Mechanical shaft seals for pumps - Grundfos

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High-speed mechanical shaft seals Where speeds exceed 15-20 m/sec, the seat must be the rotating part to reduce unbalance of the seal. See fig. 2.11. Other advantages of the rotating seat are that misalignment of the shaft causes the springs to adjust only once and prevent fretting of the sleeve under the O-ring. Fig. 2.11: (To the right) Example of a high-speed shaft seal for Grundfos BME pumping system Air cooled top for high temperatures For applications in woling high temperatures of the clean pumped medium such as hot water or thermal oil, it can be advantageous to extend the length of the pump. As a result, and air chamber will be formed below the seal chamber. Thanks to this arrangement, the standard shaft seal is located at a distance from the hot pumped medium, allowing the shaft seal to generate a stable lubricating film in the sealing gap. The exchange of pumped medium with pumped medium from the seal chamber is very low due to a throttle around the shaft. An automatic air vent valve is required to vent the seal chamber. This stand-alone sealing arrangement is independent of external connections. See fig. 2.12. Standard shaft seal Seal chamber Air chamber Pumped medium Fig. 2.12: (To the right) Example of a Grundfos CR pump with air-cooled top Air vent valve 39
40 Mechanical shaft seal types and sealing systems Magnetic-drive system The magnetic-drive system constitutes an entirely different type of sealing of a rotating shaft. For applications where it is absolutely necessary to avoid leakage from the shaft seal, an alternative to a back-to-back arrangement is a can that separates the pumped medium side from the atmospheric side. The magnetic-drive system incorporates an outer and inner rotor with magnets, separated by the can. The magnetic-drive system transfers the torque from the motor to the pump shaft. The system only has static O-rings to seal the clean pumped medium, free from magnetic particles. This stand-alone sealing arrangement is independent of external connections. See fig. 2.13. Stationary can Outer rotor with magnet and adapter to the motor Inner rotor with magnet and adapter to the pump shaft Pump shaft Fig. 2.13: Hermetically sealed system with magnetic-drive system
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 10 and 11: O-ring, stationary O-ring, rotating
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 37: 38 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
Page 63 and 64: 66 Tribology Duty parameter The mec
Page 65 and 66: Surface film 68 3.5 Tribology 3.0 2
Page 67 and 68: 70 Tribology The lapped surface has
Page 69 and 70: 72 2.0 1.5 Tribology 1.0 0.5 Dry ru
Page 71 and 72: 74 Tribology Summary This section d
Page 73 and 74: 76 Failure of mechanical shaft seal
Page 85 and 86: 88 7. Shaft seal failure analysis T
Page 87 and 88: s of shaft seal failure Incorrect i
Page 89 and 90:
Chapter 6 Standards and approvals 1
Page 91 and 92:
Example of designation for a mechan
Page 93 and 94:
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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