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TYPES OF MECHANICAL SEALS

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SUDHEERNELAKUDITI

This document summarizes the different types of mechanical seals. It begins by introducing mechanical seals, packings, and gaskets which are used to prevent fluid leakage and foreign material penetration. Seals are selected based on factors like pressure, temperature, medium, environment, and shaft speed. Seals are classified as either static or dynamic. Static seals include gaskets, direct contact seals, and sealants. Dynamic seals include those used on rotating shafts like interfacial and interstitial seals, and those used on reciprocating shafts like packings, diaphragms, and rings. The document describes examples of different seal types and concludes with factors that influence the leakage rate of mechanical shaft seals.

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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 1
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. 2
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. 3
CLASSIFICATION OF SEALS Seals are broadly classified as static and dynamic seals. 1. Static seals a. Gaskets b. Direct contact seals c. Sealants 4
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 5
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. 6
7 Fig: Gaskets
8 Fig: Gasket on engine cylinder block
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. 9
10 Fig: Direct contact seals
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. 11
12 Fig: Sealant
13 Fig: Application of sealant to gear box
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. 14
Dynamic seals used on rotating shafts: i. Interfacial seals: These are the seals in which seal touches the shaft. 15
ii. Interstitial seals: These are the seals where clearance between shaft and seal exists in radial and/or axial direction. 16
Dynamic seals used on reciprocating parts: Packings Diaphragms Rings 17
18 Fig: Packings
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. 19
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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 1
  • 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. 2
  • 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. 3
  • 4. CLASSIFICATION OF SEALS Seals are broadly classified as static and dynamic seals. 1. Static seals a. Gaskets b. Direct contact seals c. Sealants 4
  • 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 5
  • 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. 6
  • 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. 9
  • 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. 11
  • 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. 14
  • 15. Dynamic seals used on rotating shafts: i. Interfacial seals: These are the seals in which seal touches the shaft. 15
  • 16. ii. Interstitial seals: These are the seals where clearance between shaft and seal exists in radial and/or axial direction. 16
  • 17. Dynamic seals used on reciprocating parts: Packings Diaphragms Rings 17
  • 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. 19