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The Handbook of Hydraulic
Filtration is intended to
familiarize the user with all
aspects of hydraulic and
lubrication filtration from
the basics to advanced
technology.
It is dedicated as a reference
source with the intent of
clearly and completely
presenting the subject matter
to the user, regardless of the
individual level of expertise.
The selection and proper use
of filtration devices is an
important tool in the battle to
increase production while
reducing manufacturing costs.
This Handbook will help the
user make informed decisions
about hydraulic filtration.
Contamination Basics 2
Contamination Types and Sources 4
Fluid Cleanliness Standards 12
Filter Media Types and Ratings 16
Filter Media Selection 20
Filter Element Life 22
Filter Housing Selection 24
Types and Locations of Filters 28
Fluid Analysis 32
Appendix 34
Table of Contents
1
PAGESECTION
Contamination Causes Most Hydraulic Failures
The experience of designers and usersof hydraulic and lube oil systems hasverified the following fact: over 75% ofall system failures are a direct result of contamination!
The cost due to contamination is staggering, resulting from:▼ Loss of production (downtime)
▼ Component replacement costs
▼ Frequent fluid replacement
▼ Costly disposal
▼ Increased overall maintenance costs
▼ Increased scrap rate
Functions of HydraulicFluid
Contamination interferes with the fourfunctions of hydraulic fluids:1. To act as an energy transmission
medium.
2. To lubricate internal moving parts ofcomponents.
3. To act as a heat transfer medium.
4. To seal clearances between movingparts.
If any one of these functions isimpaired, the hydraulic system will notperform as designed. The resultingdowntime can easily cost a large manu-facturing plant thousands of dollarsper hour. Hydraulic fluid maintenancehelps prevent or reduce unplanneddowntime. This is accomplishedthrough a continuous improvementprogram that minimizes and removes contaminants.
Contaminant Damage
▼ Orifice blockage
▼ Component wear
▼ Formation of rust or other oxidation
▼ Chemical compound formation
▼ Depletion of additives
▼ Biological growth
Hydraulic fluid is expected to create alubricating film to keep precision partsseparated. Ideally, the film is thickenough to completely fill the clearancebetween moving parts. This conditionresults in low wear rates. When thewear rate is kept low enough, a compo-nent is likely to reach its intended lifeexpectancy, which may be millions ofpressurization cycles.
Contamination Basics
2
Filtration FactProperly sized, installed, and
maintained hydraulic
filtration plays a key role
in machine preventative
maintenance planning.
Filtration FactThe function of a hydraulic
filter is to clean oil, but the
ultimate purpose is to
reduce operating costs.
Filtration FactThe disposal cost of a
drum of waste oil can be
4X - 5X the cost of a
drum of new oil.
Actual photomicrograph of particulate contamination (Magnified 100x Scale: 1 division = 20 microns)
The actual thickness of a lubricatingfilm depends on fluid viscosity, appliedload, and the relative speed of the twosurfaces. In many components, mech-anical loads are to such an extremethat they squeeze the lubricant into avery thin film, less than 1 micrometerthick. If loads become high enough, thefilm will be punctured by the surfaceroughness of the two moving parts. The result contributes to harmful friction.
Contamination Basics
3
Micrometer Scale
Particle sizes are generally measuredon the micrometer scale. One microm-eter (or “micron”) is one-millionth ofone meter, or 39 millionths of an inch.The limit of human visibility is approx-imately 40 micrometers. Keep in mindthat most damage-causing particles inhydraulic or lubrication systems aresmaller than 40 micrometers.Therefore, they are microscopic andcannot be seen by the unaided eye.
Typical Hydraulic Component Clearances
Microns 0.5
0.5-10.5-5
1-41-255-40
18-6350-250
130-450
Component Anti-friction bearings Vane pump (vane tip to outer ring) Gear pump (gear to side plate) Servo valves (spool to sleeve) Hydrostatic bearings Piston pump (piston to bore) Servo valves flapper wallActuators Servo valves orifice
Relative Sizes of Particles
Inches.0039.0027.0016.0010.0003 .0001
Substance Grain of table salt Human hair Lower limit of visibility Milled flour Red blood cells Bacteria
Microns10070402582
ParticulateContaminationTypes
Particulate contamination is generallyclassified as “silt” or “chips.” Silt canbe defined as the accumulation of particles less than 5�m over time. Thistype of contamination also causes system component failure over time.Chips on the other hand, are particles5�m+ and can cause immediate catastrophic failure. Both silt andchips can be further classified as:
Contamination Types and Sources
4
Filtration FactNew fluid is not necessarily
clean fluid. Typically, new
fluid right out of the drum is
not fit for use in hydraulic or
lubrication systems.
Filtration FactAdditives in hydraulic fluid
are generally well below
1 micron in size and are
unaffected by standard
filtration methods.
Hard Particles▼ Silica
▼ Carbon
▼ Metal
Soft Particles▼ Rubber
▼ Fibers
▼ Micro organism
Flow
1. Particulate Silt (0-5um) Chips (5um+)
Types of Contamination
2. Water (Free & Dissolved)
3. Air
Silt
Damage
Sources
▼ Built-in during manufacturing andassembly processes.
▼ Added with new fluid.
If not properly flushed, contaminantsfrom manufacturing and assembly willbe left in the system.
These contaminants include dust,welding slag, rubber particles fromhoses and seals, sand from castings,and metal debris from machined com-ponents. Also, when fluid is initiallyadded to the system, contamination isintroduced.
During system operation, contamina-tion enters through breather caps,worn seals, and other system openings.System operation also generates inter-nal contamination. This occurs as component wear debris and chemicalbyproducts react with component sur-faces to generate more contamination.
Contamination Types and Sources
5
▼ Ingested from outside the systemduring operation.
▼ Internally generated during operation (see chart below).
Stress raisers causedby particle collisions
A B
C D
A. Three-body mechanical interactions canresult in interference.
B. Two-body wear is common in hydraulic components.
C. Hard particles can create three-body wear to generate more particles.
D. Particle effects can begin surface wear.
Abrasive Wear—Hard particlesbridging two moving surfaces,scraping one or both.
Cavitation Wear—Restrictedinlet flow to pump causes fluidvoids that implode causingshocks that break away criticalsurface material.
Fatigue Wear—Particles bridging a clearance cause a surface stress riser thatexpands into a spall due torepeated stressing of the damaged area.
Erosive Wear—Fine particles ina high speed stream of fluid eataway a metering edge or criticalsurface.
Adhesive Wear—Loss of oil filmallows metal to metal contactbetween moving surfaces.
Corrosive Wear—Water orchemical contamination in thefluid causes rust or a chemicalreaction that degrades a surface.
Generated Contamination
Contamination Types and Sources
6
Filtration FactSystem ContaminationWarning Signals
• Solenoid burn-out.
• Valve spool decentering,
leakage, “chattering”.
• Pump failure, loss of
flow, frequent
replacement.
• Cylinder leakage, scoring.
• Increased servo hysteresis.
Filtration FactMost system ingression
enters a system through the
old-style reservoir breather
caps and the cylinder rod
glands.
Prevention
▼ Use spin-on or dessicant style filters for reservoir air breathers.
▼ Flush all systems before initial start-up.
▼ Specify rod wipers and replace worn actuator seals.
▼ Cap off hoses and manifolds during handling and maintenance.
▼ Filter all new fluid before it enters the reservoir.
External Contamination Sources
Mobile Equipment 108-1010 per minute*
Manufacturing Plants 106-108 per minute*
Assembly Facilities 105-106 per minute*
* Number of particles greater than 10 microns ingressedinto a system from all sources.
Ingression Rates For Typical Systems
WaterContamination
Types
There is more to proper fluid maintenance than just removing particulate matter. Water is virtually auniversal contaminant, and just likesolid particle contaminants, must beremoved from operating fluids. Watercan be either in a dissolved state or ina “free” state. Free, or emulsified,water is defined as the water above thesaturation point of a specific fluid. Atthis point, the fluid cannot dissolve orhold any more water. Free water isgenerally noticeable as a “milky” discoloration of the fluid.
Contamination Types and Sources
7
50 PPM 2000 PPM
Typical Saturation Points
Hydraulic Fluid
Lubrication Fluid
Transformer Fluid
300
400
50
.03%
.04%
.005%
Fluid Type PPM %
1000 ppm(.10%)
300 ppm(.03%)
Visual Effects Of Water In Oil
Damage
▼ Corrosion of metal surfaces
▼ Accelerated abrasive wear
▼ Bearing fatigue
▼ Fluid additive breakdown
▼ Viscosity variance
▼ Increase in electrical conductivity
Anti-wear additives break down in thepresence of water and form acids. Thecombination of water, heat and dissimilarmetals encourages galvanic action. Pittedand corroded metal surfaces and finishesresult. Further complications occur astemperature drops and the fluid has lessability to hold water. As the freezing point
is reached, ice crystals form, adverselyaffecting total system function. Operatingfunctions may also become slowed orerratic.
Electrical conductivity becomes a pro-blem when water contamination weakensthe insulating properties of a fluid, thusdecreasing its dielectric kV strength.
Contamination Types and Sources
8
Filtration FactA simple ‘crackle test’ will
tell you if there is free
water in your fluid. Apply a
flame under the container.
If bubbles rise and ‘crackle’
from the point of applied
heat, free water is present
in the fluid.
Filtration FactHydraulic fluids have the
ability to ‘hold’ more water
as temperature increases.
A cloudy fluid may become
clearer as a system
heats up.
Typical results of pump wear due to particulate and water contamination
Sources
▼ Worn actuator seals
▼ Reservoir opening leakage
▼ Condensation
▼ Heat exchanger leakage
Fluids are constantly exposed to waterand water vapor while being handledand stored. For instance, outdoor stor-age of tanks and drums is common.Water may settle on top of fluid con-tainers and be drawn into the contain-er during temperature changes. Watermay also be introduced when openingor filling these containers.
Water can enter a system through worncylinder or actuator seals or throughreservoir openings. Condensation isalso a prime water source. As the fluidscool in a reservoir or tank, water vaporwill condense on the inside surfaces,causing rust or other corrosion problems.
Contamination Types and Sources
9
250
200
150
100
50
0
% Water In Oil0.0025
Effect of water in oil on bearing life (based on 100% life at .01% water in oil.)Reference: ”Machine Design” July 86, ”How Dirt And Water Effect Bearing Life” by Timken Bearing Co.
0.01 0.05 0.10 0.15 0.25 0.50
% B
eari
ng L
ife R
emai
ning
Effect Of Water In Oil On Bearing Life
0.0025%0.01%0.05%0.10%0.15%0.25%0.50%
=======
25 ppm 100 ppm 500 ppm1000 ppm1500 ppm2500 ppm5000 ppm
Prevention
Excessive water can usually beremoved from a system. The same pre-ventative measures taken to minimizeparticulate contamination ingressionin a system can be applied to watercontamination. However, once exces-sive water is detected, it can usually be eliminated by one of the followingmethods:
Absorption
This is accomplished by filter elementsthat are designed specifically to takeout free water. They usually consist of alaminant-type material that transformsfree water into a gel that is trappedwithin the element. These elements fit
into standard filter housings and aregenerally used when small volumes ofwater are involved.
Centrifugation
Separates water from oil by a spinningmotion. This method is also only effective with free water, but for largervolumes.
Vacuum Dehydration
Separates water from oil through a vacuum and drying process. Thismethod is also for larger volumes ofwater, but is effective with both thefree and dissolved states.
Contamination Types and Sources
10
Filtration FactFree water is heavier than
oil, thus it will settle to the
bottom of the reservoir
where much of it can be
easily removed by opening
the drain valve.
Filtration FactAbsorption filter elements
have optimum
performance in low
flow and low viscosity
applications.
Vacuum dehydration system
Air Contamination
Types
Air in a liquid system can exist ineither a dissolved or entrained (undis-solved, or free) state. Dissolved air maynot pose a problem, providing it staysin solution. When a liquid containsundissolved air, problems can occur asit passes through system components.There can be pressure changes thatcompress the air and produce a largeamount of heat in small air bubbles.This heat can destroy additives, andthe base fluid itself.
If the amount of dissolved air becomeshigh enough, it will have a negativeeffect on the amount of work performed by the system. The workperformed in a hydraulic system relieson the fluid being relatively incom-pressible, but air reduces the bulkmodulus of the fluid. This is due to thefact that air is up to 20,000 times morecompressible than a liquid in which itis dissolved. When air is present, apump ends up doing more work tocompress the air, and less useful workon the system. In this situation, thesystem is said to be ‘spongy’.
Damage
▼ Loss of transmitted power
▼ Reduced pump output
▼ Loss of lubrication
▼ Increased operating temperature
▼ Reservoir fluid foaming
▼ Chemical reactions
Air in any form is a potential source ofoxidation in liquids. This acceleratescorrosion of metal parts, particularlywhen water is also present. Oxidationof additives also may occur. Bothprocesses produce oxides which pro-mote the formation of particulates, orform a sludge in the liquid. Wear andinterference increases if oxidationdebris is not prevented or removed.
Sources
▼ System leaks
▼ Pump aeration
▼ Reservoir fluid turbulence
Prevention
▼ System air bleeds
▼ Flooded suction pump
▼ Proper reservoir design
▼ Return line diffusers
Contamination Types and Sources
11
In order to detect or correct problems,a contamination reference scale isused. Particle counting is the mostcommon method to derive cleanlinesslevel standards. Very sensitive opticalinstruments are used to count thenumber of particles in various sizeranges. These counts are reported asthe number of particles greater than acertain size found in a specified volume of fluid.
The ISO 4406:1999 (InternationalStandards Organization) cleanlinesslevel standard has gained wide accep-tance in most industries today. Thisstandard references the number of par-ticles greater than 4, 6, and 14 microm-eters in a known volume, usually 1 mil-liliter or 100 milliliters. The number of4+ and 6+ micrometer particles isused as a reference point for “silt” par-ticles. The 14+ size range indicates thequantity of larger particles presentwhich contribute greatly to possiblecatastrophic component failure.
Fluid Cleanliness Standards
12
Filtration FactKnowing the cleanliness
level of a fluid is the basis
for contamination control
measures.
Filtration FactThe ISO code index
numbers can never
increase as the particle
sizes increase
(Example: 18/20/22).
All particle distributions
have more smaller than
larger particles.
An ISO classification of 19/16/13 can be defined as:
Particles> 4 microns (c)
Particles> 6 microns (c)
Particles> 14 microns (c)
ISO CODE 19 / 16 / 13
19
16
13
4+
6+
14+
2,500 - 5,000
320 - 640
40 - 80
Range Number Micron (c) Actual Particle Count Range (per ml)
13
Fluid Cleanliness Standards
ISO 17/14/11 fluid (magnification 100x)ISO 22/19/17 fluid (magnification 100x)
ISO 4406 Chart
24 23222120191817161514131211109876
RangeNumber More than Up to and including
Number of particles per ml
80,00040,00020,00010,0005,0002,5001,300
640320160804020105
2.51.3.64 .32
160,00080,00040,00020,00010,0005,0002,5001,300
640320160804020105
2.51.3.64
Component Cleanliness Level Requirements
Many manufacturers of hydraulic andload bearing equipment specify theoptimum cleanliness level required fortheir components. Subjecting compo-nents to fluid with higher contamina-tion levels may result in much shortercomponent life.
In the table below, a few componentsand their recommended cleanlinesslevels are shown. It is always best toconsult with component manufacturersand obtain their written fluid cleanli-ness level recommendations. Thisinformation is needed in order toselect the proper level of filtration. It may also prove useful for any
subsequent warrantyclaims, as it may drawthe line between nor-mal use and excessiveor abusive operation.
Fluid Cleanliness Required forTypical Hydraulic Components
Fluid Cleanliness Standards
14
ISOComponents Code
Servo control valves 17/14/11Proportional valves 18/15/12
Vane and piston 19/16/13pumps/motors
Directional & pressure 19/16/13control valves
Gear pumps/motors 20/17/14
Flow control valves, 21/18/15cylinders
New unused fluid 21/18/15
Filtration FactMost machine and hydraulic
component
manufacturers specify a
target ISO cleanliness
level to equipment in
order to achieve optimal
performance standards.
Filtration FactColor is not a good
indicator of a fluid’s
cleanliness level.
Fluid Cleanliness Standards
15
SAE AS5049 Revision E (Table 1)Cleanliness Classes For Differential Particle Counts (Particles / 100 mL) (3)
00 0 1 2 3 4 5 6 7 8 9
10 11 12
Classes5 to 15 µm
125 250 500
1 000 2 000 4 000 8 000
16 000 32 000 64 000
128 000 256 000 512 000
1 024 000
15 to 25 µm
22 44 89
178 356 712
1 425 2 850 5 700
11 400 22 800 45 600 91 200
182 400
25 to 50 µm 50 to 100 µm >100 µm6 to 14 µm(c)
(1)(2) 14 to 21 µm(c) 21 to 38 µm(c) 38 to 70 µm(c) >70 µm(c)
4 8
16 32 63
126 253 506
1 012 2 025 4 050 8 100
16 200 32 400
1 2 3 6 11 22 45 90 180 360 720
1 440 2 880 5 760
0 0 1 1 2 4 8 16 32 64 128 256 512
1 024
(1) Size Range, Optical Microscope, based on longest dimension as measured per ARP598, APC Calibrated per ISO 4402:1991.(2) Size Range, APC Calibrated Per ISO 11171 or Electron Microscope, based on projected area equivalent diameter.(3) Classes and contamination limits identical to NAS 1638.
The filter media is that part of the element which removes the contaminant. Media usually starts out in sheet form,and is then pleated to expose more sur-face area to the fluid flow. This reducespressure differential while increasingdirt holding capacity. In some cases,the filter media may have multiple layers and mesh backing to achievecertain performance criteria. Afterbeing pleated and cut to the properlength, the two ends are fastenedtogether using a special clip, adhesive,or other seaming mechanism. The mostcommon media include wire mesh, cellulose, fiberglass composites, orother synthetic materials. Filter mediais generally classified as either surfaceor depth.
Surface Media
For surface type filter media, the fluidstream basically has a straight throughflow path. Contaminant is captured onthe surface of the element which facesthe fluid flow. Surface type elementsare generally made from woven wire.Since the process used in manufactur-ing the wire cloth can be very accurate-ly controlled, surface type media have aconsistent pore size. This consistentpore size is the diameter of the largesthard spherical particle that will passthrough the media under specified testconditions. However, the build-up ofcontaminant on the element surfacewill allow the media to capture parti-cles smaller than the pore size rating.Likewise, particles that have a smallerdiameter, but may be longer in length(such as a fiber strand), may passdownstream of a surface media.
Depth Media
For depth type filter media, fluid musttake indirect paths through the materi-al which makes up the filter media.Particles are trapped in the maze ofopenings throughout the media.Because of its construction, a depthtype filter media has many pores ofvarious sizes. Depending on the distrib-ution of pore sizes, this media can havea very high captive rate at very smallparticle sizes.
The nature of filtration media and thecontaminant loading process in a filterelement explains why some elementslast much longer than others. In gener-al, filter media contain millions of tinypores formed by the media fibers. Thepores have a range of different sizesand are interconnected throughout thelayer of the media to form a tortuouspath for fluid flow.
Filter Media Types and Ratings
16
Filtration FactSurface media can be
cleaned and re-used. An
ultrasonic cleaner is
usually the best method.
Depth media typically
cannot be cleaned and
it is not re-usable.
Surface Media
74 m
The two basic depth media types thatare used for filter elements are cellu-lose and fiberglass.
The pores in cellulose media tend tohave a broad range of sizes due to theirregular size and shape of the fibers. In contrast, fiberglass media consist offibers that are very uniform in size andshape. The fibers are generally thinnerthan cellulose fibers, and have a uni-form circular cross section. These typi-cal fiber differences account for theperformance advantage of fiberglassmedia. Thinner fibers mean more actu-al pores in a given space. Furthermore,thinner fibers can be arranged closertogether to produce smaller pores forfiner filtration. Dirt holding capacity,as well as filtration efficiency, areimproved as a result.
Filter Media Types and Ratings
17
Flow Direction
Depth Media
General Comparison Of Filter Media
Media Material
DirtHolding Capacity
Life In a System
InitialCost
Fiberglass
Cellulose (paper)
Wire Mesh
High
Moderate
Low
DifferentialPressure
Moderate
High
Low
High
Moderate
Moderate
Moderate
Low
High
CaptureEfficiency
High
Moderate
Low
Typical coarse fiberglass construction (100X)
Typical fine fiberglass construction (100X)
The MultipassTest
The filtration industryuses the ISO 4572“Multipass TestProcedure” to evaluatefilter element perfor-mance. This procedureis also recognized byANSI* and NFPA**.During the MultipassTest, fluid is circulatedthrough the circuitunder precisely con-trolled and monitoredconditions. The differential pressureacross the test element is continuouslyrecorded, as a constant amount of con-taminant is injected upstream of theelement. On-line laser particle sensorsdetermine the contaminant levelsupstream and downstream of the testelement. This performance attribute(The Beta Ratio) is determined for several particle sizes. Three important element performancecharacteristics are a result of theMultipass Test:1. Dirt holding capacity.
2. Pressure differential of the test filter element.
3. Separation or filtration efficiency, expressed as a “Beta Ratio”.
Beta Ratio
The Beta Ratio (also known as the filtration ratio) is a measure of the particle capture efficiency of a filterelement. It is therefore a performancerating.
As an example of how a Beta Ratio isderived from a Multipass Test. Assumethat 50,000 particles, 10 micrometersand larger, were counted upstream(before) of the test filter and 10,000particles at that same size range werecounted downstream (after) of the testfilter. The corresponding Beta Ratiowould equal 5, as seen in the followingexample:
Filter Media Types and Ratings
18
Flow MeterDownstream
Sample
UpstreamSample
TestFilter
�P Gauge
Reservoir
Contaminant
Variable Speed Pump
Multipass TestFiltration FactFilter media ratings
expressed as a Beta Ratio
indicate a media’s particle
removal efficiency.
Filtration FactMultipass test results are
very dependent on the
following variables:
• Flow rate
• Terminal pressure
differential
• Contaminant type
# of particles upstream# of particles downstream
“x” is at a specific particle size
50,00010,000
= 5
Bx =
B10 =
* ANSI – American National Standards Institute** NFPA – National Fluid Power Association
The example would read “Beta tenequal to five.” Now, a Beta Ratio number alone means very little. It is a preliminary step to find a filter’s particle capture efficiency. This efficiency, expressed as a percent, can be found by a simple equation:
So, in the example, the particular filtertested was 80% efficient at removing 10micrometer andlarger particles. Forevery 5 particlesintroduced to the filter at this sizerange, 4 weretrapped in the filtermedia. The BetaRatio/ Efficienciestable shows somecommon Beta Rationumbers and their corresponding efficiencies.
Filter Media Types and Ratings
19
Beta RatioDownstream
ParticlesUpstreamParticles
100,000 > (x) microns
Beta Ratio (x) Efficiency (x)
100,00050,000
100,0005,000
100,0001,333
100,0001,000
100,000500
100,000100
=
=
=
=
=
=
2
20
75
100
200
1000
50.0%
95.0%
98.7%
99.0%
99.5%
99.9%
50,000
5,000
1,333
1,000
500
100
Beta Ratios/Efficiencies
Beta Ratio Capture Efficiency (at a given particle size) (at same particle size)
1.01 1.0%
1.1 9.0%1.5 33.3%2.0 50.0%5.0 80.0%10.0 90.0%20.0 95.0%75.0 98.7%100 99.0%200 99.5%1000 99.9%
Efficiencyx = (1- 1 ) 100Beta
Efficiency10 = (1- 1 ) 100
= 80%5
A number of interrelated system factors combine to determine propermedia and filter combinations. To accu-rately determine which combination isideal for your system all these factorsneed to be accounted for. With thedevelopment of filtration sizing soft-ware such as inPHorm, this informationcan be used to compute the optimalselection.However, in many instancesthe information available may be limited. In these cases “rules ofthumb”, based on empirical data andproven examples, are applied to try and get an initial starting point.
The charts on the following pages are designed for just those instances.Be aware that rules of thumb utilize“standard” values when looking at com-ponents, ingressions, and other systemparameters. Your specific system mayor may not fit into this “standard” classification.
One of the more important points ofthe charts is to emphasize element efficiency. Note that as less efficientelements are utilized, more passes arerequired to obtain the same ISO
cleanliness level as a more efficientelement. Secondly, the charts indicatethe effect of system pressure on therequired ISO code. As system pressureincreases, the oil film thicknessbetween component parts decreases.This reduction in clearance allowssmaller micron particles to have harmful effects.The charts attempt toprovide flexibility by providing severalpossible solutions for each compo-nent/system pressure combination.
Selection software such as inPHorm(shown left) can be an extremely usefultool in the selection and specificationof the proper filtration product. Withcomputer aided selection, the user canquickly determine the pressure lossacross a given element, and/or housingcombination, within specific operatingparameters. The tedious process ofplotting viscosity at various points and calculating a pressure drop is eliminated. Additionally, selection software can predict system perfor-mance and element life – ideal for predictive maintenance programs.
Filter Media Selection
20
Filtration FactThere is no direct
correlation between
using a specific media and
attaining a specific ISO
cleanliness classification.
Numerous other variables
should be considered, such
as particulate ingression,
actual flow through filters,
and filter locations.
How to use charts:1. Choose the appropriate chart for your
system, hydraulic or lubrication.
2. Starting in the left column, the components are listed by order of sensitivity. Find the most sensitive component used in your system.
3. Following the color band to the right of the component selected, choose thepressure range that the system operateswithin. This step is not required for lubrication systems.
4. Follow the color band to the right of thepressure range selected for the suggestedISO code for the system
5. To the right of the ISO code, in the same color band, are the media efficien-cies required for the corresponding filterplacements. Depending on the selectionthere will be one to three optionsavailable.
6. Be sure that the filter placements recommendation is on the same level as the media efficiency selected.
Filter Media Selection
Component Type System Pressure Suggested Media Efficiency Number of Minimum FilterCleanliness Code Betax >200 Filter Placements Placements
2
5
2
2
2
5
10
2
5
2
5
5
10
2
5
10
2
5
5
10
5
10
5
10
10
20
10
5
10
17/14/12
16/13/11
16/12/10
18/15/13
18/14/12
17/14/11
19/16/14
18/16/14
18/15/13
20/17/15
19/17/14
19/16/13
21/18/16
20/17/15
20/17/14
<1000
1000-3000
>3000
<1000
1000-3000
>3000
<1000
1000-3000
>3000
<1000
1000-3000
>3000
<1000
1000-3000
>3000
Servo Valves
Proportional
Valves
Variable Volume
Pumps
Vane Pumps
Fixed Piston Pumps
Cartridge Valves
Gear Pumps
Flow Controls
Cylinders
1
2
1.5
2
1
1.5
2.5
1
2
1.5
2.5
1
2
0.5
1.5
2.5
1
2
0.5
1.5
1
2
1.5
2.5
1
2.5
1.5
0.5
1.5
P
P & R
P & O
P & R
P
P & O
P, R & O
P
P & R
P & O
P, R & O
P or R
P & R
O
P or R, & O
P, R & O
P or R
P & R
O
P or R, & O
P or R
P & R
P or R, & O
P, R & O
P or R
P, R & O
P or R, & O
O
P or R, & O
Hydraulic Systems
Component Type Suggested Media Efficiency Number of Minimum FilterCleanliness Code Betax >200 Filter Placements* Placements
1.5
1
2
0.5
1.5
2.5
2
2
5
2
5
10
16/13/11
17/14/12
18/15/13
Ball Bearings
Roller Bearings
Journal BearingsGear Boxes
P or R, & O
P or R
P & R
0
P or R, & O
P, R & O
Lubrication Systems
21
P = Full flow pressure filter (equalsone filtration placement)
R = Full flow return filter (equals onefiltration placement)
O = Off-line (flow rate 10% of reser-voir volume equals .5 of a filtra-tion placement)
* Number of filtration placements insystem, more placements are theoption of the specifier.
Contaminant Loading
Contaminant loading in a filter ele-ment is simply the process of blockingthe pores throughout the element. Asthe filter element becomes blockedwith contaminant particles, there arefewer pores for fluid flow, and the pres-sure required to maintain flow throughthe media increases. Initially, the dif-ferential pressure across the elementincreases very slowly because there isan abundance of media pores for thefluid to pass through, and the poreblocking process has little effect on theoverall pressure loss. However, a pointis reached at which successive block-ing of media pores significantlyreduces the number of available poresfor flow through the element. At this point the differential pressureacross the element rises exponentially.The quantity, size, shape and arrange-ment of the pores throughout the
element accounts for why some elements last longer than others.
For a given filter media thickness andfiltration rating, there are fewer poreswith cellulose media than fiberglassmedia. Accordingly, the contaminantloading process would block the poresof the cellulose media element quickerthen the identical fiberglass media element.
The multilayer fiberglass media element is relatively unaffected by contaminant loading for a longer time.The element selectively captures thevarious size particles, as the fluid pass-es through the element. The very smallpores in the media are not blocked bylarge particles. These downstreamsmall pores remain available for thelarge quantity of very small particlespresent in the fluid.
Filter Element Life
22
Diffe
rent
ial P
ress
ure
Time
IncrementalLife
Element Contamination Loading Curve
Filtration FactAs an element loads with
contamination, the
differential pressure will
increase over time; slowly
at first, then very quickly
as the element nears it’s
maximum life.
Filter Element Life Profile
Every filter element has a characteris-tic pressure differential versus contam-inant loading relationship. This rela-tionship can be defined as the “filterelement life profile.” The actual lifeprofile is obviously affected by the sys-tem operating conditions. Variations inthe system flow rate and fluid viscosityaffect the clean pressure differentialacross the filter element and have awell-defined effect upon the actual element life profile.
The filter element life profile is verydifficult to evaluate in actual operatingsystems. The system operating versusidle time, the duty cycle and thechanging ambient contaminant condi-tions all affect the life profile of the filter element. In addition, precise
instrumentation for recording thechange in the pressure loss across thefilter element is seldom available. Mostmachinery users and designers simplyspecify filter housings with differentialpressure indicators to signal when thefilter element should be changed.
The Multipass Test data can be used to develop the pressure differential versus contaminant loading relation-ship, defined as the filter element lifeprofile. As previously mentioned, suchoperating conditions as flow rate andfluid viscosity affect the life profile fora filter element. Life profile compar-isons can only be made when theseoperating conditions are identical andthe filter elements are the same size.
Then, the quantity, size, shape, andarrangement of the pores in the filterelement determine the characteristiclife profile. Filter elements that aremanufactured from cellulose media,single layer fiberglass media and multi-layer fiberglass media all have a verydifferent life profile. The graphic comparison of the three most commonmedia configurations clearly shows the life advantage of the multilayerfiberglass media element.
Filter Element Life
Element Types Life Comparison
23
00 5 10 15 20 25 30 35 40 45 50
102030
40
5060
7080
90 6
5
4
3
2
1
100
CAPACITY (GRAMS)
Cellulose MultilayerFiberglass
Single LayerFiberglass
DIF
FERE
NTI
AL
PRES
SURE
(PSI
)
DIF
FERE
NTI
AL
PRES
SURE
(bar
)
Filter HousingsThe filter housing is the pressure vesselwhich contains the filter element. Itusually consists of two or more sub-assemblies, such as a head (or cover)and a bowl to allow access to the filterelement. The housing has inlet and out-let ports allowing it to be installed into afluid system. Additional housing featuresmay include mounting holes, bypassvalves and element condition indicators.
The primary concerns in the housingselection process include mountingmethods, porting options, indicatoroptions, and pressure rating. All, exceptthe pressure rating, depend on the phys-ical system design and the preferencesof the designer. Pressure rating of thehousing is far less arbitrary. This shouldbe determined before the housing styleis selected.
Pressure RatingsLocation of the filter in the circuit is theprimary determinant of pressure rating.Filter housings are genericallydesigned for three locations in a cir-cuit: suction, pressure, or return lines.One characteristic of these locations istheir maximum operating pressures.Suction and return line filters are generally designed for lower pressuresup to 500 psi (34 bar). Pressure filter
locations may require ratings from 1500
psi to 6000 psi (103 bar to 414 bar).
It is essential to analyze the circuit forfrequent pressure spikes as well assteady state conditions. Some housingshave restrictive or lower fatigue pressure ratings. In circuits with fre-quent high pressure spikes, anothertype housing may be required to prevent fatigue related failures.
Filter Housing Selection
24
Filtration FactAlways use an element
condition indicator with any
filter, especially those that
do not have a bypass valve.
Filtration FactAn element loading with
contaminant will continue
to increase in pressure
differential until either:
• The element is replaced.
• The bypass valve opens.
• The element fails.
Visual/electrical element condition indicator
Bypass valve Assembly
Pressure housing
Filter element
Inlet port
Drain port
The Bypass Valve
The bypass valve is used to prevent thecollapse or burst of the filter elementwhen it becomes highly loaded withcontaminant. It also prevents pumpcavitation in the case of suction linefiltration. As contaminant builds up inthe element, the differential pressureacross the element increases. At apressure well below the failure point of the filter element , the bypass valveopens, allowing flow to go around theelement.
Some bypass valve designs have a“bypass to-tank” option. This allows theunfiltered bypass flow to return to tankthrough a third port, preventing unfil-tered bypass flow from entering thesystem. Other filters may be supplied
with a “no bypass” or “blocked”bypass option. This preventsany unfiltered flow from goingdownstream. In filters with nobypass valves, higher collapsestrength elements may berequired, especially in highpressure filters. Applicationsfor using a “no bypass” optioninclude servo valve and othersensitive component protection. When specifying anon-bypass filter design, makesure that the element has a dif-ferential pressure rating closeto maximum operating pressure of thesystem. When specifying a bypass typefilter, it can generally be assumed thatthe manufacturer has designed the
element to withstand the bypass valvedifferential pressure when the bypassvalve opens.
After a housing style and pressure rating are selected, the bypass valvesetting needs to be chosen. The bypassvalve setting must be selected beforesizing a filter housing. Everything elsebeing equal, the highest bypass cracking pressure available from themanufacturer should be selected. Thiswill provide the longest element life fora given filter size. Occasionally, a lowersetting may be selected to help minimize energy loss in a system, or toreduce back-pressure on another com-ponent. In suction filters, either a 2 or3 psi (0.14 bar or 0.2 bar) bypass valveis used to minimize the chance ofpotential pump cavitation.
Filter Housing Selection
25
950 psi(66 bar) 0 psi
(0 bar)
1000 psi(69 bar)1000 psi
(69 bar)
Filter(Elements Blocked)
Bypass valve50 psi setting
(3.4 bar)
Bypass Filter Blocked Bypass Filter
Flow
0
2
Beta Performance Lost by Cyclic Flow and Bypass Leakage.
Effe
ctiv
e Fi
ltrat
ion
Ratio
B10
4
6
Steady Flow–No Leakage
Unsteady Flow–No Leakage
8
10
0 2 4 6 8 10 12
12
Unsteady Flow–10% Leakage
Unsteady Flow–20% Leakage
Unsteady Flow–40% Leakage
B10 From Multipass Test
BetaLost byCyclicFlow
Element ConditionIndicators
The element condition indicator signals when the element should becleaned or replaced. The indicator usu-ally has calibration marks which alsoindicates if the filter bypass valve hasopened. The indicator may be mechan-ically linked to the bypass valve, or itmay be an entirely independent differ-ential pressure sensing device.Indicators may give visual, electrical orboth types of signals. Generally, indica-tors are set to trip anywhere from 5%-25% before the bypass valve opens.
Housing And Element Sizing
The filter housing size should be largeenough to achieve at least a 2:1 ratiobetween the bypass valve setting andthe pressure differential of the filterwith a clean element installed. It ispreferable that this ratio be 3:1 or even higher for longer element life.
For example, the graph on the nextpage illustrates the type of catalogflow/pressure differential curves whichare used to size the filter housing. Ascan be seen, the specifier needs toknow the operating viscosity of thefluid, and the maximum flow rate(instead of an average) to make surethat the filter does not spend a highportion of time in bypass due to flowsurges. This is particularly importantin return line filters, where flow multi-plication from cylinders may increasethe return flow compared to the pumpflow rate.
Filter Housing Selection
26
Filtration FactAlways consider low tem-
perature conditions when
sizing filters. Viscosity
increases in the fluid may
cause a considerable
increase in pressure differ-
ential through the filter
assembly.
Filtration FactPressure differential
in a filter assembly
depends on:
1. Housing and
element size
2. Media grade
3. Fluid viscosity
4. Flow rate
Filtration FactIt is recommended to use
an element condition
indicator with any filter,
especially those that
do not incorporate a
bypass valve.
Filter Element Sizing
3:1 OptimumRatio
CleanElement
P
Diff
eren
tial P
ress
ure
LIFE
Filter Bypass
Cracking Pressure
If the filter described in the graph wasfitted with a 50 psi (3.4 bar) bypassvalve the initial (clean) pressure dif-ferential should be no greater than 25psi (1.7 bar) and preferably 16 2¼3 psi(1.1 bar)or less. This is calculated fromthe 3:1 and 2:1 ratio of bypass settingand initial pressure differential.
Most standard filter assemblies utilizea bypass valve to limit the maximumpressure drop across the filterelement. As the filter element becomesblocked with contaminant, the pres-sure differential increases until thebypass valve cracking pressure isreached. At this point, the flowthrough the filter assembly beginsbypassing the filter element and passesthrough the bypass valve. This actionlimits the maximum pressure differen-tial across the filter element. Theimportant issue is that some of thesystem contaminant particles alsobypass the filter element. When thishappens, the effectiveness of the filterelement is compromised and theattainable system fluid cleanlinessdegrades. Standard filter assembliesnormally have a bypass valve crackingpressure between 25 and 100 PSI (1.7and 6.9 bar).
The relationship between the startingclean pressure differential across the
filter element and the bypass valvepressure setting must be considered.A cellulose element has a narrowregion of exponential pressure rise. For this reason, the relationshipbetween the starting clean pressuredifferential and the bypass valve pressure setting is very important. Thisrelationship in effect determines theuseful life of the filter element.
In contrast, the useful element life ofthe single layer and multilayer fiber-glass elements is established by thenearly horizontal, linear region of rela-tively low pressure drop increase, notthe region of exponential pressure rise.Accordingly, the filter assembly bypassvalve cracking pressure, whether 25 or75 PSI (1.7 or 5.2 bar), has relativelylittle impact on the useful life of thefilter element. Thus, the initial pressure differential and bypass valvesetting is less a sizing factor when fiberglass media is being considered.
Filter Housing Selection
27
Typical Flow/Pressure Curves For A Specific Media
0 25 50 75 100 125 150 200 225 250 275 300 325 350 375
0
0.25
0.5
0.75
1.
1.25
1.5
1.75
0
5
10
100 SUS200 SUS15
20
25
100 20 30 40 50 60 70 80 90 100Flow(GPM) (LPM)
(PSI
) Di
ffere
ntia
l Pre
ssur
e (B
ar)
3:1 RATIO▼ 50/3 = 16 2/3 psid (1.1 bar)
2:1 RATIO▼ 50/2 = 25 psid (1.7 bar)
▼ At 200 sus fluid, the maximum flowrange would be between 42 gpmand 54 gpm (159 lpm and 204 lpm)
Filter Types and Locations
▼ Suction ▼ Return
▼ Pressure ▼ Off-line
Suction Filters
Suction filters serve to pro-tect the pump from fluidcontamination. They arelocated before the inletport of the pump. Somemay be inlet “strainers”,submersed in the fluid.Others may be externallymounted. In either case,they utilize relativelycoarse elements, due tocavitation limitations ofpumps. For this reason,they are not used as prima-ry protection against contamination.Some pump manufactures do not rec-ommend the
use of a suction filter. Always consultthe pump manufacturer for inletrestrictions.
Types & Locations of Filters
28
To System
Filtration FactSuction strainers are often
referred to by “mesh” size:
60 mesh = 238 micron
100 mesh = 149 micron
200 mesh = 74 micron
Filtration FactThe use of suction filters
and strainers has greatly
decreased in modern
filtration.
Pressure Filters
Pressure filters arelocated downstreamfrom the system pump.They are designed tohandle the systempressure and sized forthe specific flow ratein the pressure linewhere they are located.
Pressure filters areespecially suited forprotecting sensitivecomponents directly downstream fromthe filter, such as servo valves. Locatedjust downstream from the system pump,
they also help protect the entire systemfrom pump generated contamination.
To System
Suction Filter
Pressure Filter
Return FiltersWhen the pump is a sensitive compo-nent in a system, a return filter maybe the best choice. In most systems,the return filter is the last compo-nent through which fluid passesbefore entering the reservoir.Therefore, it captures wear debrisfrom system working componentsand particles entering through worncylinder rod seals before such contaminant can enter the reservoirand be circulated. Since this filter islocated immediately upstream fromthe reservoir, its pressure rating andcost can be relatively low.
In some cases, cylinders with largediameter rods may result in “flowmultiplication”. The increased returnline flow rate may cause the filter
bypass valve to open, allowing unfiltered flow to pass downstream.This may be an undesirable conditionand care should be taken in sizing the filter.
Both pressure and return filters cancommonly be found in a duplex ver-sion. Its most notable characteristicis continuous filtration. That is, it ismade with two or more filter cham-bers and includes the necessary valving to allow for continuous, uninterrupted filtration. When a filter element needs servicing, theduplex valve is shifted, diverting flow to the opposite filter chamber.The dirty element can then bechanged, while filtered flow continues to pass through the filterassembly. The duplex valve typicallyis an open cross-over type, whichprevents any flow blockage.
Types & Locations of Filters
29
Cylinder has 2:1 ratio piston area to rod diameter.
Return line filter is sized for 66 gpm (250 lpm).Pressure is generally less than 25 psi (1.7 bar).
33 gpm(125 lpm)
Return LineFilters
Duplex Filter Assembly
Off-LineFiltration
Also referred to as recir-culating, kidney loop, orauxiliary filtration, thisfiltration system is totallyindependent of amachine’s main hydraulicsystem. Off-line filtrationconsists of a pump, filter,electrical motor, and theappropriate hardwareconnections. These com-ponents are installed off-line as a small sub-system separate from the working lines, or included in a fluidcooling loop. Fluid is pumped out of thereservoir, through the filter, and back tothe reservoir in a continuous fashion.With this “polishing” effect, off-line fil-tration is able to maintain a fluid at aconstant contamination level. As with areturn line filter, this type of system isbest suited to maintain overall cleanli-
ness, but does not provide specific com-ponent protection. An off-line filtrationloop has the added advantage that it isrelatively easy to retrofit on an existingsystem that has inadequate filtration.Also, the filter can be serviced withoutshutting down the main system. Mostsystems would benefit greatly from having a combination of suction, pres-
sure, return, and off-line filters.The table to the right may behelpful in making a filtrationlocation decision.
Types & Locations of Filters
30
Filtration FactRule of thumb:
size the pump flow of an
off-line package at a
minimum of 10% of the
main reservoir volume.
Filtration FactThe cleanliness level of a
system is directly propor-
tional to the flow rate
over the system filters.
Pump
Off-LineFilter
Optional Cooler
Air breatherExisting
Hydraulicor LubeSystem
Off-Line Filter
Flow Rate Effect on Off-Line FiltrationPerformance
.01
.1
23/21/18
20/18/1519/17/14
18/16/1316/14/12
15/13/10
For beta rated filters witha minimum rating of beta (10) = 75
(Number of particles > 10 micron ingressing per minute)
Source based on Fitch, E.C., Fluid Contamination Control, FES, Inc., Stillwater, Oklahoma, 1988.
Num
ber o
f par
ticle
s up
stre
am p
er m
illili
tre g
reat
er th
an re
fere
nce
size
ISO
Corr
elat
ion
1
10
102
103
103 104 105 106 107 108 109 1010 1011 1012
104
105
106
Ingression rate
1 GP
M (3
.8 lpm
)
10 G
PM (3
8 lpm
)
10
0 GPM
(380
lpm)
Types & Locations of Filters
31
Comparison of Filter Types and LocationsFILTERLOCATION ADVANTAGES DISADVANTAGES
Suction • Last chance • Must use relatively(Externally protection for the pump. coarse media,and/or largeMounted) housing size, to keep
pressure drop low due to pump inlet conditions.
• Cost is relatively high.• Much easier to • Does not protect
service than a downstream sump strainer. components from pump
wear debris.• May not be suitable for
many variable volume pumps.
• Minimum system protection.
Pressure • Specific component • Housing is relativelyprotection expensive because it
• Contributes to overall must handle full systemsystem cleanliness level. pressure.
• Can use high • Does not catch wearefficiency, fine filtration, debris from downstreamfilter elements. working components.
• Catches wear debris from pump
Return • Catches wear • No protection fromdebris from components, pump generatedand dirt entering contamination.through worn cylinder • Return line flow surgesrod seals before it enters may reduce filterthe reservoir. performance.
• Lower pressure • No direct componentratings result in lower protection.costs. • Relative initial cost
• May be in-line or is low.in-tank for easierinstallation.
Off-Line • Continuous “polishing” of • Relative initial cost is high.the main system hydraulic • Requires additional space.fluid, even if the system is • No direct component shut down. protection.
• Servicing possible withoutmain system shut down.
• Filters not affected by flowsurges allowing for optimumelement life and performance.
• The discharge line can be directed to the main system pump to provide superchargingwith clean, conditioned fluid.
• Specific cleanliness levelscan be more accurately obtained and maintained.
• Fluid cooling may be easilyincorporated.
Fluid Analysis Methods
▼ Patch Test
▼ Portable Particle Counter
▼ Laboratory Analysis
Fluid analysis is an essential part ofany maintenance program. Fluid analy-sis ensures that the fluid conforms tomanufacturer specifications, verifiesthe composition of the fluid, and deter-mines its overall contamination level.
Patch Test
A patch test is nothing more than a visual analysis of a fluid sample. It usually involves taking a fluid sampleand passing it through a fine media“patch”. The patch is then analyzedunder a microscope for both color and
content, and compared to known ISOstandards. By using this comparison,the user can get a “go, no-go” estimateof a system’s cleanliness level.
Another lesser-used deviation of thepatch test would be the actual count-ing of the particles seen under themicroscope. These numbers wouldthen be extrapolated into an ISOcleanliness level.
The margin of error for both of thesemethods is relatively high due to thehuman factor.
Fluid Analysis
32
Filtration FactThe only way to know the
condition of a fluid is
through fluid analysis.
Visual examination is not
an accurate method.
Filtration FactAny fluid analysis should
always include a particle
count and corresponding
ISO code.
Typical test kit
Portable Particle Counter
A most promising development in fluidanalysis is the portable laser particlecounter. Laser particle counters arecomparable to full laboratory units incounting particles down to the 2 +micron range. Strengths of this recenttechnology include accuracy, repeata-bility, portability, and timeliness. A testtypically takes less than a minute.Laser particle counters will generallygive only particle counts and cleanli-ness classifications. Water content, viscosity, and spectrometric analysistests would require a full laboratoryanalysis.
Laboratory Analysis
The laboratory analysis is a completelook at a fluid sample. Most qualifiedlaboratories will offer the followingtests and features as a package:
▼ Viscosity
▼ Neutralization number
▼ Water content
▼ Particle counts
▼ Spectrometric analysis (wear metals and additive analysisreported in parts per million,or ppm)
▼ Trending graphs
▼ Photo micrograph
▼ Recommendations
In taking a fluid sample from asystem, care must be taken tomake sure that the fluid sampleis representative of the system.To accomplish this, the fluidcontainer must be cleanedbefore taking the sample andthe fluid must be correctlyextracted from the system.
There is a National Fluid PowerAssociation (NFPA) standard forextracting fluid samples from a reservoir of an operating hydraulicfluid power system.(NFPA T2.9.1-1972).There is also the American NationalStandard method (ANSI B93.13-1972)for extracting fluid samples from thelines of an operating hydraulic fluidpower system for particulate contami-nation analysis. Either extractionmethod is recommended.
In any event, a representative fluidsample is the goal. Sampling valvesshould be opened and flushed for atleast fifteen seconds. The clean samplebottle should be kept closed until thefluid and valve is ready for sampling.The system should be at operating tem-perature for at least 30 minutes beforethe sample is taken.
A complete procedure follows in the appendix.
Fluid Analysis
Portable particle counter
Laboratory Analysis
33
FFLLUUIIDD AANNAALLYYSSIISS RREEPPOORRTT
SSAAMMPPLLEE DDAATTAA
COMPANY NAME: XYZ CorporationSYSTEM TYPE: Hydraulic SystemEQUIPMENT TYPE: LOADERMACHINE ID: x1111FILTER ID:
SAMPLE DATE: 06-01-94HOURS (on oil/unit): 100 / 100SYSTEM VOLUME: 20 LFLUID TYPE:CITGO AW 46ANALYSIS PERFORMED: AI-BSTV4 (W)
AAUUTTOOMMAATTIICC PPAARRTTIICCLLEE CCOOUUNNTT SSUUMMMMAARRYY
W A R N I N G1. The recommended CLEANLINESS Code is not met.
Clean-up maintenance may be warrant.
2. Dotted graph line indicates recommended ISO Code level.
CleanlinessCode
Size Counts per ml.
> 2 µm 353242.0> 5 µm 34434.0> 10 µm 2342.0 26/22/14> 15 µm 154.0> 25 µm 17.0> 50 µm 1.0
FFRREEEEWWAATTEERR
PPRREESSEENNTT
YES
NOX
PARTEST Fluid Analysis ServiceParker Hannifin Corporation16810 Fulton County Road #2Metamora, OH 43540Tele:(419)644-4311Fax:(419)644-6205
SAMPLE CODE: 1034 DATE: 06-01-94XYZ Corporation12345 Middleton Rd.Anywhere USA 41114Attn:
SIZE (microns)
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
12 5 10 15 20 25 30 40 50 60 80 100
107
5.04.03.0
2.01.5
106
5.04.03.02.01.5
105
5.04.03.0
2.01.5
104
5.04.03.02.01.5
103
5.04.03.02.01.5
102
5.04.03.02.01.5
101
5.04.03.0
2.01.5
100
5.04.03.02.01.5
10-1
5.04.03.02.01.5
10-2
Number
of
particles
per
ml
>
size
IISSOO CCHHAARRTT RANGECODE
RREEMMAARRKKSS
PPHHOOTTOO AANNAALLYYSSIISSMag.: 100x Vol.: 20 ml Scale: 1 div = 20 µm
SAMPLINGPROCEDUREObtaining a fluid sample for particlecounts and/or analysis involves impor-tant steps to make sure you are gettinga representative sample. Often erroneous sampling procedures willdisguise the true nature of systemcleanliness levels. Use one of the following methods to obtain a representative system sample.
I. For systems with asampling valveA. Operate system for a least 1/2 hour.B. With the system operating, open thesample valve allowing 200 ml to 500 ml(7 to 16 ounces) of fluid to flush thesampling port. (The sample valvedesign should provide turbulent flowthrough the sampling port.)C. Using a wide mouth, pre-cleanedsampling bottle, remove the bottle cap and place in the stream of flowfrom the sampling valve. Do NOT“rinse” out the bottle with initial sample. Do not fill the bottle morethan one inch from the top.D. Close the sample bottle immediate-ly. Next, close the sampling valve.(Make prior provision to “catch” thefluid while removing the bottle fromthe stream.)E. Tag the sample bottle with perti-nent data: include date, machine number, fluid supplier, fluid numbercode, fluid type, and time elapsedsince last sample (if any).
II. Systems without asampling valve
There are two locations to obtain asample in a system without a sampling valve: in-tank and in the line. The procedure for both follows:
A. In the Tank Samplingl. Operate the system for at least 1/2 hour.2. Use a small hand-held vacuumpump bottle thief or “bastingsyringe” to extract sample. Insertsampling device into the tank to onehalf of the fluid height. You will prob-ably have to weight the end of thesampling tube. Your objective is toobtain a sample in the middle por-tion of the tank. Avoid the top or bot-tom of the tank. Do not let thesyringe or tubing came in contactwith the side of the tank.3. Put extracted fluid into anapproved, pre-cleaned sample bottleas described in the sampling valvemethod above.4. Cap immediately.5. Tag with information as describedin sampling valve method.
B. In-Line Sampling1. Operate the system for at least 1/2 hour.2. Locate a suitable valve in the system where turbulent flow can beobtained (ball valve is preferred). Ifno such valve exists, locate a fittingwhich can be easily opened to pro-vide turbulent flow (tee or elbow).3. Flush the valve or fitting samplepoint with a filtered solvent. Openvalve or fitting and allow adequateflushing. (Take care to allow for thisstep. Direct sample back to tank orinto a large container. It is not necessary to discard this fluid.)
Appendix
34
35
Appendix
4. Place in an approved and pre-cleaned sam-ple bottle under thestream of flow per sampling valve methods above.5. Cap sample bottleimmediately.6. Tag with importantinformation per thesampling valve method.Note: Select a valve orfitting where the pressure is limited to200 PSIG (14 bar) orless.
Regardless of the methodbeing used, observe com-mon sense rules. Anyequipment which is usedin the fluid sampling procedure must bewashed and rinsed with afiltered solvent. Thisincludes vacuum pumps,syringes and tubing. Yourgoal is to count only theparticles already in thesystem fluid. Dirty sampling devices andnon-representative samples will lead to erroneous conclusionsand cost more in the long run.
Model xxxx Lab Report xxxxElement xx Date xxFlow 30 Gpm Tested By xxxFab.Int. 10 In Water Acftd Batch xxxFluid Mil-H-5606/Shell Asa-3 Counts On-Line
98/102F;14.77-15.3 C
Diff. Press. (PSID) INJECTION FLUIDTerminal 235.0 Grav (MG/L) Flow (L/Min)Clean Ass’y 5.0 Initial 1226.8 7 PointHousing 3.2 Final 1279.4 AverageElement 1.8 Average 1253.1 0.453NET 233.2System Gravimetrics (MG/L): Base: 5.0 Final: 11.8
% Net Time Delta P. Grams Inject. Particle Distribution Analysis-Part./H SizeAss’y Added Flow (Up/Down/Beta) Particle SizeElem’t 2 3 5 7 10 12
Clean 4.89 2.22 1.11 0.89 0.22 0.00Fluid 8.32 1.75 0.44 0.00 0.00 0.002.5 25.4 10.8 14.4 0.451 13,178.00 6,682.00 2,678.00 1,382.00 643.30 436.10
7.6 10,168.00 2,863.00 340.30 39.55 3.18 0.231.30 2.33 7.85 34.9 200 1,900
5 31.1 16.7 17.7 0.455 14,060.00 7,214.00 2,822.00 1,427.00 673.00 463.2013.5 11,056.03 3,391.00 406.48 35.91 1.59 0.23
1.27 2.13 6.94 39.7 420 2,00010 35.8 28.3 20.3 0.455 13,900.00 7,207.00 2,817.00 Upstream Particle Count
25.1 10,590.00 3,274.00 395.301.31 2.20 7.13
20 39.0 51.6 22.1 0.453 14,950.00 7,833.00 3,201.00 Downstream Particle Count48.4 9,496.00 2,869.00 375.00
1.57 2.73 8.54 Test Point Beta Ratio40 42.6 98.3 24.2 0.455 12,410.00 6,696.00 2,857.00 1,495.00 700.70 474.68
95.1 7,843.00 2,277.83 380.58 38.83 1.82 0.461.58 2.94 9.51 49.8 390 1,000
80 45.1 191.6 25.6 0.453 11,420.00 6,299.00 2,768.00 1,456.00 681.10 469.30188.4 6,152.00 1,709.00 234.30 32.28 5.46 2.50
1.86 3.69 11.8 45.1 120 190100 45.9 238.2 26.1 0.451 11,130.00 6,136.00 2,717.00 1,427.00 669.40 460.90
235.0 6,013.00 1,690.00 262.50 41.14 8.87 5.231.85 3.63 10.4 34.7 75.5 88.1
Minimum Beta: Ratio’s 1.27 2.13 6.94 32.6 75.5 88.1Time Avg. Beta Ratio’s 1.36 2.42 7.97 37.2 220 800
Anti-static Additive In Test Fluid
Element PressureDrop At TestTermination
Test Point Information
% of Net �Psi
Duration of Test (Minutes)
Assembly �Psi
Element �Psi
CumulativeCapacity(Grams)
Injection Flow(Liters/Min)
Final Capacity (Grams): Apparent: 26.1 Retained: 25.8
Minimum Beta Ratio ForParticle Size During Test
Weighted Avg Beta Ratio For Cumulative Dirt Added Calculated AmountParticle Size Over Test Duration During Test Of Grams Retained
Sample Multipass Lab Report
Appendix
36
V i s c o s i t y C o n v e r s i o n C h a r t
M e t r i c C o n v e r s i o n T a b l e
TO CONVERT INTO MULTIPLY BY
Inches Millimeters 25.40Millimeters Inches .03937Gallons Liters 3.785Liters Gallons .2642Pounds Kilograms .4536Kilograms Pounds 2.2046PSI Bar .06804Bar PSI 14.5Centigrade Fahrenheit (�C x 9¼5) +32Fahrenheit Centigrade (�F - 32) /1.8Microns Inches .000039Microns Meters .000001
cSt (Centistokes) SUS (Saybolt Universal Seconds)*10 4620 9325 11630 13932.4 15040 18550 23270 32490 417
Comparisons are made at 100° F (38° C). For other viscosityconversion approximations, use the formula: cSt =
* NOTE: Saybolt universal seconds may also be abbreviated SSU.
SUS4.635
Appendix
37
Viscosity vs. Temperature
2000
1000 500
200
100 50 20 10 8 6 4 3 2
1.5 1 .9 .8 .7 .6
-60
-40
-20
020
4060
8010
015
020
025
030
035
040
050
0
-51
-40
-29
-18
-74
1627
3852
6693
121
149
204
260 10
,000
5,00
0
1,00
0
500
250
100
50 40 35
Kinematic Viscosity—Centistokes
Viscosity—Saybolt Universal Seconds
Tem
pera
ture
�F
Tem
pera
ture
�C
SAE 6
0SA
E 50
Bunke
r "C"
& SA
E 50
Hydr
aulic
Flui
d M
IL-O
-560
6
MIL-
L-780
8
AN-0-9 G
rade
1010
No. 4 F
uel
No. 3 Fu
el
No. 2 F
uel
Diesel
Fuel
JP-5
Kero
sene
JP-4
Avera
geAvia
tion G
asoli
ne—
Avera
ge
SAE 7
0SA
E 40
SAE 3
0
SAE 2
0SA
E 10
Parker Hannifin CorporationHydraulic Filter Division16810 Fulton County Road #2Metamora, OH 43540Phone: (419) 644-4311Fax: (419) 644-6205http://www.parker.com/filtration
Catalog HTM-410M, 10/05, T&M Printed in USA
Contact Parker’s worldwide service and distribution network by calling:
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Parker Worldwide Sales Offices
Filtration Group Technical Sales & Service Locations
Finite Filter Division500 Glaspie StreetOxford, MI 48371Phone: (248) 628-6400Fax: (248) 628-1850
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Filter Division U.K.Churwell ValeShaw Cross Business ParkDewsbury, England WF12 7RDPhone: +44 1924 487000Fax: +44 1924 487060
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