• Dry-Run Faces (Optional): John crane type 21 mechanical seal can be fitted with specialized dry-running Carbon faces for gas-phase reactions where liquid lubrication is prohibited.
• Non-Metallic Options: For glass-lined reactors, we offer ceramic-coated or PTFE-sleeved metal parts to prevent metal contamination.
Key Features
• Reactor-Grade Upgrade: A heavily reinforced version of the standard John crane type 21 mechanical seal, designed for small to medium top-entry glass-lined or stainless steel reactors.
• Double Seal Config: Often supplied as a double seal arrangement (Back-to-Back) to provide a liquid barrier for toxic or gaseous reactor contents.
• Short Working Length: John crane type 21 mechanical seals are Ideal for reactors with limited headroom or compact sealing housings.
Technical Specs | Materials | ||
Mediums | Water, oil and weakly-corrosive mediums | Stationary Ring | Ceramic/Sic/TC |
Pressure | ≤1.0MPa | 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 | D3 | D7 | L4 | L1 | L11 |
| 0.500' | 0127 | 23.90 | 25.40 | 7.93 | 20.62 | 31.75 |
| 0.625' | 0158 | 26.70 | 31.75 | 10.28 | 22.22 | 34.93 |
| 0.750' | 0191 | 31.10 | 34.93 | 10.28 | 22.22 | 34.93 |
| 0.875' | 0222 | 33.40 | 38.10 | 10.28 | 23.80 | 36.50 |
| 1.000' | 0254 | 43.20 | 41.28 | 11.10 | 25.40 | 41.28 |
| 1.125' | 0286 | 46.30 | 44.44 | 11.10 | 26.97 | 42.85 |
| 1.250' | 0317 | 49.40 | 47.63 | 11.10 | 26.97 | 42.85 |
| 1.375' | 0349 | 52.60 | 50.80 | 11.10 | 28.58 | 42.85 |
| 1.500' | 0381 | 55.80 | 53.98 | 11.10 | 28.58 | 42.85 |
| 1.625' | 0412 | 62.20 | 60.33 | 12.70 | 34.93 | 50.80 |
| 1.750' | 0444 | 66.00 | 63.50 | 12.70 | 34.93 | 50.80 |
| 1.875' | 0476 | 66.60 | 66.68 | 12.70 | 38.10 | 53.98 |
| 2.000' | 0508 | 73.00 | 69.85 | 12.70 | 38.10 | 53.98 |
| 2.125' | 0539 | 73.30 | 76.20 | 14.28 | 42.88 | 60.32 |
| 2.250' | 0571 | 78.40 | 79.38 | 14.28 | 42.88 | 60.32 |
| 2.375' | 0603 | 82.00 | 82.55 | 14.28 | 46.02 | 63.50 |
| 2.500' | 0635 | 84.90 | 85.73 | 14.28 | 46.02 | 63.50 |
| 2.625' | 0666 | 88.40 | 85.73 | 15.90 | 49.20 | 69.85 |
| 2.750' | 0698 | 92.60 | 88.90 | 15.90 | 49.20 | 69.85 |
| 2.875' | 0730 | 94.85 | 95.25 | 15.90 | 52.37 | 73.03 |
| 3.000' | 0762 | 101.90 | 98.43 | 15.90 | 52.37 | 73.03 |
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, 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 type 21 mechanical 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
Pilot Reactor: A pilot plant reactor used a standard John crane type 21 mechanical seal that leaked vapors. We upgraded it to a Double Type 21 arrangement with a pressurized oil pot. The barrier fluid prevented any process gas from escaping.
Testimonials
Simple, effective sealing for our mixing vessels. The double arrangement gives us the safety we need.
—Lab Manager, Pharma
FAQs about John Crane Type 21 Mechanical Seal for Reactor
Q: Can a Type 21 handle reactor runout?
A: The standard Type 21 has limited runout capability. For reactors with significant wobble (>0.1mm), we recommend our heavy-duty bearing-integrated version or upgrading to a vessel-specific seal.
Q: What is the main application of the John Crane Type 21 Mechanical Seal in reactors?
A: The Type 21 is a general-duty elastomer bellows seal widely used in top-entry glass-lined and stainless steel reactors. Its short working length and self-adjusting design make it ideal for small to medium reactors with limited headroom, handling water, oils, and weakly corrosive media.
Q: What are the common causes of failure for John crane type 21 mechanical seals in reactors, and how to prevent them?
A: Common failures include elastomer bellows cracking from dry running or chemical attack, and face wear from shaft runout. Prevention tips: 1) Ensure adequate cooling/lubrication; 2) Select Viton or EPDM elastomers compatible with process temperature and chemicals; 3) For high runout, consider a heavy-duty upgraded version.
Our company is specialized in the production of sealing materials, mechanical seals , cartridge seals.
E-mail: gechacha@aliyun.com
Mobile: +86-18758835650
WhatsApp: +86-18758835650
Add: No8-2, Jinsha road Yuelin Street, Fenghua District, Ningbo, Zhejiang
