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TYPE 21

TYPE 21
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TYPE 21 Elastomer Bellows Seal A B C D E F – Face/Primary Ring – Seat/Mating Ring – Spring – Retainer – Elastomer Bellows – Drive Band Product Description The Type 21, a general purpose seal, has become an industry standard with OEM designers. Made of stainless steel, it provides a service range well beyond that which is possible with comparably priced seals of other metallurgical construction. I The positive static seal between the bellows and the shaft, along with the free movement of the bellows, means that there is no sliding action that could lead to shaft damage by fretting. This ensures that the seal will automatically compensate for normal shaft run-out and axial movements. This versatile seal can be used on a wide range of equipment including centrifugal, rotary and turbine pumps, compressors, mixers, blenders, chillers, agitators, and other rotary shaft equipment. Ideal for pulp and paper, pool & spa, water, food processing, wastewater treatment, and other general applications. Temperature: -40˚F to 400°F/-40˚C to 205°C (depending on materials used) Speed: Up to 2500 fpm/13 m/ s (depending on configuration and shaft size) Self-aligning unit automatically adjusts for shaft end play and run-out. Eliminates potential shaft fretting damage between the seal and shaft. Positive mechanical drive protects the elastomer bellows from overstressing. Single coil spring improves tolerance to clogging. Simple to fit and completely field repairable. Can be used with practically any type of mating ring.

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Elastomer Bellows Seal Type 21 Typical Arrangement/Dimensional Data Working Height Alternate Methods Note: For primary ring optional Hard Face Design, contact John Crane Engineering. Type 21 Dimensional Data (inches) Seal Size Working Height

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TYPE 21 Elastomer Bellows Seal Elastomer Temperature Limits Compound Buna-N (Nitrile) Ethylene Propylene Materials of Construction SEAL COMPONENTS Face/Primary Ring Siliconized Graphite Tungsten Carbide (Nickel Binder) Solid Silicon Carbide Elastomer Bellows Buna-N Fluoroelastomer Ethylene Propylene Neoprene Drive Band Retainer Spring Holder 316 Stainless Steel Monel® 316 Stainless Steel Monel Monel is a registered trademark of Inco Alloys International, Inc. Neoprene is a registered trademark of DuPont.

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TYPE 21 Elastomer Bellows Seal Hydrostatic Pressure Limits Pressure psi(g) Pressure bar(g) Seal Size Criteria for Installation Shaft/Sleeve Surface Finish (Shaft or Sleeve) Up to 3.125" diameter 125 Ra Over 3.125" diameter 63 Ra Ovality/Out of Roundness (Shaft) End Play/ Axial Float Allowance Recommendations for Viscous Fluids 25,000 Double Seal Hard Face Standard Seal 7,500 cSt = Centistokes (cSt x 4.62 = SSU) SSU = Saybolt Seconds Universal CUT LINE FOR SHORT PAGE

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TYPE 21 Elastomer Bellows Seal Basic Pressure Ratings Pressure psi(g) 200 Pressure bar(g) 14 Carbon vs. TC or SiC (1800 rpm) 2. Pressure capabilities to 150 psi(g)/10 bar(g) are based on lubricating oil service, F50 Carbon vs. Tungsten Carbide. 1. Lubricating liquid is defined as having lubricating properties of gasoline or better. CUT LINE FOR SHORT PAGE Seal Size The Basic Pressure Rating is for a standard Type 21 seal, as shown in the typical arrangement, when installed according to the criteria given in this data sheet and generally accepted industrial practices. The Basic Pressure...

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TYPE 21 Elastomer Bellows Seal Speed Limits Shaft Speed (rpm) 7000 Rotating Mating Ring and Stationary Seal Head 6000 Shroud Covering Spring 5000 Welded End Coil Spring 4000 Standard Seal Seal Size For your nearest John Crane facility, please contact one of the locations below. North America Morton Grove, IL, USA 1-800-SEALING Tel: 1-847-967-2400 Fax: 1-847-967-3915 Latin America São Paulo, Brazil Middle East & Africa Dubai, United Arab Emirates Tel: 971-481-27800 Fax: 971-488-62830 Asia Pacific Singapore If the products featured will be used in a potentially dangerous and/or hazardous...

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