Industrial seal self study guide - SKF.com

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Disadvantages - Poor compatibility with water - Non-homogeneous matrix makes consistent high quality difficult to maintain. - Expensive - Vulnerable to heat above 200˚F - Designs tend to have high torque - Limited Availability - Costly Operating Range Leather can handle temperatures ranging from –100°F to 200°F (-73°C to 93°C). 4 Identification It is difficult to determine from the appearance of a used seal whether the sealing element is leather or rubber. Scratch the sealing surface. If that makes the surface much lighter (brown or beige) and fibrous, rather than black and smooth, the material is probably leather. Substitute Lip Material Nitrile, polyacrylate or fluoroelastomer FELT Felt is another non-synthetic material which has long been used as a sealing material. Made of wool and sometimes laminated with synthetic rubber washers, felt is generally limited to dirt exclusion. It can be used to retain heavy lubricants under some conditions. Advantages + Excludes dust and dirt well + Retains grease efficiently Disadvantages - Cannot confine oil - May trap metal and/or dirt particles, causing shaft wear - Absorbs water which may cause shaft rusting - Few stock sizes Operating Range - Felt is used in temperatures ranging from –65°F to 200°F Substitute Lip Materials Nitrile, polyacrylate or fluoroelastomer 41
Seal Applications (cont.) °C °F 260° 500° 400° 200° 300° 100° 200° 100° 0° 32° 0° -100° -100° -240° -400° PTFE Viton Silicone Polyacrylate Leather Duralip Nitrile Duratemp Lip materials’ maximum operating temperatures fall within these ranges (fig. 4l). Material Capabilities—Temperature Resistance In performing their sealing function, seal lip materials work best within the following temperature ranges. (Also see fig. 4l). Polytetrafluoroethylene (PTFE) -400˚ to 500˚ -240˚ to 260˚ Fluoroelastomer -40˚ to 400˚ -40˚ to 204˚ (LongLife) Silicone -100˚ to 325˚ -73˚ to 163˚ Polyacrylate -40˚ to 300˚ -40 to 149˚ Duralip -40˚ to 250˚ -40 to 121˚ Nitrile -40˚ to 250˚ -40 to 121˚ Leather -100˚ to 200˚ -73˚ to 93˚ Duratemp -40˚ to 300˚ -40˚ to 149˚ F˚ C˚ Low temperatures can be as much of a problem for a seal as high temperatures. At low temperatures the sealing material gets stiff and rigid. That causes several problems. The sealing lip has trouble following the eccentricity of a shaft that’s not perfectly true. That causes it to leak every time the shaft rotates “off center” and pulls away from the seal. If it gets stiff enough, the material becomes brittle and breaks up with the movement of the shaft. Another problem can appear when the lip material starts to shrink up at low temperatures. At high temperatures, some elastomers will continue to cure again and lose their pliability. If the temperature gets high enough to burn the lip material, it often becomes hard and brittle. It can crack and break up. In such cases, it not only loses its sealing effectiveness, it can also damage the bearing and the shaft it was designed to protect. Consequently, both upper and lower operating temperature limits should be considered when choosing a lip material. See fig. 4l for operating temperature ranges of a variety of lip materials. 42
Page 1 and 2: Industrial seal self study guide Ma
Page 3 and 4: CHAPTER 1— INTRODUCTION This book
Page 5 and 6: INTRODUCTION (cont.) The Total Bear
Page 7 and 8: BASIC SEAL TYPES (cont.) A As a sha
Page 9 and 10: BASIC SEAL TYPES (cont.) As was ear
Page 11 and 12: CHAPTER 2 REVIEW To take this test,
Page 13 and 14: HM14 SKF’s non-spring loaded desi
Page 15 and 16: SEAL DESIGN GROUPS (cont.) Hydrodyn
Page 17 and 18: SEAL DESIGN GROUPS (cont.) CRWA5, C
Page 19 and 20: SEAL DESIGN GROUPS (cont.) HDSB HDS
Page 21 and 22: SEAL DESIGN GROUPS (cont.) All HS s
Page 23 and 24: SEAL DESIGN GROUPS (cont.) HSF SBF
Page 25 and 26: SEAL DESIGN GROUPS (cont.) VR2 VR2
Page 27 and 28: SEAL DESIGN GROUPS (cont.) Scotseal
Page 29 and 30: SEAL DESIGN GROUPS (cont.) “OLD
Page 31 and 32: CHAPTER 3 REVIEW (cont.) 30 7. The
Page 33 and 34: V-Ring excludes contaminants, preve
Page 35 and 36: Seal Applications (cont.) An effect
Page 37 and 38: Seal Applications (cont.) Identific
Page 39 and 40: Seal Applications (cont.) Substitut
Page 41: Seal Applications (cont.) + Handles
Page 45 and 46: Chapter 4 Review To take this test,
Page 47 and 48: Chapter 5—Seal Selection The firs
Page 49 and 50: Seal Selection (cont.) l A B Seal S
Page 51 and 52: Seal Selection (cont.) A longer lip
Page 53 and 54: Chapter 5 Review (cont.) 7. Substit
Page 55 and 56: Wear Sleeves (cont.) Speedi-Sleeve
Page 57 and 58: Wear Sleeves (cont.) 8. Drop the Sp
Page 61 and 62: fig. 7A Shaft surfaces must be smoo
Page 63 and 64: Shaft and Bore Conditions (cont.) S
Page 65 and 66: Shaft and Bore Conditions (cont.) B
Page 67 and 68: Chapter 7 Review (cont.) 6. Spiral
Page 69 and 70: Installation (cont.) For best resul
Page 71 and 72: Installation (cont.) 8. Check seal
Page 73 and 74: Installation (cont.) Corrective Act
Page 75 and 76: Installation (cont.) Split Seal Con
Page 79 and 80: Chapter 9—Troubleshooting Prelimi
Page 81 and 82: Troubleshooting (cont...) Causes Su
Page 83 and 84: Troubleshooting (cont...) Out-of-Ro
Page 85 and 86: Troubleshooting (cont...) Pressure
Page 87 and 88: Chapter 9 Review (cont...) 8. Garte
Page 89 and 90: Glossary of Seal Terms (cont...) Di
Page 91 and 92: Glossary of Seal Terms (cont...) MP
Page 93 and 94:
Glossary of Seal Terms (cont...) Sh
Page 95 and 96:
Final Exam Congratulations. You hav
Page 97 and 98:
12. A cocked seal can cause a seal
Page 99 and 100:
26. In _________________ installati
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40. A sealing lip that is cut, turn
Page 103 and 104:
54. If a shaft is lightly grooved b
Page 105 and 106:
73. More bearings fail from the ent
Page 107 and 108:
96. Ferrous and other commonly used
Page 109 and 110:
Fold Here Fold Here PLACE STAMP HER
Page 111 and 112:
110 NOTES
Page 113 and 114:
112 NOTES
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