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SEAL FACE PROPERTIES

SEAL FACE PROPERTIES. FOR A SEAL TO WORK… FACE FLATNESS. SEAL FACES ARE TO BE FLAT TO ONE LIGHT BAND OF A HEILIUM ARC LAMP REFLECTED THROUGH A QUARTZ REFERENCE OPTICAL FLAT ONE LIGHT BAND = 0.0000116 INCHES OR 11.6 ONE MILLIONTHS OF AN INCH. Optically Flat Faces. 100 psi. Rotary Face.

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SEAL FACE PROPERTIES

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  1. SEAL FACE PROPERTIES

  2. FOR A SEAL TO WORK…FACE FLATNESS • SEAL FACES ARE TO BE FLAT TO ONE LIGHT BAND OF A HEILIUM ARC LAMP REFLECTED THROUGH A QUARTZ REFERENCE OPTICAL FLAT • ONE LIGHT BAND = 0.0000116 INCHES • OR 11.6 ONE MILLIONTHS OF AN INCH

  3. Optically Flat Faces 100 psi Rotary Face Stationary Face 0 psi

  4. FOR A SEAL TO WORK…FACE LUBRICATION • BOUNDARY LAYER FILM OF LIQUID FILLS PORES AND IMPERFECTIONS. IT IS PROVIDED BY THE LIQUID IN THE STUFFING BOX. • DRY RUNNING OF A PUMP SEAL FOR ONLY A FEW SECONDS MAY DESTROY IT. • UNLESS IT IS DESIGNED THAT WAY!

  5. Microscopic Face Lubrication 100 psi Rotary Face Stationary Face 0 psi

  6. Pressure Drop 100 psi 0 psi

  7. Liquid 100 psi Liquid + Vapor 50 psi Vapor + Liquid 25 psi Vapor 0 psi Pressure Drop & Vaporization

  8. Convergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  9. Convergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  10. Convergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  11. Divergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  12. Divergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  13. Divergent Seal Faces 100 psi Rotary Face Stationary Face 0 psi

  14. SEAL BALANCE

  15. Unbalanced Seal Face OD Line Face ID Line Balance Line

  16. BALANCED VS. NON-BALANCED • When speaking of “Balance” in reference to mechanical seals, we are not talking about Mechanical or Rotational Balance. Instead, we are referring to Hydraulic Balance. • Since mechanical seals are subject to stuffing box pressure, this pressure is utilized to achieve and maintain seal face closure in a non-balanced seal. • If stuffing box pressure is very high, typically over 100psi., then the closing force may be too great to allow the “Boundary Layer Liquid” that lubricates the faces to be sufficient and the faces will wear prematurely. • A balanced seal compensates for higher pressures by locating the seal faces such that stuffing box pressure has less effect on face closure.

  17. Seal Balance

  18. Face OD Line Face ID Line Balance Line A non-balanced seal has faces located outside the “Balance Diameter” of the seal. Stuffing box pressure is applied to the faces virtually evenly.

  19. Unbalanced SealFace Areas Green+Red=Pressure Area Green+Purple=Face Contact Area Face ID Line Balance Line Face OD Line

  20. Face OD Line Balance Line Face ID Line The faces of a balanced seal are located so that a portion of the face contact occurs inside the balance diameter resulting in reduced closing force due to stuffing box pressure.

  21. Green+Red=Pressure Area Balanced SealFace Areas Red+Purple=Balanced Area Balance Line Face ID Line Face OD Line

  22. Face OD Line Face ID Line Balance Line Most metal bellows seals are balanced.

  23. ENDSEAL FACE PROPERTIES

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