generadores caterpillar

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Generat orSet A

l i cat i onandI ns

t al l at i on

i i i l l

September 19

GENERATOR SETS

APPLICATION andINSTALLATION GUIDE

CATERPILLAR ENGINE DIVISION


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1

Introduction .......................................................................................7Summary .............................................................................................9Installation........................................................................................10

Foundations......................................................................................10

G round Loa ding ............................................................................10

Concrete Base................................................................................11

Fa bricat ed S teel B a se ...................................................................13Vibra t ion .......................................................... .................................14

Linea r Vibra tion ............................................................................15

Isola t ion ........................................................ .................................16

Isolat ion for Mobile Eq uipment ................................................18

C ommercial Isolat ors .................................................................18

B ulk ............................................................ .................................20

Torsiona l....................... ............................................................. ..22

Noise ...................................................................................................23Sound Wa ves/Terms.......... ............................................................. ..23

Loudness .......................................................... .................................23A-Weighted, db(A) Mea sur ement ...................................................23

Octa ve B a nd Levels .........................................................................24

Noise Addition..................................................................................24

Noise Exposure .......................................................... ......................25

Noise Control....................................................................................25

Mecha nica l Noise .................................................... ......................25

In ta ke Noise ..................................................................................26

Exha ust Noise ...............................................................................26

Sound Level Conversion..................................................................27

Air Intake Systems .........................................................................28

Air C lean ers .....................................................................................28P recleaners ....................................................... ................................28

Ducting..............................................................................................28

Air In ta ke Rest riction ...................................................................28

Flex Connections...........................................................................29

Turbocha rger Loa ding ..................................................................29

Clea nliness ....................................................................................29

In let Air Du ct In sula tion ..............................................................30

Air Cleaner Icing..............................................................................30

Extreme Cold....................................................................................30

Exhaust Systems .............................................................................31Ma nifolds ......................................................... .................................31P iping ..................................................... ...........................................31

Exha ust B a ckpressur e ....................................................................32

Ca lculat ing E xha ust B a ckpressure ...............................................32

Flexible Connections........................................................................34

Clea nliness .......................................................................................36

Emissions..........................................................................................36

DeNOx Ca ta lyst S yst em .................................................................36

Table of Contents


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Ventilation.........................................................................................37Cooling...............................................................................................39

E ngin e Cons idera tions ....................................................................39

Hea t Reject ion ............................................................. ..................39

Tempera ture Lim it s .................................................... ..................39

P ressur e Limits .............................................................................40

Spera te Cir cuit Aftercooling ........................................................40

Cooling System.................................................................................40Sy stem Design ...............................................................................40

Tempera ture C ont rol ............................................................ ........40

Types of C ooling ............................................................. ..................41

Ra dia tor .........................................................................................41

Ra dia tor Fa ns ................................................................................41

Air Density.....................................................................................42

Speed ....................................................... .......................................42

Tempera ture ...................................................... ............................42

Hea t Exchanger ...............................................................................43

Expa ns ion Ta nks......................................................... ..................44

Heat Recovery ...............................................................................45St a nda rd Tempera tu re Hea t Recovery ....................................46

Criteria Design Criteria _

St a nda rd Tempera tu re Hea t Recovery ....................................48

High Tempera tu re Hea t Recovery C ircuits .............................48

High Tempera tu re S olid Wa ter Sy st em ...................................48

Criteria Design Criteria _

High Tempera ture Solid Wa ter .................................................49

High Tempera tu re Wa ter -St rea m Syst em ..............................49

Critical Design C riteria _

High Tempera tu re Wa ter-St eam ..............................................50Ebullient Cooling .......................................................................51

Auxilia ry Heat Sources ...................................................................51

E xha ust ................................................... .......................................51

Lubricat ing Oil ..............................................................................51

E xtern a l Consid era tions .................................................................51

Remote Ra dia tor ...........................................................................51

Submerged P ipe Cooling ..............................................................52

C ooling Tower s ............................................................ ..................53

Remote E xpan sion Ta nks .............................................................53

Expan sion Ta nk Locat ion..........................................................53

Expa ns ion Ta nk Volume ..................................................... .......54Vent ing a nd Filling ....................................................................54

Dea era tion ..................................................................................55

Mainta ining P ump Suction H eat -

w ith th e E xpan sion Ta nk ..........................................................57

In let Regula ted Syst ems ...........................................................57

Out let Regula ted Syst ems ........................................................57

P iping Cons idera tions ..................................................................58

Extern a l Rest rictions .................................................................58

Ma ximum Velocity .................................................... .................58

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Coolan t Cons idra tions ..................................................................63

Properties....................................................................................63

Trea tment ...................................................... .............................63

Antifreeze....................................................................................64

Cleanliness..................................................................................64

Servicea blit iy ..................................................... ............................64

Fuel System ......................................................................................65

Bulk Storage.....................................................................................65Auxilia ry Ta nk ........................................................... ...................66

Coolers.........................................................................................67

Fi lters ............................................................. .............................67

Fuel Selection...................................................................................67Engin e Requ irement s ...................................................................67

Crude Oil Fu els ........................................................... ..................69

Kerosene or J P 5 Fuels ..................................................................69

G a seous Fuels ...............................................................................69

P ropan e/B ut a ne Mixtures ............................................................71

Starting Systems .............................................................................72

Electr ic ................................................... ........................................72Batteries......................................................................................72

B a tt ery C ha rger .........................................................................73

Ca ble Size ...................................................................................73

Air S ta rt ............................................................ .............................74

Automa tic St a rt -St op....................................................................76

Ten Second S ta rt ing ........................................................... ........76

St a rt ing Aids .................................................................................76

J a cket Wa ter Heat ers ................................................................76

Fla me S ta rt .................................................................................76

Ether............................................................................................76Oil Heaters..................................................................................77

Alt itude/Tempera ture/Humidit y Consid era t ions .......................77

E qu ipment Ma int ena nce.................................................................78

G enera tor Set S tora ge .....................................................................79

Governors..........................................................................................80Descript ion .......................................................... .............................80

Types of G overnors ........................................................ ..................81

Ca terpilla r .....................................................................................81

ADE M ..................................................... .......................................81

Woodw a rd ......................................................... .............................82

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Electric Power Generation ..........................................................84System Design..................................................................................84

U tilit y vs On-Sit e P ower .................................................................84

G enera tor Set Sizin g .......................................................................84

P ower a nd P ower Fa ctor ..............................................................85

kW a nd kV A Requ irement s of Loa d .........................................88

G enera tor vs E ngin e S ize.............................................................89

Engin e Sizin g a nd S election ........................................................89Engin e-G enera tor Set Load Fa ctor .............................................89

G enera tor S izing a nd S election ...................................................91

E qu ipment Cons idera tions .............................................................91

Motors ..................................................... .......................................91

Squirrel Cage.................................................................................92

Wound Rotor (Slip Ring)...............................................................92

Syn chronous ..................................................... .............................92

DC Motors......................................................................................93

Silicon Cont rolled Rectifier (SC R) Sy st ems................................93

Motor St a rt ing Loa d .....................................................................93

Motor Torque ..................................................... ............................94St a rt ing (B rea ka w a y) Torque ......................................................94

Accelera t ing Torque .................................................... ..................94

Syn chronous Torque ............................................................. ........95

P eak Torque ...................................................... .............................95

Regenera tive P ower ......................................................................95

Motor St a rt ing Volta ge .................................................................96

Sta rt ing Techniq ues .................................................... ..................97

Fu ll Volta ge St a rt ing ....................................................................98

Reduced Volta ge St a rt ing .............................................................98

Auto Tra ns former-Open .............................................................100Auto Tra ns former-C losed ...........................................................100

Rea ctor-Resis tor ..................................................... .....................100

P a rt Winding ...............................................................................100

Wye (Sta r) Delta ..................................................... .....................100

Solid State....................................................................................100

Lighting........................................................................................101

Tra ns formers .......................................................... .....................103

C omput ers ................................................... ................................103

C ommun icat ions E qu ipment .....................................................103

Uninterruptible Power Supply (UPS).......................................103

X-Ra y E qu ipment .......................................................................104Applica tion Cons idera tions ...........................................................104

Mult iple G enera tor Sets .............................................................104

P a ra lleling ...................................................................................105

Regula tor Compensa tion ............................................................105

Balancing Loads on Available Phases.......................................105

S ta ndby G enera tor sets ..............................................................107

Regu la tor ...................................................... ...............................107

P ha se Arra ngement ....................................................................108

Rated Amperes............................................................................109

Num ber of P oles/Sy nchronous Speed .......................................1094


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G enera tor Ch a ra ctereistics ...........................................................110

Fa ult Cu rrent ..............................................................................110

G enera tor G rounding ..................................................................111

Sin gle B ea ring G enera tor Set s ..................................................111

NE MA-IE C Design Cons idera tions ...........................................112

NE MA Cons idera tions-Tempera tu re Rise MG 1-22.40...........112

Ma ximum Moment a ry Overloa ds MG 1-22.41 ........................112

Ma ximum Devia tion F a ceotr MG 1-22.42 ................................112Telephone I nf luence Fa ctor (TIF) MG 1-22.43 ..........................112

Sh ort Cir cuit Requ irement s MG 1-22.45..................................113

Overs peed MG 1-22.47 ...................................................... ..........113

Ha rmonic Cont ent .......................................................................113

Sw itchgea r ....................................................... ...............................117

Start-Stop.....................................................................................117

C ra nking P a nel ..............................................................................118

Shutdown Devices..........................................................................118

Control Panel Types.......................................................................119

Scope of Supply............................................................................119

Electrical Codes...........................................................................120DC P rotection a nd Cont rol.........................................................120

AC Protection-Distribution and Metering................................120

Automa tic Tra nsfer Sw itch ........................................................121

Ambien t C ondit ions ......................................................... ...........121

C ircuit P rotective Devices.............................................................121

Fuses vs Cir cuit B rea kers ..........................................................122

Fu ses ............................................................ ................................123

Cir cuit B rea ker ...........................................................................124

Conversion Factors ......................................................................126

kVkW Amperage chart ..............................................................130Electrical Formulae .....................................................................131

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7

IntroductionP roper selection an d insta llat ion of generat orsets is vita l for dependa ble performa nce andlong, trouble-free life. The purpose of thisguide is to help th e reader:

Ma ke know ledgea ble choices of pow erequipment.

Design and build insta llat ions tha t performrelia bly a t a n optimum price/va luerelat ionsh ip to th e customer.

To ensur e proper inst a lla tions a rea ccomplished, Ca terpillar ha s supportca pability un ma tched in t he industry. Fromconception of power needs, through varieddisciplines required for in sta llat ion, t o servicean d ma intena nce demanded years a ftercompletion, Ca terpillar continues its

commitment to its customers successfulinstallations.

Fifty yea rs of developing power genera tionequipment h a s culmina ted in a broad line ofpractical equipment, providing cost-effectiveselection a nd insta llat ion ea se. A single sourcefor engine, generat or, and cont rols assur estesting a nd q uality control for ma tchedpackages.

Development of insta llat ion know ledge

par a llels equipment a dva nces. While thisa pplica tion a nd inst a llation guide summa rizesma ny a spects of insta llation, Ca terpillarDealers sta nd ready t o a ssist you.

An expert softwa re program , EP G Designer, isa va ilable from your dea ler, an d offers deta iledassistance in sizing, specifying and installingengine, genera tors, cooling syst ems a ndassociated equipment.

It is th e insta ller s responsibility t o considera nd a void possibly haz a rdous conditions

w hich could develop from th e syst emsinvolved in t he specific engine inst a llat ion.The suggestions provided in this guideregar ding a voida nce of ha za rdous condit ionsa pply to all a pplica tions a nd a re necessar ily ofa genera l na ture since only th e installer isfamiliar w ith the details of a part icularinstallation. Consider the suggestionsprovided in this guide a s general exam plesonly a nd a re in no wa y intended to coverevery possible haza rd in all insta llations.

U se this guides ta ble of contents a s achecklist of subjects a ffectin g on-sit e pow erplant s. Referring to this index duringprelimina ry plan ning a voids the effort an dexpense of a fter-insta llat ion cha nges.


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8

3406B

3512B


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Summary

Th is summar y contai ns important poin ts to

remember for a successfu l instal l ati on. These

poin ts ar e ampli fi ed and expanded in th e

foll owing secti on:

1. The genera tor set must be sized properly for

the installation. Determine the duty cycle Continuous, Prime, St an dby or P eakSha ving or Sha ring (para lleled or notpara lleled w ith t he utility).

ContinuousOutput a vaila ble w ithout varying load foran unlimited time.

PrimeOutput ava ilable w ith var ying loa d for a nunlimited time.

StandbyOutput ava ilable w ith var ying loa d for thedura tion of the interruption of the norma lsource of pow er. U sua lly sized initia lly for60%of a ctua l loa d since loa ds t end toincrea se during t he 30 yea r life of th eunit. Norma l hours of opera tion a re lessth a n 100 hours per year.

Peak Shaving/SharingP rime if para lleled with the U tility.

St an dby if not pa ra lleled with t he Ut ilitya nd if th e loading meets t he definition ofP rime or St a ndby. Norma lly PeakSh a ving/Sh a ring is less th a n 200 hoursper y ear of opera tion.

Load s th a t a re too light caus e engine slobber.Overloa ding causes excessive piston loadin ga nd high exhaust t emperatures.

St an dby engines th at must be exercisedregular ly but cann ot be loaded should be only

run long enough t o achieve norma l oilpressure and t hen shut off less tha n fiveminutes of running time.

2. The genera tor set must be properlyinsta lled in a n a tmosphere which a llow s itto a chieve th e required life.

Air FlowP rovide a dequa te clea n, cool a ir forcooling a nd combustion. H igh engineroom temperatures may require ducting

cooler outside a ir t o the engine inta ke toa void power dera tion. Restriction ofra dia tor a ir reduces its cooling capa bility.

ExhaustIsolat e exha ust piping from th e enginew ith flexible conn ections. Wra p th e pipingwit h a therma l bla nket to keep exha usthea t out of the engine room. The exhaus tsta ck a nd m uffler need to be sized so th eexha ust ba ck pressure at theturbocharger outlet does not exceed

6.7 kP a (27 in.) of w a ter. Excessiveba ckpressure ra ises exha usttemperat ures a nd reduces engine life.

FuelU se clean fuel. Fuel day t a nks should bebelow th e level of th e injectors.

MountingThe generat or sets must h a ve a flat a ndsecure mounting surface. The generatorset mounting must a llow a dequat e spa ce

a round t he generat or set for ma intenan ceand repairs.

StartingB a tt eries should be close to the sta rterand protected from very coldtemperat ures. Do not disconnect bat teriesfrom a runn ing engine or a plugged-inbat tery charger.

3. SC R load s ca n a ffect generat or outputw a veform. Ma ke sure the SC R device

supplier an d th e consulting engineer a rea w a re of the possible problems.

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10

Installation

FoundationsMa jor functions of a founda tion a re to:

Support t ota l weight of generator set .

Mainta in alignment betw een engine,generat or, a nd a ccessory equipment .

Isolate generator set vibrat ion fromsurrounding structures.

Ground Loading

In itia l considera tions include genera tor setweight a nd ma terial supporting this w eight.

The wet w eight of th e total pa cka ge must becalculated. This includes accessory equipmenta nd w eight of all liquids (coolan t, oil, an dfuel,) support ed by th e founda tion.

Mat eria l supporting foundat ion m ust carr ythe tota l weight. Figure 3 shows bearing loa dca pabilities of common ma teria ls.

Figure 1

Weights of LiquidsLiquid lb/U.S. gal Specific Gravity

Water/Glycol 8.55 1.030Water 8.30 1.000

Lube Oil 7.60 0.916Diesel Fuel 7.10 0.855

Kerosene 6.70 0.800

Figure 2

Bearing Load Capability

Safe Bearing LoadMaterial psi kPa

Rock, Hardpan 70 482

Hard Clay, GravelCoarse Sand 56 386

Loose Medium Sandand Medium Clay 28 193

Loose Fine Sand 14 96.4

Soft Clay 0-14 0-96.4

Figure 3


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Fir m, level soil, gra vel, or r ock providessa tisfa ctory support for single-bearinggenera tor sets used in st at iona ry or porta bleservice. U se this support w here the w eight-bea ring capacity of the supporting ma terialexceeds pressure exerted by the equipmentpacka ge, an d wh ere alignment w ith externa lma chinery is unimporta nt.

Soil, such a s fine cla y, loose sa nd, or sa nd n earthe ground water level, is particularlyunsta ble under dyna mic loa ds a nd requiresubstan tia lly la rger founda tions. Informat ionconcerning bea ring capa city of soils at th e sitema y be ava ilable from local sources a nd mus tcomply with local building codes.

Area of load-bearing support is a djusted toa ccommoda te sur fa ce ma teria l. To determinepressure (P ) exert ed by th e genera tor set,

divide tota l w eight (W) by tota l surfa ce a rea(A) of the ra ils, pads, or vibra tion mounts .

P = WA

Where: P = Pressure in kg/m2 (psi)W = Weight in kg (lb)

A = Area in m2 (in2)

P ressure imposed by the generat or set w eightmust be less tha n th e load-carry ing ca pacityof support ing ma teria l.

Where support ra ils or mount ing feet ha veinsufficient bearing area, flotation pads candistribute the w eight. The underside a rea a ndstiffness of the pad m ust be sufficient t o

support th e equipment.

Seasonal a nd wea ther cha nges ad verselya ffect mounting sur faces. Soil cha ngesconsidera bly w hile freezing an d t ha w ing. Toa void movement from seasona l cha nges,extend founda tions below th e frost line.

Concrete Base

Severa l basic founda tions a re a pplica ble forgenerat or sets. The founda tion chosen w illdepend on factors previously outlined a s w ella s limita tions imposed by th e specific locat iona nd applica tion.

Ma ssive concrete founda tions a re unnecessa ryfor modern multicylinder medium speedgenera tor set s. Avoid excessively thick,hea vy ba ses to min imize subfloor or soilloa ding. B a ses need be only t hick enough t oprevent deflection a nd t orque reaction, whilereta ining sufficient surfa ce a rea for support.(Non-par a llel unit s r equire no founda tion

anchoring.)

If a concrete founda tion is required, min imumdesign guidelines include:

Strength must support wet weight of unitsplus dynamic loads.

Outside dimensions exceed tha t of thegenerat or set a minimum of 300 mm (1 ft)on all sides.

Depth sufficient to at ta in a minimumw eight equa l to generat or set w et weight

(only if large mass, i.e., inertia block, isspecified for vibra tion cont rol).

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Figure 4


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Ca lculat e founda tion depth t o equa l genera torset weight by:

FD = WD x B x L

FD = foundation depth, m (ft)W = tota l wet w eight of generat or set, kg (lb)D = density of concrete, kg/m3 (lb/ft 3)

Note: use 2403 for metr ic units a nd 150for E nglish units.

B = foundat ion width, m (f t )L = foundat ion length, m (f t)

Su ggested concrete mixt ure by volume is 1:2:3

of cement, sa nd, a ggregat e, with m aximum100 mm (4 in.) slump a nd 28-da y compressivest rengt h of 20 MPa (3000 psi).

Reinforce with No. 8 ga uge steel wire mesh orequiva lent, horizont a lly placed on 150 mm(6 in.) centers. An alternative method placesNo. 6 reinforcing ba rs on 300 mm (12 in.)

centers horizonta lly. B a rs sh ould clearfounda tion sur faces 75 mm (3 in.) minimum .

When effective vibration isolation equipmentis used, depth of floor concrete is tha t n eededfor st ructura l support of th e sta tic loa d. Ma jorrota ting a nd r eciproca ting components ofCa terpilla r generator sets a re individuallybala nced a nd, th eoretically, ha ve nounbala nce. P ra ctica lly, ma nufacturingtolerances and combustion forces impose somedynamic loading on the foundation. If

isolat ors a re not used, dyna mic loa ds tra nsmitto th e facility floor an d requires t he floor tosupport 125%of th e generat or set w eight.

If genera tor sets a re para lleled, possible out-of-pha se pa ra lleling an d resulting torquereactions dema nd st ronger founda tions. Thefounda tion must w ithsta nd tw ice the wetw eight of the generat or set.

Figure 5

Figure 6

TwoBearing

Generator

Structurally Rigid Base

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Fabricated Steel Base

Frequent reloca tion, initia l insta llation ease,vibra tion isolat ion or isola ting from flexingmounting surfaces, such as trailers, are majoruses for fa brica ted ba ses. Do not r igidlyconnect a ny bas e to flexing surfa ces.

B ases maint a in alignment between engine,

generat or, an d other driven equipment sucha s ra dia tor fa ns. E ngines w ith close-coupledsingle-bearing generators maintaina lignment by mounting ra ils or modest bases.Tw o-bear ing genera tors, genera tors drivenfrom eith er end of the engine, ta ndemgenerators, or tandem engines, requiresubsta nt ial boxed ba ses, see Figure 6. B a sesmust incorpora te sufficient str ength t o:

Resist outside bending forces imposed on t heengine block, couplings, and generator

frame during tran sporta tion. Limit t orsional a nd bending movement

caused by torque reactions.

P revent resonan t vibrat ion in the operat ingspeed ra nge.

Due to thermal expansion,[cast iron 5.5 x 10-6 mm/mm/1.8 C(5.5 x 10-6 in./in/1.0F)] engines ma y len gt hen2.3 mm (0.09 in.) from cold to operatingtemperature. Th is growth must not berestrained. On single-bearing a nd mosttw o-bearing generat ors, no close cleara ncedowels or ground body bolts a re used t o limit

thermal growth. Single-bearing generatorsrequiring extremely close a lignment, u se aground body bolt a t t he flywh eel end on oneside of th e engine. No oth er restra int ispermitted.

Mounting feet of tw o-bearing generat ors ca nbe doweled without harm. Slight expansionwit hin th e generat or is absorbed in thegenerat or coupling.

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VibrationMecha nica l systems with ma ss an d elast icitya re ca pable of relat ive motion. If t his motionis repetit ive, it is vibra tion. En gines producevibra tions due to combustion forces, t orq uereactions, structural ma ss a nd stiffnesscombinat ions, a nd ma nufacturing t olera nceson rota tin g component s. These forces crea te ara nge of undesira ble condit ions, ra nging fromunw a nted noise to high str ess levels a ndultima te fa ilure of engine or genera torcomponents.

Vibra ting st resses reach destructive levels atengine speeds where resonance occurs.Resona nce occurs w hen system n a tura lfrequencies coincide with engine excitations.The tota l engine-generat or system m ust bean a lyzed for critical linear a nd t orsiona lvibration.

14

Figure 7

120 180 240 360 660 1200 2400 3600 6000

Vibration Frequency cpm

100

80

60

40

30

20

10

8

6

4

3

2

1

0.8

0.6

0.4

0.3

0.2

0.1Sensory Perception

Level

Very Rough

Acceptable Limits

(No Load)

Engine And Generator

Engine Only

Peak-to-Peak

VibrationAmp

litudemils(.001)

Rough

Slightly Rough

Fair

Good

Very Smooth


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Linear Vibration

Linea r vibra tion is exhibited by noisy orsha king machines, but its exa ct na ture isdifficult to define without instrumentation.Huma n senses are inadequa te to detectrelationships between the magnitude ofvibra tion a nd period of occurr ence. A firstorder (1 x rpm) vibra tion of 0.254 mm(0.010 in.) displacement may feel about thesa me as third order measurement of0.051 mm (0.002 in.). However, as depicted inFigure 7, severity of vibra tion correlat esrea sonably w ell w ith levels of perception a ndannoyance.

Vibrat ion occurs a s a ma ss is deflected an dreturned along the same plane a nd can beillustra ted a s a single ma ss spring system, seeFigu re 8. With no externa l force imposed on

the system, the weight remains a t rest a ndthere is no vibra tion. B ut w hen the w eight ismoved or displa ced a nd t hen released,

vibra tion occurs. The w eight tr a vels up a nddown t hrough its origina l position untilfrictiona l forces ca use it t o rest. Whenexterna l forces, such a s engine combustion,cont inue to a ffect the system w hile it vibra tes,it is termed forced vibr ati on.

Time required for t he w eight to complete one

movement is called a period, see Figure 9.

Maximum displacement from the meanposition is a mplitude; int erval in w hich themotion is repeated is called the cycle.

If t he w eight needs one second to complete acycle, the vibra tion frequency is one cycle persecond.

If one min ute, hour, day, etc., were requ ired,its frequency would be one cycle per minute,hour, day, etc. A sys tem completing it s fullmotion 20 times in one minute w ould ha ve afrequ ency of 20 cycles per minut e, or 20 cpm.

15

W

Spring At Rest

(Mean Position) WSpring Extended

X

Mass-Spring System

1 Cycle

Position Of Weight (X) Amplitude

Time

Upper Limit

PeakAcceleration

PeakVelocity

Peak-To-PeakDisplacement

Distance

Neutral Position

Lower Limit

Period

Time

Figure 8

Figure 9


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Establishing vibration frequency is necessarywh en ana lyzing a problem. It a llowsident ifica tion of engine component orcondit ion causing t he vibrat ion.

Tota l dista nce tra veled by t he w eight, fromone peak t o the opposit e peak, is peak-to-peakdisplacement. This mea surement is usua lly

expressed in mils, one mil equaling one-th ousa ndth of an inch [.025 mm (.001 in.)]. Itis a guide to vibrat ion severity.

Average and root-mean-square (rms) are usedto measur e vibra tion (rms = 0.707 times thepea k of vibrat ion.) These terms a re referred toin t heoretical d iscussions.

Another meth od to an a lyze vibra tion ismeasuring mass velocity. Note that theexample is not only moving but chan ging

direction. The speed of th e weight is a lsoconst a nt ly cha nging. At its limit , the speed is0. Its speed or velocity is great est w hilepassing t hrough the n eutral position.

Velocity is extremely importa nt ; but beca useof its chan ging na tur e, a sin gle point ha s beenchosen for mea surement . This is pea k velocitynormally expressed in inches per second.

Velocity is a direct meas ure of vibra tion a ndprovides best overa ll indicator of ma chinery

condition. It does not, however, reflect theeffect of vibrat ion on britt le mat erial.

Relat ionsh ip betw een peak velocity a ndpeak-to-peak displacement is compa red by:

V P eak = 52.3 D F x 10-6

Where:V P eak = Vibration velocity in inches per

second peak.

D = P eak-to-peak displacement, in mils(1 mil - 0.00l in.).

F = Frequency in cycles-per-minute(cpm).

Accelera tion is a nother cha ra cteristic ofvibrat ion. It is the ra te of velocity cha nge. Inth e exam ple, note tha t peak a ccelerat ion is atth e extreme limit of tra vel where velocity is0. As velocity increa ses, a ccelerat iondecreases until it reaches 0 a t t he neutralpoint.

Acceleration is dimensioned in units of g(pea k), w here g equa ls th e force of gra vity(980 x 6650 mm/s2 = 386 in ./s2 = 32.2 ft /s2).

Acceleration measurements, or gs, are usedw here relat ively la rge forces a re encountered.At very high frequencies (60,000 cpm), it isperha ps the best ind ica tor of vibrat ion.

Vibra tion a ccelera tion is calcula ble form pea kdisplacement

g P eak = 1.42 D F 2 x 10-8

Ma chinery vibra tion is complex a nd consist sof many frequencies. Displacement, velocity,an d a cceleration a re all used to diagnosepart icula r problems. D ispla cementmeasurements are better indicators ofdynamic stresses and are, therefore,commonly used. Note tha t overall or tota lpeak-to-peak displa cement , described inFigure 10, is a pproxima tely t he sum ofindividual vibrations.

Isolation

G enerat or sets need no isola tion for protectionfrom self-indu ced vibra tions. They ea silywith sta nd an y vibra tions wh ich they creat e.

16

Figure 10


17/131

H ow ever, isolat ion is required if enginevibration must be separated from buildingstr uctures, or if vibrat ions from near byequipment a re tra nsmitted t o inoperativegenera tor sets. Ca terpillar G enera tor Setsw ith isolat ion m ounts betw een t he genera torset a nd base a lready satisfy theserequirements. Running units a re rarely

a ffected by exterior vibra tions. Methods ofisolat ion is t he sa me for externa l or self-genera ted vibra tions.

If n o isolat ion is required, th e genera tor setma y rest directly on the mounting surfa ce.Fa ctory a ssembled units a re dyna micallybala nced a nd t heoretica lly there is nodynamic load. Practically, the surface mustsupport 25%more th a n th e sta tic weight ofthe unit to wit hsta nd torque an d vibra toryloa ds. U nless the engine is driving equipmentw hich impose side loa ds, no a nchor bolting isrequired. This n ormally a pplies t o allnonpar a llel generat or set m ountings. Thinrubber or composition pad s min imize th eunits tendency to creep or fret foundationsurfaces.

Vibration is reduced by commerciallya va ilable fa brica ted isolat ors or bulk isola tors.B oth techniques utilize sta tic deflection, w ithincreased deflection resultin g in grea ter

isolat ion. Although int erna l da mping ofvarious materials cause performancedifferences, th e vibrat ion cha rt in F igure 11describes the general effect deflection has onisolat ion. B y using engine rpm a s th e nomina lvibra tion frequency, ma gnitud e of compressionon isolat ing ma terials can be estimated.

The unit can be separa ted from support ingsurfa ces by th ese softcommercial devices, i.e.,th ose w hich deflect un der the sta tic weight.Mounting ra ils or fabricat ed ba ses withsta nd

torque rea ctions w ithout un iform supportfrom the isola tors.

P iping connected to generat or sets requiresisolat ion, part icula rly w hen gen sets mount onspring isolat ors. Fuel an d w a ter lines, exha ustpipes, and conduit could otherw ise tra nsmitvibra tions long dist a nces. Isolat or pipeha ngers, if used, should ha ve springs t oa tt enua te low fr equencies, and r ubber or corkto minimize h igh frequ ency t ra nsmissions. To

prevent buildup of resonan t pipe vibrat ions,support long piping runs a t unequ a ldista nces, see Figure 12.

17

Basic Vibration Chart

10.08.0

6.0

4.0

2.0

1.0.8

.6

.4

.2

.10

.08

.06

.04

.02

.01100 200 400 600 800 1000 2000 4000

ResonanceNatural

Frequency

60 81 90 95 99

70 85 93 97Isolation

Efficiency %

Vibration Frequency (CPM)

Figure 11

Figure 12

A A A A

A B C B

A B C D . . .etc.= = =/ / /

Good

Poor


18/131

Isolation for Mobile Equipment

Isolat ion from a m ovable plat form is desira bleto:

1. Reduce vibrat ion.

2. Reduce noise.

3. P revent torque loa ding on generator setscaused by plat forms or tra iler beds.

Vibrat ion car ried thr oughout a n enclosurecauses ea rly fa ilure of a uxilia ry equipment.Rela ys, sw itches, gauges, and piping a rea dversely affected.

Noise, w hile norma lly only a nnoying, ca na tt a in levels objectiona ble to ow ners a ndoperat ors. If opera ting n ear property lines,noise could exceed loca l ordina nces.

P erhaps the most importa nt r eason to isolat e

mobile equipment is to a void bending of th egenerat or set by m ovement of the subba se.U nless th e plat form or tra iler bed is extremelyrigid, the generat or set must not be bolted toit. Deflection of th e bed w ould be tra nsmit tedto th e engine, causing block bending a ndpossible cra nksha ft a nd bear ing fa ilures.

La teral movement of the generator set mustbe minimized a s th e tra iler is tra nsported.This can be a chieved simply by blocking t heunit off the isola tors durin g th e move. If not

pra ctica l, snubbers can confine vertical a ndhorizontal movement.

A deta il of a spring-ty pe isola tor show s th ea ddition of thrus t blocks to restr ict la tera lmovement with out interfering w ith t he springfunction, Figure 13.

Commercial Isolators

Severa l commercial isolat ors provide va riousdegrees of isolat ion. G enerally, th e low er th ena tur a l frequency of the isolat or, th e grea terth e deflection (soft) a nd m ore effective t heisolat ion. Weight of genera tor sets ca n beunequally bala nced w ithin th e limits of theisolat ors. However, overloading w ill elimina teisolat or benefits. Isolat ors a re most effectivewh en locat ed under generat or mounting a ndengine front support , Figure 14. If a dditiona lsupport is desired, place an isolat or midwa ybetw een front a nd rear m ounts a nd underradiator.

To apply isolat ors, wet w eight a nd cent er ofgravity of the a ssembled unit must beesta blished. Assuming engine an d generat orar e assembled to a ba se, wet w eight (WT) a nda ssembled cent er of gra vity can be calcula ted.A common r eference is needed, see F igure 14.In t his case, use th e rear fa ce of th e flyw heel

housing. Because measur ements a re to bothsides of the reference, one direction ca n beconsidered nega tive.

WT (D) = WE (D2)_ WG (D1) + WR (D3)

D =WE (D2)

_ WG (D1) + WR (D3)

WT

18

BASE MOUNTING HOLES

LOCKNUT

SNUBBER BOLT

ISOLATOR MOUNTING HOLES

LEVELING BOLT

VIBRATION ISOLATOR

Figure 13

D1D

CG

WT WEWG

Rear Face of Flywheel Housing

WR

D2

D3

Figure 14

Vibration Isolator


19/131

19

If a dditiona l equipment is a dded, the processis repea ted to determine a new cent er ofgravity.

Ha ving established center of gravity for t hetota l unit, a s in Figure 15, loa ding on eachpair of isolat ors is determin ed by:

S1

= WT

B S2

= WT

AC C

Isola tors a re sized t o have na tura l frequenciesfar removed from engine exciting frequencies.If t hese frequencies w ere simila r, th e ent ire

unit w ould resona te. The tra nsmissibilitychar t in Figure 16 depicts th is condit ion. Ita lso shows t he significa nt improvementca used by decreasing the mounting na tura lfrequency to allow a r a tio increase a bove 2,or 1.414.

The most effective isola tors a re of st eel springdesign, see Figur e 17. They isolat e over 96%of all vibrations, provide overall economy, andpermit m ounting th e genera tor set on asurfa ce capable of support ing only the st a ticloa d. No allow a nce for torq ue or vibra toryloa ds is required. As w ith direct mountings,no an chor bolting is usua lly required.

How ever, w hen opera ting in pa ra llel, verticalrestraint s a re recommended an d t he isolat orfirmly fast ened t o the founda tion. S pringisolat ors a re a vailable with snubber for usew hen engines a re side loa ded or located onmoving surfa ces.

Adding rubber plat es benea th spring isolat orsblock high frequency vibrations transmittedth rough th e spring. These vibra tions a re notha rmful but cause a nnoying noise.

Rubber isola tors ar e adequa te for a pplica tionsw here vibrat ion cont rol is not severe. B ycareful selection, isolat ion of 90%is possible.They isolate n oise creat ed by t ra nsmission ofvibratory forces. Avoid using rubber isolatorswit h na tura l frequencies near engineexcitation frequencies.

Fiberglass, felt, composition, an d fla t r ubberdo litt le to isola te ma jor vibra tion forces. Thefabric materials t end to compress w ith a gea nd become ineffective. B eca use deflection ofthese types of isolat ors is sma ll, their na tura lfrequency is rela tively high compa red to theengines. Att empting t o sta ck th ese isola tors ora pply t hem indiscrimina tely could force thesyst em into resona nce.

A

CG

WT

B

S1 S2

C

Figure 15

Figure 16


20/131

Bulk

B ulk isolat ing mat eria ls are used betw een th efoundation and supporting surface but are nota s foolproof as spring or rubber t ypes.

Isolat ion of block founda tions ma y beaccomplished by 200 to 250 mm (8 to 10 in.)of w et gra vel or sa nd in t he bed of th efounda tion pit. Sa nd a nd gra vel ca n reduceengine vibra tion one-th ird t o one-ha lf. Theisolat ing value of gravel is somew ha t greaterth a n sa nd. To minimize settling of thefounda tion, gravel or sa nd must be th oroughlyta mped before pouring t he concrete block.Ma ke th e founda tion pit slightly longer andw ider tha n th e founda tion block base. Aw ooden form t he size a nd sh a pe of thefounda tion is pla ced on t he gra vel or sa nd bedfor pourin g th e concrete. After t he form isremoved, the isolat ing ma teria l is placeda round founda tion sides, completely isolat ingthe foundation from surrounding eart h.

Rubber, aspha lt-impregna ted felt, a nd

fiber-glass ha ve a lso been used for isolatin gth e founda tion block from subsoil, but th ey donot provide significa nt low frequencyisolat ion. The floor slab surrounding th efounda tion block is sepa ra ted from thefounda tion by expa nsive joint ma teria l. Thisprohibits vibra tion from tr a veling from theblock to the floor a nd a lso elimina tes losingtools in t he pit dur ing servicing.

Cork is not effective wit h dist urbing

frequencies below 1800 cps a nd , if not keptdry, w ill rot. I t is seldom used w ith m oderngenerat or sets, but is used to separa te enginefounda tions a nd s urrounding floor beca use ofresista nce to oil, acid, or t empera tur e cha ngesbetw een -20 and 95 C (0 and 200 F).

Seismic

Seismic shocks a re insufficient t o har mgenerat or sets r esting on th e floor. H owever,isolat ion d evices, part icula rly spring isolat ors,

amplify small movement generated byearth qua kes to levels w hich w ould dama geequipment. S pecia l isola tors incorpora tingseismic restra ining or dam ping devices areava ilable, but exact requirements must bereview ed by t he isolator s upplier. Isolat orsa nt icipat ing seismic shock a re bolted to theequipment ba se an d t he floor. P ositive stopsa re a dded to limit motion in a ll directions.Attached piping and auxiliary equipmentsupports must also tolerate relative

movement.Figure 19 describes seismic activity occurringthroughout the world since 1897. The UnitedSt a tes is furth er divided into regions ofearth qua ke dama ge probability.

20

Figure 17 Figure 18


21/131

21

Zone 0 No Significant Damage

Zone 1 Minor Damage

Zone 2 Moderate Damage

Zone 3 Major Damage

Zone 4 Major Faults

Seismic Zone Map of the United States

Figure 19

Figure 20


22/131

Torsional

Torsiona l vibra tions occur a s objects , such a sa n engine cra nksha ft, tw ist a nd recover.St a nda rd generat or set components with sta ndnorma l st resses ca used by combust ion forcesa nd t orq ue rea ctions. A generat or set mustprevent th e na tura l frequency of the drive

tr a in from approa ching t he units opera tingspeed. Fa ilure of cran ksha ft, couplings, gea rsor bea rings may result w ithout this at tention.

Torsiona l vibra tions originat e wit h t he pistonpower stroke. The simplified drive train inFigure 21 illustra tes relat ionship of sha ftdiameter, length, and inertia on the nat ura lsyst em fr equency.

G enera tor sets prepacka ged by Ca terpillara void critica l speeds wh ere resonan tcondit ions occur. Applica tions field m a tchin gengine a nd single-bearing generat or, orincluding equipment driven from th e front ofthe engine, necessita te a torsiona l a na lysis.This a ssures compa tibility of engine an dgenerat or. The an a lysis is ava ilable from th e

engine supplier, but is the responsibility of thegenerat or set a ssembler.

If t w o-bearing generat ors a re specified,include torsiona lly resilient (soft) couplingsbetw een engine a nd genera tor. A torsiona lstudy is a gain recommended.

The stu dy predicts operat ing cha ra cteristics ofth e ma ss elast ic system. This combina tion ofma sses (or inertia s) a nd springs const itut es

th e vibra ting s yst em. When consideringtorsiona l vibrations, the ma ss elastic systemincludes pistons, rods, cra nksha ft, flyw heel,coupling, driven equipment, a nd a ssociat edsha fting. Good results from an a na lysisrequire a ccura te input concerning:

A. En gine Speed

1. High idle.2. Low idle.

3. Full loa d.

B . Driven E quipment

1. G enera l arra ngement dr a wing or sketchof complete system w ith significa ntdimensions, including cra nksha ft pulleysa nd front-driven equipment .

2. WR2 a nd torsiona l rigidity in pound-inches per radian of deflection on

couplings between engine a nd drivenequipment.

3. WR2 a nd principal dimensions of ea chrotating mass. Weight and principaldimensions of ea ch reciprocat ing ma ss.

4. WR2 a nd principal dimensions ofconnecting shafts.

Cyclic Irregularity

Cyclic irregularity is a nondimensiona l ra tiodescribing degree of cran ksha ft t w ist

occurring between two successive firings ofcylinders during st eady -sta te opera tion.Formula s to represent t his movement w erederived before modern instr ument a tiona llow ed mea surement. The ra tio is expresseda s:

Cyclic Irregularity =rpm (ma ximum) - rpm (minimum)

rpm (average)

System speed varies with connected rotatingma ss. C yclic irregularit y differs, th erefore, for

a ba sic engine, one driving a generat or, orad ditiona l equipment.

This ratio compares merits of large slow speedengines wh ich w ere custom ma de, but h a slittle va lue applied t o modern m edium speedengines.

22

Figure 21

Torsional Vibration


23/131

Noise

Sound Waves Behaviorand MeasurementAs sound w aves ra diat e, their strengthdiminishes. As dista nce tra veled doubles, th ew a ve a mplitude is r educed by one-ha lf. This

rule applies if th e first m easur ing point is a tleast t w o or three times th e la rgest dimensionof the noise source, usua lly a bout th ree feet.

Sound w a ves impinging on a m icrophone

produce voltages proportional to soundpressures. The signa ls mea sure a mplitude orstrength of the soun d pressur ewaves.Amplitude a nd frequency a re the only soundproperties measur a ble using ordinar ytechniques.

The extensive audible range of soundcomplica tes noise rat ings. The huma n ea rhears, without damage, pressure levels100,000 times st ronger th a n t he low estdetecta ble level. Noise measurin g inst rument sha ve extra ordinar y ra nge and a re sca led indecibels (dB).

LoudnessThe hum a n ea r does not u se sound pressuredecibels to judge loudness. Rating noiseloudness is a complex operation becausehuma n h earing is a lso frequency sensitive.

Sounds w ith frequencies in t he 5,000-10,000 H z ra nge ar e the easiest to hear ;

sounds wit h very low frequ encies a re theha rdest. H earin g loss from exposure to noiseis similarly fr equency sensit ive.

A-Weighted, dB(A) Measurements

Loudness ca n be mea sured by filtering t hemicrophone signal t o reduce th e strengt h ofth e low frequency signa ls an d give morew eight to frequencies in th e 5,000-10,000 Hzra nge. (These ar e the frequ encies to wh ich t heear is most sensit ive). This is d one with a

standardized (international) A filternetw ork to make adjustments th roughout t hefrequency range according to Figure 22. Theresult is a total decibel rat ing with acorrection a pproxima ting th e ear s sensit ivity.The mea surement s a re A-scale, A-w eighted ordB (A) levels.

SoundDistance Strength

X 100%2X 50%

4X 25%

23

Figure 22

Signals EnteringFilter

LowFrequencies

HighFrequencies

Signals LeavingFilter

dB TotaldB(A) Total

Response Characteristics

of Standard A Filter

Frequency-Hertz (cycles per sec.)

RelativeResponse-Decibels

"A" WeightedFiltering

- 5

0

+ 5

-10

-15

-20

-25

-30

-35

-40

-45

-5020 50 100 200 500 1000 2000 5000 10,000

A

A


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24

Octave Band LevelsMore deta il is required of the frequencydistr ibution of a n oise tha n provided by aA-weighted measurement. Measurements arema de with filters subdividing sounds over theentire audible range into sta nda rdizedfrequency bands, permitting the pressurelevels of only th e sound w ithin eachsubdivision t o be mea sured. Ea ch filter span sa n octa ve; th a t is, the upper frequency limit istw ice the low er limit a s shown in Figure 23.Sound levels in each octa ve are mea sured indecibels an d a re referred to as octa ve bandlevels.

Noise AdditionWhen sta nding by a n engine, th e noise hear dfrom oth er engines operat ing in th e same a reaw ill depend on th e spacing of th e engines a ndw here the person is in rela tion to the spa cing.

A cha rt showing th e combined effect of upto ten equa l sound sources is shown inFigure 24.

Figure 25 shows th e versat ility of the decibelsyst em. Although calculat ions a re ma de onth e basis of sound power, the syst em usesmeas ured or calcula ted sound pressures. U seth e difference in th e pressure levels of t w osounds t o find how t heir combined levelexceeds the higher of th e tw o. First a djust thelevels for the dist a nces from t he source to th espot w here th e noises a re being a dded. To adda th ird level, use th e sa me process to combine

it wit h th e tota l of the first t wo.

BandDesignation

(CenterFrequency) BandLimits

Standard Octave BandsANSI Standard S1.11 IEC 225

8000 Hz

4000

2000

1000

500

250

125

63 Hz

44 Hz

88

176

353

707

1415

2830

5650

11300 Hz

Figure 23

03 4 5 6 7 8 9 10

2

4

6

8

10

2

Addition Of Equal Sounds

Increase In Sound Pressure dB or dB(A)

IncreaseindBordB(A)

Number of sources

Figure 24

0

.5

1

1.5

2

2.5

3

0 2 4 6 8 10 12 14

Addition Of Unequal Sounds

Decibelsad

dedtohigheroftwonoises

to

obtaintotalindB

Difference between two noises in dB

Figure 25


25/131

25

Noise ExposureExposure to excessive noise causes permanenthearing da ma ge a nd a dversely affectsworking efficiency and comfort. Recognizingthis, the U.S. G overnment crea ted theOccupational S a fety an d H ealth Act (OSHA)wh ich esta blished limits for indust rialenvironments.

When an individuals daily noise exposure,designa ted D (8), is composed of tw o or moreperiods of noise at different levels, thecombined effect is ca lculat ed by: D (8) =(C1/T1) + (C2/T2) + ... + (Cn /Tn). Where C n isduration of exposure at a specified sound levela nd Tn is t ota l time of exposure permitted a ta specified sound level, Figure 26. The n oiseexposure is a ccepta ble wh en equa l to or lesstha n 1.

Noise ControlNoise ca n be either a irborne or st ructurebornetransmitted. Structureborne noise is vibrationtra nsmitted th rough a structure; typica llyth a t su pporting t he engine. Noise cont rolmeth ods a re different for t he tw o sources.

Noise criteria for typical a reas a re show n in

Figu re 27.

Mechanical Noise

Ma ny t echniq ues for isolat ing generat or setvibra tions a re applica ble to mecha nical noiseisolation. Modest noise reductions result froma tt ention t o noise sources, i.e., reducing fanspeeds, coa ting casting a reas, a nd ducting a irflow s. B ut for a tt enua tion over 10 dB (A), unitsmust be totally isolat ed. One effective methodutilizes concrete blocks filled w ith sa nd to

house th e genera tor set. In a ddition, the unitmust incorpora te vibra tion isolat iontechniques described in th e Vibrat ion Section.A rough guide comparing va rious isolat ionmeth ods is illustr a ted in Figure 28.

Completely enclosed engines a re impra ctica ldue t o openings required for pipes, ducts, a ndventilation. Enclosures with numerousopenings ra rely at ta in over 20 dB (A)attenuation.

Figure 27

Highly Critical Hospital or

Residential Zone 71 63 44 37 35 34 33 33 33Night, Residential 73 69 52 44 39 38 38 38 38Day, Residential 76 71 59 50 44 43 43 43 43

Commercial 81 75 65 58 54 50 47 44 43Industrial-Commercial 81 77 71 64 60 58 56 55 54

Industrial 87 85 81 75 71 70 68 66 66Ear Damage Risk 112 108 100 95 94 94 94 94 94

Figure 26

Duration Allowableof Daily Exposure level

Hours dB(A)

8 906 92

4 953 97

2 10011/2 102

1 1051/2 1101/4 or less 115

Octave Bands in Cycles Per Second 31.5 63 125 250 500 1000 2000 4000 8000


26/131

26

Intake Noise

Int ake noise at tenuat ion is a chieved througheither a ir clea ner element s or inta ke silencers.Noise at tenua tion due to various air clea nersa nd s ilencers can be supplied by th ecomponent ma nufa ctur er.

Exhaust Noise

Exha ust n oise is ty pica lly airborne. Exha ustnoise a tt enua tion is commonly a chieved witha silencer t ypica lly capa ble of reducingexhaust noise 15 dB(A) when measured 3.3 m(10 ft) perpendicular to the exhaust outlet.Loca ting it n ear t he engine minimizestra nsmission of sound t o th e exha ust piping.Since the number of cylinders a nd enginespeeds result in va ried exha ust fr equencies,specific effects of mufflers m ust be predictedby th e muffler ma nufacturer.

OriginalMachine

Vibration

Isolators

Baffle

AbsorptionMaterialOnly

RigidSealedEnclosure

Enclosure,andIsolators

Enclosure,Absorptionand

Isolators

DoubleWalledEnclosure,Absorptionand Isolators

Approximate Sound LevelReduction

dB(A)

0

2

5

5

15-20

25-30

35-40

60-80

Figure 28

Figure 29


27/131

27

Sound Level ConversionSound level informa tion is present ed both interms of sound power level dB(A) and soundpressure level dB (A) a t a given dista nce fromth e noise source.

Sound power level is th e tota l sound pow erbeing ra diat ed from a source and its

ma gnitude is independent of th e distan cefrom t he source. Rela tive loudnesscompa risons betw een engines is sim ply acompa rison of their sound pow er levels a tequiva lent opera ting condit ions. When t hesound pow er level is known , th e soundpressure level at a ny dist a nce from a pointsource (such as exhaust noise) can be easilyca lculat ed. A disadva nta ge of this sy stem isth a t sound pressure level conversion is va lidfor a point source only. It can not be used for

mecha nica l noise since th e source (overallengine) is qu ite la rge.

The equa tion for determin ing t he soundpressure level of exhaust noise is:

Sound P ressure Level, dB (A) =Soun d P ower L evel, dB (A) - 10 x Log10 (CD

2)

Where C = 2 For exhaust source adjacent to a flat surface,such as a horizontal exhaust pipe adjacent to aflat roof.

or C = 4 For exhau st source some distance fromsurrounding surfa ces, such a s a verticalexhaust sta ck some dista nce above roof.

D = Dista nce from exha ust noise source (m).

If t he sound pressure level of a point source atsome dista nce is known, t he sound pressurelevel at a second dista nce can be calcula tedusing this formula:

S P L2 = S P L1 - 20 x Log10 (D2 D1)

Where SP L1 = known sound pressure level, dB(A)

S P L2 = desired sound pressure level, dB(A)D1 = known dista nce, m (ft)

D2 = desired distance, m (ft)


28/131

28

Air Intake SystemDiesel engines require a pproximat ely0.09 m3/min (3.2 cfm) of a ir per bra kehorsepower for combust ion, or 17 lb of air foreach pound of fuel. Volumetric (V) a nd ma ss(M) inta ke air flow ha ve the follow ing generalrelationships;

V (m3/min) = .01486 x M (kg/hr), or V (cfm) =.2382 x M (lb/hr)

Hea vy fuel engines require a bout 40%grea terinlet a ir flow tha n th ose burning distilla tefuels.

Air CleanersCombustion a ir must be clean a nd cool.En gine-mounted, dry-ty pe a ir clean ers ar econsidera bly more efficient th a n oil-bat h typesand remove 99.5%of AC fine dust. Cleanfilters offer little restriction so tota l a irrestriction, including ducting, sh ould n otexceed 1.2 kP a (5 in. H 2O) of wa ter column.Air clea ner service indicat ors w ill signal afilter cha nge wh en a r estriction of 6.2 kP a(25 in. H 2O) develops. Ducting m ust ha vesufficient st rength to with sta nd minimumrest rictions of 12.5 kPa (50 in. H 2O), which isa lso the str uctura l ca pability of theCa terpillar prime pow er air clea ner.

Precleaners

P reclea ners ada pt to sta nda rd air cleaners toextend filter service periods. They impose 0.25to 0.75 kP a (1 to 3 in. H 2O) a dded restr ictionsbut increa se stan da rd filter life a bout t hreetimes. Convent iona l precleaners a pproa ch70%efficiency, while exhaust augmentedprecleaners exhibit 92%efficiency. Theyfurth er extend filter element life and a remaintenance free. Heavy-duty air cleanersprovide the same protection a s sta nda rd

filters but a llow furth er extension of filterchange periods. Service periods increase six toseven times tha t of sta nda rd a ir clea ners.

Cau t i on: Under no cir cumstances should the

engi nes be operated w i thout a i r cleaners.

Ducting

When ducting is n ecessa ry t o obta in cooler orcleaner a ir, filters should rema in on theengine to prevent h a rmful dirt fr om leakinginto th e engine thr ough ducting joints. Whena ir clea ners mus t be remote-mounted it isextremely importa nt tha t a ll joints be airtight to prevent ingestion of dirt.

Give careful attention to routing and supportof air inlet ducting, w here overhead cra nesa re used to service the engines. P rovide

ad equat e support for duct w ork so tha t itsw eight is not borne by the a ir cleaner onengine-mounted a ir clea ners, or by t hetur bochar ger on remote-mounted a ir clea ners.

Avoid a brupt tra nsitions in the inta keductin g to provide th e smoothest possibleair flow path . Keep total d uct head loss(rest riction) below 0.5 kP a (2 in. H 2O) forma ximum filter life. Any a dditiona l restrictionwill reduce filter life. See the Air I ntakeRestrictionsection.

Design inlet ducting to w ithsta nd a minimumva cuum of 12.5 kPa (50 in. H 2O) for st ructura lintegrity.

If required, a ll piping must be designed an dsupport ed to meet seismic requirements.

Air Intake Restriction

B eca use excessive vacuum on t he inlet side ofth e turbocha rger (or the a ir inlet on NAengines) can result in reduced engine

performa nce, the air int a ke syst em restriction(including d irty filters, duct w ork, vents, et c.)is limited to a ma ximum of 6.2 kP a(25 in. H 2O). Since the ma ximum a ir inletrestriction is limited, it is import a nt t ominimize the air inlet syst ems restriction to1.2 kP a (5 in. H2O) w ith clean filters,ma ximizing filter life. Extern a l restrictionca used by the a ir inlet sy stem subtra cts froma ir filter life.

AC Dust (% total weight)

Micron Size Fine Course

0 - 5 39 2% 12 2%6 - 10 18 3% 12 3%

11 - 20 16 3% 14 3%

21 - 40 18 3% 23 3%41 - 80 9 3% 30 3%

81 - 200 0 92 3%


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29

Ca lculate Duct Head Losses B y:

P (kPa ) = L x S x Q2 x 3.6 x 106

D 5

P (in. H2O) =L x S x Q2

187 x D 5

P = R est rict ion , kP a (in . H 2O)

ps i = 0.0361 x in. water column

kPa = 6.3246 x mm w a ter column

L = Total equivalent length of pipe, m (f t)

Q = I nlet a ir flow, m3/min (cfm)-(found inTMI or performance book)

D = Inside diameter of pipe, mm (in .)

If duct is recta ngular:

Then:

D =(2 x a x b)

a + b

S = Den sity of air, kg/m3 (lb/ft 3)

S (kg/m3) = 352.5

Air Tempera ture+ 273 C

S (lb/ft 3) = 39.6

Air Tempera ture+ 460 F

To obta in equiva lent length of str a ight pipefor va rious elbow s:

L = 33D Standa rd ElbowX (Ra dius of elbow equa ls pipe diam eter)

L = 20D Long Elbow (Radius > 1.5 Diameter)X

L = 15D 45 ElbowX

L = 66D Squa re ElbowX

Where x = 1000 mm or 12 in.

As ca n be seen, if 90 bends a re required, ara dius of tw o times th e pipe dia meter helps tolow er resista nce.

Flex Connections

Flexible connections a re required to isolat eengine vibra tion an d noise from the ductingsys tem. The flex should be a s close to th eengine as pra ctica l. The flex engagement w iththe a ir inta ke duct sh ould be a minimum of50 mm (2 in.) a nd a ma ximum of 200 mm(8 in.). Ca re must be used to prevent exhaustpiping hea t from deteriorat ing rubber flexconnections.

Turbocharger Loading

When r emote-mounted a ir clea ners a re used,tur bocha rger loa ding from the weight of theair inlet components becomes a concern. Maketh e flexible connection directly t o th etur bocha rger a ir inlet, a s in F igure 30. Allduct w ork to th a t point m ust be support ed.

Cleanliness

When a pplying remote-mounted a ir cleaners,ducting mus t be devoid of all debris wh ichcould ha rm t he tur bochar ger. Ductconst ruction should not include an ycomponents , such a s r ivets, w hich couldloosen a nd ent er the engine.

Inst a ll an identifia ble blanking pla te ah ead ofth e turbocha rger to prevent debris fromentering during initia l insta llation of the unit.Remove th e pla te prior to sta rt ing th e enginea nd in spect th e ducting for clea nliness justprior t o initia l sta rt-up.

a

b

Air InletPipe

SupportFlexibleConnection

TurboCharger

= 50 mm (2 in.) minimum

Figure 30


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30

Inlet Air Duct Insulation

Insula tion ma y be needed on t he inta keducting for remote-mounted a ir clea ners.In sula tion reduces tur bocha rger noise emittedinto the engine room and minimizes heattra nsfer from the room t o the combustion a ir.

Air Cleaner IcingSa turat ed air with t he dew point near freezingca n cau se icing a nd clogging of the a ir clean er,w ith r esulting pow er loss a nd increased fuelconsumption. P rocedures to a void t hiscondition include prewa rming int a ke air orblow -in doors (with a lar ms) spring loaded t oopen a t 12.5 kpa (50 in. H 2O) ma ximum.B ecause conta minan ts could seriously ha rmth e engine, bypassing t he cleaners is only anemergency procedure.

Extreme ColdHea ted engine room a ir ma y be required (forsta rt ing purposes only) in a pplica tions at verycold a mbient s, -25 C (-13 F). This a ssum escombust ion a ir is being dra w n from outsideth e engine building, and t he engine ispreconditioned w ith pre-hea ters for met a l,w a ter a nd oil temperat ures of 0 C (32F ).Admitt ing engine room a ir must be donew ithout t he possibility of a llow ing dirt ordebris into the a ir inlet syst em of th e engine.


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Exhaust SystemsExhaust systems collect exhaust gases fromengine cylinders a nd discharges them a squickly an d silently a s possible. A prima rydesign considera tion of the exhaust syst em isto minimize backpressure since exhaust ga srestrictions cause performa nce losses a nd

exha ust tempera ture increa ses.

ManifoldsE ngine exha ust m a nifolds collect exha ustgases from each cylinder and channels theminto a n exha ust outlet. The ma nifoldencourages minimum ba ckpressure a ndtur bulence. Several ty pes a re ava ilable forvar ying insta llation requirements.

Dry manifolds are usua lly s tandard equipment

but may be replaced by wa tercooled,w a tersh ielded or ACWS (a ir cooled w a tershielded manifolds). The optional manifoldprotects th e opera tor from cont a ct w ith h otmetal but is not particularly effective inreducing ra diat ed heat. The Mining Sa fety &H ealth Agency, MS HA, requires w a tercooledma nifolds to maint a in engine surfacetempera tu res below 200 C (400 F). Thew at ercooled t ype has passa ges allow ingengine ja cket coola nt to flow th rough th ema nifold, thus removing heat otherw iseca rried by the exhaust gas. H eat rejection t ojacket w a ter w ill increa se 20-40%, w hile lossof exha ust h eat energy ma y cause enginedera tion a nd/or decreased a ltitud e capa bility.

Wa tersh ielded a nd ACWS ma nifoldsincorpora te a n a uxilia ry jacket or shield.En gine wa ter circulat es through the shieldbut does not come into direct cont a ct w ith t heinner ma nifold. Wa tershielding a llow s a ir tocirculat e betw een th e inn er and outer casings,a dding litt le to ja cket w a ter cooling loa d a ndnot affecting engine performance. ACWS

ma nifolds tra p the air so, as w ith w at ercooled,jacket wa ter a nd engine performa nce a reaffected.

PipingPhysical characteristics of the equipmentroom determine exhaust system layouts.Arra ngements with minimum ba ckpressuresa re fa vored. S ecurely support pipes a ndrubber dam pers or springs inst a lled in thebra cing to isolat e vibra tions.

P iping must be designed w ith engineservice in mind. In ma ny cases, an overheadcran e will be used to service the h eavierengine components.

In sta ll piping wit h 229 mm (9 in.) minimumcleara nce from combust ible ma teria ls.La gging exha ust pipes w ith suita ble, hightempera ture insulat ion or inst a llingprefabricat ed insula tion sections over t he pipeprevents heat ra diat ion. Exha ust piping

passin g thr ough wooden w a lls or roofs requiremeta l th imble guar ds 305 mm (12 in.) lar gerth a n t he pipe diam eter, see Figure 32.

Extend exhaust sta cks to avoid heat, fumesa nd odors. Also, th e exhaust pipes should notbe in close proximity t o the a ir int a ke systemfor t he engine or th e cra nkcase ventila tionsystem. Engine air cleaners, turbochargers,a nd a ftercoolers clogged wit h exha ustproducts ca n cause prema tur e fa ilures. P ipe

outlets cut at 30 to 45 an gles will reduce gastur bulence a nd noise. Ra in ca ps forced openby exhaust pressure will keep wa ter fromentering.

Long runs of exhaust piping require tra ps todra in moistur e. Tra ps inst a lled a t th e lowestpoint of the line near th e exha ust outletprevent ra in w a ter from reaching the engine.Slope exhaust lines from engine to the t ra p socondensa tion w ill dra in, see Figure 32.

31

Water

Exhaust

Air Passage

WaterShielded

Air CooledWater Shielded

ExhaustDry

WaterCooled

Figure 31


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32

Muffler placement grea tly a ffects silencinga bility. Loca ting it n ear t he engine minimizestr a nsm ission of sound to the exha ust piping.Higher exha ust t emperatures near the enginea lso reduces car bon buildup in t he muffler; adra in removes condensat ion.

Although economically tempting, a common

exhaust system for mul ti ple install ati ons is notacceptable. Combined exha ust syst ems withboilers or other engines a llow opera tingengines to force exha ust ga ses into enginesnot operat ing. Wa ter va por creat ed duringcombustion will condense in cold engines andquickly causes engine dama ge. Duct va lvessepara t ing engine exhausts is a lsodiscoura ged. High tempera tures w a rp valveseats causing leaka ge.

Exha ust dra ft fan s have been applied

successfully in combined exha ust ducts, butmost opera te only w henever exha ust ispresent . To prevent tur bocha rger w indmilling(w ithout lubricat ion), the fa ns sh ould not beoperable w hen t he engine is shut down. Theexhaust syst em of non-runn ing engines mustbe closed a nd vented.

Exhaust BackpressureExcessive exha ust rest rictions can ca useperforma nce losses, part icula rly in fuelconsumption an d exhaust tempera ture.P ressure drop a cross t he exha ust systemshould n ot exceed 6.7 kP a (27 in. H 2O) ofw a ter for most C a terpillar engines. 3600Diesel Na tur a lly Aspirat ed (NA) G a s En ginesperforma nces w ill be a dversely a ffected a bove2.5 kP a (10 in. H 2O). Exceeding th is limit on3600 E ngin es w ill increase fuel consu mpt iona pproxima tely 0.8%per ea ch 2.5 kPa(10 in. H 2O) of backpressure above the limit.En gines burning heavy fuel have an a bsolutebackpressure limita tion of 2.5 kP a(10 in. H 2O) to a void excessive exha ust va lvetemperatures.

Pressure drop includes losses due to piping,

muffler, an d ra in cap, and is mea sured in astr a ight length of pipe 3 to 5 dia meters fromthe last tra nsition cha nge a fter thetur bochar ger outlet.

Calculating Exhaust BackpressureThese formula e allow th e exha ust sy stemdesigner to calcula te a pipe dia meter w hich,wh en fabrica ted into a n exhaust syst em, willgive exhaust backpressure less tha n theappropriate limit.

Long Sweep Elbow

Flexible PipeConnection

A

A

View A-A

Muffler

Piping Pitched SlightlyTo Encourage CondensationAway From Engine

Drain

VibrationIsolators

Thimble

Figure 32


33/131

33

Ca lculat e the pipe dia meter a ccording to th eformula , then choose the next la rgercommercially a va ilable pipe size.

Backpressure limits of the exhaust systemincludes losses due to piping, mu ffler, andra in cap.

Calculate backpressure by:

P (kPa ) =L x S x Q 2 x 3.6 x 106

+ PsD 5

P (in. H2O) =L x S x Q2

+ Ps187 x D5

P = B a ckpr es su re (kP a ), (in . H 2O)

P s = pressure drop of si lencer and rain cap

ps i = 0.0361 x in. water columnkPa = 6.3246 x mm w a ter columnL = Total Equivalent Length of pipe (m) (f t)

Q = E xh aust ga s flow (m3/min ), (cfm)

D = Inside diameter of pipe (mm), (in.)

S = D en sit y of ga s (kg/m3), (lb/ft 3)

S (kg/m3) = 352.5

Sta ck Gas Temperat ure

+ 273C

S (lb/ft 3) =39.6

Sta ck Gas Temperat ure

+ 460F

To obta in equiva lent length of str a ight pipefor va rious elbow s:

L = 33D Sta nda rd Elbow (Radius of elbow equa ls pipe diameter)X

L = 20D Long Elbow (Radius > 1.5 Dia meter)X

L = 15D 45 ElbowX

L = 66D Squa re ElbowX

Where X = 1000 mm or 12 in.

As ca n be seen, if 90 bends a re required, a

ra dius of tw o times th e pipe dia meter helps tolow er resista nce.

Restrictions imposed by mufflers relat e toexhaust flow velocities. Figure 34 is applicablefor mufflers.

V =QA

V = Velocity of Exha ust G a s (ft/min)Q = Exhaust G as Flow (CFM)A = Area of Muffler (Figure 33)

Figure 33

Area (ft2) Size (in.)

0.00546 10.0123 1 1/2

0.0218 20.0341 1 1/2

0.0491 30.0668 3 1/2

0.0872 4

0.136 50.196 6

0.349 80.545 10

0.785 121.07 14

1.39 161.77 182.18 20

2.64 223.14 24

3.68 264.28 28

4.91 30

70F

500F

800F

1000F

1200F

1009080706050

40

3025

20

15

1098765

4

3

2

1

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

15000

20000

30000

40000

SilencerPressureDrop,in.H

O2

Velocity

Figure 34


34/131

Flexible Connections

The exhaust pipes ar e isolat ed from t heengine wit h flexible connections. Inst a ll theflexible conn ections close t o the engineexhaust outlet. A flexible exhaust connectionha s th ree primar y functions:

To isolat e the w eight of the exha ust pipingfrom th e engine.

To relieve exha ust component s of excessivevibra tiona l fa tigue stresses.

Allow relative shift ing of exhaustcomponents. This may result from

expa nsion an d contra ction due totemperature changes, by creep processestha t ta ke place throughout the lifeof a ny st ructure, or torque reactions wh enth e genera tor set mounts on spring ty peisolators.

P re-str etch the exha ust bellow s duringinsta llation t o allow for th ermal growth. Foursmal l str aps can be tack-welded between the

two end fl anges to hold the engi ne exhau st

bell ows in a r igi d posit ion du r in g exhaust

pipi ng in stall ation. This w ill prevent t hebellow s from being inst a lled in a flexedcondition. Att ach a wa rning ta g to the bellow snoting tha t t he weld stra ps mustbe removedprior to sta rt ing the engine.

The installation limitations of the Caterpillarsupplied flexible exha ust bellow s a re show non Figure 35.

For ma ximum dura bility, a llow t he bellow s toopera te a s close a s possible to its free sta te.

Carefu l consid erati on must be given to the

loadi ng extern al pi pin g may ind uce on the

turbocharger.

34

Installation Limitations of Bellows-Type Flexible Exhaust FittingsA B C

Bellows Maximum Offset Maximum Compression Maximum ExtensionDiameter Between Flanges from Free Length from Free Length

mm in. mm in. mm in.

8 & 12 in. 19.05 0.75 38.1 1.50 25.40 1.00

14 in. 19.05 0.75 76.2 3.00 25.40 1.00

18 in. 22.86 0.90 76.2 3.00 44.45 1.75

Installation Limitations of Flexible Metal Hose-Type Exhaust FittingsA B C

Hose Maximum Offset Maximum Compression Maximum ExtensionDiameter Between Flanges from Free Length from Free Length

mm in. mm in. mm in.

4 & 5 in. 25.4 1.0 6.25 .25 6.25 2.56 in. 38.1 1.5 6.25 .25 6.25 2.5

Flanges Must Be

Parallel

Free Length

L

A

B OR C

Diameter

Figure 35

Spring Rate forBellows-Type Flexible Fittings

Spring RateDiameter kN/m lb/in.

8 in. 29.7 17012 in. 33.9 194

14 in. 68.5 39118 in. 19.3 110


35/131

35

Therma l growth of exha ust piping, must beplann ed to a void excessive load on support ingstr uctures. Steel exha ust pipe expan ds1.13 m m/m/100 C (0.0076 in ./ft /100 F) rise inexhaust temperature. A temperature risefrom 35 C to 510C (100F to 950F ) w illcause 16.mm (0.65 in.) grow th in3.05 m (10 ft.) lengt h of pipe.

Section long pipe runs w ith expa nsion joint s.Ea ch section is fixed a t one end a nd a llow ed toexpan d a t t he oth er. Support s ar e loca ted toallow expansion away from engine, avoidstr a ins or distortions to connected equipment,an d to a llow equipment remova l with outa dditiona l support . A restra int member isoften used t o keep the ends of a long pipe runfixed in place, forcing all th erma l growthtowa rds t he expa nsion joint s, see Figure 36.

Flexible pipe connections, when insulated,must expa nd a nd contra ct freely within t heinsula tion. This genera lly requires a softma teria l or insula ted sleeve to enca se theconnection.

Pi pi ng connected t o generator sets requ i res

isolat ion, part icul ar ly when the sets are

moun ted on spr in g isolat or s. These pipescould otherwise transmit vibrations longdista nces. Isolat or pipe ha ngers, if used,should ha ve springs to a tt enuate lowfrequencies, a nd rubber or cork t o minimizehigh fr equency tr a nsm issions. To prevent

build up of resona nt pipe vibrat ions, supportlong piping runs a t uneq ua l dista nces, seeFigu re 37.

DrainLong

SweepElbow

FlexiblePipe

Connection

Slight Pitch Awayfrom Engine

RigidPipe

Support

FlexiblePipe

Connection

Vertical

PipeSupport

Thimblewith Spray Shield

RigidPipe

Support

LongSweep

Elbow

Flexible Pipe Connection

Engine Exhaust Outlet

Roller Pipe Support

Figure 36

A A A A

A B C B

A B C D . . .etc.= = =/ / /

Good

Poor

Figure 37


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CleanlinessI nstall an i denti fiable blanki ng plate to

prevent debri s from fall in g in to the

tur bochar ger d ur ing installati on. TheCa terpillar sh ipping cover ca n be used for t hispurpose. Inst a ll it directly on t op of th eturbine housing. Att a ch a wa rning ta g to theplat e indica ting it must be removed prior t osta rting th e engine.

Exha ust heat must be discha rged withoutca using discomfort to personnel or ha za rds t obuildings or equipment. Loca te exhaus tdischa rge a wa y from ventilat ing air inta kesto prevent reentry of offensive fumes a ndodors. Directing exha ust emissions in frontof a r a dia tor blow er fan is a ccepta ble; buta void premat ure clogging of th e radia torcore by prevent ing exha ust pa ssing th rough

the rad iat or.

EmissionsSpecial engine configura tions a llow opera tionwith lower exha ust emissions. G aseousexha ust emissions of diesel engines ar e thelow est of modern intern a l combust ionengines. E ngine emissions a re measur edusing a Horiba or B eckman gas a na lyzer, withequipment a nd da ta measurement techniquesconforming to U .S. Code of Federal

Regula tions, Title 40, P a rt 53 or 86.Ca terpillar En gines at ra ted load w ill notexceed:

DeNOx Catalyst SystemNOx reduction is a prima ry goal t o discoura geexhaust emissions combining w ithatmospheric elements to form smog. TheCa terpillar DeNOx cat a lyst system is acomput er-cont rolled device using etha nolinjection in combina tion w ith a proprietar ycatalyst to reduce oxides of nitrogen (NOx)emissions from diesel engines. No ammoniaadditives are required. Engine configurationa nd a ftercooler w a ter t emperature a ffectengine exha ust emissions, but t he DeNOxsyst em reduces th ese fina l NOx emissions by80%of the input levels. The system isdesigned for use wit h low sulfur fuels w ith ama ximum sulfur cont ent of 0.05%. High erlevels diminish t he cat a lysts performa nce,an d may cause permanent harm.

The convert er is comprised of a N Ox ca ta lysta nd a n oxidat ion cata lyst. A liquidhyd roca rbon, eth a nol is injected int o anoxygen r ich exhaust environment . The NOxbeds redu ce th e NOx 80%, to benign N2 a ndH 2O element s, while the oxidat ion cat a lystreacts with HC an d CO. The reducing agent isa fuel gra de etha nol meeting ASTM-D 4806specifications, commonly containing 95%etha nol, 5%dena tura nts (typica lly unleadedga soline) a nd corrosion inhibitors.

The stora ge ta nk is sized a ccording to typicaloperat ing condit ions a nd a mount of NOxreduction required. The ma ximumetha nol/NOx (gra ms) ra tio is 2, a nd etha nolw eigh s 0.789 kg/L (6.6 lb/U .S . ga l). Ana pproximat e guide is t o size the t a nk for 5%ofdiesel fuel consumed.

Emission Diesel Natural Gas(g/bhp-h) (g/bhp-h)

NA TA Catalytic LowConverter Emission

Nitrogen Oxide

(NOx) 12.0 15.0 19.0 1.2 2.0

Carbon Monoxide(CO) 3.5 2.0 1.5 1.0 1.7

Hydrocarbons

(NMHC) 0.4 1.5 1.5 0.5 0.35

36


37/131

VentilationS ix to ten percent of fuel consumed by a dieselengine is lost a s heat r a diat ed to thesurrounding a ir. In ad dition, heat fromgenerat or inefficiencies and exhaust pipingca n easily equa l engine ra

generadores caterpillar

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