Navigation : EXPO21XX > FLUID 21XX > H16: Pneumatic Parts, Seals and Accessories > C. Otto Gehrckens
  • Offer Profile
  • As an independent manufacturer, we are one of Germany’s leading suppliers of precision seals. We advise, develop and manufacture for you – always with the aim of providing you with a satisfying solution to your requirements, as well as assisting you with the smooth running of your processes. In order to avoid production downtime caused by damage to seals or by leakages, we make our high degree of materials expertise available to you. Like this, it quickly pays off for you to rely on the specialists.
Product Portfolio

  • We support you with our uncompromising demands on quality – from development to delivery. This guiding principle has proven itself: Our customers count among the best in their sectors. So that this remains the case, we stand by your side with high quality products, customer-orientated service and the range of our expertise.

    Our solutions for your success
    Over 45,000 items available in our warehouse
    • Our own in-house development and manufacture of precision O-rings and other elastomer seals.
    • Large, medium and low-volume production.
    • High quality materials for virtually all sectors, from the chemical, pharmaceutical and food industries to the oil and gas industries.
    • Approvals/certifications for a wide variety of materials and sectors.
    • Custom production.
    • Express production.
    • Lots of additional services relating to O-rings.

    Our product range spans O-rings compliant with ISO 3601 and elastomer seals in all common sealing materials.

    We produce

    • Inner diameters from 0.74 to 1,400 mm with cross sections from 0.6 to 30 mm
    • Inner diameters of your choice, from approx. 1,400 mm to 3,000 mm and above, with cross sections of 5 to 14 mm in endless vulcanisation process.
    • Mouldings, including sealing collars, flat rings and square rings on the basis of samples or drawings, made from various materials.

      • It’s true that precision O-rings are our core business. But first and foremost, we are specialists in elastomer seals and also produce moulded items. We can produce rotation-symmetrical geometrical items on the basis of customer drawings, and from almost all standard materials. These include:
        • Flat seals
        • Grooved rings
        • Profile seals
        • Dairy pipe connections
        • Clamp seals
        • Sealing Collars
        • and much more

        Your drawing is ready, and you want to get started? We can manufacture just for you, using the materials and grades of your choice. Thanks to our very own in-house toolshop, it does not have to be expensive for you. Therefore please make sure you ask us! We are always open to new challenges – and have already solved lots of them.

          • O-rings count among a machine’s most sensitive components, and must be protected from pressure damage. At high pressure, and without this protection, O-rings can be forced into the sealing gap by extrusion, and destroyed. Leaks then result. Some constructions do not permit the sealing gap to be designed so that it is sufficiently small in relation to the system pressure. In such circumstances, the use of a back-up ring makes sense. They protect the O-ring from being destroyed if high pressure occurs or larger gaps must be sealed.

            But expertise is required in this respect: Back-up rings with special properties
            The back-up rings are predominantly made from PTFE. This material’s favourable properties speak for themselves: the enormous temperature range of from -200°C to 260°C, the appropriate hardness and a virtually universal resistance to various media.

            PTFE’s flow properties protect the softer rubber rings from mechanical damage. To do so, the back-up rings are fitted behind the O-ring on the non-pressure side, or, if pressure direction changes, at both sides. When it is under pressure, the back up ring deforms and therefore bridges the gap that must be sealed.

            Depending on the application, the following variants of ISO 3601-4-compliant back-up rings are used:
            • Spiral back-up rings, type T1
            • Diagonal slit back-up rings, type T2
            • Unslit back-up rings, type T3
            • Diagonal slit concave back-up rings, type T4
            • Unslit concave back-up rings, type T5
            • Special variants

              • It is often a difficult task to fit O-rings into their tight installation spaces without damaging them, as well as to remove O-rings that have become stuck without damaging the machine. We therefore offer an effective tool for fitters and users: COG’s O-ring toolkit for fitting and removing O-rings.

                COG O-ring toolkit – contents: 5 high-quality stainless steel instruments
                • Pointed tool
                • Extraction tool
                • Pressing and pulling tool
                • Flat-headed extraction tool

                  • A special process for special large sizes: Continuous vulcanisation
                    How to proceed when the greatest precision is required at large diameters?

                    The answer: Continuous vulcanisation.
                    COG has developed a special procedure – continuous vulcanisation – in order to manufacture O-rings with a length of up to 3,000 mm (and also larger if required), with different cross sections and material types, in compliance with ISO 3601.

                    The highlight: This procedure enables uniform complete vulcanisation across the entire diameter. The result: very low tolerances and a high degree of precision. But there’s more: Their quality is equivalent to that of smaller precision O-rings manufactured in the usual way.

                    The benefits of continuous vulcanisation at a glance
                    • Very tight dimensional tolerances compliant with ISO 3601
                    • Consistent cross section over the entire O-ring
                    • Excellent surface quality
                    • Low tool costs in comparison to moulded O-rings
                    • Available with any inner diameter of your choice, from approx. 1,400 mm to 3,000 mm, and upon request even larger

                    Other procedures:
                    Two other procedures we don't offer generally exit in the market: bonding and shock vulcanisation.

                    With shock vulcanised O-rings, the cord ends are held together in special devices then hot vulcanised with a suitable adhesive mixture. Bonded O-rings are extruded cords whose ends have been joined together using adhesive – end to end. The adhesive must be chosen according to the elastomer material used, as well as to operating conditions such as pressure, temperature and the medium being used. Generally speaking, the adhesive has different physical and chemical resistance properties to the elastomers. And this results in clear negative effects. COG therefore advises against bonding.

                    The disadvantages of these two processes compared to continuous vulcanisation are the inferior physical properties in the seam area and the greater tolerances.
                      • FFKM COG RESIST®: IN A CLASS OF ITS OWN

                      • In all sectors and applications, the requirements are becoming ever more complex: Not only must seals be resistant to temperature; they must also be able to withstand a wide variety of chemicals. They must be resistant to steam – as well as to solvents. Or they need to be able to resist changes in media, plus high pressure. Only seals made from the very highest quality elastomer material meet these requirements. FFKM.

                        The O-rings in this family come into their own right there where other elastomers reach their limits. They are used in vacuum engineering and in the chemicals industry; in the semiconductor industry as well as in bio-analytics, and are also used in the oil and gas sectors.

                        For this reason, COG developed the COG Resist® range of FFKM materials. With these benefits:
                        • The greatest chemical resistance of all the flexible seal materials
                        • Stable at high temperatures of up to 325°C, depending on type used
                        • Low compression set
                        • Outstanding vacuum behaviour
                        • Flexible in its application
                        • A suitable material for the widest variety of requirements
                        • Large number of certifications
                        • Ring diameters of up to 2,000 mm possible

                        Long life, more performance: Efficiency gains thanks to COG Resist®
                        Choosing a suitable high quality elastomer seal pays off doubly: Thanks to ist longer service life, the intervals between maintenance are longer. But the opposite also applies: the use of seals that are initially seemingly economical can result in enormous costs.

                        COG Resist® offers quality that pays for itself: Its period of deployment is remarkable, and the high performance material requires considerably less maintenance. That really is top class, from performance to service life.

                          • Sector

                          • We look after over 8,000 active customers; a figure that is continuously rising. Our principal customers are well-known manufacturers from the widest range of sectors and industries, or from the technical specialist trades. A glance at the spectrum of sectors we serve underlines the particular challenge: Whether the oil and gas industry, hydraulics, pneumatics, the chemical industry, pharmaceutical industry or food technology industry – the spectrum is as diverse as the challenges presented.

                            But our aspiration always remains the same: maximum quality and appropriate solutions. Because the objective doesn’t change:
                            Securing your advancement.
                              • Oil and gas

                                Pressure. Grease. Steam. The fields of application in the oil and gas industry place great demands on every seal’s resistance properties. The central factors that everything boils down to are efficiency and safety.

                                From the drill drive on the oil platform to the underwater valve; from the refinery area to the pipeline – seals in the oil and gas industry are used in the widest range of different applications. Whether drilling, pumping or processing; whether underwater or during finishing; in static or rotating applications – the production process presents extreme challenges for the materials used. And there is a central theme: the phenomenon of explosive decompression.
                                So it’s great that reliability is one of our greatest strengths.

                                Meeting your demands: COG’s solutions
                                One of the greatest problems, and therefore one of the greatest demands in this sector, is the phenomenon of explosive decompression. First and foremost, this affects seals that need to seal off gaseous media when the gas sinks from high pressure to low in just a short time. Visible damage occurs, such as blisters on the O-ring’s surface or fissures in the material. This phenomenon is known by manufacturers and operators in the oil and gas industry as explosive decompression, and is as well-known as it is feared. The solution needs to be able to resist explosive decompression.
                              • Pharma and food

                              • THE CHALLENGES:

                                The number of factors that have an influence on the seals used in processes in this industry is immense. The interactions between the media that is to be sealed off and the often very aggressive disinfection agents is a dominant theme. Elastomer seals must be able to be used in CIP or SIP processes, as well as being resistant to fatty media. They must also be able to fulfil their sealing function in environments featuring aggressive WFI water, steam sterilisation, flavouring agents or essential oils.

                                In short: The material stress is enormous, so the demands are also accordingly high.

                                So are the required standards and certifications: There is barely an industry in which the requirements are more sensitive. FDA, USP, 3-A Sanitary Standard 18-03, CIP certificate, SIP inspections, WFI water tests and EU Directive 1935/2004 are required and must be observed. Added to all this are further requirements relating to installation spaces and the geometry of individual components.

                                COG has been working for you in this area for years.

                                Meeting your demands: COG’s solutions
                                COG supplies a multitude of proven and innovative materials for the medicinal, pharmaceutical and food technology industries. Each of these materials provides the ideal conditions for its particular area of application. Our product adviser can provide you with information on which material is best suited for which particular use.

                              • Hydraulic and pneumatic

                              • THE CHALLENGES:
                                OILS, PRESSURE, MEDIA IN ONE APPLICATION

                                Oils, high pressure and mechanical stress meet new, environmentally friendly media that present unexpected demands. There is always lots of change in this sector. And we change with it too. Nevertheless, the following applies: The individual requirement determines the solution. Our online product adviser provides assistance and shows our product portfolio. Because even for the greatest possible efficiency, there is one rule of thumb: standardisation where possible, customisation where necessary.

                                But one thing is clear: Hydraulic and pneumatic applications demand pure reliability. COG has developed its own product range especially to meet these demands, and which simultaneously withstands the multiple challenges.
                              • Chemical industry

                                In the field of chemical process technology, the clear focus is on outstanding resistance. This demanding discipline is dominated by innovative production technologies and a wide range of chemicals. From liquid dosing systems to reactors, from valves to tanks; the seals used must always demonstrate formidable resistance to chemicals, extremes of temperature or extreme pressure. When all is said and done, the sealing solution must function properly. And for as long as possible.
                              • Energy technology

                                From thermal solar systems via transformers to heat pumps: Energy technology describes a broad field. And a still broader range of applications for seals. Topics such as massive temperature fluctuations, extreme forces and contact with various different media on the one hand. Efficiency losses through energy loss on the other. The challenges too are accordingly extensive: Low gas permeability, chemical resistance to media such as antifreeze and coolants in heat pumps and a high degree of thermal flexibility are fundamental requirements.

                                In short: Energy technology can be explosive. But we step in with appropriate Solutions.

                                Meeting your demands: COG’s solutions
                                COG’s premium materials are distinguished by extraordinary chemical and thermal resistance. Depending on the area of application, we have a wide range of high-performance compounds, which has grown to meet changing requirements in the field of energy technology. Whether EPDM, FKM or FFKM – The list of possibilities and compounds is long. The right solution depends to a large degree on operating conditions.

                                So why not ask our product adviser, which product is the right one for you. Or contact our application technology department – we would be pleased to assist you with our wide range of professional expertise.
                              • Ship engineering

                              • THE CHALLENGES: HEAVY FUEL OIL, PRESSURE
                                AND MECHANICAL STRESS

                                Ship engineering means very hard work for seals: They must be able to stand up to mechanical stress, contact with heavy diesel oil, grease and other critical media. Large inner diameters and long maintenance intervals – even for such seemingly inconspicuous passengers as seals resilience is required.

                                We are pleased to contribute the necessary know how. Because when all is said and done, ship engineering has been one of our core competencies for decades.

                                Meeting your demands: COG’s solutions

                                For your ship engineering needs, you can choose from a wide array of options. Depending on your application, COG has the appropriate material in our range. Whether large inner diameters, resistance to critical media such as biologically degradable oils (HEES and HETG), gas-tightness, resistance to wear and extrusion – the materials we have developed ourselves withstand these demanding conditions, and with flying colours.

                                Our application technology team’s specialism is analysing each case individually and offering the appropriate solution. We would be pleased to help you make the right choice. Just ask us! Our product adviser provides you with your first glimpse into our portfolio.
                            • Service

                            • FAR BEYOND STANDARD
                              As your capable partner in the field of seal technology, we have set high demands of our service portfolio. Do you require your O-rings to have an extra colour coding? Must the products be packaged individually if possible? Are you under enormous time pressure?

                              We make it possible – And also provide you with a wide variety of additional services!
                                • WHEN TIME REALLY IS OF THE ESSENCE!

                                • We can also help you out of critical situations: In emergency cases, when a time delay is not acceptable, we offer our customers an express manufacturing service. During the production process, your order will be placed in the ‘fast lane’ and delivered within just a short time. We manufacture high quality precision O-rings that are not kept in warehouse stock within 5–6 working days*.

                                  COG keeps ten different commonly used materials in continuous stock, specially for our express service. These include FKM, FVMQ, VMQ, NBR and EPDM compounds.

                                  Upon request, our express manufacturing process also applies to other compounds, provided that these compounds are in stock. This also applies to variants with a cross section of over 10 mm.

                                  In these instances, please contact our internal sales department!

                                  Good to know: Express production – basic information
                                  Manufacturing time between 5 and 6 working days*
                                  10 different compound materials continuously kept in stock
                                  Maximum quantity depends on the O-ring size
                                  Express surcharge: flat fee of €250 plus VAT

                                  Good to know: Express production – basic information

                                  • Manufacturing time between 5 and 6 working days*
                                  • 10 different compound materials continuously kept in stock
                                  • Maximum quantity depends on the O-ring size
                                  • Express surcharge: flat fee of €250 plus VAT
                                • THAT CERTAIN EXTRA

                                • Sometimes, excellent material properties are simply not enough. Therefore, we also offer a wide array of individual additional special treatments. These include the following services (subject to charge):

                                  Coatings, such as for example
                                  • Molybdenum
                                  • Graphitising
                                  • Teflon
                                  • Siliconisation
                                  • Parylene

                                  Special services, such as for example
                                  • Washing in deionised water
                                  • LABS-free
                                  • Plasma cleaning

                                  Ask us about the special treatments possible for your O-rings.
                                  We would be pleased to assist!
                                • INDIVIDUALLY LABELLED, PACKED, CHECKED

                                • Your wish is our command: Whether labelling your products or packaging, designing your own labels or issuing certificates of compliance – we take care of fulfilling your wishes. We offer the following services, among others (subject to charge):
                                  • Colour coding of your O-rings
                                  • Colour coding of your packing units
                                  • Certificates of compliance in accordance with EN 10204
                                  • Special packaging
                                  • Individual packaging
                                  • Custom label design
                                  • Mechanical optical 100% checking

                                  Please ask for details of others!