Double gas barrier seal

• US 5,498,007 A
• Filed: 02/01/1994
• Issued: 03/12/1996
• Est. Priority Date: 02/01/1994
• Status: Expired due to Term

• Current Assignee: Flowserve Management Company (Flowserve Corporation)
• Original Assignee: Durametallic Corp (Flowserve Corporation)
• Inventors: Dingman, Randy R., Kulkarni, Sunil B.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beres, John L.
• Application Number:
  US08/189,794
• Time in Patent Office: 770 Days
• Field of Search: 277/27, 277/65, 277/81 R, 277/96, 277/96.1
• US Class Current: 277/400
• CPC Class Codes: F16J 15/3412 with cavities F16J15/3424 takes precedence
• CPC Class Codes: Y10S 277/93 Seal including heating or cooling feature

Abstract

A mechanical seal assembly having a deep groove pattern formed in the face of the rotating seal ring, which groove pattern includes two sets of straight angled deep grooves, the sets being angled in opposite rotational directions to provide pumping of barrier gas into the grooves irrespective of the direction of rotation. The groove pattern also includes a deep annular groove formed in the seal face and communicating with radially inner ends of the angled grooves to facilitate flow of barrier gas into and through the grooves to improve cooling of the seal faces and minimization of contact pressure between the seal faces.

Claims

1. In a gas barrier type double seal arrangement for sealing cooperation between a rotatable shaft and a housing to prevent leakage of product from an equipment chamber into the environment, said seal arrangement including an inner seal assembly coacting between the shaft and housing for preventing leakage of product into an intermediate chamber defined within the housing generally adjacent and partially surrounding the inner seal assembly, an outer seal assembly disposed axially outwardly of the inner seal assembly and coacting between the housing and shaft for preventing leakage from the intermediate chamber into the environment, each seal assembly including stator and rotor rings which are respectively nonrotatably secured to the housing and shaft in substantially concentric relationship relative to the shaft, the stator and rotor rings of each seal assembly having opposed axially-oriented contacting annular seal faces disposed in relatively rotatable sliding and sealing engagement with one another, and an inlet in communication with the intermediate chamber for supplying a pressurized inert barrier gas into said chamber, the improvement wherein the annular seal face on the rotor ring of said outer seal assembly has a deep groove arrangement therein in communication with the barrier gas of said intermediate chamber for effecting cooling of and minimizing contact pressure between the opposed seal faces of said outer seal assembly, said groove arrangement including a plurality of first straight grooves formed in the respective seal face in substantially uniformly angularly spaced relation therearound, a plurality of second straight grooves formed in the respective seal face in substantially angularly spaced relation therearound, said second grooves being individually positioned between an angularly adjacent pair of first grooves, said first grooves being individually positioned between an angularly adjacent pair of second grooves, said first and second grooves having radially outer ends which communicate with an outer diameter of the respective seal face, each of said first and second grooves projecting radially inwardly of the respective seal face from the respective outer end and having a longitudinally extending centerline which intersects at said outer end with a respective radial direction of said respective seal face so as to define an acute entrance angle therebetween, said first grooves being angled relative to the respective radial direction in one direction circumferentially around the respective seal face, said second grooves being angled relative to the respective radial direction in an opposite direction to said one direction circumferentially around the respective seal face, at least circumferentially adjacent said first and second grooves having radially inner ends which are in communication with one another to define a flow path for said barrier gas when said rotor ring is rotating, one of said circumferentially adjacent first and second grooves defining an upstream portion of said flow path and the other of said circumferentially adjacent first and second grooves defining a downstream portion of said flow path, and said first and second grooves having a depth of at least about 0.04 inch to create a hydrostatic force therein which reduces the contact pressure between the opposed contacting seal faces due to the presence of said barrier gas in said grooves.

2. A seal arrangement according to claim 1, wherein said grooves have a depth in the range of about 0.04 inch to about 0.08 inch.

3. A seal arrangement according to claim 1, wherein the acute entrance angle between the groove centerline and the respective radial direction is in the range of about 30°

to about 60°

.

4. A seal arrangement according to claim 1, wherein the groove arrangement includes an annular groove concentrically formed in the respective seal face and maintained in continuous communication with the radially inner ends of all of said first and second straight grooves, said annular groove being positioned radially outwardly of the inner diameter of the respective seal face to define a flat nongrooved annular dam face therebetween.

5. A seal arrangement according to claim 4, wherein the straight and annular grooves are all of the same depth.

6. A seal arrangement according to claim 4, wherein the straight grooves have a cross sectional area which is significantly greater than the cross sectional area of the annular groove.

7. A seal arrangement according to claim 4, wherein the straight and annular grooves have a depth in the range of about 0.050 to about 0.075 inch, wherein the annular groove has a width in the range of about 0.050 to about 0.075 inch, and wherein the first and second straight grooves have a width at least equal to the width of the annular groove.

8. A seal arrangement according to claim 4, wherein the dam face has a radial width of about 15% to about 20% of the radial width of the respective seal face.

9. A seal arrangement according to claim 4, wherein the acute entrance angle between the groove centerline and the respective radial direction is in the range of about 30°

to about 60°

.

10. A seal arrangement according to claim 9, wherein said grooves have a depth in the range of about 0.04 inch to about 0.08 inch.

11. A mechanical seal assembly disposed within a housing chamber in substantially concentric and surrounding relationship to a rotatable shaft positioned within the chamber for creating a seal therebetween, comprising:

a barrier gas chamber disposed between said housing and said seal assembly for containing therein an inert pressurized barrier gas;

said seal assembly including stator and rotor rings which are respectively nonrotatably secured to the housing and shaft in substantially concentric relation to the shaft, the stator and rotor rings having opposed axially-oriented annular seal faces disposed in relatively rotatable sliding and sealing engagement with one another at an annular contact area;

the rotor ring seal face including a deep groove arrangement therein in communication with the barrier gas of said intermediate chamber for effecting cooling of and reducing contact pressure between the opposed seal faces of said outer seal assembly;

said groove arrangement including a plurality of first straight grooves formed in the respective seal face in substantially uniformly angularly spaced relation therearound, and a plurality of second straight grooves formed in the respective seal face in substantially angularly spaced relation therearound, said second grooves being individually positioned between an angularly adjacent pair of first grooves, said first grooves being individually positioned between an angularly adjacent pair of second grooves, said first and second grooves having radially outer ends which communicate with an outer diameter of the respective seal face, each of said first and second grooves projecting radially inwardly of the respective seal face from the respective outer end and having a longitudinally extending centerline which intersects at said outer end with a respective radial direction of said respective seal face so as to define an acute entrance angle therebetween, said first grooves being angled relative to the respective radial direction in one direction circumferentially around the respective seal face, said second grooves being angled relative to the respective radial direction in an opposite direction to said one direction circumferentially around the respective seal face, and at least circumferentially adjacent said first and second grooves having radially inner ends which are in communication with one another to define a flow path for said harrier gas when said rotor ring is rotating, one of said circumferentially adjacent first and second grooves defining an upstream portion of said flow path and the other of said circumferentially adjacent first and second grooves defining a downstream portion of said flow path, and said first and second grooves having a depth of at least about 0.04 inch to create a hydrostatic force therein which reduces the contact pressure between the opposed contacting seal faces.

12. A seal arrangement according to claim 11, wherein said grooves have a depth in the range of about 0.04 inch to about 0.08 inch.

13. A seal arrangement according to claim 11, wherein the acute entrance angle between the groove centerline and the respective radial direction is in the range of about 30°

to about 60°

.

14. A seal arrangement according to claim 11, wherein the groove arrangement includes an annular groove concentrically formed in the respective seal face and maintained in continuous communication with the radially inner ends of all of said first and second straight grooves, said annular groove being positioned radially outwardly of the inner diameter of the respective seal face to define a flat nongrooved annular dam face therebetween.

15. A seal arrangement according to claim 14, wherein the straight and annular grooves have a depth in the range of about 0.050 to about 0.075 inch, wherein the annular groove has a width in the range of about 0.050 to about 0.075 inch, and wherein the first and second straight grooves have a width at least equal to the width of the annular groove.

16. A seal arrangement according to claim 14, wherein the dam face has a radial width of about 15% to about 20% of the radial width of the respective seal face.

17. A seal arrangement according to claim 14, wherein the acute entrance angle between the groove centerline and the respective radial direction is in the range of about 30°

to about 60°

.

18. A seal arrangement according to claim 14, wherein said grooves have a depth in the range of about 0.04 inch to about 0.08 inch.

19. A seal arrangement according to claim 14, wherein the dam face has a radial with of no more than about 25% of the radial width of the annular contact area, wherein the acute entrance angle between the groove centerline and the respective radial direction is in the range of about 30°

to about 60°

, and wherein said grooves have a depth in the range of about 0.04 inch to about 0.08 inch.