TYPES OF MECHANICAL SEALS

1. A technical seminar on
TYPES OF MECHANICAL SEALS
Presented by
N.SUDHEER
M.TECH(MACHINE DESIGN)
16481D1509
GUDLAVALLERU ENGINEERING COLLEGE
Sheshadri Rao Knowledge Village, Gudlavalleru, PIN:521356
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2. INTRODUCTION
Mechanical devices known as seals, packings, and
gaskets are used to prevent the leakage of fluids,
gases from cylinders and cylinder heads in engines;
pumps; and mixers etc.
These devices also prevent the penetration of
foreign matter into the concealed system.
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3. SELECTION OF SEALS
Seals are available in various forms and design
configurations and the selection of a seal depends
on:
Pressure,
Temperature,
Medium(i.e., liquid, gases),
Corrosive atmosphere, and
Shaft speed etc.
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4. CLASSIFICATION OF SEALS
Seals are broadly classified as static and dynamic
seals.
1. Static seals
a. Gaskets
b. Direct contact seals
c. Sealants
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5. 2. Dynamic seals
a. Seals used on rotating shafts
i. Interfacial
ii. Interstitial
b. Seals used on reciprocating shafts
i. Packings
ii. Diaphragm
iii. Rings
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6. STATIC SEALS
A static seal functions against mating surfaces that have no
relative motion between each other.
Gasket:
A gasket is a thin layer of soft material such as paper, cork,
copper, synthetic material, or a combination of these which
is used in between two surfaces to be sealed, such as a
cylinder head and cylinder in engine block.
A gasket can be performed or precut to the desired shape.
Clamping the gasket between the two flat surfaces makes a
tight seal.
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7. 7
Fig: Gaskets

8. 8
Fig: Gasket on engine cylinder block

9. Direct contact seals:
Direct contact seals are used where two surfaces
are directly making metal to metal contact under
high squeezing pressure, where very high
pressures are involved.
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10. 10
Fig: Direct contact seals

11. Sealants:
Instead of being performed, some gaskets are
formed in place. Squeezing a bead of plastic
gasket material or sealant from a tube into one of
the mating surfaces, such as valve covers, water
pumps, and differential covers.
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12. 12
Fig: Sealant

13. 13
Fig: Application of sealant to gear box

14. DYNAMIC SEALS
Dynamic seals exist when there is motion between
surfaces. Typical motions include reciprocating,
oscillating, and rotation.
Operational factors can greatly affect how
dynamic seals perform.
Factors such as swelling of seals in fluids, surface
roughness of mating surfaces, lubrication, internal
pressure, compression, elasticity, and friction from
surfaces.
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15. Dynamic seals used on rotating shafts:
i. Interfacial seals: These are the seals in which
seal touches the shaft.
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16. ii. Interstitial seals: These are the seals where
clearance between shaft and seal exists in radial
and/or axial direction.
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17. Dynamic seals used on reciprocating parts:
Packings
Diaphragms
Rings
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18. 18
Fig: Packings

19. The leakage rate of a mechanical shaft seal
depends on a number of factors such as:
Surface roughness of seal faces
Flatness of seal faces
Vibration and stability of shaft
Speed of rotation
Shaft diameter
Temperature, viscosity, and type of pumped
medium
Pump pressure
Seal and pump assembly.
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20. THE END
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