Abstract:
A gas valve body with a first flow chamber and, a second flow chamber including and a main valve positioned in line and between the first flow chamber and the second flow chamber. The main valve can be opened by creating a pressure differential across the main valve. An electrostatically controlled pilot valve is provided for controlling the pressure differential across the main valve for “on-ff” operation. The electrostatically controlled pilot valve may also be operated to “modulate” the pressure differential across the main valve along a range of pressure differential values.

Description:
BACKGROUND  
       [0001]     Gas-powered appliances typically have some control system included for controlling the operation of the appliance. In this context, a gas-powered appliance may be a water heater, a fireplace insert, a furnace, a gas stove, or any other gas-powered appliance. Also in this context, “gas-powered” typically means that natural gas or liquid propane gas is used as a primary fuel source, but it should be recognized that “gas powered” may also include any other suitable fuel source either in a liquid or gaseous state, as desired.  
         [0002]     In a fuel-fired, storage-type water heater, for example, a combustion chamber and an air plenum are typically disposed below or near a water tank. A burner element, fuel manifold tube, ignition source, thermocouple, and a pilot tube typically extend into the combustion chamber. When the temperature of the water in the tank falls below a set minimum, fuel is introduced into the combustion chamber through the fuel manifold tube and burner element. This fuel is ignited by the pilot flame or other ignition source, and the flame is maintained around the burner element. Air is drawn into the plenum, sometimes assisted by a blower, and the air mixes with the fuel to support combustion within the combustion chamber. The products of combustion typically flow through a flue or heat exchange tube in the water tank to heat the water by convection and conduction.  
         [0003]     Gas valves used in conjunction with gas-powered appliances are known. These gas valves are typically controlled by one or more magnetic or piezoelectric control valves. However, magnetic valves often require a relatively large amount of power to operate, and are bulky. Piezoelectric valves are often relatively expensive, unreliable over an operating temperature from, for example, −30 to 85 degrees Celsius, and often do not provide a desired displacement for optimal performance. Thus, alternative gas valves are sought.  
       SUMMARY  
       [0004]     The present invention generally relates to appliances that include a burner such as a fuel-fired burner and to methods of controlling such appliances.  
         [0005]     In one illustrative embodiment, a gas valve includes a first flow chamber, a second flow chamber, and a main valve positioned in line and between the first flow chamber and the second flow chamber. The main valve can be opened by, for example, creating a pressure differential across the main valve. An electrostatically controlled valve may then be provided for controlling the pressure differential across the main valve. In some embodiments, the electrostatically controlled valve may be adapted to “modulate” the pressure differential across the main valve. For example, the term “modulate” may include controlling the pressure differential across the main valve along a range of pressure differential values.  
         [0006]     In another illustrative embodiment, a gas valve includes a valve body having a gas inlet, a gas outlet, and a conduit connecting the gas inlet and the gas outlet. In some embodiments, the conduit includes a first flow chamber, a second flow chamber and a third flow chamber, with a first main gas valve between the first and second flow chambers, and a second main gas valve between the second and third flow chambers. The use of two main gas valves may, in some cases, increase the reliability of the gas valve by providing a certain level of redundancy.  
         [0007]     The first main gas valve and the second main gas valve may include a first electrostatic diaphragm valve and a second electrostatic diaphragm valve. A valve may also include one or more electrostatic valve and one or more traditional electromagnetic or like valve. In one illustrative embodiment, a first electrostatic diaphragm valve may be disposed between the first flow chamber and the second flow chamber, and when activated, may be used to create a pressure differential that tends to open the first main gas valve. Likewise, a second electrostatic diaphragm valve may be disposed between the second flow chamber and the third flow chamber, and when activated, may be used to create a pressure differential that tends to open the second main gas valve. In some embodiments, a pressure sensor is provided in fluid communication with the gas outlet to help control the flow of gas through the gas valve.  
         [0008]     The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, Detailed Description and Examples which follow more particularly exemplify these embodiments. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0009]     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:  
         [0010]      FIG. 1  is a schematic diagram of an illustrative water heater system;  
         [0011]      FIG. 2A  is a schematic cross-sectional view of an illustrative embodiment of a gas valve with both electrostatic pilot gas valves closed;  
         [0012]      FIG. 2B  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 2A  with one electrostatic pilot gas valve closed;  
         [0013]      FIG. 2C  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 2B  with both electrostatic pilot gas valves open;  
         [0014]      FIG. 3  is a schematic cross-sectional view of another illustrative embodiment of a gas valve;  
         [0015]      FIG. 4  is a schematic cross-sectional view of another illustrative embodiment of a gas valve;  
         [0016]      FIG. 5  is a schematic cross-sectional view of an illustrative embodiment of a pressure sensor;  
         [0017]      FIG. 6  is a schematic cross-sectional view of another illustrative embodiment of a pressure sensor;  
         [0018]      FIG. 7  is a graph of capacitance versus pressure for the pressure sensor shown in  FIG. 6 ;  
         [0019]      FIG. 8  is a schematic cross-sectional view of an illustrative embodiment of a pressure sensor;  
         [0020]      FIG. 9  is a schematic cross-sectional view of another illustrative embodiment of a pressure sensor;  
         [0021]      FIG. 10  is a graph of capacitance versus pressure for the pressure sensor shown in  FIG. 9 ;  
         [0022]      FIG. 11A  is a schematic cross-sectional view of a further illustrative embodiment of a gas valve with both electrostatic gas valves closed;  
         [0023]      FIG. 11B  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 11A  with one electrostatic gas valve closed;  
         [0024]      FIG. 11C  is a schematic cross-sectional view of the illustrative gas valve shown is  FIG. 11B  with both electrostatic gas valves open; and  
         [0025]      FIG. 12  is a schematic cross-sectional view of an illustrative trap. 
     
    
       [0026]     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.  
       DETAILED DESCRIPTION  
       [0027]     The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials may be illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.  
         [0028]     The present invention generally pertains to fuel-fired appliance gas valves that operate on fuels such as natural gas, propane, fuel oil, hydrogen, and/or other combustible fuels. Exemplary fuel-fired appliances include appliances such as gas furnaces, gas water heaters, gas stoves, gas clothes dryers, gas fireplaces and the like. Merely for illustrative purposes, the present invention will be discussed with reference to a gasous fuel-fired water heater, although it is to be understood that the invention is applicable to any fuel-fired appliance.  
         [0029]      FIG. 1  illustrates a gas water heater  10 . Water heater  10  includes a housing  12  that includes a water tank (not seen). Cold water enters the water tank through cold water line  14  and is heated by a gas burner. The resulting heated water exits through hot water line  16 . A gas control unit  18  regulates gas flow from a gas source  20  through combustion gas line  22  and into the gas burner. The gas control unit  18  can include a gas valve for regulating gas flow from the gas source  20  through the combustion gas line  22  and into the gas burner. A flue  24  permits combustion byproducts to safely exit.  
         [0030]      FIG. 2A  is a schematic cross-sectional view of an illustrative embodiment of a gas valve  100  that may be included in the gas control unit  18  of  FIG. 1 . The illustrative gas valve  100  includes a valve body  115  that has a gas inlet  112 , a gas outlet  113 , and a conduit  114  connecting the gas inlet  112  and gas outlet  113 . The conduit  114  can include any number of flow chambers. However, in the illustrative embodiment shown, the conduit  114  includes a first flow chamber  121 , a second flow chamber  122 , and a third flow chamber  123 . The first flow chamber  121  is in fluid connection with the gas inlet  112 . The third flow chamber  123  is in fluid connection with the gas outlet  113 . The second flow chamber  122  can be in selective fluid connection with both the first flow chamber  121  and the third flow chamber  123  via main valves  101  and  103 , as further described below.  
         [0031]     The first main valve  101  is disposed between the first flow chamber  121  and the second flow chamber  122 . In the illustrative embodiment, the first main valve  101  is a diaphragm valve with a resilient spring  102  causing the first main valve  101  to be a normally closed valve. The second main valve  103  is disposed between the second flow chamber  122  and the third flow chamber  123 . In the illustrative embodiment, the second main valve  103  is a diaphragm valve with a resilient spring  104  causing the second main valve  103  to also be a normally closed valve. In some embodiments, the first and second main valves  101  and  103  can be controlled by a first electrostatic diaphragm valve  130  and/or a second electrostatic diaphragm valve  140 .  
         [0032]     In the illustrative embodiment, the first electrostatic diaphragm valve  130  is disposed between the first flow chamber  121  and the second flow chamber  122 . In some embodiments, the first electrostatic diaphragm valve  130  is a diaphragm valve with a resilient bias member or spring  139  that causes the first electrostatic diaphragm valve  130  to be a normally closed valve. However, it should be recognized that a separate resilient bias member or spring  139  is not required in all embodiments. For example, in some embodiments, the diaphragm itself may provide a sufficient closing force to the first electrostatic diaphragm valve  130  via, for example, elastic restoring forces within the diaphragm.  
         [0033]     Likewise, and in the illustrative embodiment, a second electrostatic diaphragm valve  140  is disposed between the second flow chamber  122  and the third flow chamber  123 . In the illustrative embodiment shown, the second electrostatic diaphragm valve  140  is also a diaphragm valve with a resilient bias member or spring  149  causing the second electrostatic diaphragm valve  140  to be a normally closed valve. Again, a separate resilient bias member or spring  149  is not required in all embodiments.  
         [0034]     The illustrative first electrostatic diaphragm valve  130  includes a body  131  with a first opposing wall  135  and a second opposing wall  133  that define a valve chamber  161 . A first inlet port  136  and a second inlet port  137  extend into the valve chamber  161 , as shown. The first inlet port  136  extends through the first opposing wall  135  and the second inlet port  137  extends through the second opposing wall  133 . The first and second inlet ports  136  and  137  are in fluid communication with the first flow chamber  121  at a first flow opening  151 . An outlet port  138  extends from the valve chamber  161 , in some embodiments, through the first opposing wall  135 . The inlet ports  136  and  137  and the outlet port  138  can have any useful dimension. In one embodiment, for example, the inlet ports  136  and  137  and the outlet port  138  have a diameter of about 0.5 to 2 mm.  
         [0035]     In some embodiments, an air spring  134  may extend from the valve chamber  161  through the second opposing wall  133 , but this is not required in all embodiments. The air spring  134  can assist in modulation of the electrostatic valve  130  and can be any useful volume. In one embodiment, the air spring  134  can have a volume of about  3  cm 3 . In some illustrative embodiments, the electrostatic diaphragm valve  130  can be modulated by adjusting the voltage applied to the electrostatic diaphragm valve  130  (e.g., voltage applied across the electrodes described below.) In the illustrative embodiment shown, as the valve  130  begins to open, both the orifice  156  and the inlet port  137  begin to be closed by movement of the diaphragm  132 . The air spring  134  can assist in modulation of the diaphragm by allowing the volume of gas trapped on the upper side of the diaphragm  132  to be compressed into the air spring  134 .  
         [0036]     The diaphragm  132  is positioned within the valve chamber  161 . In the illustrative embodiment, the diaphragm  132  extends generally along the first opposing wall  135  in an un-activated state, as shown. Diaphragm  132  can include one or more electrodes. The electrode(s) may extend to near the edges of the valve chamber  161 , and in some embodiments, can extend outside of the chamber  161 .  
         [0037]     The second opposing wall  133  can include one or more stationary electrodes. The second opposing wall  133  and the diaphragm  132  can thus be configured so that, in the un-activated state, the separation distance between the stationary electrode(s) and the electrode(s) on the diaphragm  132  is smaller near the edges of the valve chamber  161 . This may help draw the diaphragm  132  toward the second opposing wall  133  in a rolling action when a voltage is applied between the stationary electrode(s) on the opposing wall  133  and the electrode(s) on the diaphragm  132 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve  130 .  
         [0038]     It is contemplated that the diaphragm  132  can have any useful dimensions. In one embodiment, the diaphragm  132  has a diameter in the chamber  161  from 15 to 30 mm. The diaphragm  132  can also have any useful displacement (greatest linear distance between the first opposing wall  135  and the second opposing wall  133 ). In one embodiment, the diaphragm has a displacement of from about 100 to 200 micrometers, or from 125 to 175 micrometers.  
         [0039]     In some embodiments, the diaphragm  132  can include an orifice or aperture  156  that extends or is disposed through the diaphragm  132 . This orifice or aperture  156  can allow pressure equalization and flow across the diaphragm  132  when the diaphragm is in the un-activated state. The orifice  156  can be disposed at any useful position on the diaphragm  132 , and can have any useful dimension. In one illustrative embodiment, the orifice  156  has a diameter of about 0.5 to 2 mm.  
         [0040]     For purposes of illustration, the first opposing wall  135  is shown to be generally flat and with a raised portion adjacent to the outlet  138 . However, the first opposing wall  135  may assume other shapes, depending upon the application. For example, the first opposing wall  135  may have different regions that are recessed or protrude against the diaphragm  132  in order to, for example, prevent the diaphragm  132  from achieving a suction lock or stiction against the first opposing wall  135 , or to improve the capabilities of the electrostatic valve  130 . Other shapes may also be used, including curved shapes. Although the second opposing wall  133  is shown to be generally curved, other shapes may be used, depending on the application.  
         [0041]     The body  131  may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In some embodiments, the body  131  is constructed by molding a high temperature plastic such as ULTEM™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material.  
         [0042]     The diaphragm  132  may also be made from any suitable material. In some embodiments, the diaphragm  132  has elastic, resilient, flexible and/or other elastomeric property. In one illustrative embodiment, the diaphragm  132  is made from a polymer such as KAPTON™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX™ (available from ICI Films, Wilmington, Del.), MYLAR™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.). Other suitable materials may also be used, as desired.  
         [0043]     The electrode secured to the diaphragm  132  can be provided by, for example, providing, and in some cases patterning, a conductive coating on the diaphragm  132 . For example, the diaphragm  132  electrode may be formed by printing, plating or deposition of metal or other conductive material. In some cases, the electrode layer may be patterned using a dry film resist, as is known in the art. The same or similar technique may be used to provide the stationary electrode on the second opposing wall  133  of the body  131 . Rather than providing a separate electrode layer, it is contemplated that the diaphragm  132  and/or second opposing wall  133  may be made conductive so as to function as an electrode, if desired.  
         [0044]     A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the diaphragm  132  electrode and the stationary electrode on the opposing wall  133 . The dielectric may be coated over the diaphragm  132  electrode, the stationary electrode on the opposing wall  133 , or both. An advantage of using a polymer based substrate and/or diaphragm is that the resulting electrostatic valve may be made cheaper and lighter, and/or suitable for small handheld, or even suitable for disposable or reusable applications. A suitable electrostatically actuated diaphragm valve is described in U.S. Patent Publication No., 2003/0234376, which is incorporated by reference herein.  
         [0045]     The illustrative second electrostatic diaphragm valve  140  includes a body  141  with a first opposing wall  145  and a second opposing wall  143  that define a valve chamber  162 . A first inlet port  146  and a second inlet port  147  extend into the valve chamber  162 , as shown. The first inlet port  146  extends through the first opposing wall  145  and the second inlet port  147  extends through the second opposing wall  143 . The first inlet port  146  is in selective fluid connection with the first electrostatic valve  130  via the first electrostatic valve  130  outlet port  138 . The second inlet  147  is in fluid communication with the second flow chamber  122  at a second flow opening  154 . An outlet port  148  extends from the valve chamber  162 , in some embodiments, through the first opposing wall  145 . The inlet ports  146  and  147  and the outlet port  148  can have any useful dimension. In one illustrative embodiment, the inlet ports  146  and  147  and the outlet port  148  have a diameter of about 0.5 to 2 mm.  
         [0046]     In some embodiments, an air spring (not shown) may extend from the valve chamber  162  through the second opposing wall  143  as described above. In the illustrative embodiment of  FIG. 2A , an air spring is not provided, and a seal member  144  is disposed where an optional air spring can be placed.  
         [0047]     Like above, a diaphragm  142  is positioned within the valve chamber  162 . In the illustrative embodiment, the diaphragm  142  extends generally along the first opposing wall  145  when in an un-activated state, as shown. Diaphragm  142  can include one or more electrodes. The electrode(s) can extend to near the edges of the valve chamber  162 , and in some embodiments, extends outside of the chamber  162 . The second opposing wall  143  can include one or more stationary electrodes. The second opposing wall  143  and the diaphragm  142  can be configured so that, in the un-activated state, the separation distance between the stationary electrode(s) on the second opposing wall  143  and the electrode(s) on the diaphragm  142  is smaller near the edges of the valve chamber  162 . This may help draw the diaphragm  142  toward the second opposing wall  143  in a rolling action when a voltage is applied between the stationary electrode on the opposing wall  143  and the electrode on the diaphragm  142 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve. The diaphragm  142  can have any useful dimensions. In one embodiment, the diaphragm  142  has a diameter from 15 to 30 mm within the chamber  162 . The diaphragm  142  can also have any useful displacement (greatest linear distance between the first opposing wall  145  and the second opposing wall  143 ). In one embodiment, the diaphragm  142  has a displacement of from about 100 to 200 micrometers.  
         [0048]     In some embodiments, the diaphragm  142  can include an orifice  157  or aperture  157  that extends or is disposed through the diaphragm  142 . This orifice  157  or aperture  157  can allow pressure equalization across the diaphragm  142 . The orifice  157  can have any useful dimension. In one embodiment, the orifice  157  has a diameter of about 0.5 to 2 mm.  
         [0049]     For purposes of illustration, the first opposing wall  145  is shown to be generally flat and with a raised portion adjacent the outlet  148 . However, the first opposing wall  145  may assume other shapes, depending upon the application. For example, the first opposing wall  145  may have different regions that are recessed or protrude against the diaphragm  142  in order to, for example, prevent the diaphragm  142  from achieving a suction lock and/or stiction against the first opposing wall  145 , or to improve the capabilities of the electrostatic valve  140 . Other shapes may also be used, including curved shapes, planar shapes or a combination thereof. Although the second opposing wall  143  is shown to be generally curved, other shapes may also be used, depending on the application.  
         [0050]     The body  141 , diaphragm  142 , and electrodes for the second electrostatic valve  140  can be similar to the body  131 , diaphragm  132  and electrodes for the first electrostatic valve  130  described above.  
         [0051]     An optional pilot outlet  160  can extend from the gas valve  100 . In one illustrative embodiment, the pilot outlet  160  can extend from the second flow chamber  122 . Also, an optional regulator  105  can be disposed between the gas outlet  113  and the second electrostatic valve  140  outlet port  148 .  
         [0052]      FIG. 2A  shows gas intrusion into the gas valve  100  when both electrostatic valves  130  and  140  are in a closed position. As shown, gas flows into the gas inlet  112 , into the first flow opening  151 . In the illustrative embodiment, the first flow opening  151  is in fluid connection with the second inlet port  137  and the first inlet port  136 . Gas can flow through the first and second inlet ports  136  and  137  onto the valve chamber  161  and air spring  134  (if present.)  
         [0053]     A restrictor  150  is shown disposed between the first flow opening  151  and the first inlet port  136 . The restrictor  150  can have any useful dimension such as, for example, a diameter of 0.1 to 0.5 mm. Gas can also flow through the restrictor  150  to a backside of the first main valve  101  through a first backside flow opening  152 . The restrictor  150  can limit the flow of gas to the backside of the first main valve  101  through a first backside flow opening  152 , and create a pressure drop there across. By limiting the flow of gas through the first backside flow opening  152 , the restrictor  150  can limit the gas pressure on the backside of the first main valve  101  to less than the gas pressure in the first flow chamber  121  when gas is flowing through the restrictor  150 . However, in steady state, the gas pressure on the backside of the first main valve  101  is substantially the same as the gas pressure in the first flow chamber  121 , and the spring  102  keeps the first main valve  101  closed.  
         [0054]      FIG. 2B  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 2A  with the first electrostatic valve  130  open and the second electrostatic gas valve  140  closed. As shown, gas flows from the first electrostatic valve  130  chamber  161  into the first electrostatic valve  130  gas outlet port  138 , through a connecting conduit  153  into the second electrostatic valve  140  inlet port  146  and into the second electrostatic valve  140  chamber  162 . Gas can then flow through the gas inlet port  147  and into the second flow chamber  122  via the second flow opening  154 . Gas can also flow from the connecting conduit  153  to the backside of the second main valve  103  via a second backside flow opening  155 . In some embodiments, gas flow past the restrictor  150  can cause at least a momentary pressure differential across the first flow chamber  121  and the backside of the first main valve  101 , thus causing the first main valve  101  to open, at least momentarily.  
         [0055]      FIG. 2C  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 2B  with both electrostatic gas valves  130  and  140  in an open position. As shown, gas flows from chamber  162  of the second electrostatic valve  140  into the third flow chamber  123  via the outlet port  148 . As gas flow increases though the gas valve  100 , the first and second main valves  101  and  103  respond by opening accordingly.  
         [0056]      FIG. 3  is a schematic cross-sectional view of another illustrative embodiment of a gas valve  200  with both electrostatic gas valves closed. The gas valve  200  includes a valve body  215  that has a gas inlet  212 , a gas outlet  213 , and a conduit  214  connecting the gas inlet  212  and gas outlet  213 . The conduit  214  can include any number of flow chambers. In the illustrative embodiment shown, the conduit  214  includes a first flow chamber  221 , a second flow chamber  222 , and a third flow chamber  223 . The first flow chamber  221  can be in fluid connection with the gas inlet  212 . The third flow chamber  223  can be in fluid connection with the gas outlet  213 . The second flow chamber  222  can be in selective fluid connection with both the first flow chamber  221  and the third flow chamber  223 .  
         [0057]     A first main valve  201  can be disposed between the first flow chamber  221  and the second flow chamber  222 . In the illustrative embodiment, the first main valve  201  is a diaphragm valve with a resilient spring  202  causing the first main valve  201  to be a normally closed valve. A second main valve  203  can be disposed between the second flow chamber  222  and the third flow chamber  223 . In the illustrative embodiment shown, the second main valve  203  is a diaphragm valve with a resilient spring  204  causing the second main valve  203  to be a normally closed valve.  
         [0058]     In some embodiments, the first and second main valves  201  and  203  can be controlled by a first electrostatic diaphragm valve  230  and/or a second electrostatic diaphragm valve  240 , For example, the first electrostatic diaphragm valve  230  can be disposed between the first flow chamber  221  and the second flow chamber  222 . In the illustrative embodiment, the first electrostatic diaphragm valve  230  is a diaphragm valve with a resilient bias member or spring  239  causing the first electrostatic diaphragm valve  230  to be a normally closed valve. However, it is contemplated that a separate resilient bias member or spring  239  is not required in all embodiments. For example, in some embodiments, the diaphragm itself may provide elastic restoring forces sufficient to close the valve.  
         [0059]     The second electrostatic diaphragm valve  240  can be disposed between the second flow chamber  222  and the third flow chamber  223 . In the illustrative embodiment, the second electrostatic diaphragm valve  240  is a diaphragm valve with a resilient bias member or spring  249  causing the second electrostatic diaphragm valve  240  to be a normally closed valve. Again, a separate resilient bias member or spring  149  is not required in all embodiments.  
         [0060]     The illustrative first electrostatic diaphragm valve  230  includes a body  231  with a first opposing wall  235  and a second opposing wall  233  that define a valve chamber  261 . A first inlet port  236  and a second inlet port  237  extend into the valve chamber  261 , as shown. The first inlet port  236  extends through the first opposing wall  235  and the second inlet port  237  extends through the second opposing wall  233 . The first and second inlet ports  236  and  237  are in fluid communication with the first flow chamber  221  at a first flow opening  251 . An outlet port  238  extends from the valve chamber  261 , in some embodiments, through the first opposing wall  235 . The inlet ports  236  and  237  and the outlet port  238  can have any useful dimension. In one embodiment, the inlet ports  236  and  237  and the outlet port  238  have a diameter of about 0.5 to 2 mm.  
         [0061]     In some embodiments, the inlet port  237  is disposed near a center of the second opposing wall  233 . As voltage is applied to the electrostatic valve  230 , the diaphragm  232  moves toward the second opposing wall  233  and can eventually seal the inlet port  237  disposed on the second opposing wall  233 . The inlet port  237  can assist in modulation of the electrostatic valve  230 . In some illustrative embodiments, the electrostatic diaphragm valve  230  can be modulated by adjusting the voltage applied to the electrostatic diaphragm valve  230  (e.g., voltage applied across the electrodes described below.)  
         [0062]     A diaphragm  232  is positioned within the valve chamber  261 . In the illustrative embodiment, the diaphragm  232  extends generally along the first opposing wall  235  in an un-activated state, as shown. Diaphragm  232  can include one or more electrodes. For example, an electrode can extend near the edges of the valve chamber  261 , and in some embodiments, can extend outside of the chamber  261 .  
         [0063]     The second opposing wall  233  can include one or more stationary electrodes. The second opposing wall  233  and the diaphragm  232  can be configured so that, in the un-activated state, the separation distance between the stationary electrode and the electrode on the diaphragm  232  is smaller near the edges of the valve chamber  261 . This may help draw the diaphragm  232  toward the second opposing wall  233  in a rolling action when a voltage is applied between the stationary electrode on the opposing wall  233  and the electrode on the diaphragm  232 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve.  
         [0064]     The diaphragm  232  can have any useful dimensions. In one embodiment, the diaphragm  232  has a diameter from 15 to 30 mm inside of the chamber  261 . The diaphragm  232  can have any useful displacement (greatest linear distance between the first opposing wall  235  and the second opposing wall  233 ). In one embodiment, the diaphragm has a displacement of from about 100 to 200 micrometers.  
         [0065]     The diaphragm  232  can include an orifice or aperture  256  that extends or is disposed through the diaphragm  232 . This orifice or aperture  256  can allow pressure equalization across the diaphragm  232 . The orifice  256  can be placed at any useful position on the diaphragm  232 , and can have any useful dimension. In one embodiment, the orifice  256  has a diameter of about 0.5 to 2 mm.  
         [0066]     For purposes of illustration, the first opposing wall  235  is shown to be generally flat and with a raised portion adjacent the outlet  238 . However, the first opposing wall  235  may assume other shapes, depending upon the application. For example, the first opposing wall  235  may have different regions that are recessed or protrude against the diaphragm  232  in order to, for example, prevent the-diaphragm  232  from achieving a suction lock and/or stiction against the first opposing wall  235 , or to improve the capabilities of the electrostatic valve  230 . Other shapes may also be used, including curved shapes, planar shapes, or a combination of curved and planar shapes, as desired. Although the second opposing wall  233  is shown to be generally curved, other shapes may be used, depending on the application.  
         [0067]     The body  231  may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In some embodiments, the body  231  is constructed by molding a high temperature plastic such as ULTEM™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material.  
         [0068]     The diaphragm  232  may be made from any suitable material. In some embodiments, the diaphragm  232  has elastic, resilient, flexible and/or other elastomeric property. In one illustrative embodiment, the diaphragm  232  is made from a polymer such as KAPTON™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX™ (available from ICI Films, Wilmington, Del.), MYLAR™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), or any other suitable material.  
         [0069]     The electrode secured to the diaphragm  232  can be provided, for example, by patterning a conductive coating on the diaphragm  232 . For example, the diaphragm  232  electrode(s) may be formed by printing, plating or deposition of metal or other conductive material. In some cases, the electrode layer may be patterned using a dry film resist, as is known in the art. The same or similar techniques may be used to provide the stationary electrode on the second opposing wall  233  of the body  231 . Rather than providing a separate electrode layer, it is contemplated that the diaphragm  232  and/or second opposing wall  233  may be made conductive so as to function as an electrode.  
         [0070]     A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the diaphragm  232  electrode and the stationary electrode on the opposing wall  233 . The dielectric may be coated over the diaphragm  232  electrode, the stationary electrode on the opposing wall  233 , or both. An advantage of using a polymer based substrate and/or diaphragm is that the resulting electrostatic valve may be made cheaper and lighter, and/or suitable for small handheld, or even suitable for disposable or reusable applications.  
         [0071]     The illustrative second electrostatic diaphragm valve  240  includes a body  241  with a first opposing wall  245  and a second opposing wall  243  that define a valve chamber  262 . A first inlet port  246  and a second inlet port  247  extend into the valve chamber  262 , as shown. The first inlet port  246  extends through the first opposing wall  245  and the second inlet port  247  extends through the second opposing wall  243 . The first inlet port  246  is in selective fluid connection with the first electrostatic valve  230  via the first electrostatic valve  230  outlet port  238 . The second inlet  247  is in fluid communication with the second flow chamber  222  at a second flow opening  254 . An outlet port  248  extends from the valve chamber  262 , in some embodiments, through the first opposing wall  245 . The inlet ports  246  and  247  and the outlet port  248  can have any useful dimension. In one embodiment, the inlet ports  246  and  247  and the outlet port  248  have a diameter of about 0.5 to 2 mm.  
         [0072]     In some embodiments, the inlet port  247  is disposed near a center of the second opposing wall  243 . As voltage is applied to the electrostatic valve  240 , the diaphragm  242  moves toward the second opposing wall  243 . Eventually, the diaphragm  242  seals the inlet port  247 . In some illustrative embodiments, the electrostatic diaphragm valve  240  can be modulated by adjusting the voltage applied to the electrostatic diaphragm valve  240  (e.g., voltage applied across the electrodes described below.)  
         [0073]     The diaphragm  242  is positioned within the valve chamber  261 . In the illustrative embodiment, the diaphragm  242  extends generally along the first opposing wall  245  in an un-activated state, as shown. Diaphragm  242  can include one or more electrodes. The electrode(s) can extend near the edges of the valve chamber  262 , and in some embodiments, can extend outside of the chamber  262 . The second opposing wall  243  can include one or more stationary electrodes. The second opposing wall  243  and the diaphragm  242  can be configured so that, in the un-activated state, the separation distance between the stationary electrode on the second opposing wall  243  and the electrode on the diaphragm  242  is smaller near the edges of the valve chamber  261 . This may help draw the diaphragm  242  toward the second opposing wall  243  in a rolling action when a voltage is applied between the stationary electrode on the opposing wall  243  and the electrode on the diaphragm  242 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve.  
         [0074]     The diaphragm  242  can have any useful dimensions. In one embodiment, the diaphragm  242  has a diameter from 15 to 30 mm. The diaphragm  242  can have any useful displacement (greatest linear distance between the first opposing wall  245  and the second opposing wall  243 ). In one embodiment, the diaphragm  242  has a displacement of from about 100 to 200 micrometers.  
         [0075]     The diaphragm  242  can include an orifice or aperture  257  that extends or is disposed through the diaphragm  242 . This orifice or aperture  257  can allow pressure equalization across the diaphragm  242 , when the orifice or aperture  257  is not sealed against the second opposing wall  243 . The orifice  257  can have any useful dimension. In one embodiment, the orifice  257  has a diameter of about 0.5 to 2 mm.  
         [0076]     For purposes of illustration, the first opposing wall  245  is shown to be generally flat and with a raised portion adjacent the outlet  248 . However, the first opposing wall  245  may assume other shapes, depending upon the application. For example, the first opposing wall  245  may have different regions that are recessed or protrude against the diaphragm  242  in order to, for example, prevent the diaphragm  242  from achieving a suction lock and/or stiction against the first opposing wall  245 , or to improve the capabilities of the electrostatic valve  240 . Other shapes may also be used, including curved shapes, planar shapes, or a combination of curved and planar shapes, as desired. Although the second opposing wall  243  is shown to be generally curved, other shapes may be used, depending on the application. The body  241 , diaphragm  242 , and electrodes for the second electrostatic valve  240  can be similar to the body  231 , diaphragm  232  and electrodes for the first electrostatic valve  230  described above.  
         [0077]     An optional pilot outlet  260  can extend from the gas valve  200 . In one illustrative embodiment, the pilot outlet  260  can extend from the second flow chamber  222 . Also, an optional regulator  205  can be disposed between the gas outlet  213  and the second electrostatic valve  240  outlet port  248 .  
         [0078]      FIG. 4  is a schematic cross-sectional view of an illustrative embodiment of a gas valve  300  that includes an optional pressure sensor  370 . The pressure sensor  370  can be disposed on any of the embodiments of the gas valve, as desired. The pressure sensor  370  can be electrically coupled to a controller  390  to aid in modulating the electrostatic diaphragm valves described herein. The pressure sensor  370 , with its associated control electronics, can optionally replace the pressure regulator  105 ,  205  and  405  described herein.  
         [0079]     The pressure sensor  370  can be included on the gas valve  300  as shown. In one illustrative embodiment, the pressure sensor  370  is in fluid communication with the gas outlet  313  via a pressure sensor conduit  336 . The pressure sensor conduit  336  can have any useful dimension such as  1  to  2  mm 2 . The pressure sensor  370  shown is an electrostatic diaphragm type pressure sensor, in other embodiments, the pressure sensor and be a traditional pressure sensor.  
         [0080]     The illustrative electrostatic diaphragm type pressure sensor  370  includes a body  341  with a first opposing wall  335 , a second opposing wall  343 , and a diaphragm  342  disposed between the first opposing wall  335  and the second opposing wall  343 . The first opposing wall  335  and the diaphragm  342  define a pressure sensing chamber  361 . The second opposing wall  343  and the diaphragm  342  define a chamber  360  open to the atmosphere via conduit  395 . The pressure sensor conduit  336  allows gas to flow into the pressure sensing chamber  361 . The gas flow exerts a force on the diaphragm  342  and can move the diaphragm  342  toward at least a portion of the second opposing wall  343 . Pressure can be determined by measuring the capacitance between the diaphragm  342  electrode and the opposing wall  343  electrode.  
         [0081]     In the illustrative embodiment, the diaphragm  342  extends generally along the first opposing wall  335  (the first opposing wall preferably including an electrically insulating material) in an un-pressurized state, as shown. Diaphragm  342  can include one or more electrodes on an insulating membrane as described in U.S. Patent Application Publication No., 2003/0234376. Like above, the electrode(s) can extend near the edges of the sealed chamber  360 . The second opposing wall  343  can include one or more stationary electrodes. The second opposing wall  343  and the diaphragm  342  can be configured so that, in the un-pressurized state, the separation distance between the stationary electrode and the electrode on the diaphragm  342  is smaller near the edges of the sealed chamber  360 . This may help the diaphragm  342  move toward the second opposing wall  343  in a rolling action when gas pressure is applied to the diaphragm  342 . Such a rolling action may help increase the precision of the electrostatic pressure sensor  370 , particularly at lower input pressures.  
         [0082]     The diaphragm  342  can have any useful dimensions. In one embodiment, the diaphragm  342  has a diameter from 15 to 30 mm. The diaphragm  342  can also have any useful displacement (greatest linear distance between the first opposing wall  335  and the second opposing wall  343 ). In one embodiment, the diaphragm has a displacement of from about 100 to 200 micrometers.  
         [0083]     For purposes of illustration, the first opposing wall  335  is shown to be generally planar. However, the first opposing wall  335  may assume other shapes, depending upon the application. For example, the first opposing wall  335  may have different regions that are recessed or protrude against the diaphragm  342  in order to, for example, improve the capabilities of the electrostatic pressure sensor  370 . Other shapes may also be used, including planar shapes, curved shapes, or a combination of curved and planar shapes, as desired. Although the second opposing wall  343  is shown to be generally curved, other shapes may be used, depending on the application.  
         [0084]     The second opposing wall  343  is shown in  FIG. 4  as having a generally curved shape. However, the second opposing wall  343  can have a planar shape or a combination of curved and planar shapes, as desired. The shape of the second opposing wall  343  can be selected to obtain a desired pressure versus capacitance output curve.  
         [0085]     For example,  FIG. 5  shows an illustrative pressure sensor  370  that includes a body  341  with a first opposing wall  335  and a second opposing wall  343 (including a stationary electrode), and a diaphragm  342  (including a movable electrode) disposed between the first opposing wall  335  and the second opposing wall  343 . The first opposing wall  335  and the diaphragm  342  define a pressure sensing chamber  361 . The second opposing wall  343  and the diaphragm  342  define a chamber  360  open to the atmosphere via conduit  395 . The second opposing wall  343  has a planar shape.  FIG. 7  illustrates one possible pressure versus capacitance curve for the pressure sensor  370  shown in  FIG. 5 . Note, in the illustrative embodiment, the pressure versus capacitance curve is fairly linear along a relatively wide range of pressures.  
         [0086]     The pressure sensor conduit  336  allows gas to flow into the pressure sensing chamber  361 . The gas flow exerts a force on the diaphragm  342  and moves the diaphragm  342  (and movable electrode) toward at least a portion of the second opposing wall  343  (including the stationary electrode). Pressure can be determined by measuring the capacitance between the diaphragm  342  electrode and the opposing wall  343  electrode by the controller  390 . The controller  390  can provide an output signal based, at least in part, on the measured capacitance.  
         [0087]      FIG. 6  shows another illustrative embodiment of a pressure sensor  370  that includes a body  341  with a first opposing wall  335  and a second opposing wall  343  (including a fixed electrode), and a diaphragm  342  (including a movable electrode) disposed between the first opposing wall  335  and the second opposing wall  343   a  and  343   b . The first opposing wall  335  and the diaphragm  342  define a pressure sensing chamber  361 . The second opposing wall  343   a  and  343   b  and the diaphragm  342  define a chamber  360  open to the atmosphere via conduit  395 . The second opposing wall  343   a  and  343   b  has a compound planar shape. A second opposing wall first portion  343   a  can form a first angle θ 1  with respect to the diaphragm  342 . A second opposing wall second portion  343   b  can form a second angle θ 2  with respect to the diaphragm  342 . The first angle and the second angle can be different. In the embodiment shown, the second angle θ 2  is less or smaller than the first angle θ 1 . This may alter the shape of the pressure versus capacitance curve of the pressure sensor, as desired.  
         [0088]      FIG. 8  shows another illustrative pressure sensor  370 . The pressure sensor  370  includes a first pressure sensor element  370 A and a second pressure sensor element  370 B in fluid communication with a pressure sensor conduit  336  that allows gas to flow into the pressure sensing chamber  361 . The second opposing walls  343   a  and  343   b  and the diaphragm  342  define two chambers  360   a  and  360   b  open to the atmosphere via conduits  395   a  and  395   b . The gas flow exerts a force on the diaphragm  342  (movable electrode) and can move the diaphragm  342  toward at least a portion of the second opposing wall  343   a  and  343   b  (stationary electrode). Pressure can be determined by measuring the capacitance between the diaphragm  342  electrode and the opposing wall  343   a  and  343   b  electrode by the controller.  
         [0089]     It is understood that the pressure sensor  370  can be formed of 3, 4, 5, 6 or more pressure sensor elements. A second opposing wall first portion  343   a  can form a first angle θ 3  with respect to the diaphragm  342 . A second opposing wall second portion  343   b  can form a second angle θ 4  with respect to the diaphragm  342 . The first angle and the second angle can be different. In the embodiment shown, the first angle θ 3  is less than the second angle θ 4 . In some embodiments, the first pressure sensor element  370 A may be used to measure lower input pressures, while the second pressure sensor element  370 B may be used to measure higher input pressures.  
         [0090]      FIG. 9  shows another embodiment of a pressure sensor  370  array including a first pressure sensor element S 1 , a second pressure sensor element S 2 , and a third pressure sensor element S 3 . Each pressure sensor element is shown in fluid communication with a separate pressure sensor conduit  336   a ,  336   b , and  336   c , respectively to allow gas to flow into each pressure sensing chamber  361   a ,  336   b , and  336   c , respectively. It is understood that the pressure sensor  370  array can be formed of 2, 3, 4, 5, 6 or more pressure sensor elements, as desired. Each pressure sensor includes a chamber  360   a ,  360   b  and  360   c  open to the atmosphere via conduit  395   a ,  395   b , and  395   c.    
         [0091]     A second opposing wall first portion  343   a  can form a first angle  05  with respect to the diaphragm  342   a . A second opposing wall second portion  343   b  can form a second angle θ 6  with respect to the diaphragm  342   b . A second opposing wall second portion  343   c  can form a third angle  07  with respect to the diaphragm  342   c . The first angle, second angle, and third angle can be different. In the embodiment shown, the first angle θ 5  is less than the second angle θ 6 , and the second angle θ 6  is less than the third angle θ 7 .  
         [0092]      FIG. 10  illustrates a graph of sensed capacitance value versus pressure for a pressure sensor  370  array shown in  FIG. 9 , when the same an input pressure is provided to the pressure sensor conduits  336   a ,  336   b  and  336   c . In this embodiment, the first pressure sensor element S 1  can have a linear pressure sensitive region from 0 to A-A, the second pressure sensor element S 2  can have a linear pressure sensitive region from A-A to B-B, and a third pressure sensor element S 3  can have a linear pressure sensitive region from B-B to C-C. The pressure sensor  370  array can thus provide a more precise pressure sensing value over a wider pressure range.  
         [0093]     The body  341  may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In some embodiments, the body  341  is constructed by molding a high temperature plastic such as ULTEM™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material.  
         [0094]     The diaphragm  342  may be made from any suitable material. For example, the diaphragm  342  may be made from a material having an elastic, resilient, flexible and/or other elastomeric property. In one illustrative embodiment, the diaphragm  342  is made from a polymer such as KAPTON™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX™ (available from ICI Films, Wilmington, Del.), MYLAR™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), or any other suitable material.  
         [0095]     The electrode secured to the diaphragm  342  can be provided, for example, by patterning a conductive coating on the diaphragm  342 . For example, the diaphragm  342  electrode may be formed by printing, plating or deposition of metal or conductive material. In some cases, the electrode layer may be patterned using a dry film resist, as is known in the art. The same or similar techniques may be used to provide the stationary electrode on the second opposing wall  343  of the body  341 . Rather than providing a separate electrode layer, it is contemplated that the diaphragm  342  and/or second opposing wall  343  may be made conductive so as to function as an electrode.  
         [0096]     A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the diaphragm  342  electrode and the stationary electrode on the opposing wall  343 . The dielectric may be coated over the diaphragm  342  electrode, the stationary electrode on the opposing wall  343 , or both. An advantage of using a polymer based substrate and/or diaphragm is that the resulting electrostatic valve may be made cheaper and lighter, and/or suitable for small handheld, or even suitable for disposable or reusable applications.  
         [0097]      FIG. 11A  is a schematic cross-sectional view of another illustrative embodiment of a gas valve  400 . The gas valve  400  includes a valve body  415  that has a gas inlet  412 , a gas outlet  413 , and a conduit  414  connecting the gas inlet  412  and gas outlet  413 . The conduit  414  can include any number of flow chambers, as desired. In the illustrative embodiment, the conduit  414  includes a first flow chamber  421 , a second flow chamber  422 , and a third flow chamber  423 . The first flow chamber  421  can be in fluid connection with the gas inlet  412 . The third flow chamber  423  can be in fluid connection with the gas outlet  413 . The second flow chamber  422  can be in selective fluid connection with both the first flow chamber  421  and the third flow chamber  423 , as further described below.  
         [0098]     A first main valve  401  can be disposed between the first flow chamber  421  and the second flow chamber  422 . In the illustrative embodiment shown, the first main valve  401  is a diaphragm valve with a resilient spring  402  causing the first main valve  401  to be a normally closed valve. A second main valve  403  can be disposed between the second flow chamber  422  and the third flow chamber  423 . In the illustrative embodiment shown, the second main valve  403  is a diaphragm valve with a resilient spring  404  causing the second main valve  403  to be a normally closed valve. In some embodiments, the first and second main valves  401  and  403  can be controlled by a first electrostatic diaphragm valve  430  and/or a second electrostatic diaphragm valve  440 .  
         [0099]     In the illustrative embodiment, a first electrostatic diaphragm valve  430  is disposed between the first flow chamber  421  and the second flow chamber  422 , as shown. In the illustrative embodiment shown, the first electrostatic diaphragm valve  430  is a diaphragm valve with a resilient bias member or spring  439  causing the first electrostatic diaphragm valve  430  to be a normally closed valve. However, a separate resilient bias member or spring  439  is not required in all embodiments. For example, and in some embodiments, the diaphragm itself may have elastic restoring forces sufficient to close the valve.  
         [0100]     A second electrostatic diaphragm valve  440  can be disposed between the second flow chamber  422  and the third flow chamber  423 . In the illustrative embodiment, the second electrostatic diaphragm valve  440  is a diaphragm valve with a resilient bias member or spring  449  causing the second electrostatic diaphragm valve  440  to be a normally closed valve. Again, resilient bias member or spring  449  is not required in all embodiments.  
         [0101]     The illustrative first electrostatic diaphragm valve  430  includes a body  431  with a first opposing wall  435  and a second opposing wall  433  that define a valve chamber  461 . A first inlet port  436  extends into the valve chamber  461 , as shown. The first inlet port  436  extends through the first opposing wall  435 . The first inlet port  436  is in fluid communication with the first flow chamber  421  at a first flow opening  451 . An outlet port  438  extends from the valve chamber  461 , in some embodiments, through the first opposing wall  435 . The inlet port  436  and the outlet port  438  can have any useful dimension. In one illustrative embodiment, the inlet port  436  and the outlet port  438  have a diameter of about 0.5 to 2 mm.  
         [0102]     A diaphragm  432  is positioned within the valve chamber  461 . In the illustrative embodiment, the diaphragm  432  extends generally along the first opposing wall  435  in an un-activated state, as shown. Diaphragm  432  can include one or more electrodes. The electrode(s) can extend near the edges of the valve chamber  461 , and in some embodiments, can extend outside of the chamber  461 . The second opposing wall  433  can include one or more stationary electrodes. The second opposing wall  433  and the diaphragm  432  can be configured so that, in the un-activated state, the separation distance between the stationary electrode(s) and the electrode(s) on the diaphragm  432  is smaller near the edges of the valve chamber  461 . This may help draw the diaphragm  432  toward the second opposing wall  433  in a rolling action when a voltage is applied between the stationary electrode on the opposing wall  433  and the electrode on the diaphragm  432 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve.  
         [0103]     The diaphragm  432  can have any useful dimensions. In one embodiment, the diaphragm  432  has a diameter from 15 to 30 mm. The diaphragm  432  can also have any useful displacement (greatest linear distance between the first opposing wall  435  and the second opposing wall  433 ). In one embodiment, the diaphragm has a displacement of from about 100 to 200 micrometers.  
         [0104]     In some embodiments, the diaphragm  432  can include an orifice or aperture  456  that extends or is disposed through the diaphragm  432 . This orifice or aperture  456  can allow pressure equalization across the diaphragm  432  until the orifice or aperture  456  is sealed by the second opposing wall  433 . The orifice  456  can have any useful dimension. In one embodiment, the orifice  456  has a diameter of about 0.5 to 2 mm.  
         [0105]     For purposes of illustration, the first opposing wall  435  is shown to be generally flat and with a raised portion adjacent the outlet  438 . However, the first opposing wall  435  may assume other shapes, depending upon the application. For example, the first opposing wall  435  may have different regions that are recessed or protrude against the diaphragm  432  in order to, for example, prevent the diaphragm  432  from achieving a suction lock and/or stiction against the first opposing wall  435 , or to improve the capabilities of the electrostatic valve  430 . Other shapes may also be used, including curved shapes, planar shapes, and a combination of curved and planar shapes, as desired. Although the second opposing wall  433  is shown to be generally curved, other shapes may be used, depending on the application.  
         [0106]     The body  431  may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In some embodiments, the body  431  is constructed by molding a high temperature plastic such as ULTEM™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material.  
         [0107]     The diaphragm  432  may be made from any suitable material. In some illustrative embodiments, the diaphragm  432  includes a material that has an elastic, resilient, flexible and/or other elastomeric property. In one illustrative embodiment, the diaphragm  432  is made from a polymer such as KAPTON™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX™ (available from ICI Films, Wilmington, Del.), MYLAR™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), or any other suitable material.  
         [0108]     The electrode secured to the diaphragm  432  can be provided, for example, by patterning a conductive coating on the diaphragm  432 . For example, the diaphragm  432  electrode may be formed by printing, plating or deposition of metal or other conductive material. In some cases, the electrode layer may be patterned using a dry film resist, as is known in the art. The same or similar techniques may be used to provide the stationary electrode on the second opposing wall  433  of the body  431 . Rather than providing a separate electrode layer, it is contemplated that the diaphragm  432  and/or second opposing wall  433  may be made conductive so as to function as an electrode, if desired.  
         [0109]     A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the diaphragm  432  electrode and the stationary electrode on the opposing wall  433 . The dielectric may be coated over the diaphragm  432  electrode, the stationary electrode on the opposing wall  433 , or both. An advantage of using a polymer based substrate and/or diaphragm is that the resulting electrostatic valve may be made cheaper and lighter, and/or suitable for small handheld, or even suitable for disposable or reusable applications.  
         [0110]     The illustrative second electrostatic diaphragm valve  440  includes a body  441  with a first opposing wall  445  and a second opposing wall  443  that define a valve chamber  462 . An inlet port  446  extends into the valve chamber  462 , as shown. The inlet port  446  extends through the first opposing wall  445 . The inlet port  446  is in selective fluid connection with the first electrostatic valve  430  via the first electrostatic valve  430  outlet  438 . An outlet port  448  extends from the valve chamber  462 , in some embodiments, through the first opposing wall  445 . The inlet port  446  and the outlet port  448  can have any useful dimension. In one embodiment, the inlet port  446  and the outlet port  448  have a diameter of about 0.5 to 2 mm.  
         [0111]     An elastic diaphragm  442  is positioned within the valve chamber  462 . In the illustrative embodiment, the elastic diaphragm extends generally along the first opposing wall  445  in an un-activated state, as shown. Diaphragm  442  can include one or more electrodes. The electrode(s) can extend near the edges of the valve chamber  462 , and in some embodiments, can extend outside of the chamber  462 . The second opposing wall  443  can include one or more stationary electrodes. The second opposing wall  443  and the diaphragm  442  can be configured so that, in the un-activated state, the separation distance between the stationary electrode(s) on the second opposing wall  443  and the electrode(s) on the diaphragm  442  is smaller near the edges of the valve chamber  461 . This may help draw the diaphragm  442  toward the second opposing wall  443  in a rolling action when a voltage is applied between the stationary electrode(s) on the opposing wall  443  and the electrode(s) on the diaphragm  442 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the electrostatic valve.  
         [0112]     The diaphragm  442  can have any useful dimensions. In one embodiment, the diaphragm  442  has a diameter from 15 to 30 mm. The diaphragm  442  can also have any useful displacement (greatest linear distance between the first opposing wall  445  and the second opposing wall  443 .) In one embodiment, the diaphragm  442  has a displacement of from about 100 to 200 micrometers.  
         [0113]     In some embodiments, the diaphragm  442  includes an orifice or aperture  457  that extends or is disposed through the diaphragm  442 . This orifice or aperture  457  can allow pressure equalization across the diaphragm  442  until the orifice or aperture  457  is sealed by the second opposing wall  443 . The orifice  457  can have any useful dimension. In one embodiment, the orifice  457  has a diameter of about 0.5 to 2 mm.  
         [0114]     For purposes of illustration, the first opposing wall  445  is shown to be generally flat and with a raised portion adjacent the outlet  448 . However, the first opposing wall  445  may assume other shapes, depending upon the application. For example, the first opposing wall  445  may have different regions that are recessed or protrude against the diaphragm  442  in order to, for example, prevent the diaphragm  442  from achieving a suction lock and/or stiction against the first opposing wall  445 , or to improve the capabilities of the electrostatic valve  440 . Other shapes may also be used, including curved shapes, planar shapes, or a combination of curved and planar shapes, as desired. Although the second opposing wall  443  is shown to be generally curved, other shapes may be used, depending on the application.  
         [0115]     The body  441 , diaphragm  442 , and electrodes for the second electrostatic valve  440  can be similar to the body  431 , diaphragm  432  and electrodes for the first electrostatic valve  430  described above.  
         [0116]     An optional pilot outlet  460  can extend from the gas valve  400 . In one illustrative embodiment, the pilot outlet  460  can extend from the second flow chamber  422 . Also, an optional regulator  405  can be disposed between the gas outlet  413  and the second electrostatic valve  440  outlet port  448 .  
         [0117]      FIG. 11A  illustrates gas intrusion into the gas valve  400  when both electrostatic valves  430  and  440  are in a closed position. As shown, gas flows into the gas inlet  412 , into the first flow opening  451 . In the illustrative embodiment, the first flow opening  451  is in fluid connection with the inlet port  436 . Gas can flow through the inlet port  436  onto the valve chamber  461 .  
         [0118]     An optional trap  500  is shown positioned in gas inlet  412 . In other embodiments, the trap  500  is located anywhere in the gas flow path upstream of the electrostatic diaphragm valves described herein. In some embodiments, the trap  500  removes particulate matter, water vapor, or other gas vapors such as, for example, glycol vapor, that can be harmful to the electrostatic valves downstream of the trap  500 . One embodiment of the trap  500  is shown in  FIG. 12  and described below.  
         [0119]     A restrictor  450  is shown disposed between the first flow opening  451  and the first inlet port  436 . The restrictor  450  can have any useful dimension such as, for example, a diameter of 0.1 to 0.5 mm. Gas can also flow through the restrictor  450  to a backside of the first main valve  401  through a first backside flow opening  452 . The restrictor  450  can limit the flow of gas to the backside of the first main valve  401  through a first backside flow opening  452 . By limiting the flow of gas through the first backside flow opening  452 , the restrictor  450  can limit the gas pressure on the backside of the first main valve  401  to less than the gas pressure in the first flow chamber  421 . This may tend to open the first main valve  401   
         [0120]      FIG. 11B  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 11A  with the first electrostatic valve  430  open and the second electrostatic gas valve  440  closed. As shown, gas flows from the chamber  461  of the first electrostatic valve through the first electrostatic valve  430  gas outlet port  438 , through the second flow chamber  422 , into the second flow opening  454 , into the second electrostatic valve  440  inlet port  446  and into the second electrostatic valve  440  chamber  462 . Gas can also flow from the inlet port  446  to the backside of the second main valve  403  via a second backside flow opening  455 .  
         [0121]     A restrictor  456  is shown disposed between the second flow opening  454  and the inlet port  446 . The restrictor  456  can have any useful dimension such as, for example, 0.1 to 0.5 mm 2 . Gas can also flow through the restrictor  456  to a backside of the second main valve  403  through a second backside flow opening  455 . The restrictor  456  can limit the flow of gas to the backside of the second main valve  403  through a second backside flow opening  455 . By limiting the flow of gas through the second backside flow opening  455 , the restrictor  456  can limit the gas pressure on the backside of the second main valve  403  to less than the gas pressure in the second flow chamber  422 . This may tend to open the second main valve  403 .  
         [0122]      FIG. 11C  is a schematic cross-sectional view of the illustrative gas valve shown in  FIG. 11B  with both electrostatic gas valves  430  and  440  open. As shown, gas flows from the second electrostatic valve  440  chamber  462  into the third flow chamber  423  via the outlet port  448 . As gas flow increases though the gas valve  400 , the first and second main valves  401  and  403  respond by opening accordingly.  
         [0123]      FIG. 12  is a schematic cross-sectional view of an illustrative trap  500 . In one embodiment, the trap  500  is positioned in the gas flow path ahead of the electrostatic diaphragm valves. The trap  500  includes a trap inlet  510  and a trap outlet  520 . In the embodiment shown, a series of intersecting orthogonal gas flow channels are disposed between the trap inlet  510  and a trap outlet  520  providing a gas flow path from the trap inlet  510  to the trap outlet  520 . In one embodiments, the intersecting orthogonal gas flow channels decrease in cross-sectional area.  
         [0124]     Electrostatic diaphragm valves described herein can be operated as either an on/off valve or a regulating or modulating valve where the diaphragm can operate at any position between a first closed position and a second open position. An air spring, regulator, pilot outlet, and one or more pressure sensors may or may not be included in the gas valve embodiments of the invention, as desired. Also, while similar first and second electrostatic diaphragm valves are shown in the Figures, the first electrostatic valve can be different than the second electrostatic diaphragm valve. In other embodiments, the valve can include at least one electrostatic diaphragm valve and at least one traditional electromagnetic valve.  
         [0125]     The invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the invention can be applicable will be readily apparent to those of skill in the art upon review of the instant specification.