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T E C H N O N E W S

MES TECHNOSERVICE CO., LTD.TECHN ICAL DEPARTMENT / DIESE L PRODUCT GROUP

No.013SECTIONCHIEF K. HigasaASSISTCHIEF

Coun term easur e for tu rbochar ger sur ging

STAFF H. Miyak eEN GINE TYPE All type of tu rbocha rgers DATE 2001/1/28

The tu rbocha rger su rging is somet imes reported in u sing the en gine compa ra tively long ter m.Ther e ar e some factors which cause t his su rging such a s nozzle van e deforma tion, efficiencydecline with time, resista nce increase by cont am inat ion in exhaust an d scavenging passage.Plea se car ry out t he exam ina tion of th e following items first of all when s ur ging occur red.1, Examination of the Turbocharger

Nozzle-ring condition(1) Cont am ina tion. (especially, car e mu st be paidto car bon deposit on gas pressur e side atnozzle-ring va nes.)(2) Deformation of nozzle vanes.(3) Chip off / cra ck of nozzle van es.Tur bine blad e condit ion(1) Cont am inat ion.(2) Worn awa y at th e blade tip.(3) Chip off / crack of blades.Blower cond ition(1) Cont am inat ion.(2) Chip off / crack of van es.Clearance(1) Clear an ce between blade a nd cover-ring (tu rbin e diffuser).(2) Exha ust tem perat ur e differences between gas inlet an d out let.

PRIORITYIMMEDIATELY EARLIEST CHANCE DRY DOCK

Example of nozzle vane deformation.

Vane deformation can not be recognized at first glance,

however, actually nozzle area is reduced 12% by

deform at ion. Hen ce, close insp ection is req uir ed.

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ADDRESS1-1, Tam a 3-Chome, Tam an o, Okayama J apa nTEL/FAX0863-23-2385 / 0863-23-2349

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2, Examina tion of the Main engine

Air lin e(1) Contamination of air-cooler (pressure difference of the air-cooler).(2) Cont am ina tion or clog up of mist catcher, dra ina ge sta tu s an d clog up of dra in line.(3) Fun ction of non-ret ur n valve located inside of scavenging m an ifold. (for au xiliar y blower

an d flap va lve )(4) Scavenging air pressure an d tempera tu re.(5) Inta ke air temperat ure.

Exhaust line(1) Clog up a t pr otecting grid before th e tu rbocha rger.(2) Abnorma l cont am inat ion a t exha ust passage.(3) Cont am inat ion at exhaust economizer.(4) Back pressure of the turbocharger.

Fu el oil line(1) Fu el oil specificat ion. (viscosity at fuel pum p in let)(2) Un -uniform combu stion a mong cylinder s. (fuel pum p / suction va lve / fuel va lve condit ion

and camsh aft timing)

En gine load condit ion

(1) Whet her load condit ion is in torqu e-rich or not. (conta min at ion of hu ll or pr opeller)We can comply ma in engine perform an ce an alysis, ther efore, please send u s th e enginedat a before a nd after su rging occur rence.

3, Other s

In low load opera tion (50-60% load), car bonized deposit can be ma de easier th an norm alload opera tion, th erefore, lots of carbon deposit accumu lat e ont o th e nozzle-rin g vanes.In case of plan nin g the low load opera tion at less th an 75% load for long term , werecommend adopting slow steaming atomizer to improve fuel combustion performance.For low load operat ion, det ail is d escribed on Ser vice N ote No.103[Low load opera tion].

Periodical cleaning for the turbocharger is recommended to avoid surging problem causedby car bon a ccum ula tion, an d, inter val for cleanin g is as follows.

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[Tur bine side] Wat er wash ing : every 250hr s.Dry wash ing : every 25-50hr s.

* CAUTION --- For MET tu rbocha rgers, dry washing is esta blished as sta nda rd,however, water washing is n ot recomm endable.

[Blower side] Wat er wash ing : depend s on cont am ina tion [if it is equipped]

Never use chipping ha mm ers or needle ha mm ers when cleaning the nozzle-ring. Also,san dblast sh ould be a voided to prevent t he deform at ion of the n ozzle vanes.

Concern ing clear an ce for t he t ur bochar ger, det ail is described on Techn o News No.006.

If surging problem could not be eliminat ed th ough a bove mentioned items a re a tt empted, itis possible to impr ove th e condit ion by increa sing su rging m ar gin by spec modificat ion.We have exper iences th at could solve th e surging by spec modificat ion. However, pleaseas k our local sa les office, since an exam ina tion in a dvan ce is necessar y by engine bu ilder.

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