C. Otto Gehrckens
  • Offer Profile
  • As an independent manufacturer we belong to one of the leading supplier of precision O-rings and Elastomer seals.

    COG delivers from Europe’s largest O-ring stock most various materials, including FKM an FFKM.

    Besides, our developers are always happy to meet any specific requirements of your industry.
Product Portfolio
  • O-Rings

  • The ring is important.

    COG is absolut uncompromising with the quality of their products. Because this is the reason why our clients are among the best in their respective industries. COG delivers Europe's largest O-Ring stock (over 45,000 items in stock) most differerent compounds, incl. FFKM/FFPM. Come and test over 140 years of experience and innovation!
    • Over 45,000 items in stock
    • In-house mixing, mixture development and production
    • also small-scale production
    Our product range includes:
    • O-Rings, produced according to ISO 3601 and elastomer sealings: All current materials: AU, CR, EPDM, EPM, FEPM, FFKM, FPM, FYMQ, HNBR, IIR, NBR, NR, PTFE, PVMQ, VMQ. Here you will find more information about sealing materials
    • Inside diameter from 0.74 to 1400 mm; Strength of thread from 0.6 to 30mm
    • With the production technique Endless Vulcanisation: all inner diameters between 1400 mm and 3000 mm possible for FPM, NBR and HNBR compounds with a cord diameter from 5 to 14 mm and for EPM compounds with a cord diameter from 5 to 15 mm.
    • Shape: In small ranges: sealing collars, flat rings, square rings can be produced from a model or sketch from the above mentioned materials.
      • Materials

        • Aflas® (FEPM)
        • Acrylonitrile-buta-diene natural rubber (NBR)
        • Butyl natural rubber (MR)
        • Chloroprene-natural rubber (CR)
        • Ethylen-Propylen-Dien-Kautschuk (EPDM)
        • Ethylene propylene diene natural rubber (EPDM)
        • Perfluor-natural rubber (FFPM)
        • Fluoro natural rubber (FPM)
        • Fluorosilicone natural rubber (FVMQ)
        • Hydrogenated nitrile natural rubber (HNBR)
        • Natural rubber (NR)
        • Polyurethane natural rubber (AU)
        • Polytetrafluoro-ethylene (PTFE)
        • Silicone rubber (VMQ)
        • Viton® Extreme-ETP (FEPM)
      • Customized production

      • COG has a huge selection always in stock. In addition, we´ll manufacture lots of things you won´t get elsewhere, on request specially for you. In the shortest possible time. At the fairest of prices. As a one-off order or as a batch.

        Customized production of O-Rings

        You can't find what you're looking for in our vast range? No problem - COG customised production will be pleased to help with your special requirements. Even the most "unconventional" seals can be individually manufactured at our own production facilities (in-house compounding, in-house development, in-house toolmaking). In the materials and qualities of your choice - within a matter of days. Singly and in large or small batches. It's an offer that few other manufacturers can match. And another thing that you'll be pleased to hear: customised production at COG costs less than you think. Let’s talk about your aims!
      • Storage

      • O-Rings must be stored in the proper manner to ensure that they will seal properly when fitted. Storage, cleaning and maintenance should therefore by carried out in accordance with the DIN 7716 guidelines.

        O-Rings should always be stored where they are protected from external damage such as surface damage due to staples or distortion from heavy weights laid on top of them. O-Rings must also be stored in a dry place and if possible at room temperature.

        O-Rings should be stored in sealed polythene bags where possible, should not be exposed to daylight for long periods and should be kept away from sources of ozone.

        These precautions will considerably reduce any change in the properties of the O-Ring due to premature ageing, hardening or weathering and will increase their service life without significantly restricting their use.
    • Perlast® – a class for itself.

    • For some applications there is no alternative to a perfluorelastomer. In thoses cases it is good to know if you can trust in the extraordinary Perlast® compound from COG. As a state-of-the-art product Perlast® combines PTFE resistance to chemicals and heat with FPM elastomer properties. It is used where other elastomers can not do the job and maximum reliability is required. Special Perlast® materials compliant with FDA, USP Class VI and clean room requirements are used in e.g. in the pharmaceutical and food industries.

      The Perlast® range of elastomers offer performance characteristics that span the most demanding of applications in industries. Perlast®'s flexibility provides you with a number of advantages. The combination of in-house tooling, extensive range of material grades and rapid production, means that non-standard O-Rings and custom components can be supplied just as easily as a BS/AS standard sizes – with exceptionally short lead times.

      Advantages of Perlast®:
      • Maximum chemical restistance of all elastic sealing materials
      • High temperature stability up to 325 °C, depending to the used type
      • Low compression set
      • Excellent vacuum performance
      • Flexibel in the application
      • Appropiate material for various requirements
      • Wide range of approvals/ licences
      • Ring diameter up to 2000 mm possible
        • Perlast® G75B: „The Top All Rounder“

        • Perlast® G75B has been specially formulated to provide increased acid resistance by eliminating fillers that are prone to acid attack and optimising the polymer structure. In addition, this perfluoroelastomer has low permeability and as a result, it is less prone to swelling, leading to extended in-service performance in, for example, valves, pumps and mechanical seals.
          A high modulus makes G75B resistant to extrusion and ideal for use in high pressure environments. In addition, the low long-term compression set provides a high mean-time between maintenance cycles in hot chemically aggressive environments. Perlast® G75B is suitable for both dynamic and static applications and can be moulded into O-Rings and custom shapes. Also suitable for vacuum applications. Temperature stability up to 325 °C. Available in the hardness of 78 °IRHD / Shore A 79.
        • Perlast® G75H

        • Perlast® G75H incorporates a novel reinforcement system which produces a synthetically clean compound formulated for minimum particle generation combined with excellent resistance to aggressive oxygen and fluorine based plasmas. Extensive chemical and steam resistance. Particularly suitable for applications in the semiconductor industry and also an optimal choice for dynamic applications. Because of its extremely low outgassing properties PERLAST® G75H is used in the vacuum technolgy. Specially developed for Plasma and Gas Deposition applications including ashing, etching, HDPCVD, PECVD, SACVD.
          Particularly suited for use in applications which require exposure to temperatures of up to 320°C (continuous use temperature approx. 260 °C ) combined with excellent mechanical properties. Available in the hardnesses of 75 °IRHD.
        • Perlast® G74P, G67P

        • An ultra-pure grade of translucent perfluoroelastomer. This translucent beige compound with semi-crystalline perfluoropolymer nano-filler, specially developed to meet the demands of the semiconductor and bio-analytical industries. Compatible with fluorine based chemistries and universally suitable for both wet and dry semiconductor processes including Lithography, Plasma, PVD, CVD, Etch, Stripping and Cleaning.
          Perlast® G74P combines a fully fluorinated polymer backbone, a fully fluorinated nano-filler system (no inorganic fillers) and a highly fluorinated cross-linking process, which results in a perfluoroelastomer with unrivalled purity, chemical resistance and mechanical properties.
          Perlast® G74P exhibits extremely low out-gassing properties, making it ideal for use in vacuum applications. Because of the very small filler material particles it is also suitable at very shortwave laser light. Available in the hardnesses of 64 and 75 °IRHD / Shore A 64 and 74.
        • Perlast® G75S, G74S

        • Pure white multi-purpose perfluoroelastomer compound for Life Science applications.
          Perlast® G75S is an all round material that can be used for all types of applications requiring FDA and USP Class VI compliance. It is suitable for use in all product contact applications including dry, aqueous and fatty media.

          Unlike other FDA compliant elastomers, Perlast® G75S is thermally stable at higher temperatures, and is ideal for use in applications which require exposure to temperatures up to 310°C (590°F) making it suitable for use in Stage II Sterilization processes.
          Perlast® G75S is suitable for both dynamic and static applications and can be moulded into O-Rings and custom shapes.

          Perlast® G75S has been specifically developed to cope with a wide range of process media, potent active pharmaceutical ingredients (API's) and aggressive cleaning agents, being especially suited to withstand steam-in-place (SIP) and clean-in-place (CIP) procedures within pipe work and vessels. G75S is also suitable for other critical applications such as Water-For-Injection (WFI) systems. Available in the hardnesses of 72 and 80 °IRHD.
        • Perlast® G80A, G60A, G70A, G90A

        • This black general purpose perfluoroelastomer compound with excellent chemical resistance is a very popular all rounder material. It is particularly suitable for various industries applications with an optimal cost-ratio performance for the users. Exceptionally high chemical resistance and excellent steam resistance and mechanical properties. Extremely low outgassing properties. Available in the hardnesses of 60, 70, 80 and 90 °IRHD
      • Express production

      • When speed is important!

        If really necessary and when postponement is not possible, COG offers its customers express production. This special service is to help users out of an awkward situation. This means that high-quality precision O-Rings which are not in stock can be manufactured in between 5 and 7 working days*. These orders are put in the “fast lane” in the sophisticated production process and are delivered in the shortest possible time.

        A total of 8 different frequently used materials are stocked continuously at COG specifically for the express service. These include FPM/FKM, FEPM, VMQ, HNBR, NBR and EPDM compounds. On request other mixtures can also be produced using the express production process provided these mixtures are in stock. You will need to contact our sales department here first.

        Key data for express production:
        • Production time of between 5 and 7 work days*
        • 8 different material mixtures in continuous stock
        • Maximum quantity depends on the size of the O-Rings
        • Express surcharge: flat rate of 250 EUR plus VAT.