Low airflow exhaust canopy for biological cabinets

Abstract

A canopy for a biological cabinet includes a plurality of openings, referred to as ports, covered by air dampers and designed to open and close as needed to reduce an overall volume of air required during normal operation. If the building exhaust system attempts to pull more air than is supplied by the cabinet, the intake dampers will open to allow room air in through the intake ports, thus helping the cabinet to maintain an acceptable level of intake airflow at its front access opening. If the building exhaust system does not pull a sufficient amount of air, the outlet damper will open and let the cabinet exhaust air escape through the outlet port, thus enabling the cabinet to maintain an acceptable level of intake airflow at its front access opening. The canopy may also include an internal air baffle that helps to capture the cabinet exhaust air and direct it out through the opening connected to the building exhaust duct.

1 . A biological safety cabinet, comprising:
 a plurality of walls defining a first chamber having an internal environment therein;   a canopy configured to receive exhaust airflow from the first chamber, the canopy comprising:
 a pair of side panels, a front panel, a top panel and a back panel defining a second chamber having an internal environment therein; 
 one or more intake ports provided on the canopy, wherein airflow through the one or more intake ports is controlled by one or more intake dampers; 
 one or more outlet ports, wherein airflow through the one or more outlet ports is controlled by one or more outlet dampers; and 
 an opening connected to an external exhaust system for exhausting air inside the second chamber to the external exhaust system, wherein the external exhaust system pulls a pre-determined amount of air from the second chamber. 
   
     
     
         2 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers are configured to open toward the internal environment of the second chamber. 
     
     
         3 . The biological safety cabinet of  claim 2 , wherein the one or more intake dampers open when the external exhaust system pulls more air than the pre-determined amount of air from the second chamber. 
     
     
         4 . The biological safety cabinet of  claim 1 , wherein the one or more outlet dampers are configured to open toward an environment external to the biological cabinet. 
     
     
         5 . The biological safety cabinet of  claim 4 , wherein the one or more outlet dampers open when the external exhaust system pulls less air than the pre-determined amount of air from the second chamber. 
     
     
         6 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers are attached to the canopy with one or more continuous flexible hinges and rotate around a horizontal axis. 
     
     
         7 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers are slidably attached to the canopy. 
     
     
         8 . The biological safety cabinet of  claim 1 , wherein the one or more outlet dampers are attached to the canopy with one or more continuous flexible hinges and rotate around a horizontal axis. 
     
     
         9 . The biological safety cabinet of  claim 1 , wherein the one or more outlet dampers are slidably attached to the canopy. 
     
     
         10 . The biological safety cabinet of  claim 1 , wherein the front panel is slanted. 
     
     
         11 . The biological safety cabinet of  claim 1 , wherein entire air exhausted by the first chamber is captured by the second chamber. 
     
     
         12 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers are one directional dampers that are restrained from opening toward an environment external to the biological cabinet. 
     
     
         13 . The biological safety cabinet of  claim 1 , wherein the one or more outlet dampers are one directional dampers that are restrained from opening toward the internal environment of the second chamber. 
     
     
         14 . The biological safety cabinet of  claim 1 , wherein the canopy is made of one or more of sheet metal, plastic, aluminum or fiberglass. 
     
     
         15 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers or the one or more outlet dampers are electrically controlled. 
     
     
         16 . The biological safety cabinet of  claim 1 , further comprising:
 one or more fasteners for attaching the canopy to the first chamber.   
     
     
         17 . The biological safety cabinet of  claim 1 , further comprising:
 a gasket provided around a bottom of the canopy, wherein the gasket attaches the canopy to the first chamber.   
     
     
         18 . The biological safety cabinet of  claim 1 , further comprising:
 an air baffle provided below the top panel of the canopy, wherein the air baffle is configured to guide air from the internal environment of the second chamber to the opening connected to the external exhaust system.   
     
     
         19 . The biological safety cabinet of  claim 18 , wherein the air baffle comprises a bell mouth exhaust collar that fits into the opening, the bell mouth exhaust collar reducing airflow turbulence inside the second chamber. 
     
     
         20 . The biological safety cabinet of  claim 1 , further comprising:
 one or more removable brackets inserted inside of the one or more intake ports, wherein the one or more intake dampers cover end portions of the one or more removable brackets.   
     
     
         21 . The biological safety cabinet of  claim 1 , wherein the one or more intake dampers or the one or more outlet dampers are made of light weight material. 
     
     
         22 . The biological safety cabinet of  claim 1 , wherein the canopy is configured for sealing to allow for gaseous decontamination. 
     
     
         23 . A method for regulating air inside a canopy of a biological cabinet, the method comprising:
 providing a biological cabinet comprising:
 a plurality of walls defining a first chamber having an internal environment therein; 
 a canopy coupled to the first chamber, the canopy comprising:
 a pair of side panels, a front panel, a top panel and a back panel defining a second chamber having an internal environment therein; 
 one or more intake ports provided on the canopy, wherein airflow through the one or more intake ports is controlled by one or more intake dampers; 
 one or more outlet ports provided on the canopy, wherein airflow through the one or more outlet ports is controlled by one or more outlet dampers; 
 an opening connected to an external exhaust system for exhausting air inside the second chamber to the external exhaust system; 
 
   supplying air exhausted from the first chamber into the second chamber, wherein the external exhaust system pulls a pre-determined amount of air from the second chamber.   
     
     
         24 . The method of  claim 23 , wherein the one or more intake dampers open toward the internal environment of the second chamber when the external exhaust system pulls more air than the pre-determined amount of air from the second chamber. 
     
     
         25 . The method of  claim 23 , wherein the one or more outlet dampers open toward an environment external to the biological cabinet when the external exhaust system pulls less air than the pre-determined amount of air from the second chamber.