Mechanical shaft seals for pumps - Grundfos

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O-ring, stationary O-ring, rotating Fig. 1.7: The secondary seals confine leakage to the atmosphere Spring Fig. 1.8: A spring presses the rotating seal ring against the stationary seat Torque transmission element Fig. 1.9:The torque transmission element completes the mechanical shaft seal Secondary seals Secondary seals consist of rubber parts such as O-rings or bellows, used to avoid leakage between the shaft and the rotating seal ring as well as between the stationary seat and the pump housing. To minimise leakage, the rotating seal ring must be pressed against the seat. Therefore the rotating seal ring must be able to move axially on the shaft. To obtain axial flexibility, the secondary seal must either be a bellows or an O-ring sliding on the shaft. The secondary seal that seals between the rotating seal ring and the shaft rotates together with the shaft. The secondary seal that seals between seat and pump housing is static. See fig. 1.7. Spring The rotating spring presses the rotating seal ring against the seat and the rotating O-ring along the shaft. See fig. 1.8. Torque transmission element A torque transmission element ensures that the rotating seal ring rotates together with the shaft. See fig. 1.9. All compoments of a complete mechanical shaft seal have now been introduced. 11
12 Introduction 3. Operating principle This section describes how the lubricating film is generated in the sealing gap in a liquidlubricated mechanical bellows shaft seal. The design differs slightly from the O-ring seal shown in fig. 1.9. In its simplest form, the mechanical shaft seal consists of two main parts: The rotating part and the stationary part. See fig. 1.10. Lubricating film in sealing gap Sealing gap Fig: 1.10: Mechanical bellows shaft seal 1. Pump housing 2. Stationary secondary rubber seal 3. Stationary seat 4. Rotating seal ring 5. Torque transmission ring 6. Spring 7. Torque transmission ring 8. Rubber bellows (rotating secondary seal) 9. Shaft Stationary part Rotating part
Page 1 and 2: Mechanical shaft seals for pumps
Page 3 and 4: Contents Preface 5 Chapter 1. Intro
Page 6 and 7: Chapter 1 1. Types of shaft seals 2
Page 8 and 9: Fig. 1.2: Braided stuffing box pack
Page 12 and 13: The rotating part The rotating part
Page 14 and 15: Closing force The parts of the seal
Page 16 and 17: In the examples above, where the ar
Page 18 and 19: Non-parallel seal faces System In p
Page 20 and 21: Atmosphere A B C D Vapour pressure
Page 22 and 23: 1993 Rubber bellows seal introduced
Page 25 and 26: 26 Mechanical shaft seal types and
Page 43 and 44: Chapter 3 Materials 1. Seal face ma
Page 45 and 46: The metals used for metal-impregnat
Page 47 and 48: Silicon carbide (SiC) 100 µm Fig.
Page 49 and 50: 2. Seal face material pairings Carb
Page 51 and 52: WC against WC A shaft seal with WC
Page 53 and 54: 3. Testing of shaft seals Various t
Page 55 and 56: [ °C ] 250 200 150 Organic film bi
Page 57 and 58: Chemical adhesion of surfaces All s
Page 59 and 60: 5. Materials of other shaft seal pa
Page 61 and 62:
64 Tribology The science of frictio
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66 Tribology Duty parameter The mec
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Surface film 68 3.5 Tribology 3.0 2
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70 Tribology The lapped surface has
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72 2.0 1.5 Tribology 1.0 0.5 Dry ru
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74 Tribology Summary This section d
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76 Failure of mechanical shaft seal
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88 7. Shaft seal failure analysis T
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s of shaft seal failure Incorrect i
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Chapter 6 Standards and approvals 1
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Example of designation for a mechan
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2. Approvals Specific approvals of
Page 95 and 96:
The guideline on in-place cleanabil
Page 97:
Summary Different applications requ
Page 100 and 101:
contact points 65 contact surface 8
Page 102 and 103:
M magnetic-drive system 40 malfunct
Page 104 and 105:
spring force 13, 15 springs and bel
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Mechanical shaft seals for pumps - Grundfos

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