Automatic stop cock valve

Abstract

A flow control device includes a fitting having three portals. Two of the portals are input portals and one of the portals is an exit portal. Located in one of the input portals is a normally closed back flow prevention valve. The normally closed back flow prevention valve prevents back flow of fluid through the fitting when the fluids flowing through the fitting are changed.

1 . A flow control device for use in an ophthalmic surgical system for controlling the flow of fluid to an infusion cannula, said flow control device comprising:
 a first input port connected to a source of a first fluid;   a second input port connected to a source of a second fluid;   an exit port connected to the infusion cannula;   a back flow prevention valve constructed and arranged to prevent the flow of said first fluid to said source of said second fluid.   
   
   
       2 . The flow control device as defined in  claim 1  wherein said back flow prevention valve is a duck bill valve. 
   
   
       3 . The flow control device as defined in  claim 1  wherein said back flow prevention valve is a flapper valve assembly. 
   
   
       4 . The flow control device as defined in  claim 1  wherein said back flow prevention valve is an umbrella check valve assembly. 
   
   
       5 . The flow control device as defined in  claim 1  wherein said back flow prevention valve is a ball check valve assembly. 
   
   
       6 . The flow control device as defined in  claim 1  wherein said back flow prevention valve is a poppet valve assembly. 
   
   
       7 . A flow control system comprising:
 a source for the flow of a first fluid;   a source for the flow of a second fluid;   means for switching between the flow of said first fluid and the flow of said second fluid;   an infusion line for the flow of said first fluid;   a second line for the flow of said second fluid;   a fitting constructed and arranged for insertion into said infusion line and said second line, said fitting including a first entry portal for said first fluid, and second entry portal for a second fluid and an exit portal for either said first fluid or said second fluid;   a normally closed back flow prevention valve located in said second portal, said normally closed back flow prevention valve being openable by the flow of said second fluid when the flow of fluid is changed from said first fluid to said second fluid.   
   
   
       8 . The flow control system as defined in  claim 7  wherein said normally closed back flow prevention valve is a duck bill valve. 
   
   
       9 . The flow control system as defined in  claim 7  wherein said normally closed back flow prevention valve is a flapper valve assembly. 
   
   
       10 . The flow control system as defined in  claim 7  wherein said normally closed back flow prevention valve is an umbrella valve assembly. 
   
   
       11 . The flow control system as defined in  claim 7  wherein said normally closed back flow prevention valve is spring biased ball valve assembly. 
   
   
       12 . The flow control system as defined in  claim 7  wherein said normally closed back flow prevention valve is a spring biased poppet valve assembly. 
   
   
       13 . The flow control system as defined in  claim 7  further including a third line and an infusion cannula. 
   
   
       14 . A method for preventing back flow into the source of an alternate fluid when switching between the flow of a primary fluid and the flow of an alternate fluid, said method comprising the steps of:
 connecting a first entry portal of a fitting to enable the flow of the primary fluid to an exit portal of said fitting;   connecting a second entry portal of said fitting to enable the flow of the alternate fluid to said exit portal of said fitting;   inserting a normally closed back flow prevention valve into said second entry portal of said fitting to block the flow of said alternate fluid through said fitting until the force of the flow of said alternate fluid is sufficient to cause said normally closed back flow prevention valve to open.   
   
   
       15 . The method as defined in  claim 13  wherein said normally closed back flow prevention valve prevents the back flow of the primary fluid into the flow of the alternate fluid. 
   
   
       16 . The method as defined in  claim 13  wherein said normally closed back flow prevention valve is opened when the flow of the primary fluid is terminated and the flow of the alternate fluid is initiated. 
   
   
       17 . A flow control system comprising:
 an infusion line for the flow of a first fluid;   means for stopping the flow of said first fluid;   a second line for the flow of a second fluid;   means for stopping the flow of said second fluid;   a fitting constructed and arranged for insertion into said infusion line and said second line, said fitting including a first entry portal for said first fluid, and second entry portal for a second fluid and an exit portal for either said first fluid or said second fluid.   
   
   
       18 . The flow control system as defined in  claim 17  wherein said means for stopping the flow of said first and second fluids are manually actuated valves. 
   
   
       19 . The flow control system as defined in  claim 17  wherein said means for stopping the flow of said first and second fluids are electrically actuated valves. 
   
   
       20 . The flow control system as defined in  claim 17  wherein said means for stopping the flow of said first and second fluids are mechanically actuated valves. 
   
   
       21 . The flow control system as defined in  claim 17  wherein said means for stopping the flow of said first and second fluids are pneumatically actuated valves. 
   
   
       22 . The flow control system as defined in  claim 17  wherein said means for stopping the flow of said first and second fluids are manually, electrically, mechanically, or pneumatically actuated pinch valves.