, particularly for the case of gaseous fuel such as natural gas or propane and certain chemicals. In addition, for battery operated systems, the users often forget to test and change the batteries and for line powered devices the power may be out or go out or disconnected in case of fire or the like. 
         [0006]    Valves using shape memory alloy actuation devices for preventing the flow of fluid when the temperature of the fluid is above a predetermined threshold is also disclosed in the U.S. Pat. No. 8,695,889. The valve is designed to allow the fluid to pass when the temperature of the fluid is below the predetermined threshold, and used a shape memory or bi-metal actuator for substantially closing the flow passage when the temperature of the fluid is above the predetermined threshold. Such valves, however, are not designed for closing the flow passage when heated either by the passing flow or from outside the valve. 
       SUMMARY 
       [0007]    Therefore it is an object to provide a self-contained heat-actuated safety valve for gas lines, such as natural gas or propane gas lines or fluid fuel or hazardous chemical lines, which would which automatically closes the flow of the said gas or liquid when the surrounding temperature or the temperature of the gaseous or liquid fuel or other chemical flowing through the valve rises above a predetermined threshold temperature. 
         [0008]    It is another object to provide a self-contained heat-actuated safety valve for gas lines or fluid fuel or hazardous chemical lines, which are not dependent on signals from external sensors and do not require electrical power such as from batteries or line power for their operation. 
         [0009]    It is yet another object to provide a self-contained heat-actuated safety valve for gas lines or fluid fuel or hazardous chemical lines which is not prone to leakage from seals or between moving parts. 
         [0010]    It is still a further object to provide such self-contained heat-actuated safety valve for gas lines or fluid fuel or hazardous chemical lines, which are inexpensive to fabricate. 
         [0011]    Accordingly, a valve for stopping the flow of gaseous or liquid fuel or other hazardous chemical lines when the temperature in the environment or the flowing substances is above a predetermined threshold is provided. The valve comprises: a body having at least one opening for allowing the gas or fluid to pass through when the ambient temperature close to the valve is below the predetermined threshold; and a shape memory actuated mechanism for substantially closing the at least one opening when the ambient temperature close to or inside the valve is above the predetermined threshold to prevent the gas or fluid from passing through the valve. The shape memory actuated mechanism and other moving parts are preferably self-contained within the overall valve enclosure to minimize the possibility of leakage. 
         [0012]    The flow prevention mechanism in the valve preferably comprises of a flap corresponding to the at least one opening, the flap being actuated by a shape memory alloy material based member having a shape at a temperature below the predetermined threshold such that it does not occlude the at least one opening and having a shape at a temperature above the predetermined threshold such that it does occlude the at least one opening to prevent the passage of gas or fluid through the valve outlet. The said flap actuator is preferably fabricated from a shape memory material that exhibits a two-way memory such that it has a first shape below the predetermined threshold so as the flap is such positioned not to occlude the at least one opening and has a second shape above the predetermined threshold so as to position the flap such that it would occlude the at least one opening. 
         [0013]    Alternatively, the flow prevention mechanism in the valve preferably comprises of a flap corresponding to the at least one opening, the flap being normally held in a first position by a removable stop element such that it does not occlude the at least one opening. In its said first position, the flap is biased towards its second position by a preloaded spring element in which position it would occlude the at least one opening. The said removable stop element is provided with an actuation element that is preferably made out of a shape memory alloy or bimetal element. The shape memory alloy material based actuation element is designed and fabricated to have a shape at a temperature below the predetermined threshold such that it keeps the said removable stop element in the position that holds the flap in its said first position such that it does not occlude the at least one opening. The shape memory alloy material based actuation element would then deform into another shape at a temperature above the predetermined threshold such that it would cause the said removable stop element disengage the said flap, thereby allowing the flap to be moved by the said preloaded spring element to the position of occluding the at least one opening to prevent the passage of gas or fluid through the valve outlet. Alternatively, the actuation device of the said removable stop element may be made out of a bimetal member, which is configured to perform the same function as the described shape memory alloy based actuation device. 
         [0014]    Alternatively, the flow prevention mechanism in the valve preferably comprises of ball or a cone or a section of a cone (hereinafter referred to collectively as a ball for brevity) instead of the aforementioned flap corresponding to the at least one opening. Then similar to the aforementioned flap, the ball is normally held in a first position by a removable stop element such that it does not occlude the at least one opening. In its said first position, the ball is biased towards its second position by a preloaded spring element in which position it would occlude the at least one opening. The said removable stop element is provided with an actuation element that is preferably made out of a shape memory alloy or bimetal element. The shape memory alloy material based actuation element is designed and fabricated to have a shape at a temperature below the predetermined threshold such that it keeps the said removable stop element in the position that holds the ball in its said first position such that it does not occlude the at least one opening. The shape memory alloy material based actuation element would then deform into another shape at a temperature above the predetermined threshold such that it would cause the said removable stop element disengage the said ball, thereby allowing the ball to be moved by the said preloaded spring element to the position of occluding the at least one opening to prevent the passage of gas or fluid through the valve outlet. Alternatively, the actuation device of the said removable stop element may be made out of a bimetal member, which is configured to perform the same function as the described shape memory alloy based actuation device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
           [0016]      FIG. 1  illustrates a sectional view of a first embodiment of the self-contained safety valve actuated by external heating, wherein the safety valve is in an open position. 
           [0017]      FIG. 2  illustrates the sectional view of the self-contained safety valve embodiment of FIG. 1 , wherein the safety valve is in the closed position. 
           [0018]      FIG. 3  illustrates the sectional view of the self-contained safety valve embodiment of  FIG. 1  with a screw mechanism for resetting the valve into its open position following exposure to a temperature above the predetermined threshold temperature. 
           [0019]      FIG. 4  illustrates the sectional view of the self-contained safety valve embodiment of  FIG. 1  with a bellow type mechanism for resetting the valve into its open position following exposure to a temperature above the predetermined threshold temperature. 
           [0020]      FIGS. 5A and 5B  illustrates a typical shape memory alloy actuator fabricated from a strip of said material for use in the safety valve embodiments of  FIGS. 1-4 . 
           [0021]      FIGS. 6A and 6B  illustrates an alternative construction of the shape memory alloy actuator as fabricated from a wire of said material for use in the safety valve embodiments of  FIGS. 1-4 . 
           [0022]      FIG. 7  illustrates a sectional view of a second embodiment of the self-contained safety valve actuated by external heating, wherein the safety valve is in an open position. 
           [0023]      FIG. 8  illustrates the sectional view of the self-contained safety valve embodiment of FIG. 7 , wherein the safety valve is in the closed position. 
           [0024]      FIGS. 9A and 9B  illustrates a typical shape memory alloy actuator fabricated from a strip or wire, respectively, of said material for use in the safety valve embodiment of  FIG. 7 . 
           [0025]      FIG. 10  illustrates a sectional view of a third embodiment of the self-contained safety valve actuated by external heating, wherein the safety valve is in an open position. 
           [0026]      FIG. 11  illustrates the sectional view of the self-contained safety valve embodiment of FIG. 10 , wherein the safety valve is in the closed position. 
           [0027]      FIG. 12  illustrates a sectional view of a fourth embodiment of the self-contained safety valve actuated by external heating, wherein the safety valve is in an open position. 
           [0028]      FIGS. 13A and 13B  illustrates the cross-sectional view A-A of the self-contained safety valve embodiment of  FIG. 12 . 
           [0029]      FIG. 14  illustrates a sectional view of a fifth embodiment of the self-contained safety valve actuated by external heating, wherein the safety valve is in an open position. 
           [0030]      FIG. 15  illustrates the sectional view of the self-contained safety valve embodiment of FIG. 14 , wherein the safety valve is in the closed position. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Although the safety valves described herein are applicable to different types of actuators, it has been found particularly useful in the environment of shape memory actuators. Therefore, without limiting the applicability of the invention to shape memory actuators, the invention will be described in such environment. For instance, the safety valves described herein can alternatively use a bi-metal actuator which changes shape due to a difference in thermal expansion of the metal comprising the bi-metal strip. 
         [0032]    Although many shape-memory materials may be used, a nickel-titanium alloy (NiTi) is particularly suitable. One such NiTi alloy is manufactured, for example, by Shape Memory Applications, Inc., Santa Clara, Calif In general, metallic shape-memory alloys, such as NiTi, CuZnAl, and CuAlNi alloys, undergo a transformation in their crystal structure when cooled from the high-temperature austenite form, which is generally stronger, to the low-temperature martensite form, which is weaker. When a shape-memory material is in its martensitic form, it is easily deformed to a new shape. However, when the material is heated through its transformation temperature, it reverts to austenite and recovers its previous shape with great force. The temperature at which the material reverses its high temperature form when heated can be adjusted by slight changes in material composition and through heat treatment. The shape-memory process can be made to occur over a range of a few degrees, if necessary, and the shape transition can be made to occur millions of times. 
         [0033]    Some shape-memory materials can be made to exhibit shape-memory only upon heating (one-way shape-memory), or also can undergo a shape change upon cooling (two-way shape memory). Shape-memory materials are available in many forms including, for example, wires, rods, ribbons, strips, sheets, and micro-tubing, and can be used to fabricate shape-memory structures having linear, planar and composite forms. 
         [0034]    Referring now to  FIGS. 1-2 , there is shown a first embodiment  100  of the self-contained safety valve actuated by external heating, hereinafter referred to as “safety valve.” The external heating may be due to fire or general temperature elevation without direct or proximity to fire or other heat source. The safety valve  100  is constructed with a housing  101 , which may have been assembled from more than one part for ease of manufacture and assembly. The safety valve  100  is provided with at least one inlet  102  and at least one outlet  103  to accommodate inflow  104  and outflow  105 , respectively, of the passing gaseous and/or liquid substances of interest. The inlet  102  and the outlet  103  may be provided with internal or external thread (not shown) for attachment to the intended gaseous and/or liquid substance lines. Alternatively, incoming and outgoing lines may be attached to the inlet  102  and outlet  103  by soldering, welding or any other methods appropriate for the transiting gaseous and/or liquid substance. 
         [0035]    The safety valve  100  is provided with a cap  106 , which is attached to the inside structure of the housing  101  at the indicated point  108  by a hinge joint  107 . A tensile spring  109  is attached on one end to the cap  106 , such as by a pin joint  111 , and to the inside structure of the housing  101 , such as by a pin joint  112 , as shown in  FIG. 1 . In the configuration of the rotatable cap  106  shown in  FIG. 1 , the tensile spring  109  is preloaded in tension, thereby biasing the cap  106  to rest at its shown left most position against a shape memory alloy element  110 . As can be seen in the schematic of  FIG. 1 , the rotating cap  106  and the preloaded tensile spring  109  are attached to the inner surface of the housing  101  such that they configure a so-called toggle mechanism, i.e., a bi-stable mechanism with two stable resting states, with the first stable positioning being as shown in the schematic of  FIG. 1 , where the preloaded tensile spring  109  is positioned on the right side of the joint  107  of the cap  106 , and with the second stable positioning being as shown in the schematic of  FIG. 2 , where the preloaded tensile spring  109  is positioned on the left side of the joint  107  of the cap  106 . 
         [0036]    In the first stable toggle positioning, the cap  106  is shown to be resting against the shape memory alloy element  110  as shown in the schematic of  FIG. 1 . The aforementioned gaseous and/or liquid substances are thereby free to enter from the inlet  102  and exit from the outlet  103  as indicated by the arrows  104  and  105 , respectively. Then when the temperature of the environment outside the safety valve  100  is increased, the element  116  which is made from a highly heat conductive material such as aluminum or copper or the like (and which may be integrally formed with the housing  101  or separately formed therefrom) would transmit heat to the shape memory alloy element  110 . The shape memory actuator  110  can be fabricated from a relatively thin strip or formed wire of shape memory alloy material such as one of those previously described and is trained to change its shape in response rise in temperature above a predetermined threshold temperature. 
         [0037]    In the present safety valve  100 , the shape memory alloy element  110  is trained to change its shape from that shown in the schematic of  FIG. 1  to that indicated by the numeral  117  in the schematic of  FIG. 2  by bending at the region  118  of the shape memory alloy element  110 , very close to the point of its attachment to the heat transferring element  116  for its fast response to temperature elevation above the predetermined threshold temperature. Therefore, although the shape memory alloy element  110  may be entirely formed of a shape memory material, only portion  118  may only be formed of such shape memory material. 
         [0038]    The shape memory alloy element  110 ,  FIG. 1  ( 117  after the shape change,  FIG. 2 ) acts as an actuation element such that when its temperature has been raised above the aforementioned predetermined threshold temperature, it would change shape to that of  117 ,  FIG. 2 , thereby forcing the aforementioned toggle mechanism comprising of the cap  106  and the preloaded tensile spring  109  to be forced to be transferred from its first stable positioning shown in the schematic of  FIG. 1  to its second stable positioning shown in the schematic of  FIG. 2 . It is noted that in its said second stable positioning,  FIG. 2 , the surface  113  of the cap  106  rests against the top surface  114  of the outlet passage of the safety valve  100 ,  FIG. 1 . In addition, an O-ring or the like sealing element  115  which can be made out of relatively elastic element,  FIG. 1 , is also provided between the mating surfaces  113  and  114  to ensure fluid sealing of the outlet passage  119 ,  FIGS. 1-2 . Furthermore, as shown in  FIGS. 1 and 2 , the direction of fluid flow can be such that it would tend to keep the cap  106  closed with regard to the outlet  103  and sealed against the sealing element  115 . In addition, the spring  109  is configured such that it can also bias the cap  106  towards a sealing engagement with the sealing element  115  when the cap is in its second stable positioning. 
         [0039]    In operation, one or more safety valves  100  are positioned along the desired gaseous and/or liquid line. The installed safety valves  100  are installed in their normally open configuration shown in  FIG. 1 . Then if the temperature around a safety valve rises above the aforementioned predetermined threshold temperature setting of the safety valve, the heat transferred via the highly conductive element  116  causes the temperature of the safety valve shape memory alloy actuation element  110  to rise to the predetermined threshold temperature level. As a result, the shape memory alloy  110  changes its shape to that of  117  shown in  FIG. 2 , thereby forcing the cap  106  to move from its first stable positioning shown in  FIG. 1  to its second stable positioning shown in  FIG. 2  as described earlier, and thereby cause the flow passage to the outlet  119  and thereby the flow of the said gaseous and/or liquid to be stopped. 
         [0040]    In the embodiment of  FIG. 1 , when the safety valve  100  is exposed to an ambient temperature above the predetermined threshold temperature for which it is designed, its shape memory alloy actuator element  110  actuates as described above and causes the cap  106  to move to its configuration shown in  FIG. 2  and cause the flow of the said gaseous and/or liquid to be stopped. Then when the ambient temperature falls below the said predetermined threshold temperature, the cap  106  remains in its configuration of  FIG. 2  and the valve passage  119  for the flow of the line gaseous and/or liquid substances remains closed. Such safety valve designs are highly useful in housing or commercial buildings or various plants and the like so that after fire and serious damage to the building structures and/or equipment or the like that makes the related buildings and/or plants or the like inoperable and sometimes abandoned for a period of time, the flow of gaseous and/or liquid fuel or other chemicals substances is not accidentally resumed or even intentionally resumed by someone to cause further damage. 
         [0041]    In other applications, however, it might be desirable that following each safety valve flow closure following an environmental temperature rise above the aforementioned predetermined threshold temperature, hereinafter referred to as the “high temperature threshold”, once the environmental temperature drops a prescribed amount below the temperature “high temperature threshold”, hereinafter referred to as the “low temperature threshold”, then the safety valve is to be returned to its open configuration to allow free flow of the line gaseous and/or liquid substances. 
         [0042]    It is appreciated by those skilled in the art that the above task of resetting the safety valve  100  to its open positioning following a “high temperature threshold” event may be accomplished using many different means and mechanisms, including manually returned. In certain applications, it might be preferred that the user disconnects the safety valve from at least the input or the output line for inspection and to ensure that it has not been subjected to permanent damage due to the exposure to the high temperature threshold event, particularly if it is due to fire or other similar events. However, in certain cases, where the environmental temperature does go over the high temperature threshold often, for example, due to excessive heat being emitted from a nearby furnace, or in cases that the material being transferred is hazardous and is not desired to be spilled out from the connecting pipes, then an externally actuated means is desired to be provided for resetting the safety valve to its open positioning. It will be appreciated by those skilled in the art that many such resetting mechanisms may be provided. An example of such a resetting mechanism is shown in the schematic of  FIG. 3 . 
         [0043]    In the schematic of  FIG. 3 , the safety valve is shown with the cap  106  in its closed position. In this safety valve embodiment, generally referred to by reference numeral  120 , the safety valve is provided with a resetting screw  121 , which can also be provided with a relatively round tip piece  122 . Then when the cap  106  is in its closed position shown in  FIG. 3 , the safety valve  120  can be reset to its open positioning shown in  FIG. 1  by advancing the screw  121  upward and thereby causing the tip element  122  to lift the cap  106  upwards towards the position indicated by the numeral  123  and drawn by dashed lines. At around its positioning  123 , the cap  106  has been moved passed its singular positioning between its aforementioned first and second stable positions, and would thereby be forced by the spring  109  to move into its aforementioned first stable positioning  124  (also as shown in the schematic of  FIG. 1 ). As the cap  106  is forced to move into its positioning  124 , the shape memory alloy actuating element  110  is deformed back to its original configuration as shown in  FIG. 3  and also in  FIG. 1  by the cap  106 . The resetting screw  121  is then retracted to its positioning shown in  FIG. 3  to make the safety valve fully functional by allowing external heating as was previously described to actuate the cap  106  back to its second stable positioning ( FIGS. 2 and 3 ) and stop the flow of the passing gaseous and/or fluid substances. 
         [0044]    In practice, the resetting screw is properly sealed to prevent any leakage of the flowing gaseous and/or liquid fluid out of the valve. Such means of externally providing sealing elements that are pressurized against the surfaces of the screw  121  and the valve housing  101  and other similar methods of providing proper sealing to prevent leakage around the screw  121  are well known in the art and may be selected depending on the type of gaseous and/or liquid substances that are being passed through the valve. 
         [0045]    Alternatively, the resetting element of the disclosed safety valves may be constructed as being inherently sealed, for example by using a closed end, preferably metal, bellow  126  as shown in the schematic of  FIG. 4 . In this embodiment, the bellow has an integral top  127 , and is attached to the surface of the safety valve  101  as shown in  FIG. 4 , such as by welding or the like. The setting screw  121  shown in the embodiment of  FIG. 3  is then replaced by a sliding pin  128 , with the previously described tip element  122 as shown in the schematic of  FIG. 4 . The pin  128  may also be provided with a compressive return spring  129  to return it to its retracted positioning shown in  FIG. 4  following each safety valve resetting as was described for the setting screw  121  of  FIG. 3 . The pin  128  otherwise functions as the setting screw  121  as was previously described for the embodiment of  FIG. 3 . The use of such a bellow  126  element which is fully sealed to the housing  101  of the present safety valves ensures that no gaseous and/or fluid substance that is passing through the safety valve would leak outside. Such an embodiment is particularly suitable for safety valves used on gas lines as long as the gas pressure is not too high. Otherwise when the passing gaseous and/or liquid material passing through the safety valve are at relatively high pressure, then the use of the setting screw  121  shown in  FIG. 3  may be more appropriate. 
         [0046]    It will be appreciated that the shape memory alloy element  110  may also be provided with a preloaded spring (elastic) element  125 ,  FIG. 2 , that once it has changed shape from the configuration  110  shown in  FIG. 1  to that of configuration  117  shown in  FIG. 117 , then when the temperature of the shape memory alloy element falls below the predetermined threshold temperature, the preloaded spring (elastic) element  125  would force the shape memory alloy element ( 117  in  FIG. 2 ) to deform back to its original (pre-shape change,  110  in  FIG. 1 ) configuration. In the schematic of  FIG. 2 , the preloaded spring (elastic) element  125  is shown as a helical spring that is attached on one end to the shape memory alloy element  117  and on the other end to the inside of the valve housing  101 . The spring element  125  is preloaded in tension enough to deform the shape memory alloy element  117  back to its configuration shown in  FIG. 1  when the temperature of the shape memory alloy element  117  drops below the aforementioned predetermined threshold temperature, but the level of tensile preloading force is low enough to allow the shape memory alloy element  110  to actuate the cap  106  from its first stable positioning,  FIG. 1 , to its second stable positioning,  FIG. 2 , when its temperature rises above the predetermined threshold temperature. 
         [0047]    In the configuration shown in  FIG. 2 , the spring element  125  is shown as a helical tensile spring mainly for the sake of clarity. However, it will be appreciated by those skilled in the art that many other preloaded spring/elastic elements may also be used to perform the same task. In an embodiment, the preloaded spring element is a bending element that can stretch along at least a portion of the length of the shape memory alloy element and engage the shape memory alloy at its tip. Such an elastic element provides the aforementioned function of the helical spring element  125  in a bending mode. 
         [0048]    As was previously indicated, the shape memory actuation element  110 ,  FIG. 1 , may be fabricated from a strip or wire or other similarly shapes of the said material. 
         [0049]    For example, shape memory alloy actuator  110 ,  FIG. 1 , may be made as shown in the schematic of  FIG. 5A  and indicated by the numeral  130  from a relatively thin strip  131  of shape memory alloy. In  FIG. 5A  the shape memory actuator  130  is shown to be shaped as the element  110  in  FIG. 1 , in which the safety valve is in its open configuration. As can be seen in  FIG. 5A , the shape memory alloy strip  131  is bent to the illustrated shape, with the frontal surface  132  being the surface that is attached to the inner surface of the safety valve heat conducting element  116 . The frontal portion  132  of the strip  131  may be provided with a cutaway section  133 , which can be large enough to provide a clear view of the frontal surface  134  (which can be colored, such as being green) of the element  135 . The element  135  with the clearly marked surface  134  (for example painted green to clearly contrast its other side surface colors) is used to indicate when the safety valve is in its open positioning,  FIG. 1 . The colored or marked surface  134  (for example green) would be clearly visible to the onlooker through a provided transparent window (shown by dashed lines in  FIG. 1  and indicated by the numeral  137 ) on the element  116  which is properly sealed to the safety valve heat conducting element  116 . The element  135  may be made out of any material that is compatible with the gas and/or liquid that passes through the safety valve. The element is attached to the surface  136  of the shape memory alloy strip  131  so that upon actuation, i.e., upon shape change to the configuration shown in  FIG. 5B  ( 117  in  FIG. 2 ), the surface  134  (indicating an open valve) is moved away from the view of the window  137 ,  FIG. 1 . When desired, the surface  138 ,  FIG. 5B , that comes into the view of the window  137  may be provided with a different color (e. g., red or white) to indicate that the valve is closed. When both open and closed indication is desired, the element  135  may held against the frontal surface  132  of the strip  131 , and rotated by the rotation of the back portion  136  of the strip  131  from the configuration of  FIG. 5A  to that of  FIG. 5B . 
         [0050]    Alternatively, the shape memory alloy actuator  110 ,  FIG. 1 , may be made as shown in the schematic of  FIG. 6A  and indicated by the numeral  140  from a wire element  131  of shape memory alloy. In  FIG. 6A  the shape memory actuator  140  is shown to be shaped as the element  110  in  FIG. 1 , in which the safety valve is in its open configuration. As can be seen in  FIG. 6A , the shape memory alloy wire  141  is formed to the illustrated shape, with the surface of the frontal portion  142  being the surface that is attached to the inner surface of the safety valve heat transfer element  116 ,  FIG. 1 . The frontal portion  142  of the shape memory alloy wire  111  is also seen to provide access for viewing the frontal surface  143  (such as by being colored, such as being green) of the element  144 . The element  144  with the clearly marked surface  143  (for example painted green to clearly contrast its other side surface colors) is used to indicate when the safety valve is in its open positioning,  FIG. 1 . The colored or marked surface  143  (for example green) would be clearly visible to the onlooker through a provided transparent window (shown by dashed lines in  FIG. 1  and indicated by the numeral  137 ) on the element  116 . The element  144  may be made out of any material that is compatible with the gas and/or liquid that passes through the safety valve. The element is attached to the area  145  of the shape memory alloy wire  141  as shown in  FIGS. 6A and 6B , so that upon actuation, i.e., upon shape change to the configuration shown in  FIG. 6B  ( 117  in  FIG. 2 ), the surface  143  (indicating an open valve) is moved away from the view of the window  137 ,  FIG. 1 . When desired, the surface  146 ,  FIG. 6B , that comes into the view of the window  137  may be provided with a different color (e. g., red or white) to indicate that the valve is closed. When both open and closed indication is desired, the element  144  may held against the frontal portion  142  of the shape memory alloy wire  141 , and rotated by the rotation of the back portion  147  of the wire  141  from the configuration of  FIG. 6A  to that of  FIG. 6B . 
         [0051]    In the safety valve embodiments of  FIGS. 1-6 , shape memory alloy actuators (element  110  in the embodiment  100  of  FIG. 1 ) are used to rotate a cap (element  106  in the embodiment of  FIG. 1 ) and thereby cause it to move to the position if closing the flow of gas and/or fluid through the safety valve ( FIG. 2 ). Alternatively, a shape memory alloy element may be used to release the element that is used to close the flow of gas and/or fluid through the safety valve, where the flow closing element is otherwise biased by at least one spring (elastic) element to move into the flow closing positioning. The basic design and operation of two such safety valve mechanism embodiments are described below. 
         [0052]    Referring to  FIGS. 7-8 , there is shown a first embodiment  150  of such self-contained safety valve that upon external heating to a predetermined threshold temperature would cause a shape memory alloy element change its shape and thereby release a biased flow closing element to move into its flow closing positioning. The external heating may have fire or general temperature elevation without direct or proximity to fire or other heat source. 
         [0053]    Similar to the safety valve embodiment  100  of  FIGS. 1-2 , the safety valve  150  is also constructed with a housing  151 , which may have been assembled from one or more than one part for ease of manufacture and assembly. The safety valve  150  is similarly provided with at least one inlet  152  and at least one outlet  153  to accommodate inflow  154  and outflow  155 , respectively, of the passing gaseous and/or liquid substances of interest. The inlet  152  and the outlet  153  may similarly be provided with internal or external thread (not shown) for attachment to the intended gaseous and/or liquid substance lines. Alternatively, incoming and outgoing lines may be attached to the inlet  152  and outlet  153  by soldering, welding or any other methods appropriate for the transiting gaseous and/or liquid substance. 
         [0054]    The safety valve  150  is also provided with a cap  156  (similar to the cap  106  in  FIGS. 1-2 ), which is attached to the inside structure of the housing  151  at the indicated point  158  by a hinge joint  157 . At least one preloaded compressive spring  159  is attached on one end to the cap  156 , such as by a pin joint (not shown), and to the inside structure of the housing  151 , such as by another pin joint (not shown),  FIG. 7 . In the configuration of the rotatable cap  156  shown in  FIG. 7 , the preloaded compressive spring  159  is seen to be biasing the cap  156  to rotate in the counterclockwise direction, thereby causing its surface  160  to come to rest against the top surface  161  of the outlet passage of the safety valve  150  as is shown in  FIG. 8 , thereby closing the flow through the safety valve. 
         [0055]    The cap  156  is provided with an “L” shaped element  162 , which when the safety valve  150  is in its open configuration as shown in  FIG. 7 , engages the “inverted U” shaped shape memory alloy element  163 , which functions as a stop element to hold the preloaded spring biased cap  156  in the configuration shown in  FIG. 7 . Thereby the aforementioned gaseous and/or liquid substances are free to enter from the inlet  152  and exit from the outlet  153  as indicated by the arrows  154  and  155 , respectively. Then when the temperature of the environment outside the safety valve  150  is increased, the element  164  which is made from a highly heat conductive material such as aluminum or copper or the like would transmit heat to the shape memory alloy element  163 . The shape memory element  163  (or a portion thereof) can be fabricated from a relatively thin strip or formed wire of shape memory alloy material such as one of those previously described ( FIGS. 5 and 6 ) and is trained to change its shape in response rise in temperature above a predetermined threshold temperature. In the present safety valve  150 , the shape memory alloy element  163  is trained to change its shape from that shown in the schematic of  FIG. 7  to that indicated by the numeral  165  in the schematic of  FIG. 8  by bending, such as at the region  166  of the shape memory alloy element  163 ,  FIG. 7 , very close to the point of its attachment to the heat transferring element  164  for its fast response to temperature elevation above the said predetermined threshold temperature. The shape memory alloy element  163  may be similarly attached to the surface of the element 164  as shown in  FIG. 7  by welding, soldering or other methods known in the art. 
         [0056]    Therefore when the temperature of the shape memory alloy element  163  has been raised to above the aforementioned predetermined threshold temperature it would change shape to that of  165  shown in  FIG. 8 . The cap  156  is then released and the preloaded compressive spring  159  (indicated by the numeral  167  in  FIG. 8 ) would force the cap to rotate and come to rest against the outlet  161 ,  FIGS. 7 and 8 . It is noted that in its latter positioning, the surface  160  of the cap  156  rests against the top surface  161  of the outlet passage of the safety valve  150 ,  FIG. 7 . In addition, an O-ring or the like sealing element  168  which can be made out of a relatively elastic element is also provided between the mating surfaces  160  and  161  to ensure proper sealing of the outlet passage  119 ,  FIGS. 1-2 . 
         [0057]    In the embodiment  150  of  FIG. 7  the biasing spring  159  is shown to be a preloaded helical compressive spring. It will be however appreciated by those skilled in the art that a wide range of preloaded tensile, compressive, torsion springs and other types of elastic elements such as those operating in bending or their combination may also be used to provide the required biasing force/torque to rotate the cap  156  from its positioning shown in  FIG. 7  to that of  FIG. 8 . 
         [0058]    It will also be appreciated by those skilled in the art that the frontal surface  171  of the “L” shaped element  162  may be appropriately marked, for example painted in green color, to indicate when the safety valve is in its open positioning,  FIG. 7 . The colored or marked surface  171  would then be clearly visible to the onlooker through a provided transparent window (shown by dashed lines in  FIG. 7  and indicated by the numeral  172 ) on the element  164 . 
         [0059]    It will be appreciated by those skilled in the art that similar to the shape memory alloy actuator  110  of  FIG. 1 , the shape memory alloy element  163  of the embodiment  150  of  FIG. 7  may also be constructed by a strip of shape memory alloy material as shown in the schematic of  FIG. 9A  and indicated by the numeral  170  or from a shape memory alloy wire as shown in the schematic of  FIG. 9B  and indicated by the numeral  175 . As can be seen in  FIG. 9A , the shape memory alloy element is formed from a strip of shape memory alloy material  173 , which is bent into the indicated inverted “U” shaped form of element  163  for assembly in the safety valve in its open configuration as shown in  FIG. 7 . As can be seen in  FIG. 9A , frontal surface  174  of the shape memory alloy element  170 , which is the surface that is attached to the inner surface of the safety valve heat conducting element  164 . The frontal portion  174  of the strip  173  may be provided with a cutaway section  179 , which can be large enough to provide a clear view of the frontal surface  171  (which can be colored green) of the element “L” shaped element  162 ,  FIG. 7 . The visible and clearly marked surface  171  (for example painted green to clearly contrast its other side surface colors) is used to indicate that the safety valve is in its open positioning,  FIG. 7 . The colored or marked surface  171  would be clearly visible to the onlooker through a provided transparent window (shown by dashed lines in  FIG. 7  and indicated by the numeral  172 ) on the element  164 . Then when the safety valve  150  is in its closed configuration shown in  FIG. 8 , the said colored or marked surface  171  is no longer visible to the onlooker and is an indication that the safety valve is in its closed configuration. 
         [0060]    Alternatively, the shape memory alloy actuator  163 ,  FIG. 7 , may be made as shown in the schematic of  FIG. 9B  and indicated by the numeral  175  from a wire element  181  of shape memory alloy. In  FIG. 9B  the shape memory actuator  181  is shown to be shaped as the element  163  in  FIG. 7 , in which the safety valve is in its open configuration. As can be seen in  FIG. 9B , the shape memory alloy wire  181  is formed to the illustrated shape, with the surface of the frontal portion  177  being the surface that is attached to the inner surface of the safety valve heat conducting element  164 ,  FIG. 7 . The frontal portion  177  of the shape memory alloy wire  181  is also seen to provide access for viewing the frontal surface  171  (which can be colored green) of the “L” shaped element  162 ,  FIG. 7 . The clearly marked surface  171  (for example painted green) is used to indicate that the safety valve is in its open positioning,  FIG. 7 . The colored or marked surface  171  would be clearly visible to the onlooker through the provided transparent window  172  provided in the element  164 . 
         [0061]    Referring now to  FIG. 10 , there is shown a third embodiment  180  of the self-contained safety valve that is actuated by external heating. The external heating may be due to fire or general temperature elevation without direct or proximity to fire or other heat source. The safety valve  180  can be constructed with a housing  182 , which can be assembled from one or more than one part for ease of manufacture and assembly. The safety valve  180  is provided with at least one inlet  183  and at least one outlet  184  to accommodate inflow  185  and outflow  186 , respectively, of the passing gaseous and/or liquid substances of interest. The inlet  183  and the outlet  184  may be provided with internal or external thread (not shown) for attachment to the intended gaseous and/or liquid substance lines. Alternatively, incoming and outgoing lines may be attached to the inlet  183  and outlet  184  by soldering, welding or any other methods appropriate for the transiting gaseous and/or liquid substance. 
         [0062]    The safety valve  180  is provided with a cap  187 , which is attached to the inside structure of the housing  182  at the indicated point  188  by a hinge joint  189 . A tensile spring  190  is attached on one end to the cap  187 , such as by a pin joint  191 , and to the inside structure of the housing  182 , such as by a pin joint  192 , as shown in  FIG. 10 . In the configuration of the rotatable cap  187  shown in  FIG. 10 , the tensile spring  190  is preloaded in tension, thereby biasing the cap  187  to rest at its shown left most position against either the interior surface of the housing  182  or against an end of the actuating pin  193 . As can be seen in the schematic of  FIG. 10 , the rotating cap  187  and the preloaded tensile spring  190  are attached to the inner surface of the housing  182  such that they configure a so-called toggle mechanism, i.e., a bi-stable mechanism with two stable resting states, with the first stable positioning being as shown in the schematic of  FIG. 10 , where the preloaded tensile spring  190  is positioned on the right side of the joint  189  of the cap  187 , and with the second stable positioning being when the preloaded tensile spring  190  is positioned on the left side of the joint  189  of the cap  187 , as shown in the schematic of  FIG. 11 . 
         [0063]    The at least one shape memory alloy material based actuation device of the safety valve  180  consists of a bellow  194 , which has one end attached and sealed to the outside surface of the safety valve housing  182 . A cap element  195  attached to an opposite end of the bellow  194  and seals the interior volume of the bellow from the environment outside the safety valve  180  as shown in the schematic of  FIG. 10 . The actuating pin  193  is positioned inside the bellow  194  and is held biased away from contact with the cap  187  by the lightly preloaded compressive spring  197 . At least one shape memory alloy posts  196  are positioned between the cap  195  of the bellow  194  and the outer surface of the safety valve housing  182  as shown in  FIG. 10 , to prevent the bellow  194  which is preloaded in tension in the configuration shown in  FIG. 10  from further pushing the actuating pin  193  into the safety valve housing. The at least one shape memory alloy posts  196  can be fabricated as wires of appropriate cross-sectional areas and are either rigidly attached on at least one of their ends to the cap  195  or the outer surface of the safety valve housing  182 , for example by welding or brazing or soldering, and on the other end (if not fixedly attached) held in a provided indentation (not shown) in the surface of the elements. The tensile preloaded bellow  194  may also be provided with an added preloaded tensile spring (inside or outside the bellow  194 —not shown) to provide tensile biasing load for pushing the actuating pin  193  inside the housing  182  of the safety valve  180 . 
         [0064]    In the first stable toggle positioning, the cap  187  is shown to be resting against either the interior surface of the housing  182  or against the actuating pin  193  as shown in the schematic of  FIG. 10 . The aforementioned gaseous and/or liquid substances are thereby free to enter from the inlet  183  and exit from the outlet  184  as indicated by the arrows  185  and  186 , respectively. Then when the temperature of the environment outside the safety valve  180  is increased, the aforementioned at least one shape memory alloy post  196  which is trained to change its shape in response to a rise in temperature above a predetermined threshold temperature would change its shape from that shown in  FIG. 10  to that indicated by the numeral  199  or that indicated by the numeral  201  in the schematic of  FIG. 11 . Once the at least one shape memory alloy post  196 ,  FIG. 10 , has changed shape to that of either  199  or  201 ,  FIG. 11 , then the tensile preloaded bellow (indicated by the numeral  202  in  FIG. 11 ) and if present, together with the aforementioned tensile preloaded spring (not shown), would force the actuating pin  193  further into the housing  182  of the safety valve  180 , thereby pressing against the surface  203  of the cap  187 , forcing it to rotate in the counterclockwise direction, moving from its first stable position shown in  FIG. 10  and passed its aforementioned singular toggle position and then pulled by the tensile preloaded spring element  190  to its second stable positioning shown in the schematic of  FIG. 11 . Then as it was previously described for the embodiment  100  of  FIGS. 1-2 , in its said second stable positioning,  FIG. 11 , the surface  204  of the cap  187  rests against the top surface  205  of the outlet passage of the safety valve  180 ,  FIG. 10 . In addition, an o-ring or the like sealing element  206  which can be made out of a relatively elastic element,  FIG. 10 , is also provided between the mating surfaces  205  and  205  to ensure sealing of the outlet passage  207 ,  FIGS. 10 and 11 . 
         [0065]    It will be appreciated by those skilled in the art that when both ends of the at least one shape memory alloy posts are attached to the outside surfaces of the safety valve housing  182  and the cap  195  of the bellow  194  as shown in the schematic of  FIG. 10 , then when the posts are subjected to temperatures at or above the aforementioned predetermined temperature threshold, then the posts must have been trained to change shape to the configuration  199  shown in  FIG. 11 . In such safety valve actuation mechanism designs, the shape changing shape memory alloy posts  196  will also generate a force that would tend to push the actuating pin  193  into the safety valve housing as was described earlier and thereby may be used to eliminate the need for relatively large tensile preloading of the bellow  194  and the need for the aforementioned added preloaded tensile spring (not shown). 
         [0066]    In operation, one or more safety valves  180  are positioned along the desired gaseous and/or liquid line. The installed safety valves  180  are installed in their normally open configuration shown in  FIG. 10 . Then if the temperature around a safety valve rises above the aforementioned predetermined threshold temperature setting of the safety valve, the heat causes the temperature of the at least one shape memory alloy posts  196  of the safety valve  180  to rise to or above the predetermined threshold temperature and thereby change shape to the trained shape  199  (or  201 ) shown in  FIG. 11 . The tensile preloaded bellow  194  (and/or the aforementioned tensile preloaded spring provided in or outside the bellow  194 —not shown) will then force the pin  193  into the safety valve housing  182  and as was described earlier force the cap  187  to its second stable positioning as shown in  FIG. 11 , and thereby cause the flow passage to the outlet  207  and thereby the flow of the said gaseous and/or liquid to be stopped. 
         [0067]    In the embodiment of  FIG. 10 , when the safety valve  180  is exposed to an ambient temperature above the predetermined threshold temperature for which it is designed, its at least one shape memory alloy posts change shape as was described above and causes the cap  187  to move to its configuration shown in  FIG. 11  and cause the flow of the gaseous and/or liquid to be stopped. Then when the ambient temperature falls below the predetermined threshold temperature, the cap  187  still remains in its configuration of  FIG. 11  and the safety valve passage  207  for the flow of the line gaseous and/or liquid substances remains closed. Such safety valve designs are highly useful in housing or commercial buildings or various plants and the like so that after fire and serious damage to the building structures and/or equipment or the like that makes the related buildings and/or plants or the like inoperable and sometimes abandoned for a period of time, the flow of the line gaseous and/or liquid fuel or other chemicals substances is not accidentally resumed or even intentionally resumed by someone to cause further damage. 
         [0068]    It will be, however, appreciated by those skilled in the art that in certain applications, it is desired that the safety valve  180  be resettable from its closed configuration shown in  FIG. 11  back to its open configuration shown in  FIG. 10 . The task of resetting the safety valve  180  to its said open positioning following a “high temperature threshold” event may be accomplished using many different means and mechanisms. As previously mentioned, in many applications, it is preferred that the user disconnects the safety valve from at least the input or the output line for inspection and to ensure that it has not been subjected to permanent damage due to the exposure to the high temperature threshold event, particularly if it is due to fire or other similar events. However, in certain cases, where the environmental temperature does go over the said high temperature threshold often, for example, due to excessive heat being emitted from a nearby furnace, or in cases that the material being transferred is hazardous and is not desired to be spilled out from the connecting pipes, then an externally actuated means is desired to be provided for resetting the safety valve to its open positioning. It is appreciated by those skilled in the art that many such resetting mechanisms may be provided. Example of such a resetting mechanisms were described for the embodiment  100  of  FIG. 1  in  FIGS. 3 and 4 , and the same resetting mechanisms may also be used for the embodiment  180  of  FIG. 10 . 
         [0069]    In the embodiments of  FIGS. 1, 7 and 10 , cap elements  106 ,  156  and  187 , respectively, which are hinged to the structure of the safety valves are used to rotate from the valve open configuration to that of the valve closed configuration once the safety valve is externally (or internally for the case of embodiments of  FIGS. 1 and 7 ) subjected to temperatures at or above a predetermined threshold temperature. That is, the flow closing elements, i.e., the said cap elements  106 ,  156  and  187 , respectively, are guided (via rotation or any other appropriately guided motion such as translational or a combination of rotational and translational) from their safety valve open positioning to that of safety valve closed positioning. Alternatively, the said flow closing element may be free floating, i.e., its motion may not be constrained to a given path relative to the safety valve housing via a rotary or translational joint or certain linkage type mechanism or the like. An example of such a safety valve design is described below as the fourth embodiment  200  and is illustrated in the schematic of  FIG. 12 . 
         [0070]    Referring now to  FIG. 12 , there is shown a fourth embodiment  200  of the self-contained safety valve that is actuated by external heating. The external heating may be due to fire or general temperature elevation without direct or proximity to fire or other heat source. The safety valve  200  is constructed with a housing  208 , which may be assembled from one or more than one part for ease of manufacture and assembly. The safety valve  200  is provided with at least one inlet  209  and at least one outlet  210  to accommodate inflow  211  and outflow  212 , respectively, of the passing gaseous and/or liquid substances of interest. The inlet  209  and the outlet  210  may be provided with internal or external threads (not shown) for attachment to the intended gaseous and/or liquid substance lines. Alternatively, incoming and outgoing lines may be attached to the inlet  209  and outlet  210  by soldering, welding or any other methods appropriate for the transiting gaseous and/or liquid substance. 
         [0071]    The safety valve  200  is provided with a solid ball  213 , which held against a shape memory alloy element  215  which is formed with two curved beam sections  216  and  217  as shown in the cross-sectional view A-A of  FIG. 13A , by the preloaded compressive biasing spring  214  as shown in  FIG. 12 . The shape memory alloy element  215  of the safety valve  200  is fixedly attached to the inner surface of the element  219 , which is made out of a highly heat conducting material such as copper or the like which is attached and sealed to the wall of the safety valve housing  208 . The element  219  is provided with a larger outside head  220  to increase the rate of heat transfer from the exterior of the safety valve  200  to the shape memory alloy element  215 . 
         [0072]    In its positioning, the ball  213  is shown to be restrained by resting against the two curved beam sections  216  and  217  of the shape memory alloy element  215  as shown in  FIG. 12  and its cross-sectional view A-A of  FIG. 13A . The aforementioned gaseous and/or liquid substances are thereby free to enter from the inlet  209  and exit from the outlet  210  as indicated by the arrows  211  and  212 , respectively. Then when the temperature of the environment outside the safety valve  200  is increased, the shape memory alloy element is trained to change its shape in response to rise in temperatures above a predetermined threshold temperature to that shown in  FIG. 13B . As can be observed in the schematics of  FIGS. 13A and 13B , the shape change consist essentially in the two curved beam sections  216  and  217  of the shape memory alloy element  215  to bending outward to the positions  221  and  222 , respectively, thereby allowing the preloaded compressive spring  214  to push the ball  213  passed the shape memory alloy element  215 , and press it against the provided matching inlet  223  into the safety valve flow passage  224 , as shown by dashed line in  FIG. 12 . The flow of the passing gaseous and/or liquid substances through the safety valve  200  will thereby stop. 
         [0073]    In general, it is highly desirable that the regions  226 ,  FIG. 13B , of the shape memory alloy element  215  is mostly deformed during the aforementioned shape change since they are close to the heat transferring elements  219  and  220 , and the shape memory alloy element  215  should therefore respond rapidly to the indicated rise in temperature. As discussed above, the entire shape memory alloy element  215  need not be formed of a shape memory alloy. In this regard, only a portion, such as portion  226  closest to the element  219  may be formed of shape memory alloy. 
         [0074]    In operation, one or more safety valves  200  can be positioned along the desired gaseous and/or liquid line. The installed safety valves  180  are installed in their normally open configuration shown in  FIG. 12 . Then if the temperature around a safety valve rises above the aforementioned predetermined threshold temperature setting of the safety valve, the heat causes the temperature of the shape memory alloy element  215  to rise to or above the predetermined threshold temperature. The shape memory alloy element will then change shape from the one shown in  FIG. 13A  to the one shown in  FIG. 13B . The ball  213  is the free to be pushed down by the preloaded compressive spring  214 .The ball  213  is then moved downward and seated in the matching seating surface  223 ,  FIG. 12 , and thereby cause the flow passage  224  to the outlet  210  and thereby the flow of the said gaseous and/or liquid through the safety valve to be stopped. 
         [0075]    In the embodiment of  FIG. 12 , when the safety valve  200  is exposed to an ambient temperature at or above the predetermined threshold temperature for which it is designed, its shape memory alloy element  215  would change shape as was described above and causes the ball  213  to move to its positioning shown by dashed line and indicated by the numeral  225  as shown in  FIG. 12  and cause the flow of the said gaseous and/or liquid to be stopped. Then when the ambient temperature falls below the said predetermined threshold temperature, the ball  213  still remains in its said positioning and the safety valve passage  224  for the flow of the line gaseous and/or liquid substances remains closed. Such safety valve designs are highly useful in housing or commercial buildings or various plants and the like so that after fire and serious damage to the building structures and/or equipment or the like that makes the related buildings and/or plats or the like inoperable and sometimes abandoned for a period of time, the flow of the line gaseous and/or liquid fuel or other chemicals substances is not accidentally resumed or even intentionally resumed by someone to cause further damage. 
         [0076]    It will also appreciated by those skilled in the art that in place of using shape memory alloys in the design of the safety valve embodiments of  FIGS. 1, 3, 4, 7 and 12 , different types of bimetal elements known in the art may be used instead. One advantage of using bimetal elements for the safety valve actuation and release mechanisms is that once the ambient and the internal temperature of the safety valve have dropped below the aforementioned predetermined threshold temperature, then the bimetal element would automatically return to its original shape to open the valve. This is in contrast to one-way shape memory alloy actuation and release mechanisms that require to be deformed back to their original shape. A disadvantage of bimetal elements for the present safety valve applications is that their range of deformation is relatively small, and may thereby be more suitable for release mechanisms such as for the safety valve embodiment of  FIG. 7 . In contrast, shape memory alloys can undergo very large deformations and are thereby more suitable for most other embodiments. 
         [0077]    In the embodiments of  FIGS. 1, 7 and 10 , the flow closing (cap) elements  106 ,  156  and  187 , respectively, which are hinged to the structure of the safety valves are used to rotate from the valve open configuration to that of the valve closed configuration once the safety valve is externally (or internally for the case of embodiments of  FIGS. 1 and 7 ) subjected to temperatures at or above a predetermined threshold temperature. Alternatively, the flow closing elements may be designed to slide (or undergo a combination of translational and rotational motion) rather rotate from their valve open to valve close positioning. An example of such a safety valve design is described below as the fifth embodiment  230  and is illustrated in the schematic of  FIG. 14 . 
         [0078]    Referring to  FIG. 14 , there is shown a fifth embodiment  230  of the self-contained safety valve that is actuated by external heating. The external heating may be due to fire or general temperature elevation without direct or proximity to fire or other heat source. The safety valve  230  is constructed with a housing  231 , which may have been assembled from one or more than one part for ease of manufacture and assembly. The safety valve  230  is provided with at least one inlet  232  and at least one outlet  233  to accommodate inflow  234  and outflow  235 , respectively, of the passing gaseous and/or liquid substances of interest. The inlet  232  and the outlet  233  may be provided with internal or external thread (not shown) for attachment to the intended gaseous and/or liquid substance lines. Alternatively, incoming and outgoing lines may be attached to the inlet  232  and outlet  233  by soldering, welding or any other methods appropriate for the transiting gaseous and/or liquid substance. 
         [0079]    The safety valve  230  is provided with a cap  236 , which can slide laterally indicated by the arrow  237 , such as in a guide provided in the interior of the housing  231  (not shown). In the position shown in  FIG. 14 , the safety valve  230  is in its open state and the gaseous and/or liquid substances are thereby free to enter from the inlet  232  and exit from the outlet  233  as indicated by the arrows  234  and  235 , respectively. 
         [0080]    The at least one shape memory alloy material based actuation device of the safety valve  230  consists of a bellow  238 , which is attached and sealed to the outside surface of the safety valve housing  231 . A cap element  239  is also attached to the opposite end of the bellow  238  and seals the interior volume of the said bellow from the environment outside the safety valve  230  as shown in the schematic of  FIG. 14 . An actuating pin  240 , such as with a cap  241  is positioned inside the bellow  238  and is held biased by the lightly preloaded compressive spring  242  against the cap  239  as shown in  FIG. 14 . At least one shape memory alloy posts  243  are positioned between the cap  239  of the bellow  238  and the outer surface of the safety valve housing  231  as shown in  FIG. 10 , to prevent the bellow  238  which is preloaded in tension in the configuration shown in  FIG. 10  from further pushing the actuating pin  240  into the safety valve housing  231 . The at least one shape memory alloy posts  243  can be fabricated as wires of appropriate cross-sectional areas and are either rigidly attached on at least one of their ends to either the cap  239  or to the outer surface of the safety valve housing  231 , for example by welding or brazing or soldering, and on the other end (if not similarly fixedly attached) held in a provided indentation (not shown) on the said surfaces. The tensile preloaded bellow  238  may also be provided with an added preloaded tensile spring (inside or outside the bellow  238 —not shown) to provide tensile biasing load for pushing the actuating pin  240  inside the housing  231  of the safety valve  230  when ambient temperature rises to or above the aforementioned predetermined threshold temperature as will be described later. 
         [0081]    The actuating pin is attached to the cap  236 , such as by a hinge joint  244  as shown in  FIG. 14 . Then when the temperature of the environment outside the safety valve  230  rises to or above the aforementioned predetermined threshold temperature, the at least one shape memory alloy post  243  which is trained to change its shape in response to rise in temperature above the threshold temperature would change its shape from that shown in  FIG. 10  to that indicated by the numeral  245  or that indicated by the numeral  246  in the schematic of  FIG. 15 . Once the at least one shape memory alloy post  243 ,  FIG. 14 , has changed shape to that of either  245  or  246 ,  FIG. 15 , then the tensile preloaded bellow (indicated by the numeral  247  in  FIG. 15 ) and if present, together with the aforementioned tensile preloaded spring (not shown), would force the actuating pin  240  further into the housing  231  of the safety valve  230 , thereby translating the cap  236  laterally to the left as shown by the arrow  237  in  FIG. 14 , placing it over the inlet surface  248  of the outlet passage  249  of the safety valve outlet  233  and closing the passage  249  to the through flow. In addition, an  0 -ring or the like sealing element  251  which is can be made out of a relatively elastic element,  FIG. 14 , is also provided between the mating surfaces of the cap  237  and the inlet  248  to ensure sealing of the outlet passage  249 ,  FIGS. 14 and 15  to the extent necessary for the fluid passing through the valve and/or the application for the valve. 
         [0082]    It will be appreciated by those skilled in the art that when both ends of the at least one shape memory alloy posts are attached to the outside surfaces of the safety valve housing  231  and the cap  239  of the bellow  238  as shown in the schematic of  FIG. 14 , then when the posts are subjected to temperatures at or above the aforementioned predetermined temperature threshold, then the posts must have been trained to change shape to the configuration  245  shown in  FIG. 15 . In such safety valve actuation mechanism designs, the shape changing shape memory alloy posts  238  will also generate a force that would tend to push the actuating pin  240  into the safety valve housing as was described earlier and thereby may be used to eliminate the need for relatively large tensile preloading of the bellow  238  and the need for the aforementioned added preloaded tensile spring (not shown). 
         [0083]    In operation, one or more safety valves  230  are positioned along the desired gaseous and/or liquid line. The installed safety valves  230  are installed in their normally open configuration shown in  FIG. 14 . Then if the temperature around a safety valve rises above the aforementioned predetermined threshold temperature setting of the safety valve, the heat causes the temperature of the at least one shape memory alloy posts  238  of the safety valve  230  to rise to or above the said predetermined threshold temperature and thereby change shape to the trained shape  245  (or  246 ) shown in  FIG. 15 . The tensile preloaded bellow  238  (and the aforementioned tensile preloaded spring provided in or outside the bellow  238 —not shown) will then force the pin  240  into the safety valve housing  231  and as was described earlier force the cap  236  laterally over the outlet passage  249  as shown in  FIG. 15 , and thereby cause the flow passage to the outlet  249  and thereby the flow of the said gaseous and/or liquid to be stopped. 
         [0084]    In the embodiment of  FIG. 14 , when the safety valve  230  is exposed to an ambient temperature above the predetermined threshold temperature for which it is designed, its at least one shape memory alloy posts change shape as described above and cause the cap  236  to move to its configuration shown in  FIG. 15  and cause the flow of the gaseous and/or liquid to be stopped. Then when the ambient temperature falls below the predetermined threshold temperature, the cap  236  will still remain in its configuration of  FIG. 15  and the safety valve passage  249  for the flow of the line gaseous and/or liquid substances remains closed. This is the case since in general, shape memory alloy based elements, in this case the at least one post  243 , do not deform back from their deformed shapes ( 245  or  246  in  FIG. 15 ) to their original shape  243  of  FIG. 14 . Such safety valve designs are highly useful in housing or commercial buildings or various plants and the like so that after fire and serious damage to the building structures and/or equipment or the like that makes the related buildings and/or plants or the like inoperable and sometimes abandoned for a period of time, the flow of the line gaseous and/or liquid fuel or other chemicals substances is not accidentally resumed or even intentionally resumed by someone to cause further damage. 
         [0085]    It will be, however, appreciated by those skilled in the art that in certain applications, it is desired that the safety valve  230  be manually or automatically resettable from its closed configuration shown in  FIG. 15  back to its open configuration shown in  FIG. 15  following exposure to temperatures at or above the aforementioned predetermined threshold temperatures. Manual resetting to the safety valve open configuration can be done simply by manually pulling the cap  239  back away from the safety valve housing until the shape memory alloy of the shape  245  of  FIG. 15  has been deformed back to its original shape  243  shown in  FIG. 14 . 
         [0086]    When the shape memory alloy element is designed to take the shape  246  as a result of an aforementioned high temperature event, then as the cap  239  is pulled back away from the safety valve housing, the at least one shape memory alloy posts  246  are deformed back to their original shape  243  shown in  FIG. 14 . It will be, however appreciated by those skilled in the art that the at least one shape memory alloy posts  243 ,  FIG. 14 , may be provided with the previously described elastic (spring) elements (not shown) that would return the deformed shape memory alloy posts of the shape  246 ,  FIG. 15 , back to their original shape  243  once the ambient temperature has dropped below the said predetermined threshold temperature. In which case, the cap  239  must still be pulled back manually away from the safety valve housing to allow the shape memory alloy posts to return to their positioning shown in  FIG. 14  and support the cap  239 . 
         [0087]    It will be appreciated by those skilled in the art that if the at least one shape memory alloy posts  243  are fixedly attached to the cap  239  and the outside surface of the safety valve housing  231 ,  FIG. 14 , then upon exposure to ambient temperatures at or above the predetermined threshold temperature, the shape memory alloy posts  243  would change shape to that indicated by the numeral  245  in  FIG. 15 . Then if the at least one shape memory alloy posts  243  are provided with the previously described elastic (spring) elements (not shown) that would return the deformed shape memory alloy posts of the shape  245  back to their original shape  243  as shown in  FIG. 14 , then by providing appropriate level of tensile preloading in the bellow  238  and appropriately sizing and training the at least one shape memory allow posts  243 , once the ambient temperature has dropped below the predetermined threshold temperature, the at least one shape memory alloy posts would automatically pull the cap  239  to its original positioning shown in  FIG. 14 . The flow closing cap  236  is thereby pulled back to its positioning shown in  FIG. 14 , bringing the safety valve  230  to its open state. The resulting safety valve  230  is therefore provided with an automatic means of being reset following exposure to temperatures above the predetermined threshold temperatures once the ambient temperature drops below the threshold temperature. 
         [0088]    It will also be appreciated by those skilled in the art that the above means to automatically reset safety valve  230  following exposure to temperatures above the predetermined threshold temperatures and once the ambient temperature drops below the said threshold temperature is possible by keeping the actuating pin  240  engaged with the flow closing cap  236 . It is therefore also appreciated by those skilled in the art that many other mechanisms may also be designed that operate in rotation or translation or their combination to move the flow closing element (cap  236  in  FIG. 14 ) to achieve similar automatically resetting mechanisms. 
         [0089]    It will be appreciated by those skilled in the art that since in the embodiments  180  and  230  of  FIGS. 10 and 14 , respectively, the shape memory alloy elements are located outside of the valve housing, the safety valve embodiments are therefore capable of responding much more rapidly to rise in ambient temperature than those of the other embodiments. In many applications, such a fast acting characteristic is highly desirable for heat activated safety valves. In some applications, however, particularly where the valve could be subjected to short duration ambient temperatures above the aforementioned predetermined threshold temperature due to some local transient events, then it is highly desirable that the safety valves do not respond to relatively short duration and transient rise in ambient temperature. The embodiments  100 ,  150  and  200  of  FIGS. 1, 7 and 12 , respectively, provide such a characteristic since the external heat has to first heat the heat conducting elements (elements  116 ,  164 , and  219  in the embodiment of  FIGS. 1, 7 and 12 , respectively), before heating the indicated shape memory alloy elements to the predetermined shape change activation threshold temperature. It is also appreciated by those skilled in the art that by selecting materials with higher heat capacity and providing larger heat conducting elements  116 ,  164 , and  219  in the embodiment of  FIGS. 1, 7 and 12 , respectively, the amount of time required for the corresponding safety valves to respond to the rise in the ambient temperatures above the aforementioned predetermined threshold temperature can be increased (to configure a time delay). 
         [0090]    It will also be appreciated by those skilled in the art that once the safety valves of the disclosed embodiments are closed due to exposure to temperatures at or above the aforementioned threshold temperatures, then the pressure exerted by the flowing gaseous and/or liquid substances would also assist in keeping the safety valves closed to the passing flow. 
         [0091]    In the above description of the operation of the safety valve embodiments of  FIGS. 1, 3, 4, 7, 12 and 14 , the shape memory alloy elements of the indicated safety valves are described as having been heated from some source external to the interior of the said safety valves through certain thermally highly conductive elements to cause the safety valve to close when the external temperature rises above the aforementioned predetermined threshold temperature. It will be, however, appreciated by those skilled in the art that the shape memory alloy elements may also be similarly heated and change shape by the gaseous and/or fluid fuel or other chemical substances that are flowing through the safety valve. It is therefore appreciated that the safety valves and other safety valve embodiments disclosed would function similarly when subjected to externally ambient temperatures above their predetermined design threshold temperatures as well as when the temperature of the passing gaseous and/or fluid substances rise above the said predetermined threshold temperature. 
         [0092]    This is particularly useful for anti-scalding valves which would close the flow of fluid, such as hot water, when the water flowing through the valve is more than a predetermined temperature. Of course, in such applications, the highly conductive element (e.g.,  116 ) may not be necessary. Furthermore, in such applications, if the valve is not assessable to return the same to an open configuration (e.g., is inside a closed wall), an automatic return mechanism (such as those described above) may be useful which returns the cap  106  to its first positioning as the temperature of the fluid passing there through returns to a safe temperature below the predetermined threshold temperature. 
         [0093]    Also, more than one outlet may be provided, each with a separate cap and shape memory alloy actuator and each actuator can be configured to actuate at a different threshold temperature. For example, a first actuator may actuate at temperature T 1 , a second at T 2 , a third at T 3  and a fourth at T 4 , where T 4  is greater than T 3 , which is greater than T 2 , which is greater than T 1 . In such a configuration, the fluid flow, such as hot water will gradually decrease as the temperature of the fluid increases until the fluid reaches T 4 , at which point flow stops. 
         [0094]    While there has been shown and described what are considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.

Technology Classification (CPC): 5