Compressed gas cylinder cabinet with regulated exhaust control

Abstract

A gas cabinet and a method of controlling air flow through said gas cabinet. The gas cabinet includes an enclosure; a damper having at least two flow rate positions; an exhaust outlet; a set of sensors; and a programmable logic controller configured to change a flow rate position of the damper from a first flow rate position to a second flow rate position based on the state of the sensors. The method includes using the damper to lower the amount of exhausted air required under normal operating conditions and using the damper to increase the amount of exhausted air when a possible gas leak is detected.

What is claimed is: 
     
         1 . A gas cabinet, comprising:
 an enclosure;   a damper having at least two flow rate positions;   an exhaust outlet;   a set of sensors; and   a programmable logic controller configured to change a flow rate position of said damper from a first flow rate position to a second flow rate position based on the state of said sensors.   
     
     
         2 . The gas cabinet of  claim 1 , wherein said set of sensors includes one or more sensors selected comprising a gas flow sensor, a gas sensor, a gas cylinder weight sensor, a low pressure sensor, or a high pressure sensor. 
     
     
         3 . The gas cabinet of  claim 1 , wherein said programmable logic controller is configured to change said damper from said first flow rate position to said second flow rate position if one or more sensors of said set of sensors indicates a gas leak within said enclosure, said second flow rate position having a higher flow rate than said first flow rate position. 
     
     
         4 . The gas cabinet of  claim 3 , wherein (i) said first flow rate position is a fully closed position and said second flow position is a fully open position or (ii) said first flow rate position is a partially closed position and said second flow rate position is a more open position than said first position. 
     
     
         5 . The gas cabinet of  claim 1 , wherein said damper includes:
 a first set of fixed openings;   a moveable plate having a second set of openings;   means for moving said second plate relative to said first set of openings; and   wherein in a first position of said plate corresponding to said first flow rate position, said plate blocks each of said fixed openings and in a second position of said plate corresponding to said second flow rate position, each opening of said second set of openings aligns with a respective opening of said fixed openings.   
     
     
         6 . The gas cabinet of  claim 1 , wherein said damper includes:
 a first set of fixed openings;   a moveable plate having a second set of openings;   means for moving said second plate relative to said first set of openings; and   wherein in a first position of said plate corresponding to said first flow rate position, said plate blocks more of each opening of said fixed openings then are blocked by said plate in a second position corresponding to said second flow rate position.   
     
     
         7 . The gas cabinet of  claim 1 , wherein said damper includes:
 a set of moveable louvers and means for opening and closing said louvers.   
     
     
         8 . The gas cabinet of  claim 1 , further including:
 a set of valves configured to control a flow of gas from a gas cylinder mounted in said cabinet to a gas supply line exiting from said cabinet; and   wherein said programmable logic controller is configured to close said set of valves if one or more sensors of said set of sensors indicates an out of specification condition.   
     
     
         9 . The gas cabinet of  claim 8 , wherein said exhaust outlet is connected to an exhaust fan through an exhaust duct and said programmable logic controller is connected to an exhaust static pressure sensor in said exhaust duct; and
 said programmable logic controller is configured to (i) increase the fan speed of said exhaust fan if one or more sensors of said set of sensors indicates a gas leak and (ii) not change the flow rate position of said damper if said exhaust static pressure sensor indicates that the pressure in said exhaust duct is greater than a preset minimum pressure.   
     
     
         10 . The gas cabinet of  claim 8 , wherein said exhaust outlet is connected to an exhaust fan through an exhaust duct and said programmable logic controller is connected to an exhaust flow sensor in said exhaust duct; and
 said programmable logic controller is configured to (i) increase the fan speed of said exhaust fan if one or more sensors of said set of sensors indicates a gas leak and (ii) to close said set of valves if said exhaust flow sensor indicates that the air flow rate is less than a preset minimum flow rate.   
     
     
         11 . The gas cabinet of  claim 1 , wherein said enclosure is fitted with a door. 
     
     
         12 . The gas cabinet of  claim 11 , wherein said damper is the only means for air entry into said cabinet when said door is closed and latched. 
     
     
         13 . The gas cabinet of  claim 11 , wherein said damper is contained with said door. 
     
     
         14 . A method, comprising:
 providing a gas cabinet, comprising:
 an enclosure; 
 a damper having at least two flow rate positions; 
 an exhaust outlet; 
 a set of sensors; and 
 a programmable logic controller configured to change the flow rate position of said damper from a first flow rate position to a second flow rate position based on the state of said sensors; and 
   if the exhaust static pressure within said cabinet is lower than a preset minimum pressure then changing said damper from said first flow rate position to said second flow rate position if one or more sensors of said set of sensors indicates a gas leak within said enclosure, said second flow rate position having a higher flow rate than said first flow rate position.   
     
     
         15 . The method of  claim 14 , wherein (i) said first flow rate position is a fully closed position and said second flow rate position is a fully open position or (ii) said first flow rate position is a partially closed position and said second flow rate position is a more open position than said first position. 
     
     
         16 . The method of  claim 14 , said gas cabinet further including:
 a set of valves configured to control a flow of gas from a gas cylinder mounted in said cabinet to a gas supply line exiting from said cabinet; and   closing said set of valves if one or more sensors of said set of sensors indicates an out of specification condition.   
     
     
         17 . The method of  claim 16 , wherein said exhaust outlet is connected to an exhaust fan through an exhaust duct and said programmable logic controller is connected to an exhaust static pressure sensor in said exhaust duct;
 increasing the fan speed of said exhaust fan if one or more sensors of said set of sensors indicates a gas leak; and   not changing said flow rate position of said damper if said exhaust static pressure sensor indicates that the pressure in said exhaust duct is greater than said preset minimum pressure.   
     
     
         18 . The method of  claim 16 , wherein said exhaust outlet is connected to an exhaust fan through an exhaust duct and said programmable logic controller is connected to an exhaust flow sensor in said exhaust duct;
 increasing the fan speed of said exhaust fan if one or more sensors of said set of sensors indicates a gas leak; and   closing said set of valves if said exhaust flow sensor indicates that the air flow rate is less than a preset minimum flow rate.   
     
     
         19 . The method of  claim 14 , wherein said set of sensors includes one or more sensors selected from the group consisting of a gas flow sensor, a gas sensor, a gas cylinder weight sensor, a low pressure sensor, and a high pressure sensor. 
     
     
         20 . The method of  claim 14 , wherein said damper includes a first set of fixed openings and a moveable plate having a second set of openings; and
 changing said damper from a first position corresponding to said first flow rate position to a second position corresponding to said second flow rate position includes moving said moveable plate relative to said first set of openings wherein in said first position, said plate blocks more of each opening if said fixed openings then are blocked by said plate in a second flow rate position.   
     
     
         21 . The method of  claim 14 , wherein said damper includes a first set of fixed openings and a moveable plate having a second set of openings; and
 changing said damper from a first position corresponding to said first flow rate position to a second position corresponding to said second flow rate position includes moving said moveable plate relative to said first set of openings wherein in said first position said plate, said plate blocks each of said fixed openings and in said second position of said plate each opening of said second set of openings align with respective openings of said fixed openings.   
     
     
         22 . The method of  claim 14 , further including:
 monitoring the state of said sensors and if said sensors indicate a gas leak, first increasing the speed of exhaust fans connected to said exhaust outlet followed by closing gas delivery valves within said cabinet followed by determining if an exhaust pressure of said cabinet is less than a preset minimum pressure; and   performing said changing said damper from said first flow rate position to said second flow rate position only if said exhaust pressure is less than said preset minimum pressure.   
     
     
         23 . The method of  claim 22 , further including:
 determining if an exhaust flow rate of said cabinet is greater than a preset exhaust flow rate and if said exhaust flow rate of said cabinet is not greater than a preset exhaust flow rate then closing said gas delivery valves if said gas delivery valves are not already closed.   
     
     
         24 . The gas cabinet of  claim 14 , wherein said enclosure is fitted with a door. 
     
     
         25 . The gas cabinet of  claim 24 , wherein said damper is the only means for air entry into said cabinet when said door is closed and latched. 
     
     
         26 . The gas cabinet of  claim 24 , wherein said damper is contained with said door.