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Type CK 738 (W, D, G, GD)

High-performance Modular Mixer and Agitator Cartridge Seal for Glass-lined Chemical Reaction Vessels — Standard Solutions Comply to Vessel Seal Standard DIN 28138

Type CK 738 is a versatile, high-performance cartridge seal solution for glass-lined vessels applicable in various industries, including high-purity pharmaceutical applications. High-end materials, balanced faces and a thrust bearing, in combination with a special sleeve design, secure stability of the seal settings and proper operation even in heavy-duty environments. Type CK 738 is available in liquid-lubricated (W), gas-lubricated (G), dry-running (D) or with a unique gas/dry face combination (GD). 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. Advantages of gas-lubricated versions (G, GD) include the non-contacting, wear- and particle-free operation in addition, which makes these seals the perfect solution for high-end pharmaceutical applications. The GD design reduces the overall barrier gas consumption compared to G version.

The special modular design ensures maximum application flexibility through interchangeable sealing components. The standard cartridge design is available to fit on top-entry, steel agitator vessels to DIN 28136, with mounting flange to DIN 28137-2 and agitator shaft end dimensions to DIN 28159. Modifications of adaptive hardware to fit non-DIN mixers or special equipment are available on request. Components are standardized with seal Type CK 728 for steel vessels.

All versions are suitable for operation in potentially explosive atmospheres. Depending on individual explosion protection requirements, the seal operating limits may differ from the parameters given below.

Document Finder


  • California Residents: PROPOSITION 65 WARNING
  • Dual-cartridge seal to DIN 28138 to fit glass-lined vessels.
  • Fits mounting flange to DIN 28137-2 and shaft ending to DIN 28159.
  • Back-to-back seal arrangement with balanced faces.
  • Reversed pressure capabilities inboard.
  • Special designs and material options on request.
  • Available in four variants of lubrication system: 
– W — liquid-lubricated wet seal
– D — dry-running contacting seal
– G — gas-lubricated non-contacting seal
– GD — gas-lubricated non-contacting inboard, dry-running outboard

  • Suitable for application in explosive areas. Certificates of conformity according to European Directive 94/9/EC (ATEX) Cat. 3, 2 or 1 on request.


Temperature Limits

-40°F to 392°F/-40°C to 200°C (-148°F/-100°C modified)

Pressure Limits

Vacuum to 25 bar(g)

Dry-running variants up to 16 bar(g)

Non-contacting gas seals up to 10 bar(g)

Speed Limits


Size Limits

40mm to 160mm

Recommended Applications

  • Mixer and agitators
  • Other rotating equipment

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