Fixed volume valve system

Abstract

Embodiments of the present invention provide valves that provide for uniform holdup volume. An embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage.

1 . A valve comprising: 
 a valve body defining: 
 a valve chamber having a valve seat;  
 an inlet flow passage;  
 an outlet flow passage;  
 a diaphragm control flow passage, wherein the diaphragm control flow passage intersects the valve seat; and  
   a diaphragm movable towards and away from the valve seat, wherein the diaphragm control flow passage is separated from the inlet flow passage and the outlet flow passage by the diaphragm; and    wherein the valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage.    
   
   
       2 . The valve of  claim 1 , wherein the valve seal conforms to the valve seat shape when at least the threshold vacuum is applied to the pressure control passage.  
   
   
       3 . The valve of  claim 1 , wherein the valve seat has a semi-hemispherical shape.  
   
   
       4 . The valve of  claim 3 , wherein the valve body comprises multiple pieces.  
   
   
       5 . The valve of  claim 4 , wherein a first portion of the valve body comprises a dispense block defining the inlet and outlet flow passages and a second portion of the valve body comprises a valve plate defining the valve seat and the diaphragm control flow passage.  
   
   
       6 . The valve of  claim 6 , wherein the diaphragm is sandwiched between the dispense block and the valve plate.  
   
   
       7 . The valve of  claim 6 , further comprising an o-ring at least partially disposed in a first annular ring defined in the valve plate, wherein the o-ring contacts the diaphragm.  
   
   
       8 . The valve of  claim 7 , wherein the dispense block comprises a second annular ring, wherein the diaphragm is partially disposed in the second annular ring.  
   
   
       9 . The valve of  claim 5 , wherein the inlet flow passage leads to a dispense chamber of a multi-stage pump.  
   
   
       10 . The valve of  claim 9 , wherein the inlet flow passage intersects the valve chamber at a center axis.  
   
   
       11 . The valve of  claim 9 , wherein the outlet flow passage intersects the valve chamber at a center axis.  
   
   
       12 . The valve of  claim 9 , wherein the inlet and outlet flow passage are both off-center.  
   
   
       13 . The valve of  claim 9 , wherein the inlet flow passage and outlet flow passage are different sizes.  
   
   
       14 . A valve assembly having a first valve, the valve assembly comprising: 
 a valve body comprising a first piece coupled to a second a piece, wherein the first piece and the second piece define a first valve chamber, further wherein the first piece defines a first flow passage and a second flow passage intersecting the valve chamber and the second piece defines a first valve seat and a third flow passage intersecting the first valve seat; and    a first valve diaphragm movable within the valve chamber, wherein the first and second flow passages are separated from the third flow passage by the first valve diaphragm;    wherein the first valve seat is shaped so that the first valve diaphragm conforms to the first valve seat to provide a fixed first valve holdup volume when a threshold or greater vacuum is applied to the third flow passage.    
   
   
       15 . The valve assembly of  claim 15 , wherein the valve seat has a semi-hemispherical shape.  
   
   
       16 . The valve assembly of  claim 14 , further comprising a second valve having a second valve chamber.  
   
   
       17 . The valve assembly of  claim 16 , wherein the first portion of the valve body defines a fourth flow passage and a fifth flow passage, the fourth and fifth flow passages intersecting the second valve chamber; 
 wherein the second portion of the valve body defines the second valve seat and defines a sixth flow passage intersecting the second valve seat; and    wherein the second valve seat is shaped so that a second valve diaphragm conforms to the second valve seat to provide a fixed second valve holdup volume when a threshold or greater vacuum is applied to the sixth flow passage.    
   
   
       18 . The valve assembly of  claim 17 , wherein first valve seat and the second valve seat have semi-hemispherical shapes.  
   
   
       19 . The valve assembly of  claim 17 , further comprising an sheet of electrometric material coupled between the first portion of the valve body and the second portion of the valve body and wherein the first valve diaphragm is a first portion of the sheet of elastomeric material and the second valve diaphragm is a second portion of the sheet of elastomeric material.  
   
   
       20 . The valve assembly of  claim 19 , further comprising a first o-ring at least partially disposed in a first annular ring about the first valve seat and a second o-ring at least partially disposed about the second valve seat.  
   
   
       21 . The valve assembly of  claim 17 , wherein the first valve is a purge valve for a multistage pump.  
   
   
       22 . The valve assembly of claim of  claim 21 , wherein the second valve is one of an inlet valve, isolation valve, barrier valve or vent valve for a multistage pump.  
   
   
       23 . A multistage pump having a feed chamber and a dispense chamber, the multistage pump comprising: 
 a pump body defining an inlet flow passage to and an outlet flow passage from a first valve;    a valve plate coupled to the dispense body, the valve plate defining a first valve seat for the first valve;    a first valve diaphragm movable in the first valve; and    wherein the first valve seat is shaped so that the first valve diaphragm conforms to the first valve seat to provide a fixed first valve holdup volume when a threshold or greater vacuum is applied to the first valve.    
   
   
       24 . The multistage pump of  claim 23 , wherein the inlet flow passage to the first valve leads from the dispense chamber to the first valve.  
   
   
       25 . The multistage pump of  claim 24 , wherein an entrance to the inlet flow passage to the first valve is coaxial with a center axis of the first valve seat and an entrance to the outlet flow passage of the first valve is non-coaxial with the center axis of the first valve seat.  
   
   
       26 . The multistage pump of  claim 24 , wherein the entrance to the inlet flow passage to the first valve is non-coaxial with a center axis of the first valve seat and an entrance to the outlet flow passage of the first valve is coaxial with the center axis of the first valve seat.  
   
   
       27 . The multistage pump of  claim 24 , wherein the inlet flow passage to the first valve has a smaller cross-section than a cross-section of the outlet flow passage of the first pump.  
   
   
       28 . The multistage pump of  claim 24 , further comprising: 
 an inlet valve diaphragm movable in an inlet valve;    an isolation valve diaphragm movable in an isolation valve;    a barrier valve diaphragm movable in a barrier valve;    a vent valve diaphragm movable in a vent valve; and    the pump body further defining a set of flow passages proving an inlet flow passage to and an outlet flow passage from each of an inlet valve, an isolation valve, a barrier valve and a vent valve;    the valve plate further comprising, a valve seat for the inlet valve, a valve seat for the isolation valve, a valve seat for the barrier valve and a valve seat for the vent valve; and    wherein the first valve is a purge valve.    
   
   
       29 . The multistage pump of  claim 28 , wherein the inlet valve seat is shaped so that the inlet valve diaphragm conforms to the shape of the inlet valve seat when the threshold or greater vacuum is applied to the inlet valve.  
   
   
       30 . The multistage pump of  claim 29 , wherein the inlet valve is larger than the purge valve.  
   
   
       31 . The multistage pump of  claim 29 , wherein: 
 the vent valve seat is shaped so that the vent valve diaphragm conforms to the shape of the vent valve seat when the threshold or greater vacuum is applied to the vent valve;    the barrier valve seat is shaped so that the barrier valve diaphragm conforms to the shape of the barrier valve seat when the threshold or greater vacuum is applied to the barrier valve; and    the isolation valve seat is shaped so that the isolation valve diaphragm conforms to the shape of the isolation valve seat when the threshold or greater vacuum is applied to the isolation valve.    
   
   
       32 . The multistage pump of  claim 31 , wherein each of the first valve seat, vent valve seat, inlet valve seat, isolation valve seat and barrier valve seat have a semi-hemispherical shape.  
   
   
       33 . The multistage pump of  claim 28 , wherein the first valve diaphragm, vent valve diaphragm, barrier valve diaphragm, inlet valve diaphragm and isolation valve diaphragm are portions of a single sheet of elastomeric material coupled between the valve plate and the pump body.  
   
   
       34 . The multistage pump of  claim 23 , wherein the first flow passage leads from the dispense chamber to the first valve and the second flow passage leads from the first valve to the feed chamber.