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The Basics of CoalescinCompressed Air & Gas Filtration
Bulletin 1300 - 700/USA
Finite
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For more information regarding coalescing filtration, please callFiniteat 1-800-521-4357
Finite
The Basics of Coalescing
is intended to familiarize the
user with all aspects of
coalescing 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 decrease
production costs.
This handbook will help the usermake informed decisions about
coalescing filtration.
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W H ATISCOALESCINGFILTR ATION? 4
W H YFILTERCOMPRESSEDAIR? 5
THECOMPRESSEDAIRENVIRONMENT 6
SUBMICRONICCONTAMINATION 7
THREECONTAMINATIONTHREATS 8-9
COALESCINGMECHANISMS 10-11
COALESCINGFILTERDESIGN 12
FILTEREFFICIENCY 13
FINITEMEDIAGRADES 14-15
FINITEMEDIATYPES 16
FILTERSELECTION 17
FILTERHOUSINGS 18
FILTERINSTALLATION 19
MAINTENANCE 20FILTERELEMENTLIFEPROFILE 21
COALESCINGFILTERLOADINGCURVE 22
THEDIRECTCOSTOFPRESSUREDROP 23
APPLICATIONS 24-27
table of contents
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co.alesc.ing fil.tra.tionA steady state process whereby aerosols are caused toagglomerate (come together) into even larger droplets as theypass through the filter elements fiber matrix, eventually becominglarge enough to be gravitationally drained away.
Air In
Air Out
This filter housing cutawaydepicts the coalescingprocess. Air enters thehousing and flows throughthe filter media passing fromthe inside element surface tothe outside. Coalesced liquidcollects in the bowl where itis drained and clean airexits the housing throughthe outlet port.
co.alesc.ing \ko- -les\ co.alesce; co.alesced;1. to grow together 2. to unite as a whole
3. to unite for a common end: join forces
fil.tra.tion \fil-tra-sh n\1. the process of filtering 2. the process of passingthrough or as if through a filter
e
e
co.alesc.ing fil.traw
ha
t
is
a dictionary definition
4Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
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Look for these exciting
filtration facts through-
out the handbook.filtercompressed air?
fact
Standard nominal five micron inline filters cannot remove
submicronic contaminants as required in critical
applications. The lowest particle removal limit for these
general purpose filters is 2 m. Eighty percent of aerosol
contaminants are under 2 m in size. Coalescing filters,
however, are specifically designed to remove submicronic
oil, water and solid contamination from compressed air.
Standard graded-porosity coalescing filters remove over
99.97% of all aerosols in the 0.3 to 0.6 m range. In
addition, these filters are over 99.98% effective at
removing all aerosols and solid particles larger than 0.3 m.
Thus, oil aerosols at a 20 ppm contamination level are
reduced to a 0.004 ppm concentration acceptable for
virtually all pneumatic applications.
coalescing filters are specifically
designed to remove submicronic
contamination from compressed air
Submicronic contaminants in
compressed air systems
plug orifices of sensitive
pneumatic instrumentation; they
wear out seals, erode system
components, reduce the
absorptive capacity of desiccant
air/gas dehydrators, foul heat
transfer surfaces, reduce air tool
efficiency, and damage finished
products. The results include:
product rejects, lost production
time and increased maintenance
expense. For example, trace
amounts of submicronic oil can
cause serious fish eye blemishing
in automotive finishing operations.
Water left in air lines can freeze
during exposure to cold, blocking
flow or rupturing pipes. Compres-
sor lubricant not captured in a
coalescing filter will eventually
collect in pneumatic components,
causing premature component
repair or replacement. Environ-
mental concerns will be raised if
oily, compressed air is continually
discharged into the atmosphere
through a pneumatic muffler.
why
tion?
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convey materials, provideand control energy andprotect equipment orpersonnel. Clean air in theseand other criticalapplications must be free ofboth solid particulatecontamination and liquid
A
B
D
F G
E
Cother typicalapplications:
Pneumatic conveyors Beverage dispensers Spray paint equipment Gas separator systems Pneumatic power systems Air logic and control circuits Laboratory and process gas usage Air gauging in manufacturing
processes Breathing air
(fixed or portable systems) Cooling and protecting sensitive
instruments Air bearings for mechanical
power transmission Aeration in pharmaceutical
and chemical processes
coalescing filters provide clean air for a variety of applications
aerosols. These oil andwater aerosols are beyondthe control of conventionalfilter systems and can onlybe removed with coalescingfilters.
the compressed air environment
6
A Compressor Room/Controls
B Medical/Dental
C Food Packaging/Beverage Bottling
D Microelectronics
E Plastic Blow Molding
F Spray Painting/Powder Coating
G Packaging/Printing
Cleancompressed air isessential in such
industries as foodprocessing, electronics,health care, photography,dairy and instrumentation.Compressed air and othergases are widely used to
Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
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The symbol for a
micron is: m
Compressed air is so widelyused it is often called the...
...industrys fourth utility
fact
Did you know that
micron is also kn
as a micrometer,
is one millionth of
meter?
fact
Most process and lab
gas applicationsrequire a high degree ofpurity. Most compressed airapplications also workbetter if the air is clean anddry. The four classes ofcontaminants incompressed air are water,oil, solid (particulate) andunwanted gases. Typicallythe first three are in theform of aerosols. An aerosolis a suspension of small
solid or liquid particles in agas. Typically, the particlesare between 0.1 and 10microns in diameter. Amicron, identified by thesymbol m and alsoknown as a micrometer, isone millionth of a meter (orabout 0.000039 inches) insize. A typical strand ofhuman hair is approximately80 microns in diameter,while a grain of table salt isapproximately 100 microns
in size. The lower level ofvisibility to the human eye is40 microns.
OSHA regulations statethat air may not containmore than five milligrams(mg.) of oil mist particlesper cubic meter of plant air,or one ounce of oil in200,000 cubic feet yetanother reason why cleancompressed air is a concernin industrial applications.
Air contamination is
particularly threatening inprecision applications wherethe cleanliness of theworkplace and the purity ofthe product are critical. Inclose-tolerance systemswhere extremely fineorifices and partsclearances are the norm, itis vital for the system air tobe free of all suspendedliquid aerosols as well assolids.
Relative Sizes of Particles
Substance Microns Inches
Grain of table salt 100 .0039
Human Hair 80 .0032
Lower limit of visibility 40 .0016
Milled Flour 25 .0010
Red Blood Cells 8 .0003
Bacteria 2 .0001
submicronic contamination
why submicronic contamination is a problem
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water, oil and solids are three contaminant threats
water vapors
water emulsions
condensed moisture
oil vapors
paint vapors
volatile solvent vapors
compressor lube oils
condensed oils
carbonized oils (varnis
solutions of dissimilar o
mixes of all the above
Possible Contaminants:
water
three contaminatio
Oil is alsopresent incompressedairsystems.It islargelyintroduced
into the airstream by the
air compressor. The amountof oil introduced in thisfashion varies by the typeof compressor used.Estimates of thehydrocarbon content ofdischarge air from typicalcompressors are expressedin parts per million (ppm):
contains 20-30 ppm ofhydrocarbon aerosolsfrom industrial andautomotive sources.Oil-less compressorscan condenseapproximately 10 ppmof hydrocarbons duringthe compression cycle.This is enough oil togum-up air linecomponents and tocollect in air dryersystems. A majority ofthe oil aerosolsemitted by aircompressors are 2 mand smaller.
oil Screw
25 to 75 ppm at 200F.
Reciprocating 5 to 50 ppm at 350F.
Centrifugal 5 to 15 ppm at 300F.
At a concentration of 25ppm, a typicalcompressor flowing 100SCFM for 35 hours willintroduce eight ouncesof oil into the pneumaticsystem.
Even if an oil-lesscompressor is used, oilcontamination of the airstream remains a problembecause ambient air
18 gallons of water perday.
Water aerosols incompressed air range from0.05 to 10 m. While airdryer systems can be
The contaminants ofgreatest concern inprecision compressed airsystems are water, oil andsolids. Water vapor ispresent in all compressedair; it becomes greatlyconcentrated by thecompression process. Infact, compressed air issaturated with water untilit is dried. A 25 hp
compressor delivering100 standard cubic feetof air per minute (SCFM)at 100 PSIG can produce
used effectively toremove water fromcompressed air, theywill not remove thesecond major liquidcontaminant oil.
water
oil
Possible Contaminants
Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI8
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The third contaminant found incompressed air is solid matterincluding rust and scale. Solidparticulates, combined withaerosol water and oil, can clogand shorten the life of airsystem components as well asfilter systems. Most rust andscale contaminants typicallyfound in compressed airsystems are 0.5 to 5 minsize.
solid
Actual pictomicroraph of particulate contaminants
(Magnified 100x Scale: 1 division = 20 microns)
pipe scale / rust
rocks
pollen
yeast cells
airborne carbon
mold
welding flash
penicillin
Possible Contaminants:
25
s
olid
Oil and water contamination increase silting
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 1 2 3 4 5
Submicronic particle buildup can interfere
with movement and cause wear
threats
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coalescing mech
Separation of aerosol andsolid contaminants from airis primarily dictated bygravity. Contaminantsgreater than 10 min sizesettle out of the air streamfairly quickly. However,
extremely small aerosolparticles remain suspended,particularly in flowing asopposed to still air. Mostcoalescing filters aredesigned to causecombining of smalleraerosols into larger droplets.The enlarged droplets are
now susceptible to theeffects of gravity.Coalescing is the termgiven to this combiningprocess.
The coalescing processcan be visualized as the
atmospheric conditions atwork in a thunderstorm many small water vapormolecules present inturbulent moisture-laden aircondense into aerosolswhich then collide or cometogether to formincreasingly larger droplet
masses until they gainenough weight to react togravity and fall to earth asraindrops.
Coalescing filterseliminate submicroniccontamination through three
concurrent processes,depending on aerosol size:
1. Diffusion: Aerosols .001to .2 m.
2. Interception: Aerosols .2to 2 m.
3. Direct Impact: Aerosolsover 2 m.
three mechanisms of the coalescing process
Did you know that in
1994 Finite Filter
joined C.A.G.I. -
Compressed Air and
Gas Institute, an
organization commit-
ted to the develop-
ment of the indus-
try?
fact
Aerosols and solids in the0.001 to 0.2 mrange are subject torapid random Brownian motion,moving completely independently ofthe bulk air stream as extremelysmall aerosols in flowing air. Thismotion causes them to migrate fromthe air stream and to collide withexposed filter surfaces. Solidcontaminants adhere permanently tothese surfaces via intermolecular
forces. Liquid droplets, however,migrate gravitationally down the filterfibers, joining other droplets to formlarger masses of liquid which can bedrained from the system. While therate of diffusion activity increases withheightened temperature and pressure,contaminants of this size exhibitrandom motion and are subject todiffusion coalescing even under non-turbulent, low velocity flow conditions.
diffusion.001 to .2 m
BROWNIAN MOTION PATH
10Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
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interception.2 to 2 m
AEROSOLS FOLLOWSLIP-STREAM
For contaminants 0.2 to 2 min size,interception is the predominantcoalescing mechanism. Thesecontaminants conform to the streamline of the air flow and are the mostdifficult to remove because they canpass around filter fibers and escapefrom the filter uncollected. In general,efficiency of the intercept mechanism
increases as pore size (or fiberdiameter) decreases. Fibers with anaverage diameter of 0.5 mare used tooptimize performance in this range.When aerosols approach a fiber within1/2 of their diameter in the filter matrix,their inertial forces are overcome andthey are captured.
direct impactIMPACT AREA
Contaminants 2 mand larger areremoved by the direct impact methodbecause they have sufficient mass anddevelop enough momentum to leavethe air flow stream line. These contami-nants collide with the filter media, acoalescing process termed inertial ordirect impaction.
2 m and Larger
isms
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coalescing filter designParker Hannifin CorporationFiltration and Separation DivisioOxford, MI
aerosol growth by forcingthe aerosols to collectinto larger dropletssusceptible to the forcesof gravity. The largeroutside pores also allowthe air stream to pass
freely, minimizingpressure drop.
A drain layer conductscollected contaminantsfrom the outer filterelement surface to thesump in the bottom of thefilter housing where it canbe periodically drainedaway. The larger outerpores of the filter elementreduce air turbulence,preventing reentrainmentof oil or othercontaminants due toexcessive turbulence.
Coalescing filters aretypically longer in shape
than standard inline filters.This length helps assurefilter efficiency by divertingthe air stream flow frompassing through the filterwet zone generally thelower 1/2 to 2 inches of the
filter (air passing throughthe wet zone couldreentrain liquids, carryingthem downstream anddefeating the coalescingprocess).
Also important in thedesign of coalescing filtersis the relationship betweenthe filter element outsidediameter and the housingsinside diameter. Thespacing between these twosurfaces must be sized sothat air velocity isminimized, thus reducingthe possibility of oil orwater vapor carryover.
coalescing filters flow from the inside of the element out
This coalescing filter depicts how the air flows from the inside out. This housing
contains a coalescer with a built in prefilter.
Unlike standard inlinefilters, coalescing
filters carry air flow fromthe inside out;contaminants arecaptured in the filter
matrix and collecttogether into larger andlarger droplets throughcollisions with the glassmicrofibers. Thesedroplets eventuallyemerge on the outside ofthe filter tube where theycollect and are drainedaway by gravity.
Modern coalescingfilters use a graded-
porosity filter mediumwith fine glass fibers inthe interior and largerfibers on both the insideand outside surfaces. Byvarying the fiber sizedistribution in the filtermanufacturing process,filters can be tailored tomeet specific applicationrequirements.
Typical filter elements
have 8 to 10 mpores onthe inner surface,reducing to 0.5 mporesin the interior of theelement, and widening to40 to 80 m pores on theouter surface.
The inner elementsurface acts as a prefilterto remove largecontaminants while theinternal pores are smallenough to removesubmicronic aerosols andsolids from the airstream. The reduceddensity of the exteriorsurface enhances
12
Coalescing Section
Generous ExitCavity
Large RemoteSump
Differential PressureIndicator
WET DIRTY AIR CLEAN DRY AIR
GradedPorosity
Drain Valve
RigidRetainer
Air-OilCounterFlow
OIL
AIR
Figure 2. TYPICAL COALESCING FILTER CROSS SECTION.
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percentage of a particular micron size measures filter efficiency
Pressure Drop (PSID)@ Rated Flow
ParticulateFilters -
G, S, F, T, 3PMicron Rating
GradeDesignation
Coalescing Filters- C, Q, H, 7CVP
MaximumOil Carryover1
PPM w/w
CoalescingEfficiency
.3 to .6 MicronParticles
MediaDry
MediaWet With
10-20 wt. oil
2 99.999% .001 .01 1.5 4-64 99.995% .003 .01 1.25 3-46 99.97% .008 .01 1.0 2-3
7CVP 99.5% .09 .5 .25 .5-.78 98.5% .2 .5 .5 1-1.5
10 95% .85 1.0 .5 .5
3PU N/A N/A 3.0 .25 N/AAU 99%+ N/A N/A 1.0 N/A
(Grades 2, 4 and 6 are .01 micron fil ters)
Finitemedia specificationsF
ilter efficiency ismeasured by the
percentage of contaminantsof a particular micron sizethat are captured by thefilter. Filter efficiency is
important because it affectsnot only contaminantremoval performance, butalso filter life (higherefficiency requires greatercontaminant-holdingcapacity).
Filter efficiency ratings forcontaminant removal varyfrom 90% to more than99.99%, providing a rangeof capabilities to fit the
needs of a variety ofsystems. Since moreefficient filter media mayhave shorter service lives, itis sometimes desirable tosacrifice some efficiency inthe interest of economy.
In applications where highefficiency and extendedfilter service life are critical,a prefilter is used to removelarge quantities of solidparticles before they reachthe coalescing filter. Thiscan increase thecoalescers service life byup to six times. Foroptimum performance,select a prefilter with a3 m absolute rating.
The table above shows,by grade, typicalcontaminant removal
MYTH: Coalescers
only remove liquid
contaminants.
TRUTH: Coalescing
filters are designedwith submicronic
pores so that they can
capture tiny liquid
contaminants.
However, since solids
cannot change shape,
like liquids can,
coalescers can captur
them at an even higher
efficiency.
fa
ct
efficiency and operatingcharacteristics of variouscoalescing filters.
Efficiency ratings are validfor flows from 20% to 120%of rated flow at 100 PSIG. Atflows below 20%, or in non-continuous flow systems,aerosols do not agglomerateas efficiently into largerdroplets, allowing more topass through the filteruncollected. At flows above120% of rated flow, airvelocity is so high that somecontaminants can bereentrained into the airsystem.
filter efficiency
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finite med
finites media grades are suitable for most applications
500x
500x
500x
grade 2 grade 4 grade 6
grade 8 gradeAgrade3P
Grade A adsorptionfilters are used toremove hydrocarbonvapor and aspreparation forbreathing air whenpreceded by acoalescer.
Grade 10 filters areused as prefilters forgrade 6 to removegross amounts ofaerosols or tenaciousaerosols which aredifficult to drain.
Grade 3P pleatedcellulose filbers areused for particulateinterception where veryhigh dirt holdingcapacity and relativelyfine pore structure arerequired.
Grade 6 filters are usedwhen total removal ofliquid aerosols andsuspended fines isrequired. Because of itsoverall performancecharacteristics, thisgrade is most oftenrecommended.
Grade 4 filters are veryhigh efficiencycoalescers; for el-evated pressures orlighter weight gases.
Grade 2 filters are usedfor extremely fineparticulate and lasttrace aerosol coalesc-ing filtration; for lightermolecular weight gasesand aerosols at higherpressures.
14Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
Grade 8 filters providehigh efficiency filtrationin combination withhigh flow rate and longelement life.
grade 10
500X 500X 500X
500X 500X 125X 125X
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grade7 CVPGrade 7 filters are usedin bulk coalescingapplications when
relatively high efficiencyand low pressure drop
are required.
Left: This inner layer ofthe 7CVP effectively
traps dirt particles,protecting and extend-ing the life of the outerlayer.
Right: This outer layerof the 7CVP consists ofa dense matrix of glass
fibers. The coalescingouter layer provides
highly efficient aerosolremoval with very low
pressure drop.
Finitesinnovative
coalescing filter
media eliminates compressor lubricator oils,
bulk water and particulate contamination
with extremely
low pressure
drop.
With only 0.25 PSID of pressure drop, it
has an
efficiency of
99.5%.500X
500X
a grades
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finitemedia types16
Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
oalescing element composed of anpoxy saturated, borosilicateass micro-fiber tube with intimateterlocking contact with rigid
eamless retainer. Surrounded bycoarse fiber drain layer, retained
y a synthetic fabric safety layer.
type Clow: Inside to Outut
typeQFlow: Inside to Out
Coalescing element with the sameconfiguration as C tube, but with 3pleated cellulose prefilter built-in. Incmolded polyurethane end seals.
Coalescing element made of pleatedglass media. Metal retained for addedstrength. Includes metal end caps andgasket for proper sealing.type DVP = High Temperature Option
Flow: Inside to Outut
type CVP
typeGFlow: Out to Inside
type HFlow: Inside to Out
Coalescing element similar to typeC, however no rigid retainer isused. Typically for lower pressureor higher temperature applications.
Finite media typesCoalescing = type C, CVP, H, Q
Particulate = type G, T, F, 3P
Adsorber = type A
Flow: Out to InsidePleated cellulose particulate removelement. Includes molded polyurethend seals.
type3P
Flow: Out to Inside
Particulate removal elementonstructed of the same fiber
matrix as type C, but with no rigidetainer or drain layer.
typeFFlow: Out to Inside
Particulate removal element like Gtube, except fluorocarbon saturantreplaces epoxy.
coalescing
adsorber
particulate type T
Particulate removal element like Gtube, except high temperaturefluorocarbon saturant replaces epoxy.
typeAFlow: Out to Insideydrocarbon vapor removal element.ltrafine grained, highly concentrated,ctivated carbon sheet media.ncludes molded polyurethanend seals.
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choosing the right filter for your application
IIIIIf the coalescing filterequipment is sized in
standard cubic feet perminute (SCFM), select afilter for a particular
application on the basisof airflow and systempressure rather thanpipe size.
The real capacity ofa coalescing filter canbe elusive sinceexcessive air flowthrough the filterelement raises pressure
drop and, by increasingthroughput velocity,increases the chance ofcontaminantreentrainment.
Select a filter largeenough to ensure thatthe air exits the filter atlow velocity and doesnot carry over coalescedliquid.
Economic factors arealso important in theselection of a coalescingfilter. As discussed
earlier, a balancebetween performanceand economicconsiderations will berequired in the
selection process. Filter service life,which has a majorimpact on the cost of acoalescing filtersystem, is discussedunder Maintenance,on page 20.
our sizing and application software
TM
Inphorm, ourselection software isan extremely useful
tool in the selectionand specification ofthe proper filtrationunit. With computeraided selection, theuser can quicklydetermine thepressure loss across agiven element, and/orhousing combination,within specificoperation parameters.InPhorm can alsopredict systemperformance andelement life. Thisfeature is ideal forpredictivemaintenanceprograms.
filter
se
le
ction
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Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
The filter housingis the pressure
vessel which containsthe filter element. Itusually consists oftwo or more sub-assemblies, such as ahead (or cover) and a
bowl to allow accessto the filter element.The housing has inletand outlet portsallowing it to beinstalled into acompressed airsystem. Additionalhousing features mayinclude mountingholes, automaticdrains and element
condition indicators.
Location of the filter inthe system is theprimary determinantof pressure rating.Most industrialapplications usepressures in the90-125 PSIG range.At natural gascompressor boosterstations, pressurescan reach up to 5000PSIG. It is essential toanalyze the systemfor frequent pressure
pressure ratings
spikes as well assteady stateconditions. Somehousings haverestrictive or lowerfatigue pressureratings. In systemswith frequent highpressure spikes, adifferent housingstyle may berequired to preventfatigue relatedfailures.
The primary concernsin the housingselection processinclude mountingmethods, portingoptions, drainingoptions, indicatoroptions, and pressure
rating. All, except thepressure rating,depend on thephysical systemdesign and thepreferences of thedesigner. Thepressure rating of thehousing is far lessarbitrary. This shouldbe determined beforethe housing style is
selected.
filter housings
filter housing selection
18
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filter installation
Proper installation of a coalescing filter
system can have a considerable impact on the
cost and effectiveness of the system.
If all air within your operation does not require
purification to the same degree, install coalescing
filters providing the desired efficiency and
performance at points of use. Air flow through point-
of-use filters will be lower than through a central
filter system, allowing the use of a smaller filter and
extending filter service life. Whats more, each point
of use will receive air meeting specific cleanliness
specifications. In addition to point-of-use filters,
mainline filters can be installed at junctions in the air
system where air purity needs change significantly.
Where required by especially contaminated air,
and/or the need for higher coalescing filter
efficiency, install conventional 3 m prefilters
upstream from each coalescing filter to remove
large quantities of contaminants. This will lengthen
the coalescers service life.
When installing coalescing filters at work stations,
the additional 2-6 PSID pressure drop contributed
by the filter at rated flow through its life should be
factored into equipment selection and distribution
system sizing.
When installing any filter, position it in a visible
place where it will not be overlooked bymaintenance personnel. Affix a label or tag to each
filter detailing the installation date, the recommended
filter element replacement date and the replacement
element number. Inspection intervals should also be
formalized and confirmation of inspections indicated
on the label or tag.
Finally, make sure coalescing filters are plumbed
so that air flows from the inside of the element to
outside. Coalesced liquid will drip from the outside of
the element tube to the sump of the filter housing.
If plumbed incorrectly (outside to inside), liquid will
not drain properly. This will result in reentrainment of
oil and a dramatic reduction in coalescing
performance.
The diagrams on pages 24-27 show typical
industrial compressed air systems. The location of
coalescing filters in these systems is also indicated.
installation can have a
considerable impact on
the cost and effectiveness
of your system
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maintenance
Filter element replacement cyclesare an important factor in the
design of a coalescing filter system.Generally speaking, more efficientfilters will need to be replaced moreoften because they will entrap morecontaminants, hastening clogging. Theamount of solid contaminants in theair stream determines filter life. Whileliquids agglomerate and subsequentlydrain to the filter sump, solidcontaminants become entrapped inthe filter element, restricting air flowand increasing pressure drop. Use ofa built-in prefilter, such as Finite Qmedia to remove solid particulatematter can reduce dirt loading in thecoalescer and prolongfilter life.
20Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
This advertisement appeared in trade journals in the 80s. The cartoon depicts the headache of having oil in your compressed air lines.
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Element Types Life Comparison
Every filter element has acharacteristic pressure differen-
tial versus contaminant loading
relationship. This relationship can bedefined as the filter element lifeprofile. The actual life profile isobviously affected by the systemoperating conditions. Variations in thesystem flow rate affect the cleanpressure differential across the filterelement and have a well-definedeffect upon the actual element lifeprofile.
The quanity, size, shape and ar-
rangement of the pores in the filterelement determine the characteristiclife profile. Filter elements that aremanufactured from cellulose media,single layer microglass media andUNI-CAST microglass all have a verydifferent life profile. The graphiccomparison of three most commonmedia configurations clearly showsthe life advantage of the UNI-CASTmicroglass filter element.
the UNI-CAST
microglass
elements
provide a longer
life profile than
cellulose media
and single layer
fiberglass
Cellulose M edia Single Layer M icroglass UNI-CAST M icroglass
Finites unique
UNI-CAST design was
developed to optimize
filter performance,
resulting in a filter
element with lower
differential pressure and
a higher dirt loading
capacity.
fact
Contaminant Holding Capacity
Different
ia
l
Pres
sure
(PSID
)
filter element life profile
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the filter should bereplaced.
The chart above showsa typical pressure dropcurve for a coalescingfilter system designed toprovide optimum cost/efficiency.
The initial low readingremains nearly constantfor the first 75% of thefilters life. Theoretically,no reentrainment ofaerosols should occur inthe first 80% of the filterslife.
Ignoring pressure drop
Pressure drop is theearly warning
indicator of coalescingfilter failure. Increasingpressure drop is a signthat the filter is becomingclogged and its efficiencyis becoming impaired.
Flow rate, operatingpressure, and theamount and type ofcontaminants in the airstream all affect the rateof pressure loss acrossa coalescing filter.
When a pressure dropof 8-10 PSID is indicated,
coalescing filter loading curve
Loading curve for a standard graded-porosity coalescing filter shows the classicrelationship between pressure drop and life. Dirt loads into the filter element fairlyconstantly over the first 75% of a filters life; thus, pressure drop remains fairly con-stant over this period. Over the last part of a filters life, pressure drop increasesdrastically and oil reentrainment begins. Typically, a filter should be replaced whenpressure drop reaches 8 to 10 psig.
Life Factor (time, total flow, etc.) 80% 100%
80% life expended(No reentrainment, minimum power loss)
0
1-1/2
5
10
PRESSUREDROP
(PSID)
Increasing pressure drop is a sign that the filter is becomingclogged and its efficiency could become impaired
can be costly, both interms of reduced airquality due tocontaminantreentrainment and thepower costs associatedwith forcing compressedair through an obstructed
filter. Page 23 illustratesthe point.
Between replacements,drain the filter bowl dailyto remove coalescedliquid and preventreentrainment, or installan optional automaticdrain.
pressure drop vs. life factor
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$Example Calculation:
9/KW HR = .03/ft3@ 100 PSIG.03/ft3@ 100 PSIG = 30/1000 ft3@ 100 PSIG30/1000 ft3@ 100 PSIG = 1.5/1000 ft3@ 5 PSID
Add: .5 for fixed charges, repair, operating cost.2/min. @ 1000 SCFM, while dissipating 5 PSIDi.e. 2/min. = $1.20/HR = $9.60/shift = $28.80/day.
Cents per Kilowatt Hour
City
the following calculation to identifypressure drop cost in your application:
Use
0
2
4
6
8
10
12
14
16
18
U.S.
Average
Seattle Denver Houston Chicago Los
Angeles
San
Francisco
Boston New York
Residential
Commercial
Industrial
At an electrical rate of 9 cents per KW hour. . .
...If a filter element is allowed to generate an extra 5 PSID of pressuredrop operating in a 1000 SCFM system. . .
...the cost of generating that lost pressure is $28.80 every day.
the
directcost
ofpressure
drop
As solid contaminant loads in a filterelement, pressure drop builds in the
compressed air system. This increaseselectrical consumption, as the compressorsare forced to work harder or longer to deliverthe compressed air needed. This increasedusage of electricity manifests itself in higher
utility bills, as more electricity needs to bepurchased to run the compressors.
This is one reason the selection of thefilter media and the sizing of the filter are soimportant.
The chart below shows that electrical costsvary widely between geographical areas in theUnited States. Compare the rate for your area tothe 9 cents per kilowatt-hour rate used in theexample. That will give you a good idea of howmuch it would cost to operate your compressedair system with excessive pressure drop.
Many times it is a more economical choiceto change out a dirty filter element than it is tocontinue to operate with that elementsassociated elevated pressure drop.
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applicati
1 0.1 0.1 (.08) -94 (-70) 0.01 (.0082 1 1 (.8) -40 (-40) 0.1 (.083 5 5 (4.2) -4 (-20) 1 (.834 15 8 (6.7) 37 (+3) 5 (4.25 40 10 (8.3) 45 (+7) 25 (21)6 - - - 50 (+10) - -
Class
* Particle size is based on a filtration ratio b20. The minimum accuracy ofthe measuring method used is 20% of the limiting value of the class.
**At 14.7 psi (1 bar) absolute pressure, +70oF (+20oC) and a relative humidof 60%.
It should be noted that at pressures above atmospheric, the contaminantconcentration is higher.Notes:1. The quality of the air delivered by non-lubricated compressors isinfluenced by the quality of the intake air and the compressor design.2. The minimum accuracy of the measuring method used is 20% of the
limiting value of the class.
Solid Water Oil
International ISO StandardsNotification as specified in ISO8573 - 1
Maximumparticle
size* (um)
MaximumConcentration**
mg/m3(ppm)
MaximumPressure
DewpointoF (oC)
MaximumConcentration
mg/m3(ppm)
From aeration in pharmace
tical and chemical processe
to pneumatic power system
the possibilities for
applications are endless.
Finite has some suggested
applications that may fit you
needs. Let one of Finites
application engineers find a
system that is right for you.In this application above, a Finite filter is used on a respiratory breathingsystem. The filters makes the air clean and safe for breathing.
Finite offersoutstanding point-
of-use protection toexpensive analytical
instruments, suchas chart recorders
in a food processingplant.
In this textilapplication,
Finite filtersused to prosensitivemoving paron this loom
qualityInternational ISO Standard
ISO8573-1 is fast becoming theindustry standard method forspecifying air cleanliness. Thefollowing diagrams describe
various systems in terms of theircorresponding ISO classification.
quality
General Notes:1.This application dataapplies to all types ofcompressors so long asair-oil separators andaftercoolers (whereindicated) are in goodworking order.
2.All systems are 100PSIG at the compressor.
3.Systems with highwater content or exces-sive oil carry-over shouldemploy grade 10C tocoalesce. In addition, itwould be a good choiceto oversize the filter.
4.If system pressure isreduced by 1/2 immedi-ately downstream of acoalescer (whichsuccessfully removed allcondensed water) thepressure dew point canbe reduced by 15F to18F artificially dryingthe air stream.
5.Uncontrolled, com-
pressed air contami-nants are extremelyabrasive, corrosive andacidic with pH valuesfrom 4.5 to 6.0 due tohydration of carbondioxide, nitrogen oxidesand chlorinated solvents.
24Parker Hannifin CorporationFiltration and Separation DivisioOxford, MI
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Any small compressor with no aftercooler,air intended for intermittent, general use.
Compressor Room (Source)
Air Preparation Equipment:
ISO Class 2
Receiver
350FM C
Regulator
AutoDrain
Approx. 176F
50 PSIG
Use media grade 8C or 10C
Place this point-of-use filter as far from compressor aspossible to facilitate heat radiation
Point-Of-Use
Air Preparation Equipment:
Any compressor with aftercooler. Air
intended for use with lubricated air tools,air motors, cylinders, shot blasting, non-frictional valves.
OTHER SPECS MET:Compressed Air & Gas Institute:
CGA G7.1 (Grades A & Ba1),
C
AutoDrain
100F
AC
Regulator
50 PSIG
Compressor Room (Source)
Air Preparation Equipment:
Point-Of-Use
Air Preparation Equipment:
Use mediagrade 8C
Any compressor with aftercooler & 2-stagecoalescing. Air intended for use withlubricated control valves, cylinders and partsblow-down, etc.
OTHER SPECS MET:Mil. Std. 282 H.E.P.A.U.S.P.H.S. 3AAccepted particles for milk
C
AutoDrain
100F
AC
Compressor Room (Source)
Air Preparation Equipment:
Point-Of-Use
Air Preparation Equipment:
Regulator
AutoDrain
82F
50 PSIG
Use mediagrade 8C
Use mediagrade 6C
4
ISO Class 2 3
ISO Class 1 1
ns
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Any compressor with aftercooler, 2-stage coalescing& refrigerated dryer. Air intended for use with air-gauging, air conveyors, spray-painting, foodprocessing, instrumentation, blow molding, cosmetics,film processing, bottling, pharmaceuticals, dairy,breweries, medical, robotics & close tolerance valves.
SPECS MET:CGA G7.1 (Grade D & E) ISAS7.3 Fed. Std. 209 (CIass 100)
Compressor Room (Source)
Air Preparation Equipment:
C
AutoDrain
100F
AC
RefrigeratedDryer
Use mediagrade 8C
Regulator
AutoDrain
Dew Point 40F
50 PSIG
Point-Of-Use
Air Preparation Equipment:
Any compressor with aftercooler, 2-stage coalescing &deliquescent dryer. Air intended for use with general pneumaticsystems, body shop spray painting and components sensitiveto high moisture content.
C
AutoDrain
100F
AC
DeliquescentDryer
Use mediagrade 8C
Use mediagrade 3P
Regulator
AutoDrain
Dew Point64F
50 PSIG
Use mediagrade 6C
Compressor Room (Source)Air Preparation Equipment:
Point-Of-UseAir Preparation Equipment:
OTHER SPECS MET:CGA G7.1 (Grade C)
Use mediagrade 6C
ISO Class 1
ISO Class 1 14
1
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Compressor Room (Source)
Air Preparation Equipment:
Point-Of-Use
Air Preparation Equipment:
Any compressor with aftercooler, two-stage anddouble coalescing and a regenerative-type desiccantdryer. Air intended for use in applications involvingrapid expansion of compressed air, critical instrumen-tation, high purity gases, computer chip drying, etc.CAUTION: This air is too dry for respiratory use.
SPECS MET:CGA G7.1 (Grade F),
C
AutoDrains
100F
AC
Use media3PU (Heatless Dryer)10DS (Heat Generated)
RegulatorAutoDrain
50 PSIG
Any compressor with aftercooler, 2-stage coalescing, refrigerated dryer &carbon absorber. Air intended for use as industrial breathing air &decompression chambers. CAUTION: Always use high temperaturesynthetic lubricants & monitor (alarm for carbon monoxide concentrationsexceeding 20ppm). This system will not eliminate toxic gases!
C
AutoDrain
100F
A
C RefrigeratedDryer
Use mediagrade 8C
Compressor Room (Source)
Air Preparation Equipment:
RegulatorAutoDrain
50 PSIG
Use mediagrade 6C
Use mediagrade AU
Point-Of-Use
Air Preparation Equipment:
OTHER SPECS MET:O.S.H.A. 29CFR 1910.134
Use mediagrade 10C Use media
grade 6C
Use mediagrade 6C
ISO Class 1 12
ISO Class 1 14
Dew Point40F
Dew Point-40F
applications
RegenerativeDessicant
Dryer
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Filtration Group Technical Sales & Service Locations
Filtration Group North America
Filtration andSeparation Division500 Glaspie St.Oxford, MI 48371Phone: (248) 628-6400Fax: (248) 628-1850
Haverhill, MAPhone: (978) 858-0505Linthicum, MDPhone: (410) 636-7200
Hydraulic Filter Division16810 Fulton County Road #2Metamora, OH 43540-9714Phone: (419) 644-4311Fax: (419) 644-6205
Process FiltrationDivision6640 Intech BoulevardIndianapolis, IN 46278Phone: (317) 275-8300Fax: (317) 275-8413
Tell City, INPhone: (812) 547-2371
Racor Division3400 Finch RoadP.O. Box 3208Modesto, CA 95353Phone: (800) 344-3286Phone: (209) 521-7860Fax: (209) 529-3278
Beaufort, SCPhone: (843) 846-3200
Henryetta, OKPhone: (800) 451-7299
Holly Springs, MSPhone: (662) 252-2656
Filtration Group Headquarters
6035 Parkland Blvd.Cleveland, Ohio, USA 44124-4141Phone: (216) 896-3000Fax: (216) 896-4021http://www.parker.com/filtration
Filtration Group Asia Pacific
Parker Hannifin Asia PacificCompany, LTDFiltration GroupDae Venture Plaza169 Samsung-DongKangnam-Ku, SeoulKorea 135-882Phone: +82 2 559 0400Fax: +82 2 556 8187
Filtration Group Latin America
Parker Hannifin Ind. e Com.
Ltda. Filter DivisionAV Getulio Vargas, 1331/1333123-05-000 Jacarei, SPBrazilPhone: +55 (11) 3917 1222Fax: +55 (11) 3917 1102
Filter Division EuropeChurwell ValeShaw Cross Business ParkDewsbury, West YorkshireEngland WF12 7RDPhone: +44 (0) 1924 487000Fax: +44 (0) 1924 487001
ArnhemThe NetherlandsPhone: +31 (0) 26 3760376
Etten-LeurThe NetherlandsPhone: +31 76 508 53 00
MaidstoneEnglandPhone: +44 (0) 1622 723300
Thetford, NorfolkEnglandPhone: +44 (0) 1842 763299
Urjala As.FinlandPhone: +358 (0)3 54100
Parker Worldwide Sales OfficesContact Parkers worldwide service and distribution network by calling:
Argentina ............. +54 (11) 4752 4129Australia ............... +61 (2) 9 634 7777Austria ..................... 43-2622-23501-0Belgium .................... +32 (67) 280900Brazil ........................ 55-12-3955-1000Canada ...................... 1-800-272-7537Central & SouthAmerica/Caribbean... 1-305-470-8800
China ................... +86 (21) 6445 9339Czech Republic .... 42-0-2-830-85-221Denmark .................. 45-0-43-56-04-00Finland ......................... +358 3 54 100France ...................... 33-0-254-741403Germany .............. 49-0-2131-513-350
Hong Kong ............ +852 (2) 428 8008Hungary ....................+36 (1) 252 8137India ........................... 91-22-790-7081Italy ............................... 39-02-451921Japan ......................... 81-3-6408-3900Jordan ....................... (962) (6) 810679Korea Choongnam.... 82-41-583-1410Korea Kyoungnam .... 82-55-389-0100
Korea Seoul ................ 82-2-559-0420Mexico ....................... 1-800-272-7537Netherlands............. 31-0-541-585000New Zealand ............+64 (9) 573 1523Norway ........................ 47-64-91-1000Poland ....................... 48-22-863-4942
Singapore .................... +65 6261 5233South Africa ........... +27 (11) 392 7280Spain ..................... +34 (91) 675 7300Sweden ...................... 46-8-5979-5000Switzerland............. 41-0-22-307-7111Taiwan ................. +886 (2) 2298 8987Thailand ...................... +662 693 3304United Arab Emirates . 971-2-6788587
United Kingdom .... 44-0-1924-487000USA ............................ 1-800-272-7537
Venezuela .............. 58-212-238-54-22
Note: The (+) sign in front of the countrycode indicates that you may need to dial anadditional prefix.
Call 1-800-CPARKERfor any Parker ProductsIn Europe, 00800-2727-5374or visit our Web site
www.parker.com.
Parker Hannifin Corporation
Filtration and Separation Division500 Glaspie St./P.O. Box 599Oxford, MI 48371