Bearings For PumPs And ComPressors

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Bearings forPumPs and ComPressors

As one of the world’s leading manufacturers of rolling bearings, linear technologycomponents and steering systems, we can be found on almost every continent – withproduction facilities, sales offices and technology centres – because our customersappreciate short decision-making channels, prompt deliveries and local service.EuropeAsiaThe AmericasOceaniaAfricaThe NSK companyNSK commenced operations as the first Japanesemanufacturer of rolling bearings back in 1916. Eversince, we have been continuously expanding andimproving not only our product portfolio but also ourrange of services for various industrial sectors. In thiscontext, we develop technologies in the fields ofrolling bearings, linear systems, components for theautomotive industry and mechatronic systems. Ourresearch and production facilities in Europe, Americasand Asia are linked together in a global technology2network. Here we concentrate not only on thedevelopment of new technologies, but also on thecontinuous optimisation of quality – at every processstage.Among other things, our research activities includeproduct design, simulation applications using a varietyof analytical systems and the development of differentsteels and lubricants for rolling bearings.

Partnership based on trust –and trust based on qualityTotal Quality by NSK: The synergies of our global network of NSK Technology Centres.Just one example of how we meet our requirements for high quality.NSK is one of the leading companies with along tradition in patent applications for machineparts. In our worldwide research centres, we notonly concentrate on the development of newtechnologies, but also on the continualimprovement of quality based on the integratedtechnology platform of tribology, material technology,analysis and mechatronics.More about NSK at www.nskeurope.com or call uson 44 (0) 1 636 605 123Bearings for Pumps and Compressors 3

NSK is serving thePumps & Compressors IndustryTable of contentsIntroductionStandard Bearing RangeScope of the Applications›› Bearing Solutions for Pumps›› Bearing Solutions for Compressors56810Selection of bearings for pumps and compressorsSpecial Deep Groove Ball Bearings for Pumps›› High Capacity Deep Groove Ball Bearings12›› LNG Pump Bearings13›› Creep-Free Bearings144HPSTM Angular Contact Ball BearingsSpecial Bearings for Screw Compressors1720Case Studies›› Preventing Creep in Submersible Pumps Bearings 22›› Refrigerant Screw Compressors Workingwith Ammonia23

As a global supplier to world leading pumps and compressors manufacturingcompanies, NSK has the experience and understanding of helping its customersto manage their costs and improve production efficiencies.Pumps and Compressors are used in a wide range ofprocess industries where requirements are for bearingsoffering long life in order to increase Mean TimeBetween Failures (MTBF). Downtime in productionprocesses leads to huge costs and loss of productivity.At the same time, Pump and Compressor manufacturersare looking for more compact machines leading todownsizing of bearings.The combination of increased life time and downsizingplaces increasingly severe demands on ball and rollerbearings; and satisfying those needs call for bearingsof the highest quality and reliability.All the products developed by NSK specifically forthese applications, are featured in this brochure.In addition to our standard product range, ourresearch and development centres around the worldcontinue to develop the next generation of applicationdedicated products by understanding the uniquerequirements of our customers so that we can helpthem to continuously improve their machines. Forscrew compressors, we have developed cylindricalroller bearings and HPS angular contact ball bearingsfitted with a patented plastic cage in Linear PolyPhenylene Sulfide (L-PPS) offering superiorcharacteristics compared to standard plastic cages.For pump applications, depending on the pump type,bearings can run under axial loads, radial loads orcombined loads; small to high speeds and differentlubrication conditions. In any case, conditions arequite tough and the need for high MTBF is a challengefor bearings.Our team of application engineers, local to youroperation, are in contact with OEM R&D teams helpingthem to find new bearing solutions at each stage oftheir projects. The experience accumulated after yearsof involvement in pump and compressor applicationsis the key for mutual success.For compressor applications, bearings are subjectedto high axial and radial loads. They play a key role asthey have to ensure correct positioning of the rotorsin the axial and radial direction. This is extremelyimportant as good positioning of the rotors is directlylinked to compressor efficiency. Therefore, axial andradial deflection of the bearings must be kept assmall as possible.We invite you to have a look through our uniquerange of innovative problem solving products and ifyou have an interest in any of our products, pleasecontact your NSK Sales office.Bearings for PumPs and ComPressors 5

Standard Bearing RangeSingle Row Radial Ball BearingsAvailable ranges: 600, 6800, 6900,16000, 16100, 6000, 6200, 6300,6400 Series›› Standard and special applications›› Steel, brass or polyamide cage›› Low noise›› Full sealing options›› Wide range of greases›› Standard or special steelsSingle Row Cylindrical RollerBearings with Brass Cage, SteelCage or Polyamide Cage›› Pressed steel cage series: EW›› Polyamide cage series: ET›› Machined brass cage series: EMSingle RowAngular Contact Ball Bearings*›› Pressed steel cage series›› Polyamide cage series›› Machined brass cage series*See also the new HPS range:page 166

Double RowAngular Contact Ball BearingsAvailable ranges: 3200 – 3300 /5200 – 5300 Series›› Steel or polyamide cage›› Open›› Shielded ZZ or 2Z›› Sealed DDU or 2RSTapered Roller Bearing›› Inch & metric sizes›› Standard steel / carburized steel /HTF treatment›› Custom made sets with spacersHPS Spherical Roller Bearings›› High load capacity›› High limiting speed›› High strength cage›› Low noise and vibrationThis is a non-exhaustive overview of NSK bearings used in Pumps & Compressors.If you require additional bearings, please contact NSK.Bearings for Pumps and Compressors 7

Bearing Solutions for PumpsHPSTM Angular Contact Ball Bearings seriesCreep-Free bearingLNG pump bearingCentrifugal PumpsBearing Selection›› Cylindrical Roller Bearings›› Angular Contact Ball Bearings›› Double Row Angular ContactBall Bearings›› Deep Groove Ball Bearings –special: HR series*Bearing Requirements›› Long life under high axialloads›› Small axial free playOperating Conditions›› Speed: 1500 rpm – 3000 rpm›› Axial & radial loadsPiston PumpsBearing Selection›› Cylindrical Roller Bearings –Special L-PPS cage›› Tapered Roller Bearings – P6Xaccuracy – Carburized steel›› Needle Roller BearingsOperating Conditions›› Heavy axial and radial load›› Medium speed8Bearing Requirements›› Reduced width tolerance forprecise mounting›› Oil compatibility with cage

Submersible PumpsBearing Selection›› Cylindrical Roller Bearings›› Angular Contact Ball Bearings›› Double Row Angular Contact Ball Bearings›› Deep Groove Ball Bearings – special: Creep-Free bearings*Operating Conditions›› Vertical shaft›› Axial load›› Large temperature difference between inner & outer rings.Bearing Requirements›› Sealing performance›› Prevent top bearing creeping in housingLNG Pumps*Bearing Selection›› Deep Groove Ball Bearings›› Angular Contact Ball BearingsOperating Conditions:›› Speed: 1160 rpm – 3600 rpm›› Gas temperature: –196 C up to 0 C›› Mainly axial load›› Very poor lubricationBearing Requirements:›› Self lubricating›› Corrosion resistancePicture courtesy of Nikkiso* See further information on page 12 to 15Bearings for Pumps and Compressors 9

Bearing Solutions for CompressorsHigh load capacity Cylindrical RollerBearings with L-PPS cageHigh load capacity HPSTM Angular ContactBall Bearings with L-PPS cageOil Injected Screw CompressorBearing Selection›› Cylindrical Roller Bearings –with L-PPS cage*›› HPS Angular Contact BallBearings – with L-PPS cage*›› Tapered Roller Bearings›› Needle Roller BearingsBearing Requirements›› Specific axial & radialclearances to provide precisescrew guidance›› Plastic cage compatibility withspecial oils.Operating Conditions›› Medium speed›› Large axial & radial loads›› Oil circulationOil free Screw CompressorBearing Selection›› Cylindrical Roller Bearings –with outer ring guided brasscage, P6 or P5 accuracy›› Angular Contact Ball Bearings– with outer ring guided brasscage, P6 or P5 accuracy›› 4-point contact ball bearings– with outer ring guided brasscage, P6 accuracy, reducedaxial clearance10Operating Conditions›› High speed (0.7 M.dmN–1.4 M.dmN)›› Moderate axial & radial loads›› Oil jet lubricationBearing Requirements›› Specific axial & radialclearances to provide precisescrew guidance›› High speed performance›› Heat resistance

Roots BlowerBearing Selection›› Cylindrical Roller Bearings›› Angular Contact Ball Bearings›› Double Row Angular ContactBall Bearings›› Deep Groove Ball BearingsBearing Requirements›› Long life›› Heat resistanceOperating Conditions›› Oil-free›› Medium to high temperature›› VibrationPiston CompressorBearing Selection›› Cylindrical Roller Bearings›› High Capacity Deep GrooveBall Bearings›› Needle Roller Bearings›› Special bearing solution for oilfree typesOperating Conditions›› High radial load associatedwith reciprocating motionBearing Requirements›› Long life under toughconditions* See further information on page 20/21Bearings for Pumps and Compressors 11

Special Deep Groove Ball Bearings for PumpsHigh Capacity Deep Groove Ball BearingsHigh capacity deep groove ball bearings (HR series) have bigger rolling elementsthan standard deep groove ball bearings. Typically this will provide a 7% to 19%increase in dynamic load rating, depending on size, resulting in a 22% to 68%increase in ISO L10 life. The HR series can dramatically improve the life of amachine or can be used to downsize existing machines.Bearing NomenclatureExample:HR6203C3High capacity designBasic bearing numberRadial clearanceBigger rolling elements:load capacity increasedBore diameter(mm)1517202530StandardHR Design354045505560Parts No.New HR SeriesStandardBasic load rating (N)Basic load rating (N)Crincreased ratioCrC0rCrC0r62028 5503 9507 6503 750630213 3005 90011 4005 4501.17620311 3005 3509 5504 8001.18630315 6007 10013 6006 6501.15630418 2009 05015 9007 9001.141.09620515 3008 10014 0007 850630523 70012 20020 60011 2001.15620623 30012 80019 50011 3001.19630629 80015 80026 70015 0001.12620728 30016 00025 70015 3001.101.18630739 50021 50033 50019 200620832 50019 90029 10017 8001.12630847 00026 20040 50024 0001.16620936 50022 60031 50020 4001.16630957 00034 50053 00032 0001.08621039 00025 80035 00023 2001.11631066 50040 50062 00038 5001.07621148 00032 00043 50029 3001.10631178 00046 00071 50044 5001.09621258 00038 00052 50036 0001.10Standard HR series are open types. Shielded and sealed versions are also being produced. Please contact NSK.121.12

Lng Pump BearingsLNG pump bearings are employed as upper and lower support bearings on themainshaft of a motor which drives the special pumps used for receiving anddischarging LNG to road tankers and storage tanks. The bearings, immersedin Liquefied Natural Gas (LNG) at -162 C, are using the cryogenic liquid as alubricant while operating at speeds up to 3,600 rev/min.Bearing Nomenclature6315Example:HT35DC3Basic bearing numberStainless steelFluororesin cageRadial clearanceTo cope with these tough conditions, NSK developeddeep groove* ball bearings using special materials.Rings and balls are made from martensitic stainlesssteel to provide corrosion resistance. The bearingcage is made from Fluororesin, a material that offersthe extremely useful property of being self-lubricating,even at very low temperatures. This is significantbecause during operation, the cage – a two piece unitheld together by special rivets – actually transfers athin film of Fluororesin from the retainer pocket tothe ball, and then to the raceway surface, maintaininggood lubrication conditions. NSK LNG pump bearingsextend service intervals in this very demandingenvironment.Bearing l inner andouter ringsStainlesssteel balls* Some sizes are also available as angular contact ball bearings.Bearings for PumPs and ComPressors 13

Special Deep Groove Ball Bearings for PumpsCreep-Free BearingsNSK introduces a new bearing series that is indispensable in the pump free-endbearing position, and for any applications with creep problems. O-ring compressionprovides dramatically enhanced creep resistance. As the boundary dimensions areidentical, the housing does not need to be reworked when replacing standard bearings.This results in reduced cost of the conversion.Bearing NomenclatureCXExample:6203ZZC3Creep-Free Bearing(with O-ring)Basic bearing numberSeal typeRadial clearanceBearing borediameterBearing outerdiameterBearing widthd mmD mmB mmCr (N)C0r 191417211518231619254 5505 1008 1005 1006 8009 7005 6007 65011 4006 0009 55013 6009 40012 80015 90010 10014 00020 60013 20019 50026 70016 00025 70033 50016 80029 10040 50020 90031 50053 0001 9702 3903 4502 3703 0504 2002 8303 7505 4503 2504 8006 6505 0006 6007 9005 8507 85011 2008 30011 30015 00010 30015 30019 20011 50017 90024 00015 20020 40032 00010121517202530354045Bearing load ratingsRecommen dedHousing Fits*G6 or H7Bearing numberOpen CX-6209CX-6309* Although the recommended fits are G6 or H7, G6 is specified when conditions prioritize location under light pre-load.** Low-contact seal available for seal type bearings. Contact NSK for details.14Shield typeContact UVVZZDDUVVZZDDUVVZZDDUVVZZDDUVVZZDDUVVZZDDUVV

1. Structure and performance of Creep-Free BearingsCompression of the O-rings, which are mounted in twogrooves on the outer ring, improve creep prevention. Nospecial machining is required; bearings can be used withthe same housing as standard bearings. In creep limitload tests, the more housing clearance is reduced, thegreater the improvement in creep prevention. This is dueto the compression of the O-ring mounted in the outerring.Structure of the Creep-Free BearingO-RingCreep limit load test (example: 6204)Creep resistance, N700600Creep-Free BearingConventional bearing (without O-ring)500400300200100005101520253035Housing clearance (diameter) (μm)Application example Pump Motor Bearings402. Features and applications of Creep-Free Bearings›› Prevents creepingO-ring compression prevents creep.›› No special machining of the housing is requiredBearings can be replaced since boundarydimensions are identical to standard bearings.›› Easy to assembleAssembly is easy since bearings can be fitted witha loose tolerance.›› Reusable housingVery little abrasion occurs on the bore surface ofthe housing, making reuse possible.3. Note on mounting Creep-Free BearingsHousing shape and dimension: the housing shapemust be in accordance with sketch. We recommend agroove and a chamfer, chamfer angle being between15 and 30 , and its minimum dimension being0.01 x Bearing Outer Diameter. For more information,please see NSK brochure “Creep Free Bearings“.Housing shape and dimensionChamfer angle15 – 30 Chamfer dimension0.01D mmBearings for PumPs and ComPressors 15

HPS Angular Contact Ball BearingsCentrifugal pump in a waste water treatment plant – Angular contact ball bearings are widely used in centrifugal pumps and screw compressors.Original Equipment Manufacturers are looking for more compact design of their machines leading to increasing load conditions for the bearings.The answer to this is the new HPSTM Series of angular contact ball bearings16

Continually developing products with greater strength and higher accuracy, NSKintroduces HPS (High Performance Standard) angular contact ball bearings. Thesebearings fully incorporate the advantages of NSK’s world-class design, materials, andmanufacturing technology, setting a new standard for bearings. This allows premiumperformance in each feature you can expect from an angular contact ball bearing: highspeed, high load capacity, excellent running accuracy, and high reliability.Special features of the new HPS Angular ContactBall Bearings›› H igh load capacity: 5% increase compared toprevious series. Thanks to improved steelcleanliness, optimum internal design andmanufacturing process, NSK HPS bearings achievehigher load ratings resulting in an extended lifetime (up to 18%) or the possibility to downsize.›› H igh rotating speed: Between 15 and 20% morethan conventional series. Permissible speed hasbeen increased by 15-20%, due to internal design,precise processing and manufacturing technology.›› H igh precision: Improved dimensional and runningaccuracy. New HPS series are manufactured withP5 (ISO Class 5) running accuracy, and P6 (ISO Class 6)dimensional accuracy›› U niversal matching: In standard, every HPSbearing is manufactured with universal design tobe mounted in a pair, triplex or quad set›› T ight axial clearance/preload tolerance:From 8 to 12 μm enabling precise shaft positioning›› T hree high performance cages availableT85: Polyamide 4-6, for general purposeapplicationsT7: L-PPS (Linear Poly-Phenylene Sulphide),for oil-injected screw compressorsMR: Machined brass (ball guided) for highreliability applications (including API pumps)Bearings for Pumps and Compressors 17

HPS Angular Contact Ball BearingsBearing Nomenclature7310Example:BEAT85SUSeries and bore numberCNBCNB: standard axial clearanceGA: light preloadContact angle 40 Single UniversalHigh load capacityT85: polyamide cageMR: ball guided brass cageT7: L-PPS plastic cageMatched Measured Axial Clearance (µm)Bore diameter 028-2630502432-2650802941-39For DB and DF arrangementsDifferent possible arrangements: HPSTM bearings can be mounted inback-to-back pairs (DB) as well as face-to-face pairs (DF), or tandem (DT).Back to back(DB)18Face to face(DF)Tandem(DT)

Bearing NumbersBoundary Dimensions (mm)Basic Load Ratings (N)dDBr EA157203BEAr1 (min)Limiting Speed(min-1)CrCOr0.38 1503 75030 0001.00.611 1004 95026 000110.60.39 8004 80026 00042131.00.614 3006 90022 0001740121.00.311 6006 10022 0007303BEA1747141.10.616 8008 30020 0007204BEA2047141.00.615 6008 15019 0007304BEA2052151.10.619 80010 50018 0007205BEA2552151.00.617 60010 20017 0007305BEA2562171.10.627 20014 90015 0007206BEA3062161.00.623 70014 30014 0007306BEA3072191.10.636 50020 60013 0007207BEA3572171.10.632 50019 60012 0007307BEA3580211.51.040 50024 40011 0007208BEA4080181.10.638 50024 50011 0007308BEA4090231.51.053 00033 00010 0007209BEA4585191.10.640 50027 10010 0007309BEA45100251.51.062 50039 5009 0007210BEA5090201.10.642 00029 7009 5007310BEA50110272.01.078 00050 5008 0007211BEA55100211.51.051 50037 0008 5007311BEA55120292.01.089 00058 5007 5007212BEA60110221.51.061 50045 0007 5007312BEA60130312.11.1102 00068 5006 7007213BEA65120231.51.070 00053 5007 1007313BEA65140332.11.1114 00077 0006 3007214BEA70125241.51.075 50058 5006 7007314BEA70150352.11.1124 00087 5006 0007215BEA75130251.51.078 50063 5006 3007216BEA80140262.01.087 50070 0006 000Bearings for Pumps and Compressors 19

Special Bearings for Screw CompressorsHigh load capacity Cylindrical RollerBearings with L-PPS cageFeatures of screw compressor bearings›› L-PPS plastic cage: This plastic cage offerssuperior heat and wear resistance, cage strength,and chemical stability. These characteristics changelittle even if the bearing is exposed to compressoroil, refrigerants, or ammonia gas. L-PPS is greatlysuperior to traditional polyamide cage material.›› Increased load capacity: The optimal bearinginternal design associated with the L-PPS plasticcage provides higher bearing load ratings resultingin improved fatigue life.›› Increased axial load limit for angular contactbearings: Higher load ratings result in increasedaxial load.›› Improved lubrication performance: Theoptimised cage design is rolling element guidedthereby allowing more internal free space,resulting in flow of lubricant improved.High load capacity HPSTM AngularContact Ball Bearings withL-PPS cageBearing Nomenclature (HPSTM Angular Contact Ball Bearing)Example:7310BEAT7Series and bore numberSUCNBCNB: standard axial clearanceGA: light preloadContact angle 40 Single UniversalHigh load capacityL-PPS plastic cageThis screw compressor specification includes all HPS features, and L-PPS « T7 » cage.Range: From 12 to 80 mm bore (7201BEA to 7216BEA))Brrr1φdrrrBearing Nomenclature (High Load Capacity Cylindrical Roller Bearings)rrExample:r1φD1φdNU310ET7Bearing typeSeries and bore numberHigh load capacityL-PPS plastic cageThis screw compressor specification includes high-capacity design, and L-PPS « T7 » cage.Range: From 20 to 100 mm bore (NU204ET7 to NU2320ET7)20

gth against0 Cgth against0 CcececeFeatures› Standard cage material› High crystallization rate provides superior high temperaturestrength› Superior heat resistance› Greater heat resistance thannylon 46› Superior resistance to oil andchemicals› Wear resistant› Good dimensional stabilityStandard grade› Contains fiberglass› Contains fiberglass› Contains fiberglassPlastic melting point› 262 C› 290 C120› 280 CResistance tocompressor oilStrength retention, %L-PPSTensile strength againstcompressor oil at 150 CTarget for heat resistanceL-PPS10080Nylon 6660402000100200300400500600700800Long-term, continuous Resistanceusegear oiltoTensile strength againstgear oil at 180 CNylon 66Nylon 46Short-term use150Resistance tocompressor oilPerformance of L-PPS cage materialTensile strength againstcompressor oil at 150 CL-PPSHeat resistance10080Heat resistanceat 180 CNylon 6660120401002080060 04012020Resistance100 to080 0L-PPSResistancetogear oil100200300400500600Nylon 66700800TensilestrengthagainstTest duration, hoursgear oil at 180 Ccompressor oil Tensile strength – compressor oil at 150 C1002003004005001204010020600L-PPS700800Wear resistanceNylon 6680060 05001 0001 500L-PPS2 000Test duration, hours408020Nylon 66HBSC105001 0001 50080L-PPS60Linear-Poly40Phenylene20Sulfide (L-PPS)0Nylon 660805001 0001 5002 00080L-PPS20 to gear oil Tensile strength –HeatResistancegear resistanceoil atHBSC1180 C6000401002002 000200250300HBSC160Nylon 6640120L-PPSL-PPS1002080060 0100200Heat resistanceat500180 CNylon 66400300Test duration, hoursL-PPS12020L-PPSNylon 66400300500Test duration, stduration,hoursNylon6660120401002080060 0400L-PPS8001 200Test duration, hours40Nylon 6620Heat resistance Heat resistance at 180 C005001 0001 5002 000Test duration, hours80HBSC160Nylon 6640L-PPS200Nylon 66hoursTest duration,401000100Test duration, hours60060120Test duration, hoursOperating temperature ( WearC) 100resistance120Strength retention, %Test duration, hoursStrength reteSnttrieonng, t%h retentionS, t%rength reteAnmtioounn, t%of wear, µmgth againstoil at 150 CNylon 46Amount of wear, µmilNylon 660100200300400500Test duration, hourstrength retention, %gth againstoil at 150 CMaterialoAnm,%ount of weAamr, µmount of wearS, µmtrength retenSttiroenn,g%th retentioSnt,r%ength retenSttiroenn,g%th retention, %ilFeatures of cage material120Wear resistance(µm)10080604020L-PPSNylon 66Bearings for PumPs and ComPressors 21

Case Studies –Bearing Solutions for Pumps & CompressorsPreventing Creep on Submersible Pumps BearingsSubmersible pumps are widely used in a variety ofapplications such as construction, waste water,mining, agriculture and general industry.Most submersible pumps comprise of a verticalelectric drive motor coupled directly to the impeller.They are required to operate for long periods withthe minimum amount of maintenance.Bearing ArrangementThe bottom, locating bearing, is generally a doublerow angular contact ball bearing or a pair of angularcontact bearings. This reacts the axial load and radialload generated by the pumped fluid. The bearing isheavily loaded and needs to be correctly selected toreach target life. The top free bearing, is generally adeep groove ball bearing. This takes a light radialload. C3 clearance is generally used to compensatefor clearance reduction due to heat generation fromthe electric motor.NSK SolutionNSK Creep-Free bearings offer more: with theirintegrated double O-rings, they provide bettercreep prevention. They provide submersible pumpmanufacturers with the following advantages:›› Very good creep prevention›› Easy assembly. The Creep-Free bearings can befitted with a loose housing bore tolerance›› Housing is re-usable as very little abrasion occurson the housing bore›› Cost reduction. Pump manufacturers do not needto machine a groove in the housing bore andinsert their own O-ring.Traditional submersible pumpTop bearingCreep Phenomenon on Top BearingsThe lightly loaded top bearing should, theoretically,have a very long life. However, its life is sometimesdrastically reduced by creep. The combined effect oflight radial load and loose fit in the housing canresult in creep between outer ring and housing.Creep is a phenomenon where relative slippageoccurs between fitted surfaces. Creep produces apolish on the bearing ring surface, occasionallyaccompanied by scoring or wear.CountermeasureOne popular countermeasure used by pumpmanufacturers is to machine an annular groovein the housing bore and to insert an O-ring. TheO-ring prevents creep between bearing outsidediameter and housing.Bottom bearingO-ringCreep-Free bearing22

Refrigerant Screw Compressors working with AmmoniaRefrigerant compressors are designed specificallyfor air conditioning, heat pumping, and industrialrefrigeration. Refrigerant compressors are specificallydesigned to be the heart of an industrial cooling orair-conditioning system (HVAC). They are integralcomponents of the refrigeration cycle, in whichrefrigerant gases are cyclically evaporated andcondensed. There are three main types of refrigerantcompressors: scroll, screw, and piston.Bearing ArrangementRefrigerant screw compressors comprise of twoscrews in mesh. Gas enters at the inlet side and isgradually compressed along the screw. Compressedgas leaves through the outlet port. At the inlet, acylindrical roller bearing is used on both male andfemale screw to carry the radial load. At the outlet,a cylindrical roller bearing is also used for radialloads. However, it is combined with a set of angularcontact ball bearings which reach the high axial loadassociated with the compression. The commonrefrige rant gases such as Chlorofluorocarbons (CFCs)are now banned substances. New compressors arenow exposed to Hydrochlorofluorocarbons (HCFCs) orHydrofluorocarbons (HFCs). The problem of globalwarming and ozone layer depletion is driving the useof “natural” refrigerants such as carbon dioxide (CO2)or ammonia (NH3).and a decrease in the strength which can lead tocage failure. Brass cages show corrosion crack whenin contact with ammonia. In the past, cages made ofcast iron were used for ammonia compressors. Castiron cages show good results but are not popular andare quite expensive.NSK SolutionFor refrigerant screw compressors NSK offers itsL-PPS cage for both cylindrical roller bearings andangular contact ball bearings. The L-PPS cage providessuperior heat and wear resistance, cage strength andchemical stability characteristics that change little,even if exposed to compressor oil, refrigerants orammonia gas.Typical Refrigerant – Screw CompressorTroubles with Cages when using AmmoniaWhen using ammonia as a refrigerant, the oil usedfor lubrication should be miscible with ammonia.Consequently synthetic oils are necessary. Polyamidecages which are quite popular in screw compressorsbearings are not suitable when operating above70 C with synthetic oils (which could containadditives). Ammonia also has an adverse effecton polyamide. There is a rapid ageing of the cageBearings for Pumps and Compressors 23

European NSK Sales OfficesUKNSK UK Ltd.Northern Road, NewarkNottinghamshire NG24 2JFTel. 44 (0) 1636 605123Fax 44 (0) 1636 643276info-uk@nsk.comFranceNorwaySpainNSK France S.A.S.Nordic Sales OfficeNSK Spain, S.A.Quartier de l’EuropeNSK Europe Norwegian Branch NUFC/ Tarragona, 161 Cuerpo Bajo2, rue Georges GuynemerØstre Kullerød 52a Planta, 08014 Barcelona78283 Guyancourt CedexN-3241 SandefjordTel. 34 93 2892763Tel. 33 (0) 1 30573939Tel. 47 33 293160Fax 34 93 4335776Fax 33 (0) 1 30570001Fax 47 33 GermanyPoland & CEESwedenNSK Deutschland GmbHNSK Polska Sp. z o.o.NSK Sweden OfficeHarkortstraße 15Warsaw BranchKarolinen Företagscenter40880 RatingenUl. Migdałowa 4/73Våxnäsgatan 10Tel. 49 (0) 2102 481002-796 WarszawaSE-65340 KarlstadFax 49 (0) 2102 4812290Tel. 48 22 645 15 25Tel. 46 5410 3545info-de@nsk.comFax 48 22 645 15 29Fax 46 5410 3544info-pl@nsk.cominfo-de@nsk.comItalySouth AfricaTurkeyNSK Italia S.p.A.NSK South Africa (Pty) Ltd.NSK Rulmanları Orta Doğu Tic. Ltd. ŞtiVia Garibaldi, 215 – C.P. 10327 Galaxy Avenue19 Mayıs Mah. Atatürk Cad.20024 GarbagnateLinbro Business ParkUlya Engin İş Merkezi No: 68 Kat. 6Milanese (MI)Sandton 2146P.K.: 34734 - Kozyatağı - İstanbulTel. 39 02 995 191Tel. 27 (011) 458 3600Tel. 90 216 3550398Fax 39 02 990 25 778Fax 27 (011) 458 3608Fax 90 216 Please also visit our website: www.nskeurope.comGlob

Bearings for PumPs and ComPressors 5 As a global supplier to world leading pumps and compressors manufacturing companies, NSK has the experience and understanding of helping its customers to manage their costs and improve production effi ciencies. Pumps and Compressors are used in a wide range of process industries where requirements are for .

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CRANE DEMING HAYWARD TYLER PYLES WILSON SNYDER . DURCO IMO SIMS ZOELLER TYPES OF PUMPS REPAIRED BY KENNEDY INDUSTRIES, INC.: Boiler Feed Pumps Piston Pumps Horizontal Split Case Pumps Submersible Pumps Vertical Turbine Pumps End Suction Pumps Circulating Pumps Sewage Pumps Vacuum Pumps Amine Pumps Slurry and Abrasive .

Bruksanvisning för bilstereo . Bruksanvisning for bilstereo . Instrukcja obsługi samochodowego odtwarzacza stereo . Operating Instructions for Car Stereo . 610-104 . SV . Bruksanvisning i original

(RCT bearings), ball screw support bearings, turntable bearings, as well as rectilinear motion bearings (linear ball bearings, linear roller bearings and linear flat roller bearings). A-5 Outerring Inner ring Cage Ball Deep groove ball bearing Fig 1.1 Ball Cage Outer ring Inner ring Angular contact ball bearing Fig. 1.2 Inner ring Outer ring .

ABAC Compressor Pump Units 5 Service Kits 5 ABAC Piston Compressor Accessories 6 rotary screw Compressors Genesis Screw Compressors 7 Formula Screw Compressors 8 Formula Screw Compressors 30kW-75kW 9 Spinn Rotary Screw Compressors 9-10 Micron 11 Synthetic Coolant & Lubricants 11 Air Compressors - special Applications Whispair Compressors 16

READING COMPREHENSION PRACTICE EXAM. GENERAL INSTRUCTIONS: You will have 90 minutes for this test. Work rapidly but carefully. Do no spend too much time on any one question. If you have time after you have finished the test, go back to the questions you have left unanswered. The three parts of this test are English Usage, Sentence Correction, and Reading Comprehension. When you have finished .