Dichtomatik O-rings
DICHTOMATIKO-RINGS
The information contained herein is considered to be reliable, butno assurances, warrants or guarantees whatsoever, of any kind, areprovided with regard to its correctness or suitability for any purpose.The information reproduced herein is based on laboratory tests andis not necessarily indicative of the performance of the end product.Complete testing and the performance of the end product are theuser’s responsibility
CONTENTSCOMPANY 4Industry-specific and customized service concepts 6Product portfolio of the Dichtomatik brand 7O-RINGS – A CLASSIC ON FUTURE COURSE 8Fields of application9Special applications9Standard dimensions11Tolerances/Surface deviations11QUALITY ASSURANCE 12MATERIALS 14Standard materials 15Material certifications 16Comparative presentation of some elastomer properties 17TERMS 18INSTALLATION SPACES AND DESIGN RECOMMENDATIONS 20Static seals 21Dynamic seals 21Design guidelines 36Layout guidelines 39Installation instructions 40Back-up rings 41
COMPANY4
The Freudenberg Group was founded in 1849 and is stillowned by the approximately 300 descendants of the company founder. The resulting financial stability and socialawareness are decisive success factors that create trust.Today, Freudenberg is a global, broadly diversified group ofcompanies divided into Business Groups that operate in awide variety of sectors. The company has always been considered an innovation and technology leader, fromVileda brand household products to technically complexsealing solutions.Freudenberg Sealing Technologies (FST) is the largest Business Group in the Freudenberg Group and is part of theSeals and Vibration Control Technology division. It is a supplier, development and service partner for customers ina wide range of market segments, such as the automotiveindustry, civil aviation, mechanical engineering and shipbuilding, the food and pharmaceutical industry and theagricultural and construction machinery industry.Starting with the Simmerring developed by Freudenbergin 1929, FST now has a broad, continuously customer- oriented product portfolio of premium sealing technologyfor highly demanding applications – from tailor-made individual solutions to complete sealing packages. The company benefits from more than 170 years of engineering andmaterials experience in the research, development andintroduction of innovative product and process solutions.Freudenberg Sealing Technologies rounds off its portfoliowith complementary industry-standard solutions from theDichtomatik product brand. The two-brand strategy is partof FST's comprehensive service portfolio and guarantees afull range of seals and product-related services. Dichtomatikproducts are manufactured by certified suppliers and areavailable in numerous seal forms and materials. They aresuited for moderate operating conditions in static anddynamic a pplications and for fluid seals in a wide range ofmarket segments. These include the hydraulics industry, thewind power plant industry, agricultural machinery and systems and components for general mechanical engineering. For more specific applications, e.g. in the foodindustry, Dichtomatik brand products are also available incertified materials.Freudenberg Industrial Services offers technical servicessuch as the preparation of drawings, radial force measurements, comprehensive quality and material documentationas well as material modifications and testing to ensure thatall seals function reliably even in individual applications.Furthermore, local availability ensures short distances andfast response times to best serve customer needs.FST SERVES THE ENTIRESEALING MARKET AND THUSMEETS ALL MARKETREQUIREMENTS – QUICKLY,RELIABLY AND FROM A SINGLESOURCE.5
INDUSTRY-SPECIFICAND CUSTOMIZED SERVICE CONCEPTSONLINE ORDERING PLATFORM EASYThe EASY online ordering platform enables easy order processing, as well as price, delivery time and stock queriesaround the clock. Besides detailed product information,installation space and cross-sectional drawings are available for download. The EASY Business Connector isused to transfer your orders directly to your SAP system.This ensures that you are always up to date on the statusof your order. Register today if you do not yet have anEASY account.APPLICATION KNOW-HOWDichtomatik products are also certified for special applications, e.g. in the food industry. This enables us to find theright solution for every application. To ensure that sealsfunction reliably even in individual applications, our teamof experts offers technical services such as drawing preparation, radial force measurements, comprehensivequality and material documentation as well as materialmodifications and testing. Customer-specific sealing solutions, kitting and single packaging are just some of theother services that can be offered (perhaps dependingon country-specific service offerings).LOGISTICAL SERVICES AND QUALITY STANDARDSThe 6,500 m² warehouse in Hamburg, which functions asa European logistics hub, has just one objective: deliveringDichtomatik’s uniquely high number of warehoused itemsas quickly as possible to the locations they are needed at.In addition to the roughly 60,000 standard dimensions,around 15,000 customer-specific seals are available fromstock. Additional warehouse locations around the worldsupport the supply chain to ensure rapid availability for ourcustomers.Special logistics solutions, such as Kanban or vendor- managedinventory, quality testing and simplified customs processesdue to certifications, simplify order processing. The locationin Hamburg (incl. the warehouse) is certified according toDIN ISO 9001 and DIN ISO 14001, thus guaranteeingstandardized processes in the quality and environmental management system. In addition, current processes are6analyzed and improved in regular Kaizen workshops. Furthermore, warehouse processes are supported by newtechnologies. For example, the forklifts have been convertedinto mobile workstations by using tablets and portableprinters, and innovative glove scanners are used for scanningprocesses. Our other warehouses also meet the highestquality requirements and are part of regular certifications.
PRODUCT PORTFOLIOOF THE DICHTOMATIK BRANDSTATIC APPLICATIONSTRANSLATIONAL MOVEMENTSThe whole range of static seals – O-rings, cords, x-rings,cover seals, bolt seals, flange and profile seals, etc. – is available in a large number of dimensions – metric, inch andother international standards. The variety of materials, alsowith application-specific certifications, leaves nothing tobe desired.Pistons and rod seals, wipers, guide belts and rings forhydraulics are available from stock in countless standarddimensions in the materials NBR, PTFE, TPU, hard fabric andNBR fabric-reinforced. Application-specific modifications ofthe design or material can also be realized.ROTATING MOVEMENTSIMPORTANT NOTERotary shaft seals are available in the standard versionswith and without protective lips and in the materials NBRand FKM. In addition to the standard designs, the productrange also includes special designs of rotary shaft seals,axial seals, shaft sleeves and radial seals for rotary andswivel movements.Dichtomatik products comply with the industrial standard.For this reason, they are not recommended for use in theautomotive industry, especially in safety-relevant applications. An overview of complementary premium sealingsolutions can be found at www.fst.com.7
O-RINGS – A CLASSICFOR MODERN TIMESO-rings are circumferentially closed, circular sealing elements made of elastomeric materials and are producedby way of vulcanization in molds. The O-ring achieves itssealing effect by deforming the cross section after installation and pressing in the installation space and can be8pressed radially or axially inside the installation space. Inthe operating condition, the media pressure strengthensthe sealing function, since the elastomer material behaveslike an incompressible fluid under pressure.
FIELDS OF APPLICATIONSPECIAL APPLICATIONSO-rings are mainly used to seal stationary machines andsystem components (static application) against liquid andgaseous media, e.g. flange and cover seals, pipe fittings andthe cylinder head and base in hydraulic cylinders. Under certain conditions, O-rings can also be used for reciprocating, rotating and superimposed screw movements(dynamic application). If the installation space is designedproperly, they are constructed properly and the correctmaterial is chosen, pressures up to 1,000 bar can be sealed.If necessary, back-up-rings must be used. O-rings are usedin many different industries, e.g. hydraulics, vehicle construction, vacuum applications and in plant andmechanical engineering. Aseptic pipe fittings to DIN 118641 Form A, standardd1dimensions available from stock, material FKM 75 perox.with conformity tests FDA (Food and Drug Administration), EU (VO) 1935/2004, EU (VO) 2023/2006, 3A Sanitary Standards Class I and CIP/SIP (Cleaning In Place/ Sterilization In Place) Hydraulic fittings (straight screw-in and pipe connections according to AS 568, metric threads with conicalcountersink according to ISO 6149, EO series and SAEflanges), standard dimensions in NBR 90 and FKM 90available from stock Ozone and weather-resistant O-rings in NBR 70 and 90 Low temperature hydraulics (HNBR 75 and 90 with reference tests to John Deere factory standards)d2 Gas appliances and systems with DVGW type examinationcertificates DIN EN 549/DIN EN682 Food contact with reference tests FDA 21 CFR § 177.2600,EU (VO) 1935/2004d1 inner diameterd2 cord thickness Drinking water with DVGW type examination certificateWA/WB, ACS, BS 6920Dichtomatik O-rings are available in EPDM, FKM, NBR,VMQ and with FEP coating (including a FKM or VMQ core).Materials with the necessary certifications are available forspecial applications (gas appliances and systems, drinkingwater, food).Detailed information on our products and the availablecertifications and conformity tests can be found in oure-Catalog or on our online ordering platform EASY.9
ProfileMaterialHardness Temperature[Shore A] [ C]ColorEPDM,sulfurcross-linked70black-45 to 130EPDM,peroxidecross-linked70-50 to 150blackFKM,peroxidecross-linked75-15 to 200blackFKMHNBR70-20 to 200black75-20 to 200green80-20 to 200black90-20 to 200green70-30 to 150blackMaterial characteristics Very stable in hot water and with steam, washing lyes,caustic soda and caustic potash, silicone oils and greases,many polar solutions, many diluted acids and chemicals Good resistance to ozone Incompatible with mineral oil products (lubricants andfuels) Good chemical resistance to mineral oils and greases,synthetic oils and greases, motor, transmission and ATFoils up to 150 C, fuels, HFD flame-resistant pressurefluids, aliphatic, aromatic and chlorinated hydrocarbons,water up to a maximum of 80 C Very good weathering, ozone and aging resistance Very low gas permeability (thus well-suited for vacuumuses) HNBR is formed by the full or partial hydration of NBR Heat, ozone and aging stability are significantlyimproved in this manner. Very good mechanical characteristics, such as good wear resistance, are achieved Media resistance is comparable to that of NBNBR70-30 to 10080-30 to 10090-30 to 100PTFE-200 to 260 Good chemical resistance to mineral oils and greases,blackwhitehydraulic oils (H, HL, HLP), the flame-resistant pressurefluids HFA and HFB. HFC up to about 50 C and waterup to a maximum of 80 C Good chemical resistance to aggressive acids, bases,alcohols and oils Resistance to high and extremely low temperatures Good chemical stability in water (up to 100 C), aliphaticengine and transmission oils, animal- and plant-basedoils and greasesVMQ70-55 to 200red-brown Not resistant to fuels, aromatic mineral oils, water vapor(short periods up to a maximum of 120 C are possible),silicone oils and greases, along with acids and alkalinecompounds10
ProfileMaterialHardness Temperature[Shore A] [ C]ColorMaterial characteristicsFKMFEPencapsulate-20 to 205transparent/black Including an elastic FKMVMQFEPencapsulate-60 to 205transparent/red-brown Including an elastic VMQSTANDARD DIMENSIONSSURFACE COATINGDichtomatik brand products are stocked in the standarddimensions of DIN ISO 3601-1 and AS568B/BS1806. In addition, different sizes of JIS 2401 (General Industry) andNorm R (NF T 47-501) are also a vailable from stock.Dichtomatik O-rings are available on request with varioussurface coatings that are specially adapted to the applicationor the required properties. A surface coating can be used tomake assembly easier, provide optimized abrasion resistanceor be used for color differentiation. If you have any questionsregarding the application or the selection of a suitablecoating, we will be happy to advise you.TOLERANCES / SURFACE DEVIATIONS Dimensional tolerances in accordance with DIN ISO3601-1, industry class B Surface deviations in accordance with DIN ISO 3601-3,type feature N For special applications, the permissible tolerances forspecial items are limited to industry class A and to thetype feature S for shape and surface deviationsAn overview of the dimensions and tolerances currentlyavailable can be found online in our e-Catalog and on ouronline ordering platform EASY.11
QUALITY ASSURANCEFor Dichtomatik brand products, we actively strive forproduct quality with a zero-defect target through coordination with customers and production. Our batch tracingsystem allows every step in the supply chain to be traced12back and for statements to be made regarding productcharacteristics and ingredients. Batch information is provided on the product labels as well as on the corresponding delivery bills.
DIMENSIONAL INSPECTIONSHAPE AND SURFACE TESTINGThe measurement of the inner diameter (Ø d1) is preferablyperformed with the help of non-contact optical measuringmachines and measuring microscopes. For large dimensions, conical and step plug gauges are also used. ForO-rings with an inner diameter of more than 250 mm, circumferential measuring tapes are also used. The O-ringcross section (cord thickness Ø d2) is measured with aforce-reduced measuring probe. The contact force exertedbetween the probe surfaces should be 1 N. The dimensionaltolerances are based on DIN ISO 36011, Industrial Class B.The quality specifications for Standard Dichtomatik O-ringsare based on DIN ISO 36013 grade N. Special quality inaccordance with grade S and other additional requirementscan also be agreed as the basis for delivery. Compliance withthe quality specifications is monitored using magnifyinglamps and digital microscopes.Types of deviationHARDNESS TESTFor hardness measurements on finished products, measuring systems such as IRHD (International RubberHardness Degree) micro hardness measurement accordingto DIN ISO 48 and a measuring system for Micro Shore Aare available. Measurements on test plates are carried outusing a Shore A hardness measuring system. Appropriatefixtures and ovens are available for carrying out compression set tests. The compression set is tested in accordancewith DIN ISO 8151.JointBurr formationNotchDeburring widthTESTING TENSILE STRENGTH AND ELONGATION AT BREAKA tensile testing machine is used to measure the tensilestrength and elongation at break, which enables measurements to be made on finished products and standard testbars by means of appropriate fixtures.Flow linesDeepening, open poresDimensional, non-contact inspection using optical measuringmachinesSurface inspection with a digital microscope13
MATERIALSDichtomatik O-rings are available in four standard and various special materials. Most of these are elastomermaterials. The starting material for elastomers is rubber,which can be obtained as natural rubber but is now mainlyproduced as synthetic rubber in the chemical industry. Elastomers are differentiated by the underlying base polymer.The final material is produced by mixing the base polymerwith appropriate fillers, plasticizers, processing aids, vulcanizing agents, accelerators and other additives. This process14makes it possible to achieve the desired material propertiesand thus to offer standard materials with a wide range ofapplications as well as special mixtures for very specificapplications.The O-ring ultimately obtains its stable shape through thevulcanization process, in which the plastic rubber compoundchanges to a rubber-elastic state and the O-ring receives itsfinal mechanical properties (hardness, tensile strength,elongation at break, compression set, .).
STANDARD MATERIALSThe wide range of O-ring dimensions is available from stock in four standard materials:Base elastomerAbbreviationHardness [Shore A]ColorDIN ISO 1629Nitrile butadiene rubberFluorinated rubberNBRFKMTemperature [ C]depthheight7080 90black-30-30 100 to 120* 100 to 120*80black-20 20070black-45 13070red-brown-55 200Ethylene propylene dienerubberEPDMSilicone rubbe(Vinyl methyl polysiloxane)VMQFluorinated rubber perox.FKM perox.75black-15 200Ethylene propylene dienerubber perox.EPDM perox.70black-50 150*temporarilyThe operating temperature range and media resistance areprimary criteria in the selection of materials. Nevertheless,the mechanical and technological values of an elastomercompound must be taken into account in an appropriatemanner, since they are decisive for the service life of theseal.NBR (NITRILE BUTADIENE RUBBER)FKM (FLUORINATED RUBBER)NBR is the most commonly used material for O-ringsbecause of its good mechanical properties and resistanceto lubricating oils and greases based on mineral oil. Theseproperties are mainly determined by the acrylonitrile content (ACN between 18% and 50%). A low ACN contentresults in good low-temperature flexibility but limitedresistance to oils and fuels; as the ACN content increases,low-temperature flexibility decreases and oil and fuel resistance increases.FKM materials are characterized by their very high temperature and chemical resistance. In addition, the very goodresistance to aging and ozone as well as the very low gaspermeability (good suitability for vacuum applications) andthe self-extinguishing fire behavior are also worth mentioning.The standard NBR material for Dichtomatik O-rings has amedium ACN content to cover a wide range of applicationswith balanced properties. It exhibits good mechanicaland technological values, e.g. high abrasion resistance,low gas permeability and good resistance to mineral oilbased lubricating oils and greases, hydraulic oils H, HL,HLP, flame- retardant hydraulic fluids HFA, HFB, HFC, aliphatic hydrocarbons, silicone oils and greases, water upto approx. 80 C.NBR, on the other hand, is generally not resistant to aromatic and chlorinated hydrocarbons, fuels with a higharomatic content, polar solvents, glycol-based brake fluidsand flame-retardant hydraulic fluids HFD. The resistance toozone, weathering and aging is low. However, this does nothave a negative effect in the majority of applications.The FKM standard material for O-rings shows very goodresistance properties in mineral oils and fatty, aliphatic, a romatic and chlorinated hydrocarbons, fuels, hardlyinflammable pressure fluids HFD and many organic solvents and chemicals.In addition to the standard FKM materials, various specialcompounds are available, which are tailored to specialapplications through different compositions of the polymerchains and varying fluorine contents (65% to 71%).FKM is generally not resistant to hot water, steam, polar solvents, glycol-based brake fluids and low-molecularorganic acids.15
EPDM (ETHYLENE PROPYLENE DIENE RUBBER)VMQ (VINYL METHYL POLYSILOXANE)EPDM materials generally exhibit good hot water, steam,aging and chemical resistance and a wide thermal application range. They are divided into the sulfur and peroxidecross-linked types, whereby the peroxide compounds havea higher thermal load capacity and a significantly lowercompression set.Silicone rubbers are characterized in particular by their widethermal application range and excellent resistance toozone, weathering and aging. The mechanical properties ofsilicone are rather low compared to other elastomers. Ingeneral, silicone materials are physiologically harmless, i.e.they are used in food-related and medical areas, amongothers.EPDM has good resistance to hot water and steam, detergents, sodium hydroxide and potassium hydroxide solution,silicone oils and greases, many polar solvents and a largenumber of diluted acids and chemicals. Special qualities arerecommended for glycol-based brake fluids. EPDM materials are absolutely incompatible with all mineral oil products (lubricants, fuels). The temperature application limitsare from 45 C to 130 C (50 C to 150 C peroxide cured).The standard silicone material can be used in a temperature range from 55 C to 200 C and is resistant to water(up to 100 C), aliphatic motor and gear oils, animal andvegetable oils and fats. Silicone is generally not resistantto fuels, aromatic mineral oils, steam (short-term up to 120 C possible), silicone oils and greases, acids and alkalis.MATERIAL CERTIFICATIONSIn addition to the usual requirements for O-ring materials,special proof or certification regarding material suitabilityis required in certain applications. Particularly where sealsare used in safety-related, food-related or medical areas, itis advisable to regulate and monitor the materials used.This includes certifications for the following applications: Gas installations, gas appliances, gas supply Drinking water fittings, drinking water supply The food Industry16In addition to the various standard materials, a largenumber of special materials are available for special applications, which are certified for use in the food and pharmaceutical industries, for example.A complete list of the special materials and available certifications can be found on our web site.
COMPARATIVE PRESENTATIONOF SOME ELASTOMER eroxidVMQHNBRFFKMFVMQCRAU/EUCompression set1131213223Tearability2232412321Abrasion resistance22–322423321Resistance to aging4122121121Ozone resistance4122121121Oil and grease resistance2155321232Gasoline resistance4**2**55431233Hot water resistance80**80**130150100100*****1008050Steam resistance––130175120*–***120*––Heat resistancestandard materials [ C]100200130150200150260175100100Heat resistancespecial materials [ C]120–––250–330–––Cold resistancestandard materials [ C]-30-15-45-50-55-30-15-55-40-40Cold resistancespecial materials [ C]-50-35–––-40-35–-50–1 very good / 2 good / 3 moderate / 4 low / 5 weak / * short term / ** better only with a special mixture / *** mixture dependentSurface treatment/gliding intensificationThe typical properties of elastomer materials also include“non-gliding” and “adhesive” surfaces. In certain applications and during the assembly of O-rings (especially withautomatic feed), the friction that arises can have a negativeeffect. A reduction in friction to facilitate assembly and evenextend service life can be achieved by using various methodsof gliding intensification. A distinction is made between:n: short-term gliding intensification, e.g. to facilitateassembly through- longer-term gliding intensification through- halogenation (fluorination)- PTFE coating- Introduction of dry lubricants into the surface long-term friction reduction through gliding intensifyingadditives in the elastomer compound, such as molybdenum disulfide (MoS2) or polytetrafluorethylene ing17
TERMSTENSILE STRENGTH, ELONGATION AT BREAKCOLD RESISTANCEThe execution of the tensile test is described in DIN 53504.A standardized tensile test specimen is stretched until itbreaks. The tensile strength (tearing strength) of a material[N/mm2] is the force [N] necessary to tear a sample in relation to the initial cross section of the sample [mm2].The mechanical and technological properties of elastomerschange with decreasing temperatures. For example, hardness and tear strength increase while elongation atbreak decreases. Above a certain temperature, the materialbecomes so hard and brittle that it breaks like glass underload. If the material is not mechanically stressed in thefrozen state (e.g. during storage), it regains its original properties after heating.The elongation at break (tearing elongation) [%] is the elongation of a marked gauge length on the standardsample at the moment of tearing in relation to the originalgauge length.The values for tensile strength and elongation at break onthe finished O-ring can lead to lower results due to thegeometry deviating from the standard test specimen. Thisaspect should be taken into account when assessing themountability of small O-rings over larger diameters.Various tests are available to assess the flexibility at lowtemperatures. Frequently quoted values include the brittleness point according to DIN 53546 and the TR10 temperature according to ASTM D 1329. Interpretation ofthese values allows for conclusions to be made on the practical limits of low-temperature use.TEAR PROPAGATION RESISTANCECOMPRESSION SET DVRThe tear propagation resistance [N/mm] is the force thatopposes tear propagation when a standard specimen of acorresponding thickness is cut into a defined area. The tearpropagation test is described for two different specimensin DIN 53507 and DIN 53515. The value determined in thisway can be used to estimate the sensitivity of an elastomerto tear propagation of cut damage.Depending on the compound composition, time, temperature and deformation, elastomer materials exhibit, in addition to elastic behavior, a degree of plastic deformationor “flow.” A component that has been deformed over a longperiod of time in the installation space no longer returns100% to its original cross section after disassembly, butretains a proportion of permanent deformation.The DVR is tested according to DIN 53517 or ASTM D 395 Band can be in the range of 0% to 100%, whereby 0% represents the ideal value and 100% the worst possibleresult. The DVR is calculated as follows:DVR d0 - d2d0 - d1x 100d0 original thickness of the sampled1 thickness of the specimen in deformed stated2 thickness of the sample after relaxationTensile test on a standard test object18When assessing a value for the compression set, it is important to pay close attention to the test parameters. Forexample, the same material can achieve better or worseresults by changing the temperature in the test. The sameapplies to the duration of the test.
PROPERTY CHANGE AFTER AGINGESSENTIAL REQUIREMENTS FOR STORAGE CONDITIONSIn order to assess the aging behavior and suitability ofmaterials in certain media, the changes in properties of thematerials after storage in these media are determined. Temperature: The storage temperature should beDIN 53508 describes artificial aging in air. The determination of the behavior of elastomers in liquids, vapors andgases is described in DIN 53521. Here, for example, theabsolute change in hardness and the percentage change intensile strength, elongation at break and volume are determined in relation to the values of the unaged samples. Heating: The elastomer products should be shieldedbetween 10 C and 25 C. Higher temperatures can leadto a reduction in service lifeagainst heat sources. Heaters in storage rooms should beplaced at a distance of at least 1 m from the stored goods Air humidity: The relative humidity should not exceed 65% Seals should be protected against strong air exchange,especially draughts. They can be stored in packaging, e.g.polyethylene bags or airtight containersSTORAGE OF ELASTOMER PRODUCTSThe physical properties of seals made of elastomer materials and plastics can change during long-term storage.Due to the aging process, surface changes can sometimeslead to defects. Measures can be taken to minimize influencing factors such as humidity, heat, light, oxygen, ozoneand radioactive radiation. These are laid down in international standards. Strong light influence, especially UV radiation and directsunlight, should be avoided Electrical equipment that generates ozone should not beinstalled in storage rooms for elastomers It must be ensured that the seals are stored free of stress,i.e. without tension, pressure or other deformationsThe maximum storage period for seals made of elastomermaterials depends on the type of elastomer in questionand compliance with the storage guidelines in accordancewith DIN 7716 (Rubber products – Requirements forstorage, cleaning and maintenance) and ISO 2230 (Rubberproducts – Guidelines for storage).Different types of sealing materials also have differentstorage and usage times. After this period, it is importantto check the materials. If there is no damage, the storagetime can be extended. Depending on the geometry, pre- assembled parts must be checked at least every sixmonths. In order to achieve the longest possible servicelife of seals, they should be stored and shipped in packaging made of PE-coated packing paper, aluminum foil oropaque PE film.Tensile test on the final O-ring product19
INSTALLATION SPACES ANDDESIGN RECOMMENDATIONS20
STATIC SEALSDYNAMIC SEALSThe installation spaces (grooves) for O-rings should berecessed at right angles if possible. The dimensions for therequired groove depth and groove width depend on the respective application and cord thickness. The dimensionslisted are recommendations for the corresponding installation type and refer to the nominal dimensions. They shouldbe observed because the sealing function depends on theexact design of the installation space.It is also possible to use O-rings in dynamic applications.The prerequisites are: lower pressures and speeds small installation spaces due to the frictional resistance, a lower compressionshould be chos
certain conditions, O-rings can also be used for recipro - cating, rotating and superimposed screw movements (dynamic application). If the installation space is designed properly, they are constructed properly and the correct material is chosen, pressures up to 1,000 bar can be sealed. If necessary, back-up-rings must be used. O-rings are used
2.4 Homomorphism and quotient rings 28 2.5 Special rings 30 2.6 Modules 34 2.7 Rings with chain conditions 35 3. Smarandache rings and its properties 3.1 Definition of Smarandache ring with examples 38 3.2 Smarandache units in rings 41 3.3 Smarandache zero divisors in rings 46
Heavy Duty Back-Up Rings Heavy Duty back-up rings are configured with a greater axial thickness (T) dimension. The extra thickness provides more extrusion protec-tion for O-Rings. These rings are interchange-able with MS27595, MS28774, MS28782 and MS28783 back-up rings used in MIL-G-5514 packing glands. Heavy duty rings are available
seminear-rings using loops and groupoids which we call as groupoid near-rings, near loop rings, groupoid seminear-rings and loop seminear-ring. For all these concepts a Smarandache analogue is defined and several Smarandache properties are introduced and studied. The ninth chapter deals with fuzzy concepts in near-rings and gives 5
Missing rings & false rings (to identify these, need a "master chronology") Species limitations (some trees have no rings, non-annual rings, or poorly defined rings) Trees must crossdate! (can't develop a chronology or link to climate without this) Top of p 52 Today's class activity
Seal Rings The sets are comprised of double-turn rings in either 2 rings per set or 3 rings per set. The double-turn rings fit tighter in the bore or on the shaft, provide complete 360 surface contact and resist higher axial/radial forces than single-turn ring sets, for medium to heavy duty applications.
A hybrid design is possible: rings can be constructed in a hier-archy such that groups of nodes share a simple ring interconnect, and these “local” rings are joined by one or more “global” rings. Figure 1 shows an example of such a hierarchical ring design. Past works [43, 51, 21, 44, 19] proposed hierarchical rings as a scalable network.
Saturn’s most prominent rings are the A, B, and C The age and fate of Saturn’s rings Jonathan Henry When Saturn was the only known ringed planet, the rings were believed to be as old as the solar system—4.6 billion years in the conventional chronology. The existence of the rings to the present day was taken as evidence of this chronology.
Thomas Coyne, LEM, Dir. Greg Lesko Nina Mascio Debbie Walters, LEM Faith Formation Lori Ellis, LEM, Religious Education Baptism/Marriage Please contact Lori Ellis at 412-462-8161 Confession Schedule Mondays at St. Therese at 7:00 p.m. Saturdays at Holy Trinity from 3:00-3:45 p.m. Saturdays at St. Max from 3:00-3:45 p.m. Hall Rentals Please call 412-461-1054 Website www.thomastheapostle.net .
