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The Basics of CoalescingCompressed Air & Gas Filtration

Bulletin 1300 - 700/USA

Finite®

For more information regarding coalescing filtration, please call Finite® at 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 user

make informed decisions about

coalescing filtration.

W H AT IS COALESCING FILTRATION? 4W H Y FILTER COMPRESSED AIR? 5THE COMPRESSED AIR ENVIRONMENT 6SUBMICRONIC CONTAMINATION 7THREE CONTAMINATION THREATS 8-9COALESCING MECHANISMS 10-11COALESCING FILTER DESIGN 12FILTER EFFICIENCY 13FINITE MEDIA GRADES 14-15FINITE MEDIA TYPES 16FILTER SELECTION 17FILTER HOUSINGS 18FILTER INSTALLATION 19MAINTENANCE 20FILTER ELEMENT LIFE PROFILE 21COALESCING FILTER LOADING CURVE 22THE DIRECT COST OF PRESSURE DROP 23

APPLICATIONS 24-27

table of contents

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 element’s 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 whole3. 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.tra

what is a dictionary definition

4 Parker Hannifin CorporationFiltration and Separation DivisionOxford, MI

Look for these exciting

filtration facts through-

out the handbook.filtercompressed air?

fact

Standard nominal five micron inline filters cannot removesubmicronic contaminants as required in criticalapplications. The lowest particle removal limit for thesegeneral purpose filters is 2 µm. Eighty percent of aerosolcontaminants are under 2 µm in size. Coalescing filters,however, are specifically designed to remove submicronicoil, water and solid contamination from compressed air.Standard graded-porosity coalescing filters remove over99.97% of all aerosols in the 0.3 to 0.6 µm range. Inaddition, these filters are over 99.98% effective atremoving all aerosols and solid particles larger than 0.3 µm.Thus, oil aerosols at a 20 ppm contamination level arereduced to a 0.004 ppm concentration – acceptable forvirtually all pneumatic applications.

coalescing filters are specifically

designed to remove submicronic

contamination from compressed air

S ubmicronic contaminants incompressed air systemsplug orifices of sensitive

pneumatic instrumentation; theywear out seals, erode systemcomponents, reduce theabsorptive capacity of desiccantair/gas dehydrators, foul heattransfer surfaces, reduce air toolefficiency, and damage finishedproducts. The results include:product rejects, lost productiontime and increased maintenanceexpense. For example, traceamounts of submicronic oil cancause serious fish eye blemishingin automotive finishing operations.Water left in air lines can freezeduring exposure to cold, blockingflow or rupturing pipes. Compres-sor lubricant not captured in acoalescing filter will eventuallycollect in pneumatic components,causing premature componentrepair or replacement. Environ-mental concerns will be raised ifoily, compressed air is continuallydischarged into the atmospherethrough a pneumatic muffler.

why

.tion?

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

C

other 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/ControlsB Medical/DentalC Food Packaging/Beverage BottlingD MicroelectronicsE Plastic Blow MoldingF Spray Painting/Powder CoatingG Packaging/Printing

C lean compressed 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 DivisionOxford, MI

The symbol for amicron is: µm

Compressed air is so widelyused it is often called the...

...industry’s fourth utility.

fact

Did you know that a

micron is also known

as a micrometer, which

is one millionth of a

meter?

fact

M ost process and lab gas applications

require 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 smallsolid or liquid particles in agas. Typically, the particlesare between 0.1 and 10microns in diameter. Amicron, identified by thesymbol “µm’’ 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 micronsin 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 isparticularly 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 ParticlesSubstance Microns InchesGrain of table salt 100 .0039Human Hair 80 .0032Lower limit of visibility 40 .0016Milled Flour 25 .0010Red Blood Cells 8 .0003Bacteria 2 .0001

submicronic contaminationwhy submicronic contamination is a problem

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 (varnish)

solutions of dissimilar oils

mixes of all the above

Possible Contaminants:

wat

er

three contamination

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 µmand smaller.

oil• Screw –

25 to 75 ppm at 200°F.• Reciprocating –

5 to 50 ppm at 350°F.• Centrifugal –

5 to 15 ppm at 300°F.

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 µm. 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 hpcompressor 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



8

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 µm insize.

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


25

solid

Oil and water contamination increase silting

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Submicronic particle buildup can interferewith movement and cause wear

n threats

coalescing mechan

Separation of aerosol andsolid contaminants from airis primarily dictated bygravity. Contaminantsgreater than 10 µm in 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 theatmospheric 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 threeconcurrent processes,depending on aerosol size:

1. Diffusion: Aerosols .001to .2 µm.

2. Interception: Aerosols .2to 2 µm.

3. Direct Impact: Aerosolsover 2 µm.

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 µm range 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 µm

BROWNIAN MOTION PATH


interception.2 to 2 µm

AEROSOLS FOLLOWSLIP-STREAM

For contaminants 0.2 to 2 µm in 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 µm are 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 impact

IMPACT AREA

Contaminants 2 µm and 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 µm and Larger

anisms

coalescing filter designParker Hannifin CorporationFiltration and Separation DivisionOxford, MI

aerosol growth by forcingthe aerosols to collectinto larger dropletssusceptible to the forcesof gravity. The largeroutside pores also allowthe air stream to passfreely, 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 thefilter (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 housing’sinside 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 housingcontains a coalescer with a built in prefilter.

U nlike standard inlinefilters, coalescing

filters carry air flow fromthe inside out;contaminants arecaptured in the filtermatrix 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 elementshave 8 to 10 µm pores onthe inner surface,reducing to 0.5 µm poresin the interior of theelement, and widening to40 to 80 µm 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.

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 .53PU 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 filters)

Finite® media specificationsF ilter efficiency is

measured by thepercentage of contaminantsof a particular micron sizethat are captured by thefilter. Filter efficiency isimportant 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 theneeds 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 thecoalescer’s service life byup to six times. Foroptimum performance,select a prefilter with a3 µm absolute rating.

The table above shows,by grade, typicalcontaminant removal

MYTH: Coalescers

only remove liquid

contaminants.

TRUTH: Coalescing

filters are designed

with submicronic

pores so that they can

capture tiny liquid

contaminants.

However, since solids

cannot change shape,

like liquids can,

coalescers can capture

them at an even higher

efficiency.

fact

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

finite medi

finite’s media grades are suitable for most applications

500x

500x

500x

grade 2 grade 4 grade 6

grade 8 grade Agrade 3P

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.


Grade 8 filters providehigh efficiency filtrationin combination withhigh flow rate and longelement life.

grade 10

500X 500X 500X

500X 500X 125X 125X

grade 7 CVPGrade 7 filters are usedin bulk coalescingapplications when

relatively high efficiencyand low pressure drop

are required.

Left: This inner layer ofthe 7CVP effectivelytraps 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.

Finite’s innovative

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

ia grades

finitemedia types16 Parker Hannifin Corporation

Filtration and Separation DivisionOxford, MI

Coalescing element composed of anepoxy saturated, borosilicateglass micro-fiber tube with intimateinterlocking contact with rigidseamless retainer. Surrounded bya coarse fiber drain layer, retainedby a synthetic fabric safety layer.

type CFlow: Inside to Outut

type QFlow: Inside to Out

Coalescing element with the sameconfiguration as “C” tube, but with “3P” typepleated cellulose prefilter built-in. Includesmolded 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

type GFlow: Out to Inside

type HFlow: Inside to OutCoalescing element similar to type“C,” however no rigid retainer isused. Typically for lower pressureor higher temperature applications.

Finite media types

Coalescing = type C, CVP, H, Q

Particulate = type G, T, F, 3P

Adsorber = type A

Flow: Out to InsidePleated cellulose particulate removalelement. Includes molded polyurethaneend seals.

type 3P

Flow: Out to InsideParticulate removal elementconstructed of the same fibermatrix as type “C,” but with no rigidretainer or drain layer.

type FFlow: Out to InsideParticulate removal element like “G”tube, except fluorocarbon saturantreplaces epoxy.

coalescing

adsorber

particulate type T

Particulate removal element like “G”tube, except high temperaturefluorocarbon saturant replaces epoxy.

type AFlow: Out to InsideHydrocarbon vapor removal element.Ultrafine grained, highly concentrated,activated carbon sheet media.Includes molded polyurethaneend seals.

choosing the right filter for your application

IIIII f the coalescing filterequipment is sized in

standard cubic feet perminute (SCFM), select afilter for a particularapplication 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 theselection 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 usefultool 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 selection


T he filter housingis the pressure

vessel which containsthe filter element. Itusually consists oftwo or more sub-assemblies, such as ahead (or cover) and abowl to allow accessto the filter element.The housing has inletand outlet portsallowing it to beinstalled into acompressed airsystem. Additionalhousing features mayinclude mountingholes, automaticdrains and elementcondition 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 pressurerating. 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 isselected.

filter housings

filter housing selection

18

filter installation

P roper 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. What’s 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 µm prefilters

upstream from each coalescing filter to remove

large quantities of contaminants. This will lengthen

the coalescer’s 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 by

maintenance 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

maintenance

F ilter 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 “Q”media to remove solid particulatematter can reduce dirt loading in thecoalescer and prolongfilter life.


This advertisement appeared in trade journals in the ‘80s. The cartoon depicts the headache of having oil in your compressed air lines.

Element Types Life Comparison

E very filter element has acharacteristic pressure differen-

tial versus contaminant loadingrelationship. 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

Finite’s 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

Differential Pressure (PSID)

filter element life profile


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 thefilter’s life. Theoretically,no reentrainment ofaerosols should occur inthe first 80% of the filter’slife.

Ignoring pressure drop

P ressure drop is the “early 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 filter’s life; thus, pressure drop remains fairly con-stant over this period. Over the last part of a filter’s 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

10P

RE

SS

UR

E D

RO

P(P

SID

)

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 obstructedfilter. Page 23 illustratesthe point.

Between replacements,drain the filter bowl dailyto remove coalescedliquid and preventreentrainment, or installan optional automaticdrain.

pressure drop vs. life factor

$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 LosAngeles

SanFrancisco

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 direct cost of pressure drop

A s 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 higherutility 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 element’sassociated elevated pressure drop.

applicatio

1 0.1 0.1 (.08) -94 (-70) 0.01 (.008)2 1 1 (.8) -40 (-40) 0.1 (.08)3 5 5 (4.2) -4 (-20) 1 (.83)4 15 8 (6.7) 37 (+3) 5 (4.2)5 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 humidityof 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

Dewpoint oF (oC)

MaximumConcentration**

mg/m3 (ppm)

From aeration in pharmaceu-

tical and chemical processes

to pneumatic power systems,

the possibilities for

applications are endless.

Finite has some suggested

applications that may fit your

needs. Let one of Finite’s

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 textileapplication,Finite filters areused to protectsensitivemoving partson 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 15°F to18°F artificially “drying”the 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.


Any small compressor with no aftercooler,air intended for intermittent, general use.

Compressor Room (Source)Air Preparation Equipment:

ISO Class 2

Receiver

350° FM C

Regulator

AutoDrain

Approx. 176° F

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-UseAir Preparation Equipment:

Any compressor with aftercooler. Airintended 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

100° F

AC

Regulator

50 PSIG



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

100° F

AC



Regulator

AutoDrain

82° F

50 PSIG

Use mediagrade 8C

Use mediagrade 6C

4

ISO Class 2 3

ISO Class 1 1

ons


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)


C

AutoDrain

100° F

AC

RefrigeratedDryer

Use mediagrade 8C

Regulator

AutoDrain

Dew Point 40° F

50 PSIG


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

100° F

AC

DeliquescentDryer

Use mediagrade 8C

Use mediagrade 3P

Regulator

AutoDrain

Dew Point64° F

50 PSIG

Use mediagrade 6C



OTHER SPECS MET: CGA – G7.1 (Grade C)

Use mediagrade 6C

ISO Class 1

ISO Class 1 14

1



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

100° F

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

100° F

AC

RefrigeratedDryer

Use mediagrade 8C


RegulatorAutoDrain

50 PSIG

Use mediagrade 6C

Use mediagrade AU


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 Point40° F

Dew Point-40° F

applications

RegenerativeDessicant

Dryer

Filtration Group Technical Sales & Service LocationsFiltration 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) 846-3200Henryetta, OKPhone: (800) 451-7299Holly 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 Parker’s 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 ... 1-305-470-8800China ................... +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 .... 82-55-389-0100Korea 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 . 971-2-6788587United Kingdom .... 44-0-1924-487000USA ............................ 1-800-272-7537Venezuela .............. 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 sitewww.parker.com.

Parker Hannifin CorporationFiltration and Separation Division500 Glaspie St./P.O. Box 599Oxford, MI 48371Phone: (248) 628-6400

(800) 521-4357Fax: (248) 628-1850http://www.parker.com/finitefilter/Reprinted May 2004

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