A Face/Primary Ring B Seat/Mating Ring C Drive Band D Bellows E Spring D TYPE 21 E 21 B C A Product Description The Type 21 is a compact, unitized, single spring, elastomer bellows mechanical seal. For centrifugal, rotary, and turbine pumps, compressors, blenders, chillers, and other rotary equipment. For many water-based applications, such as wastewater treatment, pulp and paper, food processing, marine, and other general applications. Performance Capabilities Temperature: -4 C to 15 C/-4 F to 3 F depending on materials used Pressure: Up to 2 bar g/29 psig Speed: Up to 15 m/s/3 fpm Design Features Unitized, Easy-to-Fit Design Bellows Design is Pressure Supported and Eliminates Creases or Folds Compact Design Fits DIN 2496, ISO 369, and ANSI B73.1 M-1991 Positive Key Drive via Drive Bands Protects Bellows from Torsional Strain
21 TYPE 21 Type 21 Typical Arrangement/Dimensional Data CIRCULATION CONNECTION Sleeve Shoulder, Impeller Boss, Spacer, Shaft Circlip, or Abutment Ring (not supplied) D4 MIN. BORE D3 L3* L3** (mm ONLY) L3 D1±.5mm/.2" SHAFT OR SLEEVE DIAM. Type 21 Dimensional Data (inches) Seal Size/D1 (inches) D3 D4 L3 L3*.375.787.866.591.5.945 1.24.591.812.625 1.24 1.12.591.875.75 1.26 1.339.787.875.875 1.417 1.496.787.937 1. 1.535 1.614.787 1. 1.125 1.654 1.732 1.24 1.62 1.25 1.811 1.89 1.24 1.62 1.375 1.929 2.8 1.24 1.125 1.5 2.126 2.283 1.181 1.187 1.625 2.25 2.362 1.181 1.375 1.75 2.42 2.559 1.181 1.375 1.875 2.52 2.677 1.181 1.5 2. 2.598 2.756 1.181 1.5 2.125 2.717 2.874 1.181 1.687 2.25 3.31 3.189 1.299 1.687 2.375 3.15 3.346 1.299 1.812 2.5 3.268 3.465 1.299 1.812 2.625 3.465 3.661 1.299 2.75 3.54 3.74 1.299 2.875 3.78 3.976 1.299 3. 3.898 4.94 1.575 3.125 4.55 4.252 1.575 3.25 4.94 4.291 1.575 3.375 4.252 4.488 1.575 3.5 4.49 4.66 1.575 3.625 4.488 4.685 1.575 3.75 4.646 4.882 1.575 3.875 4.83 5. 1.575 4. 4.882 5.79 1.575 Note: For other working lengths, consult John Crane. L3* = Interchangeable with the Type 21 standard seal. Seal Unit Axial Flexibility at Working Length L3 Seal Size Flexibility 1 to 16mm/ ±1.mm/.375 to.625" ±.4" 19 to 1mm/ ±1.5mm/.75 to 4." ±.6" Note: Equipment axial displacement must occur within these limits.
TYPE 21 Type 21 Dimensional Data (mm) Seal Size/D1 Seal Size (mm) Code D3 D4 L3 L3* L3** 1 1 2 22 15 27.5 35. 12 12 22 24 15 26.5 34. 14 14 24 26 15 29. 34. 15 15 25 27 15 29. 34. 16 16 26 28 15 29. 34. 18 18 32 34 2 31.5 39. 2 2 34 36 2 31.5 39. 22 22 36 38 2 31.5 39. 24 24 38 4 2 34. 44. 25 25 39 41 2 34. 44. 28 28 42 44 26 36.5 44. 3 3 44 46 26 35.5 43. 32 32 46 48 26 35.5 48. 33 33 47 49 26 35.5 48. 35 35 49 51 26 34.5 47. 38 38 54 58 3 37. 47. 4 4 56 6 3 37. 47. 43 43 59 63 3 37. 52. 45 45 61 65 3 37. 52. 48 48 64 68 3 35. 5. 5 5 66 7 3 37.5 5. 53 53 69 73 3 37.5 6. 55 55 71 75 3 37.5 6. 58 58 78 83 33 42.5 6. 6 6 8 85 33 4.5 58. 63 63 83 88 33 4.5 58. 65 65 85 9 33 4.5 68. 68 68 88 93 33 4.5 68. 7 7 9 95 33 48. 68. 75 75 99 14 4 48. 68. 8 8 14 19 4 47.5 77.5 85 85 19 114 4 47.5 77.5 9 9 114 119 4 52.5 77.5 95 95 119 124 4 52.5 77.5 1 1 124 129 4 52.5 77.5 Note: For larger seal sizes, consult John Crane. L3 = Standard seal working length. L3* = Working length for seals to DIN L1K (seat not included). L3** = Working length for seals to DIN L1N (seat not included).
Basic Pressure Ratings TYPE 21 Pressure (bar g) 25 2 15 1 5 Standard Operation up to 15 m/s / 3 fpm Tracking Against Cup Mounted Design Seat/Mating Ring Pressure (psig) 2 4 6 8 1 (mm) 1 2 3 4 (inches) Seal Size 35 3 25 2 15 1 5 The Basic Pressure Rating is for a standard 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 Rating assumes stable operation at 36 rpm in a clean, cool, lubricating, non-volatile liquid with an adequate flush rate. When used with the Multiplier Factors, the Basic Pressure Rating can be adjusted to provide a conservative estimate of the dynamic pressure rating. For process services outside this range, or a more accurate assessment of the dynamic pressure rating, contact John Crane for more information. Multiplier Factors Sealed Fluid Lubricity Face/Primary Ring & Seat/Mating Ring Materials Sealed Fluid Temperature (for carbon only) Selection Considerations Petrol/Gasoline, Kerosene, or Better Water and Aqueous Solutions Flashing Hydrocarbons Carbon vs. Tungsten Carbide or Silicon Carbide Silicon Carbide vs. Silicon Carbide Carbon Graphite vs. Aluminum Oxide Ceramic Up to 8 C/175 F From 8 C to 12 C/175 F to 25 F From 12 C to 15 C/25 F to 3 F From 15 C to 26 C/3 F to 5 F Multiplier Factor x 1. * x.6 x 1. x.75 x.6 x 1. x.9 x.8 x.6 Speed Up to 18 rpm x 1. From 18 to 36 rpm Example for Determining Pressure Rating Limits: Seal: 5.8mm/2" Diameter Type 21 Product: Petrol/Gasoline Face Materials: Carbon Graphite vs. Aluminum Oxide Ceramic Operating Temperature: 65 C/15 F Operating Speed: 18 rpm * For water duties, the temperature for fluorocarbon should not exceed 135 C/275 F; for water/steam duties, the ethylene propylene limit is 15 C/3 F. See Multiplier Factors for Water and Aqueous Solutions Graph. The ratio of sealed pressure to vapor pressure must be greater than 1.5, otherwise consult John Crane. If the specific gravity is less than.6, consult John Crane. Data only applicable to specialized grade of silicon carbide used with the Type 21 seal. Using the Basic Pressure Rating Limits graph, the maximum pressure would be 2 bar g/29 psig. From the Multiplier Factors chart, apply the multiplier factors for the specific service requirements to determine the maximum operating pressure for the application: 2 bar g/29 psig x 1. x.6 x 1. x 1. = 12 bar g/174 psig The maximum operating pressure for this.8mm/2" Type 21 seal is 12 bar g/174 psig.
TYPE 21 Multiplier Factors for Water and Aqueous Solutions Multiplier Factor 1.2 1..8.6.4.2 Carbon vs. Ceramic Carbon vs. Tungsten Carbide Silicon Carbide vs. Silicon Carbide Carbon vs. Silicon Carbide Example for Determining Pressure Rating Limits: Seal: 75mm/3" Diameter Type 21 Product: Water Face Materials: Silicon Carbide vs. Silicon Carbide Operating Temperature: 1 C/212 F Operating Speed: 36 rpm 2 4 6 8 1 12 14 16 ( C) 32 68 14 14 176 212 248 284 32 ( F) Temperature Using the Pressure Rating Limits graph, the maximum pressure would be 14 bar g/23 psig. From the Multiplier Factors for Water and Aqueous Solutions chart, apply the multiplier factors for the specific service requirements to determine the maximum operating pressure for the application: 14 bar g/23 psig x.6 x 1. = 8.4 bar g/122 psig The maximum operating pressure for this 75mm/3" Type 21 seal is 8.4 bar g/122 psig. Housing Squareness to Shaft Axial Run-out (mm) FIM.24.2.16.12.8.4 Axial Run-out (inches) FIM.9.8.7.6.5.4.3.2.1 1 2 3 4 Shaft Speed (rpm) The above specifications are given for general guidance only. If recommendations are required for a specific application, consult John Crane.
TYPE 21 Materials of Construction SEAL COMPONENTS MATERIALS Description Standard Options Face/Primary Ring Resin-Impregnated Carbon Graphite Antimony-Loaded Carbon Graphite Sintered Silicon Carbide Tungsten Carbide Bellows Nitrile/Buna-N Ethylene Propylene Fluorocarbon HNBR Drive Bands and Spring 316 Stainless Steel Europe Slough, UK Tel: 44-1753-224 Fax: 44-1753-224224 Latin America São Paulo, Brazil Tel: 55-11-3371-25 Fax: 55-11-3371-2599 Middle East, Africa, Asia Dubai, United Arab Emirates Tel: 971-4-343894 Fax: 971-4-343897 North America Morton Grove, Illinois USA 1-8-SEALING Tel: 1-847-967-24 Fax: 1-847-967-3915 For your nearest John Crane facility, please contact one of the locations above. If the products featured will be used in a potentially dangerous and/or hazardous process, your John Crane representative should be consulted prior to their selection and use. In the interest of continuous development, John Crane Companies reserve the right to alter designs and specifications without prior notice. It is dangerous to smoke while handling products made from PTFE. Old and new PTFE products must not be incinerated. 23 John Crane Inc. Print 6/ www.johncrane.com IISO 91 and QS-9 Certified S-21