Vacuum relief assembly

Abstract

A vacuum relief assembly for relieving the vacuum created in a freezer chamber of an ultra low temperature freezer. The assembly comprises tubing having an inlet port open to the external environment and an exit port open to the freezer chamber, the inlet and exit ports in fluid communication with each other. A valve is coupled to the tubing that either permits or prevents fluid flow between the external environment and the freezer chamber. A heating element contacts the tubing and is operable to apply heat thereto so as to prevent the tubing from becoming occluded with condensation. The vacuum relief assembly may further include an activation switch for energizing the heating element and a timing circuit for turning the heating element off after a predetermined period of time.

1 . A vacuum relief assembly for an ultra low temperature freezer, the freezer having a freezer chamber surrounded by an external environment and contained by insulated peripheral walls including a pair of side walls, a top wall, a bottom wall, and a rear wall, and an insulated door hingedly secured to one of the side walls, said assembly comprising: 
 tubing having an inlet port open to the external environment and an exit port open to the freezer chamber, said inlet port in fluid communication with said exit port;    a first valve coupled to said tubing and having an open and closed position, said first valve permitting fluid communication between the external environment and the freezer chamber when in the open position, said first valve preventing fluid communication between the external environment and the freezer chamber when in the closed position; and    a heating element contacting said tubing and operable to apply heat thereto so as to prevent condensation from occluding said tubing.    
   
   
       2 . The vacuum relief assembly of  claim 1 , wherein said heating element is a foil heating element wrapped around at least a portion of said tubing.  
   
   
       3 . The vacuum relief assembly of  claim 1 , further comprising: 
 an activation switch operatively coupled to said heating element and operable to cause said heating element to produce heat.    
   
   
       4 . The vacuum relief assembly of  claim 3 , wherein the freezer door has an open and closed position, said activation switch further operatively coupled to the freezer door and operable to cause said heating element to produce heat when the freezer door is placed in at least one of the open and closed positions.  
   
   
       5 . The vacuum relief assembly of  claim 3 , wherein the freezer further comprises a latching handle mounted to the freezer door and being moveable between first and second positions, said activation switch further operatively coupled to the latching handle and operable to cause said heating element to produce heat when the latching handle is placed in at least one of the first and second positions.  
   
   
       6 . The vacuum relief assembly of  claim 3 , further comprising: 
 a timing circuit operatively coupled to said heating element and operable to cause said heating element to stop producing heat after a predetermined period of time.    
   
   
       7 . The vacuum relief assembly of  claim 3 , further comprising: 
 a thermal switch operatively coupled to said heating element and operable to cause said heating element to stop producing heat when at least a portion of said tubing reaches a specified temperature.    
   
   
       8 . The vacuum relief assembly of  claim 1 , wherein the freezer further comprises a latching handle mounted to the freezer door, the latching handle being moveable between first and second positions, said first valve being in the open position when the latching handle is placed in the second position, said first valve being in the closed position when the latching handle is placed in the first position.  
   
   
       9 . The vacuum relief assembly of  claim 8 , wherein said first valve further comprises: 
 a mounting pin coupled to said inlet port and having an access port in fluid communication with said inlet port;    said latching handle coupled to said mounting pin and further comprising an access port in fluid communication with the external environment, said access port in said mounting pin in fluid communication with said access port in said latching handle when said latching handle is in the second position, said access port in said mounting pin fluidly sealed from said access port in said latching handle when said latching handle is in the first position.    
   
   
       10 . The vacuum relief assembly of  claim 1 , wherein said assembly is carried by the freezer door.  
   
   
       11 . The vacuum relief assembly of  claim 1 , wherein said first valve is a check valve.  
   
   
       12 . The vacuum relief assembly of  claim 1 , wherein said heating element is a positive temperature coefficient heating element.  
   
   
       13 . An ultra low temperature freezer comprising: 
 a freezer chamber surrounded by an external environment and contained by insulated peripheral walls including a pair of side walls, a top wall, a bottom wall, and a rear wall;    an insulated freezer door hingedly secured to one of the side walls; and    a vacuum relief assembly coupled to said freezer comprising:    tubing having an inlet port open to the external environment and an exit port open to the freezer chamber, said inlet port in fluid communication with said exit port;    a first valve coupled to said tubing and having an open and closed position, said first valve permitting fluid communication between the external environment and the freezer chamber when in an open position, said first valve preventing fluid communication between the external environment and the freezer chamber when in the closed position; and    a heating element contacting said tubing and operable to apply heat thereto so as to prevent condensation from occluding said tubing.    
   
   
       14 . The ultra low temperature freezer of  claim 13 , wherein said heating element is a foil heating element wrapped around at least a portion of said tubing.  
   
   
       15 . The ultra low temperature freezer of  claim 13 , further comprising: 
 an activation switch operatively coupled to said heating element and operable to cause said heating element to produce heat.    
   
   
       16 . The ultra low temperature freezer of  claim 15 , wherein said freezer door has an open and closed position, said activation switch further operatively coupled to said freezer door and operable to cause said heating element to produce heat when said freezer door is placed in one of the open and closed positions.  
   
   
       17 . The ultra low temperature freezer of  claim 15 , wherein said freezer further comprises a latching handle mounted to said freezer door and being moveable between first and second positions, said activation switch further operatively coupled to said latching handle and operable to cause said heating element to produce heat when said latching handle is placed in one of the first and second positions.  
   
   
       18 . The ultra low temperature freezer of  claim 15 , further comprising: 
 a timing circuit operatively coupled to said heating element and operable to cause said heating element to stop producing heat after a predetermined period of time.    
   
   
       19 . The ultra low temperature freezer of  claim 15 , further comprising: 
 a thermal switch operatively coupled to said heating element and operable to cause said heating element to stop producing heat when at least a portion of said tubing reaches a specified temperature.    
   
   
       20 . The ultra low temperature freezer of  claim 13 , wherein the freezer further comprises a latching handle mounted to the freezer door, the latching handle being moveable between first and second positions, said first valve being in the open position when the latching handle is placed in the second position, said first valve being in the closed position when the latching handle is placed in the first position.  
   
   
       21 . The ultra low temperature freezer of  claim 20 , wherein said first valve further comprises: 
 a mounting pin coupled to said inlet port and having an access port in fluid communication with said inlet port;    said latching handle coupled to said mounting pin and further comprising an access port in fluid communication with the external environment, said access port in said mounting pin in fluid communication with said access port in said latching handle when said latching handle is in the second position, said access port in said mounting pin fluidly sealed from said access port in said latching handle when said latching handle is in the first position.    
   
   
       22 . The ultra low temperature freezer of  claim 13 , wherein said assembly is carried by the freezer door.  
   
   
       23 . The ultra low temperature freezer of  claim 13 , wherein said first valve is a check valve.  
   
   
       24 . The ultra low temperature freezer of  claim 13 , wherein said heating element is a positive temperature coefficient heater.  
   
   
       25 . A vacuum relief assembly for an ultra low temperature freezer, the freezer having a freezer chamber surrounded by an external environment and contained by insulated peripheral walls including a pair of side walls, a top wall, a bottom wall, and a rear wall, and an insulated door hingedly secured to one of the side walls, said assembly comprising: 
 tubing comprising a housing having a first and second end, said first end configured as an inlet port open to the external environment, and a porting tube having a first end coupled to said second end of said housing, said porting tube having a second end configured as an exit port open to the freezer chamber, said inlet port in fluid communication with said exit port;    a first valve coupled to said tubing along said housing and having an open and closed position, said first valve permitting fluid communication between the external environment and the freezer chamber when in an open position, said first valve preventing fluid communication between the external environment and the freezer chamber when in the closed position; and    a heater thermally coupled to said tubing along said porting tube and operable to apply heat thereto so as to prevent condensation from occluding said tubing.    
   
   
       26 . The vacuum relief assembly of  claim 25 , wherein said first valve is a check valve.  
   
   
       27 . The vacuum relief assembly of  claim 25 , wherein said heater is a positive temperature coefficient heater.  
   
   
       28 . A method for relieving a vacuum between a freezer chamber of an ultra low freezer and an external environment comprising: 
 providing a fluid communication path between the external environment and the freezer chamber;    opening a valve to permit fluid flow along the communication path so as to relieve the vacuum; and    using a heater to heat at least a portion of the communication path between the external environment and the freezer chamber so as to prevent condensation from occluding the communication path.    
   
   
       29 . The method of  claim 28 , wherein the freezer includes a freezer door having an open and closed position, the method further comprising: 
 causing the heater to produce heat when the freezer door is placed in at least one of the open and closed positions.    
   
   
       30 . The method of  claim 29 , further comprising: 
 causing the heater to stop producing heat after a predetermined period of time.    
   
   
       31 . The method of  claim 29 , further comprising: 
 causing the heater to stop producing heat when the temperature of at least a portion of the communication path reaches a specified temperature.