Integrated valve design for gas chromatograph

Abstract

A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves and multiple thermal conductivity detectors (TCD's). This allows separation and measurement of a gas sample in one compact integrated unit. Other features may also be present. For example, a first heating zone may include a band heater placed around the multi-valve block to heat the carrier gas and to keep the multi-valve block at a desired temperature. A second heating zone may include a spool and a cartridge heater to heat the columns through which the gas sample flows. Two sets of screws, one through the top of the multi-valve and one through the bottom, may be included to simplify maintenance of the multi-valve system. Insulation defining an oven can be placed around the assembly to stabilize the temperature of the multi-valve assembly.

What is claimed is:  
     
         1 . A multi-valve assembly, comprising: 
 a unit including a plurality of plates and diaphragms attached together to form multiple valves, each of said valves being individually actuatable and having a plurality of valve ports.    
     
     
         2 . The multi-valve assembly of  claim 1 , wherein said unit forms a reception area for at least one fluid property detector.  
     
     
         3 . The multi-valve assembly of  claim 2 , wherein said fluid property detector is a thermal conductivity detector.  
     
     
         4 . The multi-valve assembly of  claim 1 , wherein a number of said plates have a ring shape forming an open area in the body of each of said number of plates.  
     
     
         5 . The multi-valve assembly of  claim 4 , wherein said integrated unit further includes a spool occupying a portion of said open area, said plates defining at least a first heating zone and said spool defining at least a second heating zone.  
     
     
         6 . The multi-valve assembly of  claim 5 , wherein each of said first and said second heating zones include at least one temperature detector and wherein said first heating zone is maintained about a first predetenrined temperature and said second heating zone is maintaned at about a second predetermined temperature.  
     
     
         7 . The multi-valve of  claim 5 , wherein said first heating zone is maintained by a band heater located approximately concentrically around at least one of said plates and said second heating zone is maintained by a second heater in said spool.  
     
     
         8 . The multi-valve assembly of  claim 5 , wherein gas sample tubing and carrier gas tubing( attach to said valve ports, at least a portion of said gas sample tubing being inside said second heating zone and at least a portion of said carrier gas tubing being in said first heating zone.  
     
     
         9 . The multi-valve assembly of  claim 1 , further comprising a plurality of actuator ports in at least one of said plates, each of said valves corresponding to a pair of actuator ports.  
     
     
         10 . The multi-valve assembly of  claim 9 , further comprising a plurality of solenoids, each of said solenoids being attached to one of said pairs of actuator ports via tubing, each of said solenoids capable of actuating a corresponding one of said valves.  
     
     
         11 . The multi-valve assembly of  claim 2 . further comprising: 
 a plurality of fluid property detectors located in said reception area;    a temperature detector proximate to at least one of said fluid property detectors.    
     
     
         12 . The multi-valve assembly of  claim 1 , further comprising: 
 an insulative housing surrounding said plurality of plates.    
     
     
         13 . The multi-valve assembly of  claim 1 , further comprising a first set of screws and a second set of screws, wherein said multi-valve assembly includes at least three plates, said plates being in a generally stacked arrangement, wherein a first of said plates is a top plate, a second of said plates is a bottom plate and a third of said plates is a middle plate, said first set of screws being inserted through said top plate, said second set of screws begin inserted through said bottom plate, wherein said at least three plates are attached together, said top plate being detachable from said middle plate upon removal of said first set of screws from said top plate while said middle plate and said lower plate remain attached while said second set of screws remain inserted through said bottom plate.  
     
     
         14 . The multi-valve assembly of  claim 1 , wherein each valve corresponds to ane area on said plurality of plates, at least one of said plurality of plates including an elevated surface at each of said areas.  
     
     
         15 . The multi-valve assembly of  claim 1 , further comprising: 
 a set of a plurality of pistons corresponding to each valve, said each of sets of pistons having first and second subsets wherein each valve is in either an ON condition or an OFF condition, with said first subset being, actuated when each valve is in an ON condition and with said second subset being actuated when each valve is in an OFF condition.    
     
     
         16 . A multi-valve device comprising: 
 an integrated block having multiple valves and multiple detectors, each of said valves being suitable to direct selectively a fluid flow and each of said detectors positioned to analyze at least a portion of said fluid flow.    
     
     
         17 . The multi-valve device of  claim 16 , further comprising: 
 a plurality of fluid sample detectors at least partially within said integrated block.    
     
     
         18 . The multi-valve device of  claim 16 ,wherein said multi-valve device defines first and second heating zones, said second heating zone being, concentrically surrounded by said first heating, zone.  
     
     
         19 . The multi-valve device of  claim 18 , wherein a gas sample is heated in said second heating, zone and a carrier gas is heated in said first heating zone.  
     
     
         20 . The multi-valve device of  claim 16 , further comprising: 
 a first set and a second set of screws tightened paitially through said multi-valve device, said multi-valve device being, conifigured to paitially disassemble upon removal of said first set of screws.