Type: Double cartridge mechanical seal
Replace Brand: John Crane mechanical seal
Specification: type 6/type 8/type 9/type 21/109b/2100/5610/8b1/8b2
Temperature: high temperature mechanical seal
Balance: Unbalanced
Type: Multi-Spring
Accreditation: ISO, SGS, UL, ROHS
Service: OEM/ODM
Origin: China
Key Features
• Zero Emissions: A dual-pressurized double cartridge mechanical seals are designed for hazardous, toxic, or volatile fluids.
• Gas Lubricated (Hybrid): The "LP" typically stands for specialized face geometry (sometimes gas-lift or liquid lubricated depending on config) for low emission performance.
• Integrated Pumping: Features a highly efficient internal pumping ring to circulate barrier fluid for cooling.
• Face-to-Face or Tandem: Modular design allows for different dual seal arrangements to suit API Plan 52 or 53.
• Engineered Faces: Faces are optimized for low heat generation, extending the life of both the double cartridge mechanical seal and the barrier fluid.
John Crane Double Cartridge Mechanical Seal Technical Specs | Materials | ||
Mediums | Water, oil and weakly-corrosive mediums | Stationary Ring | Ceramic/Sic/TC |
Pressure | ≤1.4MPa | Rotary Ring | Carbon/Sic/TC |
Temperature | -20℃ to 120℃ | Secondary Seal | NBR/EPDM/Viton |
Speed | ≤15m/s | Spring and Metal Part | Stainless Steel |


Product Specifications
| D1 (inch) | Size Code | D1 (mm) | Size Code | D3 | D7 | L1 | L4 |
| 0.500 | 0127 | 12 | 0120 | 30.14 | 25.40 | 20.64 | 7.93 |
| 14 | 0140 | 33.32 | 31.75 | 22.23 | 10.30 | ||
| 0.625 | 0158 | 16 | 0160 | 33.32 | 31.75 | 22.23 | 10.30 |
| 0.750 | 0191 | 18 | 0180 | 36.50 | 34.93 | 22.23 | 10.30 |
| 20 | 0200 | 39.67 | 38.10 | 23.80 | 10.30 | ||
| 0.875 | 0222 | 22 | 0220 | 39.67 | 38.10 | 23.80 | 10.30 |
| 24 | 0240 | 45.50 | 41.28 | 25.40 | 11.10 | ||
| 1.000 | 0254 | 25 | 0250 | 45.50 | 41.28 | 25.40 | 11.10 |
| 1.125 | 0286 | 28 | 0280 | 48.50 | 44.44 | 26.97 | 11.10 |
| 30 | 0300 | 52.37 | 47.63 | 26.97 | 11.10 | ||
| 1.250 | 0317 | 32 | 0320 | 52.37 | 47.63 | 26.97 | 11.10 |
| 33 | 0330 | 56.00 | 50.80 | 28.58 | 11.10 | ||
| 1.375 | 0349 | 35 | 0350 | 56.00 | 50.80 | 28.58 | 11.10 |
| 1.500 | 0381 | 38 | 0380 | 59.20 | 53.98 | 28.58 | 11.10 |
| 1.625 | 0412 | 40 | 0400 | 67.00 | 60.33 | 34.93 | 12.70 |
| 43 | 0430 | 69.85 | 63.50 | 34.93 | 12.70 | ||
| 1.750 | 0444 | 45 | 0450 | 69.85 | 63.50 | 34.93 | 12.70 |
| 1.875 | 0476 | 48 | 0480 | 73.03 | 66.68 | 38.10 | 12.70 |
| 2.000 | 0508 | 50 | 0500 | 76.20 | 69.85 | 38.10 | 12.70 |
| 2.125 | 0539 | 53 | 0530 | 82.55 | 76.20 | 42.85 | 14.28 |
| 2.250 | 0571 | 55 | 0550 | 85.73 | 79.38 | 42.85 | 14.28 |
| 2.375 | 0603 | 60 | 0600 | 88.90 | 82.55 | 46.02 | 14.28 |
| 2.500 | 0635 | 63 | 0630 | 92.08 | 85.73 | 46.02 | 14.28 |
| 2.625 | 0666 | 65 | 0650 | 98.43 | 85.73 | 49.20 | 15.90 |
| 2.750 | 0698 | 70 | 0700 | 101.60 | 88.90 | 49.20 | 15.90 |
| 2.875 | 0730 | 73 | 0730 | 104.78 | 95.25 | 52.37 | 15.90 |
| 3.000 | 0762 | 75 | 0750 | 107.95 | 98.43 | 52.37 | 15.90 |
Workshop
This workshop is equipped with professional processing equipment and integrated with standardized material warehousing management, enabling a one-stop production process from precision machining to finished product delivery. It ensures part machining accuracy and production efficiency of John Crane double cartridge mechanical seal, meeting various high-specification manufacturing requirements.




Product Research, Development and Testing
Our Product R&D and Testing focuses on optimizing seal performance through advanced simulation and material analysis. All John Crane double cartridge mechanica seals undergo rigorous trials, including thermal cycling and pressure tests, to ensure durability, minimal leakage, and long service life in demanding industrial environments.




Industry Solutions




Case Study
Benzene Transfer: Strict emissions regulations required a double seal upgrade. We installed the 48LP equivalent with Plan 53A. The double cartridge mechanical seal seal has operated with zero detectable emissions for 3 years.
Testimonials
A premium double cartridge mechanical seal. We use it on our most critical chemical reactors and pumps.
—EHS Manager, Chemical Plant
FAQs About John Crane Double Cartridge Mechanical Seal
Q: Does this require a gas panel?
A: If configured as a liquid-lubricated dual seal (standard), it needs a fluid reservoir (Plan 53). If configured for gas lift (Type 28 style), it needs a gas panel. Please specify your barrier media.

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