Type CK 726 (D)


Mixer and Agitator Cartridge Seal to Vessel Seal Standard DIN 28138 for Steel Chemical Reaction Vessels — with Integrated Bearing

The Type CK 726 is a dual, pressurized, liquid-lubricated cartridge seal for top-entry mixing and agitating equipment. An integrated radial bearing secures an optimal shaft alignment and proper seal operation. A value-engineered design, high level of standardization and broad material options make this seal a cost-efficient solution for general-duty applications in the chemical and pharmaceutical industry. Standard versions are compliant with vessel seal standard DIN 28138 Parts 1 and 3. They are designed for use on steel-made agitated chemical reaction vessels to DIN 28136, to fit on a mounting flange to DIN 28141 and agitator shaft end dimensions to DIN 28154. Hardware adaptations to fit to non-DIN equipment are available on request.

By exchanging the seal faces, a CK 726 wet seal can easily be converted to a contacting, dry-running seal. Type name then changes to CK 726D. Advantages of contacting dry-running seals include freedom from contamination by barrier liquid and a low face wear rate, together with a cost-efficient, easy-to-install (gas) supply system. To simplify inventory, seal components are standardized with the other seal types of this family CK 725(D) and CK 736(D).

The seal is suitable for operation in potentially explosive atmospheres. Depending on individual explosion protection requirements, the seal operating limits may differ from the values given in the parameters section. Furthermore, additional monitoring devices may be required.

For undemanding applications the wet seal versions can be operated without pressurizing the barrier liquid, please consult John Crane.


  • Dual-cartridge seal with integrated radial bearing to DIN 28138 for stainless steel vessels.
  • Fits mounting flange to DIN 28141 and shaft ending to DIN28154.
  • Back-to-back seal arrangement with unbalanced faces.
  • Reversed pressure capabilities inboard.
  • Liquid lubricated (CK 726) or dry-running (CK 726D) face versions available.
  • Non-standard sizes, special designs and material options are available on request.
  • Debris well and cooling flange options available.
  • Suitable for application in explosive areas. Certificates of conformity according to European Directive 94/9/EC (ATEX) Cat. 1, 2, or 3 on request.
  • Limits of operation without pressurized barrier fluid are available upon request.


Temperature Limits

-40°F to 392°F/-40°C to 200°C

Pressure Limits

Vacuum to 16 bar(g)

Speed Limits


 Dry-running variant: 300fpm/1.5m/s

Size Limits

40mm to 160mm

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