Vickers Guide to - Eaton

1 Vickers Guide toSystemic contamination ControlContents2 Vickers Systemic contamination Control3 The Systemic Approach to contamination Control3 Quantifying Fluid Cleanliness5 Sources of Contamination8 Damage Caused by Contamination16 Setting a Target Cleanliness Level18 Achieving Target Cleanliness22 Locating contamination Control Devices27 Flushing New or Rebuilt Systems29 Confirming and Monitoring Achievement of Target Cleanliness31 ProActive Maintenance2 Fluid Power is one of the most reliableand repeatable forms of power andmotion control. All that is required iscomprehensive state-of-the-art systemdesign and modern systemic contami-nation control. When problems areencountered, 80% of the time they arerelated to inadequate contaminationcontrol practices. Understanding thishandbook will greatly assist the designor maintenance engineer in achievingthe balanced system cleanliness that isthe cornerstone of fluid power has a more than 75-year history of dedication to helping engineersdevelop, operate and maintain reliable,high quality power and motion controlsystems.

2 This Guide is only part of thepackage Vickers offers to enable thedesigner and user to achieve the most effective hydraulic power andmotion a hydraulic or oil lubricated machine, the development of a targetcleanliness level and the plan to achieveit is as much a part of system design as the selection of the pump, valves,actuators or bearings. Unfortunately,when some system designers select afilter, they look no further than a filtermanufacturer s catalog, with little regardfor the particular system s total require-ments. Proper selection and placementof contamination control devices in asystem to attain the targeted cleanlinesseliminates (the root cause of) up to 80%of hydraulic system failures. Additionally,the system cleanliness approach assuresthe user of the hydraulic system a cost-effective approach to contaminationcontrol that allows the price of the filtersand elements to be quickly recovered bythe savings of improved performance,increased component life, increased oillife, increased uptime and fewer stress the interacting relationshipbetween component design, systemdesign, filter performance and filterplacement, Vickers has named ourapproach to filters and filtration VickersSystemic* contamination Control.

3 Thisbook is dedicated to defining the theoryand practice of quality, cost-effectivesystemic contamination Systemic contamination Control*systemic (si -ste m' i k) Of or pertaining to a system orsystems.(American Heritage Dictionary, HoughtonMifflin Company.) Working toward the most effective protection consistent with economy, wemust first define our goal. In systemiccontamination control the goal is alwaysthe same: to clean the fluid to the pointthat contamination is not a factor in thefailure (catastrophic, intermittent, ordegradation) of any component in thesystem during the desired useful life ofthat system. The first step towards thisgoal is the setting of a target cleanlinesslevel that takes into account the specificneeds of the the target has been set, the nextstep is to select and position filters inthe system so that the target can beachieved in a cost effective requires an understanding of filterperformance, circuit dynamics and filter placement.

4 While all three factorsare important, the last two issues circuit dynamics and filter placement often receive much less attention thanthey there are several sources for highefficiency filters that can initially keepthe hydraulic or lubrication fluids most systems that have contamina-tion problems, the cause is either poorlyconceived filter placement, because of a lack of understanding of the dynamicsof fluid flow, or the inability of the filterelements to maintain their performancelevels throughout their service life in the system. The engineering guidelinesneeded to deal with both filter placementand system dynamics are presented inthis the machine is in operation, the last and ongoing step is to confirm thatthe target cleanliness level is beingmaintained. This is most often accom-plished by sending a fluid sample to aparticle counting laboratory that givescleanliness code data to establishedstandards.

5 If the target is being met, the system only needs to have filtersmaintained and the fluid retested periodically. If the cleanliness target is not being achieved, corrective actionsneed to be taken. Sometimes a changein maintenance practices is needed, but at other times a shift to a finer grade of filter elements or additional filter housingsmay be needed. Intelligent considerationof contamination control during thedesign phase is the best way to avoidboth short- and long-term problems andgain the assurance that each hydraulicallypowered or oil lubricated machine willgive long, reliable FluidCleanlinessThe first step in setting a target cleanliness level is to understand that cleanliness is not a general term butrather a specific quantitative value. The current international standard forcleanliness of a hydraulic or lubricatingfluid is defined by ISO 4406. Using anapproved laboratory particle countingprocedure, the number and size (inmicrometers) of solid particles in a milliliter of fluid is data from a hydraulic fluid sample counted by an automatic particlecounter is: Vickers Systemic Approach toContamination Control Set a target Cleanliness Level Select filters and filter placementsto achieve target Sample fluid and confirm achievementThe Systemic Approach To contamination Control3 Computer "reads" and classifies the particles by the changes in light received by the photo-detectorWaste fluidPrinter2 xxx5 xxx10 xxx15 xxx25 xxx50 xxxLightsourcePhoto-detectorscreenAutoma tic Particle CountingParticles Size X Number of particles in Micrometersgreater than X sizein one ml of test fluid2 m51205 m8910 m4315 m2225 m350 (Note.)

6 Particle counts are normally run on 10 to 100 milliliters offluid and then factored to report results for 1 milliliter. This is thereason results of fractional particles can be reported.)4 Once the results are obtained, thepoints are plotted on a CleanlinessChart. This chart has range codes (farleft edge) that give a number, 0 through25, that corresponds to a specific num-ber of particles. Taking the range codefor the number of 5 m and larger parti-cles and the range code for the numberof 15 m and larger particles and com-bining them together with a slash (/)gives us the ISO Cleanliness Code forthat fluid. For the particle count in theexample, the 89 particles of 5 m andlarger size are in the 14 range and the22 particles of 15 m and larger is in the12 range. This means the example fluidis described as a ISO 14 , the current ISO standarddoes have a weakness in that it canmask a significant build-up of very finesilt sized particles by the non-reportingof the counts smaller than 5 m.

7 Toremedy this, Vickers has adopted, andISO is considering, expanding the codeto three ranges correlating to 2 m, 5 mand 15 m. For the example presented,the Cleanliness Code becomes 20/14 this Vickers document wewill show cleanliness codes with 3ranges, the last two being bold type tosignify that they are the current "X" in micrometerNumber of particles greater than "X" size in oneml of test fluidRange codeExampleNumber of particles greater than size per milliliter20/14/12 Cleanliness Code Particle size in micrometers100,0001 2 5 10 15 20 25 30 35 40 45 50 Range Code10,0001, ,0004,0003,0002, ,0002480,0002340,0002229,0002110,000205, 000192,500181, ,00030,00040,00050,000150,000200,000300, ,50015, Code Chart5 There are four primary sources for solidcontamination to enter a hydraulic are.

8 Contaminated new oil, built-incontamination, ingressed contaminationand internally-generated of these sources needs to beunderstood as each is a major consider-ation in filter New OilAlthough hydraulic and lubrication fluidsare refined and blended under relativelyclean conditions, the fluid travels throughmany hoses and pipes before it is storedin drums or in a bulk tank at the user sfacility. At this point, the fluid is no longerclean as the fluid lines it has traveledthrough have contributed metal and rubber particles, and the drums haveadded flakes of metal or scale. Storagetanks are a real problem because watercondenses in them causing rust from the atmosphere can also find its way into the tank unlesssatisfactory air breathers are the fluid is stored under reasonableconditions, the principal contaminants on delivery to the machine will be metal,silica and fibers. With fluids from reputablesuppliers, sampling has shown typicalCleanliness Levels of 17/16/14or a portable transfer cart fitted with a high efficiency filter, contaminationshould be removed from new fluidsbefore the contamination enters anddamages the components in the of ContaminationContamination particles found in new fluid include rust, scale, fibers and sand(photomicrograph at 100x).

9 Dirty New OilSources of contamination Contaminated New Oil Built-in contamination Ingressed contamination Internally GeneratedContamination6 Built-in ContaminationNew machinery always contains a certain amount of built-in in system assembly and in newcomponent flushing reduces this butnever eliminates it. Typical built-in contaminants are burrs, chips, flash,dirt, dust, fiber, sand, moisture, pipesealant, weld splatter, paint and flushing amount of contamination removedduring the system flush depends notonly on the effectiveness of the filtersused, but also the temperature, viscosity,velocity and turbulence of the flushingfluid. Unless high velocities and turbulence are attained, much of thecontamination will not be dislodged until the system is in operation, with catastrophic component failure a possibleresult. Irrespective of the standard offlushing executed by the machine builder,an off-load period of running-in shouldbe regarded as essential for any new orrebuilt hydraulic or lubrication ContaminationContamination from the immediate surroundings can be ingressed into thefluid power or lubrication system.

10 Onlarge installations, such as those withinsteelworks or automotive plants, it is relatively easy to know the environmentalconditions, though they vary example, a coke oven system operates in conditions very differentfrom a similar system in a cold mill. Formobile equipment, there is a very widevariation in environmental conditions byapplication, location and even by weatherconditions ( high winds).The key is to severely limit the accessenvironmental contamination has toenter the hydraulic or lubrication are four major ways dirt can enter a system: reservoir vent ports(breathers), power unit or systemaccess plates, components left openduring maintenance and cylinder of Ingressed ContaminationRESERVOIR VENT PORTS allow airexchange into and out of the reservoir to compensate for changes in fluid levelcaused primarily by cycling cylindersand thermal expansion and contractionof the fluid.