Modified vacuum actuated valve assembly and sealing mechanism for improved flow stability for fluids sub-atmospherically dispensed from storage and delivery systems

Patent metadata

Field	Value
Publication number	US-9909670-B2
Application number	US-201514638397-A
Country	US
Kind code	B2
Filing date	Mar 4, 2015
Priority date	Mar 4, 2015
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A modified vacuum actuated valve assembly and sealing mechanism is provided for improved sub-atmospheric flow stability characterized by the absence of delivery pressure spikes and flow excursions. The valve assembly includes a non-stationary thermoplastic seat and a stabber. The stabber is characterized by a top portion having a circular periphery designed to mechanically engage and disengage with an inner sealing surface of the thermoplastic seat. The sealing surface is coined to eliminate surface irregularities contained therein, thereby producing a relatively smooth coined mating inner sealing surface for the circular top portion of the stabber. The valve assembly also includes a modified bellows capable of fine tuning the delivery pressure of the valve assembly.

First claim

The invention claimed is:

1. A vacuum-actuated valve assembly, comprising:
a modified bellows defined at least in part by an enclosed chamber sealed to isolate said chamber from an outside region surrounding the bellows, said bellows comprising side regions configured to longitudinally expand in response to a predetermined vacuum condition surrounding the outside region of the bellows, said bellows having a top portion threadably engaged to a port body along an outer diameter of the bellows, and said bottom portion of the bellows substantially defined by a contact plate;
a pin having a top end extending towards the bottom portion of the bellows and a bottom end extending through an opening of a stationary thermoplastic seat and an opening in a top portion of a stabber to contact a surface of the stabber;
the stationary seat consisting essentially of a thermoplastic material and further wherein said thermoplastic seat is characterized by the absence of elastomeric material, said stationary seat comprising the opening extending from an outer surface of the seat to an inner sealing surface of the seat, said seat further comprising a grooved region extending along said inner sealing surface of said stationary seat;
the stabber comprising a body portion and the top portion each of which is situated within the interior of the stationary seat, said interior of the stationary seat defined, at least in part, by an inner diameter greater than an outer diameter of the top portion and an outer diameter of the body portion thereby creating a passageway between the stabber and the seat;
wherein said top portion of the stabber is engaged within said grooved region of the stationary seat so as to be maintained in mechanical engagement therealong when the bellows is in a non-expanded state, said engagement creating a seal that blocks the passageway and prevents the flow of fluid therethrough, thereby creating a closed configuration of the valve assembly;
wherein expansion of the bellows along the side regions in a longitudinal direction in response to the predetermined vacuum condition surrounding the outside region of the bellows increases the length of the side regions of the bellows by an incremental amount sufficient to urge the contact plate downward against the top end of the pin, thereby causing said bottom end of the pin to push down against the surface of the stabber and disengage the top portion of the stabber from within the grooved region along the inner sealing surface of the stationary seat, thereby mechanically disengaging the seal to unblock the passageway and create a gap between the top portion of the stabber and the inner sealing surface of the stationary seat to create an open configuration of the valve assembly for the fluid to pass therethrough.

2. The vacuum-actuated valve assembly of claim 1 , wherein said top portion is a frusto-conical shape.

3. The vacuum-actuated valve assembly of claim 1 disposed within an interior of a storage and delivery device.

4. The vacuum-actuated valve assembly of claim 1 , wherein said stationary seat remains substantially unaltered in shape during one or more cycles of transitioning between the open configuration and the closed configuration.

5. The vacuum-actuated valve assembly of claim 1 , wherein a single revolution of the threaded bellows translates into a delivery pressure change of about 10 torr.

6. The vacuum-actuated valve assembly of claim 1 , wherein said top portion of said stabber circumferentially extends along said inner sealing surface of said stationary seat.

7. The vacuum-actuated valve assembly of claim 1 , wherein said fluid is a gas selected from the gaseous hydrides arsine (AsH 3 ), phosphine (PH 3 ), diborane (B2H6), hydrogen (H2) and halide boron triflouride (BF 3 ), silicon tetrafluoride (SiF 4 ), germanium tetrafluoride (GeF4), Selenium hexafluoride (SeF6), phosphorus trifluoride (PF3) and oxides carbon dioxide (CO2) and carbon monoxide (CO) as sources of arsenic (As), phosphorus (P), boron (B), silicon (Si) germanium (Ge), selenium and carbon.

8. The vacuum-actuated valve assembly of claim 1 , wherein mechanically disengaging the seal to create the open configuration is characterized by an absence of detectable delivery pressure spikes as measured by a pressure transducer and flow excursions as measured by a flow controller.

9. The vacuum-actuated valve assembly of claim 1 , wherein the delivery pressure is substantially the same as the actuation pressure.

10. The vacuum-actuated valve assembly of claim 1 , wherein the open configuration of the valve assembly allows said fluid to flow to an end-user at flow rates ranging from about 0.1-10 sccm.

11. The vacuum-actuated valve assembly of claim 1 , wherein said thermoplastic material is polychlorotrifluoroethylene (PCTFE).

12. The vacuum-actuated valve assembly of claim 1 , wherein the gap between the top portion of the stabber and the inner sealing surface of the stationary seat is in a range of 0.0005 inches to 0.010 inches.

13. The vacuum-actuated valve assembly of claim 1 , wherein said grooved region of the seat comprises a coined surface configured to elastically compress within a predetermined elastic-like zone upon engagement with the top portion of the stabber.

14. The vacuum-actuated valve assembly claim 13 , wherein the elastic-like zone thickness ranges from about 1 microns to about 100 microns at an operating condition of 0 to 2000 psig.

15. A sealing structure and mechanism for a valve assembly, comprising:
a stationary seat consisting essentially of a thermoplastic material and further wherein said thermoplastic seat is characterized by the absence of elastomeric material;
the stationary seat comprising an opening extending from an outer surface of the stationary seat to an inner sealing surface of the stationary seat, said seat further comprising a grooved region extending along said inner sealing surface of said stationary seat;
said grooved region of the seat comprising a surface configured to compress within a predetermined zone upon engagement with a top portion of a stabber;
the stabber comprising a body portion and the top portion each of which is situated within the interior of the stationary seat;
the interior of the stationary seat defined, at least in part, by an inner diameter greater than an outer diameter of the top portion and an outer diameter of the body portion thereby creating a passageway between the stabber and the seat;
wherein said top portion of the stabber is adapted to move between a closed configuration and an open configuration, said closed configuration defined by said top portion of the stabber engaged within said grooved region of the stationary seat so as to be maintained in mechanical engagement therealong, said engagement creating a seal that blocks the passageway thereby creating a closed configuration of the valve assembly;
the open configuration defined by the top portion of the stabber disengaged from within said grooved region so as to be spaced away from the grooved region along the inner sealing surface of the stationary seat to unblock the passageway and create a gap between the top portion of the stabber and the inner sealing surface of the stationary seat to create an open configuration of the valve assembly.

16. The sealing structure and mechanism for a valve assembly of claim 15 , wherein mechanically disengaging the seal from the closed configuration to create the open configuration is characterized by an absence of detectable delivery pressure spikes as measured by a pressure transducer and flow excursions as measured by a f

Assignees

• Heiderman Douglas C
• Sinha Ashwini K
• Crvelin Paul
• Vassallo Andrew
• Praxair Technology Inc

Inventors

• Heiderman Douglas C
• Sinha Ashwini K
• Crvelin Paul
• Vassallo Andrew

Classifications

• F17C2205/0338

  Pressure regulators · CPC title

• F17C2205/0394

  in direct contact with the pressure vessel · CPC title

• F17C2201/058

  portable (<30 l) · CPC title

• F17C2223/0153

  Liquefied gas, e.g. LPG, GPL · CPC title

• F17C2223/0123

  gaseous, e.g. CNG, GNC · CPC title