High and Low Temperature Shutdown Pneumatic Thermostat And Method

Abstract

A pneumatic thermostat and method, particularly suitable for oil and gas burner systems, which incorporates a dual seat valve with valve seats on each end, and a pair appropriately sized plugs, attached via a rod which is placed through the dual seat valve. This assembly is preferably coupled to a thermal expansion sleeve and internal rod, which move the assembly back and forth. With these mechanics and peripheral features, which can include for example high and low temperature venting and a bypass system, embodiments of the present invention can maintain a target temperature and shut-down pressure in the event that a temperature drops below an operating range.

What is claimed is: 
     
         1 . A pneumatic thermostat comprising:
 a valve assembly comprising:
 a dual seat valve; 
 a first valve seat disposed or formed onto on a first end of said dual seat valve; 
 a second valve seat disposed or formed onto a second end of said dual seat valve; 
 a passageway connecting said first valve seat and said second valve seat; 
 a connecting member disposed within said passageway, said connecting member rigidly connecting a first plug to a second plug and configured to translate within said passageway; and 
 said first plug configured to seat against said first valve seat and said second plug configured to seat against said second valve seat. 
   
     
     
         2 . The pneumatic thermostat of  claim 1  further comprising a bypass stem configured to allow a flow of fluid through said thermostat to an end device during a bypass operation. 
     
     
         3 . The pneumatic thermostat of  claim 1  further comprising a bypass stem configured to autonomously reset when a bypass pressure is reduced. 
     
     
         4 . The pneumatic thermostat of  claim 1  further comprising a bypass supply port. 
     
     
         5 . The pneumatic thermostat of  claim 4  wherein said bypass supply port comprises an internal cross-sectional area which is smaller than a sum total of all cross-sectional areas of exhaust paths when a bypass stem is in a reset configuration. 
     
     
         6 . The pneumatic thermostat of  claim 1  further comprising a thermal expansion sleeve mated to an internal rod and said internal rod communicably coupled to said dual seat valve. 
     
     
         7 . The pneumatic thermostat of  claim 1  further comprising a dial stem communicably coupled to a third valve seat, said first plug configured to seat against said third valve seat. 
     
     
         8 . The pneumatic thermostat of  claim 7  further comprising a sleeve coupled to a dial stem and wherein said third valve seat is disposed or otherwise formed onto a terminal end of said dial stem. 
     
     
         9 . The pneumatic thermostat of  claim 1  further comprising a body encompassing said valve assembly and at least a portion of a bypass stem, said body comprising a plurality of ports. 
     
     
         10 . The pneumatic thermostat of  claim 1  wherein said first plug and said second plug are at least substantially equal in size. 
     
     
         11 . The pneumatic thermostat of  claim 1  wherein said first valve seat and said second valve seat comprise a conical shape. 
     
     
         12 . The pneumatic thermostat of  claim 1  wherein said connecting member comprises a rod. 
     
     
         13 . The pneumatic thermostat of  claim 1  wherein said first plug and said second plug each comprise a curved shape. 
     
     
         14 . The pneumatic thermostat of  claim 1  wherein said curved shape comprises a spherical shape, except for a connection location of said connecting member. 
     
     
         15 . The pneumatic thermostat of  claim 1  wherein said pneumatic thermostat is configured to provide a valve open condition when subjected to an operating temperature. 
     
     
         16 . The pneumatic thermostat of  claim 15  further configured to provide a valve closed configuration when subjected to a temperature that is greater than the operating temperature. 
     
     
         17 . The pneumatic thermostat of  claim 16  further configured to provide a valve closed configuration when subjected to a temperature that is less than the operating temperature. 
     
     
         18 . A method for controlling a flow of hydrocarbon gas to a burner, the method comprising:
 shuttling a pneumatic thermostat valve between three states via a force generated from thermal expansion and/or contraction of a member, wherein the three states comprise:
 a first state, the first state being a closed-valve state experienced when the member is in an expanded member condition; 
 a third state, the third state being a closed-valve state experienced when the member is in a retracted member condition; and 
 a second state, the second state being an open-valve state experienced when the member is in a condition between the expanded member condition and the retracted member condition and wherein hydrocarbon gas is allowed to flow from the pneumatic thermostat valve during the open-valve state. 
   
     
     
         19 . The method of  claim 18  wherein the expanded condition is adjustable by manipulating a user input. 
     
     
         20 . The method of  claim 19  further comprising bypassing the pneumatic thermostat valve by manipulating a user input.