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MULTIPLEXQUALITY MONITORING INSTRUMENTS LTD.www.oilmist.comThis Adobe Acrobat PDF file has been downloaded fromthe Quality Monitoring Instruments Ltd. website at www.oilmist.comThis is a web edition and as such is not optimised for print.This information is subject to change. Please contact us for moreinformation. Our contact details can be found below.Thank you.QMI Ltd.MULTIPLEXQualityMonitoringInstruments Ltd.5 Hampstead West224 Iverson RoadLondonNW6 2HLTel: 44 (0)20 7328 3121Fax: 44 (0)20 7328 5888Email: [email protected]: www.oilmist.com

OIL MIST DETECTION AS AN AID TO MONITORINGAN ENGINE’S CONDITIONPUBLICATION 524AUTHORBrian J.SmithAIMarEST, MIDGTEAkroyd Stuart Award 2001

IntroductionAs diesel engines become progressively moreefficient by burning fuel more effectively, the onlyremaining significant potential for operational costsaving to be exploited is to introduce features toensure that unnecessary maintenance is reduced.Owners and operators of diesel power plants areincreasingly seeking ways to replace preventivemaintenance schedules based on operational hoursby on-condition maintenance programmes thatconfine maintenance to the actual needs of theengine. Such a philosophy requires appropriate useof accurate health and condition monitoringequipment that not only tracks critical performanceparameters, but also provides suitable protectionagainst more serious damage being inflicted due toincipient seizures. Oil Mist Detectors are animportant component part of this changingphilosophy.The History Of Oil Mist DetectionThe earliest recorded experience of oil mist fires andcrankcase explosions go back to the very beginningof diesel engine development. Rudolf Dieselmentions them in his early writings.Matters were finally brought to a head regardingexplosions and fires when a major disaster aboardthe MV "REINA DEL PACIFICO" in 1947 tookplace just as she was leaving Belfast dockyards aftera complete refit. This incident involving the death of28 people has been well documented. A BritishGovernment Inquiry was set up to find ways ofmaking sure no more tragedies of this magnitudeoccurred again.The outcome of the research into the above accidentwas the development of standards aimed atimprovement of the design, application, andassociated performance, of pressure relief doorsmounted on the crankcase. This was a step forwardin safety. The solution however only went half wayto solving the problem because the pressure reliefdoors, were essentially confined to controlling theeffect of an internal explosion, to ensure minimumexternal damage to personnel and equipment.Essentially the design was such as to unload thepressure through a relief valve on the door, theevacuation taking place through a gauze packing toquench the flame. A further feature of the designwas the rapidly closing valve to prevent the ingressof air that could promote a secondary explosion.This initial work therefore centred on the control ofthe effect rather than preventing the cause. As bothengine ratings and the physical size of enginesincreased during the 1960's, it was evident thataddition steps should be taken to reduce the risk orinternal explosions, so inevitably interest wasdirected towards detection of the conditions existingimmediately prior to an explosion.It was realised that a crankcase explosion resultedfrom the self ignition of an oil vapour from a hotspot, the vapour itself being caused by theprogressive and excessive increase in temperatureof an internal surface due to high friction loads, dueto incipient seizure between surfaces.Effort was therefore applied to the development ofmonitoring equipment that would detect the onset ofa problem which would initially manifest itself bythe generation of localised high density oil mist.The first crankcase oil mist detector was marketedin the early 1960's. The design principle used hasbeen retained by many suppliers of this equipmentto this day, and involves the extraction of the oilmist from selected points within the crankcasewhich is then transferred in sequence via discretepipes to a central detector usually mounted on theengine, with a facility for remote reading at acentralised panel.Figure 1: Stop This!

Oil Mist DetectionAdvances in technology have been such that healthmonitoring has now become increasingly importantwith regard to diesel engine maintenance and safety.Oil mist can give some of the first signs ofimpending problems for all the moving parts of theengine. It is acknowledged that temperature andpressure indication can also provide appropriateearly warning of potential problems with certaincomponents, particularly those components that canbe fitted with temperature probes.Today's diesel engines are varied in design and are amixture of slow, medium, and high-speed, large andsmall cylinder bore. Diesel engineers have beenparticularly concerned with hazards associated withusing large bore engines due to the possibility ofexplosive type atmospheres in the diesel enginecrankcases. As a result Classification Societiesrequire that crankcase oil mist detection equipmentor temperature bearing sensors be fitted to largebore diesel engines in order to reduce the riskassociated with these engines.Over the last 15 years QMI has been fitting oil mistdetection equipment to engines of various boresizes, including slow, medium, and high-speedengines.Classification Of Oil MistClass 1An inherent layer of oil mist can be found in allengine spaces. It is caused by vapourisation of thelubricating oil as a direct result of localised normal,but nevertheless high temperatures, and the worksustained by the oil in the process of lubricating andcooling bearings, piston and piston rings and geartrains. This mist condenses on the cooler crankcasewalls and is reasonably constant although it willinevitably increase slightly with power output. Thistype of oil mist does not typically create a problem.In fact, for the correct operation of the QMIMultiplex Oil Mist Detection System, itspresence is essential.Class 2This type of oil mist is generated from hot spots thatoccur as a result of high-localised friction loads orloss of lubrication of the bearings. Oil mist will begenerated above the inherent layer of oil mistcreated by oil splash that is already present fallingon to the hot spots. Oil droplets hitting the hot spotsboil and create a larger quantity of oil mist.Monitoring the build up of this oil mist is anexcellent way to detect wear of the bearings andpistons at a very early stage.Class 3This type of oil mist is similar to Class 2 exceptinstead of the oil boiling it aerosols on beingexposed directly to the products of combustionescaping past the piston rings.Class 4A large number of marine fires in machine roomsbegin with oil mist in the surrounding area. Oil mistescaping from injectors, leaking fuel, lubricating orhydraulic oil pipes can gather in engine and machineroom spaces. This type of oil mist can be detectedby oil mist detection equipment such as thatdeveloped by QMI. It should be possible to preventmost fires and minimise damage if an early warningis given.What We Should Know about Oil MistThere are two types of oil mist but only one thatshould concern us and they are known as blue andwhite smoke.workzone0 1.99operatinglevels of 0-1.99 mg/loil mistdanger zone501.99 to 50 mg/lexplosivelevel50 mg/lmg/lOperating Levels of Oil MistFigure 2: Operating Levels of Oil MistBlue SmokeBlue smoke is identified by its colour and can onlybe caused when the oil temperature rises to 800 C orhigher. This mist has a particle size of about onemicron. It is not present in the machinery that ismonitored. It is worth noting the importance ofbeing able to identify one type of smoke from theother. Blue smoke can be seen and is extremelydangerous. It normally only occurs during a majorfire.

White SmokeIt is important to detect this type of oil mist as it canbe generated at quite low temperatures and has aparticle size of between 3 and 10 microns. It isdescribed in Classes 1, 2, 3 and 4 above. Ifconcentrations greater than 50mg oil /l air of oilmist, which is the lower explosive level (LEL), hasaccumulated, it will take a temperature as low asapproximately 200 C to ignite the oil mist. This canresult in a crank space explosion and considerabledamage to the engine. Most engines will haveseized before this amount of oil mist has beengenerated. Early detection can significantly reducecorrective maintenance costs.The main user of oil mist detection systems is theMerchant Fleet as it is mandatory to have eitherbearing temperature sensors or an oil mist detectionsystem on engines over a certain size depending onthe Classification Society requirements.The problem with temperature sensors is they canonly look at the bottom end of the engine, whereasoil mist detectors can monitor the top and bottom ofthe engine. The Merchant Fleet normally fits oilmist detectors or, in some instances, both oil mistdetection and bearing temperature sensors.As already stated there is an inherent oil mist levelwithin the engine that acts as the base line. (SeeClass 1.)If the oil mist readings are manually orelectronically logged the increased levels of oil mistwill become apparent as wear takes place.Remember wear starts from small beginnings andwith awareness of this preventative action can betaken.The QMI Oil Mist Detection SystemQMI have for the past 18 years been developing theMultiplex System to detect oil mist in dieselengine crankcases and in sensitive operatingenvironments. Our efforts were directed toovercome a number of problems that were wellknown to users.What is most needed in an Oil Mist Detector?aA fast and accurate response - this can onlybe achieved with a detector mounted oneach crankcase to detect the level of oil mistat the source of the problem. This eliminates unnecessary pipe-work where oil mistcan condense and take time to travel to themonitor.bNo false alarms - to make this possibleabsorption must be replaced with light scatter so that there can be no mistake betweenoil mist and dirty lenses. Detailed explanation of these terms is given later.cDirect reading of a known value such asmg/l and having a linear output.dMust have a known maximum oil mistalarm level, not one that can be changed atwill.eMust work on direct readings taken in eachcompartment of the crankcase.fMust not use compressed air for calibration,as this tends to contaminate the lenses sothat it is not possible to distinguish betweena false alarm or an engine problem. Alsocontaminated air gums up the valves withinthis type of oil mist detector.gIt must be possible to accurately read the oilmist levels in each crankcase simultaneously without scanning.Crankcase ExplosionsWhen an explosion occurs within the confines of acrankcase the crankcase door is vulnerable todamage. Where a set of correctly designed pressurerelief valves are fitted, the pressure is relieved and itis unlikely that external structural damage will beexperienced. In both instances however injuries tooperators can occur if they are close by when theincident occurs. There is also the added risk of asecondary explosion caused by the ingress of freshair into the confines of the crankcase.An oil mist detection system can stop damage to theengine and, most importantly injury to engine roompersonnel by allowing early detection of enginewear and bearing damage which could lead to anexplosive environment within the engine.Oil mist detection equipment, when used in thecorrect way, can therefore be used as a healthmonitoring facility to assist in the determination ofthe condition of the machinery, so that the necessaryservicing can be highlighted at an early stage of acondition change taking place.

hIt should be possible to log oil mist readingseither manually or electronically.INo siphons or valve that can block and stopoil mist reaching the monitor.jLast, and most important, an oil mist monitoring system that has the monitor mountedin the control room and not on the engine.QMI uniquely uses the light scatter method tomeasure oil mist concentration see Fig. 2. This isalso known as NephelometryThe measurement of oil mist using theNephelometry light scatter method greatly differsfrom conventional Obscuration light absorptionsystems used by other suppliers.Optos to compensate the oil mist readings. Thisallows for up to 50% of contamination on the lenses.The main advantage with the system is that thedetectors can be calibrated and it is also possible toobtain a true zero. If there is no oil mist no light canbe scattered to the receiver. If, however oil mist ispresent, then light will be received from the scatter.Thus it follows the more oil mist there is the morelight will be received. By use of a complexprogram, it is possible to obtain readings that arelinear in mg/l and this makes it easier to read as itrelates to the known LEL of oil mist. By using lightscatter small detectors can be placed along side eachcrank compartment thereby obtaining readingssimultaneously within approximately 0.5 seconds ofthe mist being produced.Schematic diagram showingprinciple of absorptometryLight scatter has the advantage of being linear inoutput and has a true zero. This means it is possibleto quantify the oil mist as a measurement in mg/l.TRANSMITTERHow Does Light Scatter Work?Schematic diagram showingprinciple of nephelometryNephelometryis highly sensitive at low levels.Zero mist gives zero signal.Signal increases with mist level.Short light path an htsourcetransmitterOIL MISTTypical graph produced by nephelometerREADOUT100SHORT LIGHT PATH0OIL MIST UNITSFigure 3:The Principle of NephelometrySAMPLETUBERECIEVERTypical graph producedby absorptometer100READOUTA good analogy of how light scatter works is theflecks of dust seen in a beam of sunlight streamingthough a window. In reality these are not dustparticles but light scatter reflecting from the sun offthe dust. The QMI system transposes the sun with anLED transmitter; the dust then becomes oil mistparticles.Incorporated is a receiver atapproximately 90 degrees to the transmitter. Thisreceives the light scatter. Directly opposite the LEDtransmitter is another receiver that measures theamount of contamination building up on the LEDOIL MIST PARTICLESABSORB LIGHTAbsorbtometrySensitivity difficult at low levels.Zero mist reads 100%.Increasing mist reduces signal bysmall amounts.Long light path necessary toachieve sensitivitySHORT LIGHT PATH0OIL MIST UNITSFigure 4: The Principle of AbsorptometryHow Does Absorption Work?Obscuration used by many oil mist detectionequipment suppliers works in the opposite directionto light scatter in that if there is no oil mist there isa 100% light transfer. Obscuration works on theprinciple of having a sensing chamber with atransmitting LED at one end and an LED receiver atthe other. Therefore when oil mist is passed into thesensing chamber the light diminishes. The more oilmist contained in the space between the transmitterand the receiver, the less light is received by theLED receiver. At the same time contaminated aircan be drawn onto the LEDS from the comparatorsource.

This can lead to a false alarm as the differencebetween a contaminated LED and a high oil mistconcentration cannot be recognised. (This is a veryreal problem and should be emphasised.)Obscuration does not allow a true zero as theinstrument needs to be set up on a running engine,therefore the oil mist level seen by the monitor is notknown.Absorption is not linear. This is why this type of oilmist monitor cannot relate quantified measurementssuch as mg/l. It has to rely on looking for deviationsto operate the alarm system. Each crankcompartment needs to be scanned at least twice toset a deviation and this is then compared with acompressed clean air comparator.Normally this air supply iscontaminated as there is usually noclean air supply available in theengine room. The contaminated airis one factor in creating dirty lenses.The MonitorThe QMI monitor is normally placed in the controlroom or on the bridge well away from the dangerzone i.e. the engine. Therefore should conditionsbecome dangerous no personnel will be injured.Nowadays most engine rooms are unmannedtherefore all information about the engine should beimmediately transmitted to the control room staff.Other types of oil mist detectors allow the user toraise the maximum alarm setting indefinitely. QMIhas a maximum pre-set program and can only bechanged for high readings by changing the EPROMand this is not freely available.The two major problems with anobscuration system are they areprone to false alarm and are veryslow in detecting rising oil mist.Figure 6: The QMI Monitoroil mist inlet from crankspacesclean airinlet forcomparisoninfra redrecieverThe monitor processes all the informationtransferred from the detectors that are mounted onthe engine. It gives continuous information tooperatives in three ways:switching device to select samples from each crankspacemeasuring chambermist outletreturning toengineATraffic Lights - RED, AMBER, andGREENThese indicate the state of oil mistand areas of alarmwithin the engine or the monitoringsystem. There is a set of lights foreach detector.GREEN - indicates up to 80% ofalarm settingAMBER - indicates from 80 - 99%of alarm setting.RED - indicates 100% of alarm setting.ALL THREE FLASHING indicates an instrument fault.BDigits The digits are used to set thealarm levels in mg/l during the setting up procedure, and as a percent-infra redtransmitterfan or ramjetFigure 5: Photoelectric Tube UnitDescription Of The QMI Multiplex SystemThe equipment consists of a small number ofcomponents such as The Monitor, Detectors, Fanand Multi-way Junction Box.

Cage of the alarm setting in the running mode. It also indicates systemfaults should they occur by meansof a self-diagnostic program.where it proceeds to give all the relevant readingand alarms to the operatives. There is no interactionbetween detectors as they are independent of eachotherAlarm relays and engine slow/shutdown There are 4 relays built intothe unit. The first is used as an earlywarning alarm when 80% of thealarm setting is reached. The second and third are activated whenthe oil mist gets to its full alarm setting i.e. 100%. The second relayoperates the main alarm and thirdrelay the engine slow or shutdownsystem. A fourth relay comes intouse when there is a fault in the operating system, which is independentof the engine operation.The Multi-Way Junction BoxThis is a Junction between the detectors and themonitor. Each detector is wired together with theFan Failure sensor to the Junction Box that islocated near to or on the engine. A multi-core cableis run from this unit to the monitor.As the instrument is completely micro processordriven a number of other useful functions can beincorporated such as using the monitor on more thanone engine each with its own slow/shutdownfunction. Oil mist readings from each detector canbe data-logged. The program also allows it to ignoretransient blow-by and indicates the area of theengine where the trouble has occurred. In the eventof a failure it locks onto the channel that first goesinto alarm.The DetectorsFigure 8: The Multi-Way Junction BoxFan with Magnetic SensorThis is a small AC 110/240V unit that is used todraw the oil mist through all of the detectors via asingle manifold. Mounted on this fan is anelectromagnetic sensor to prove that the impeller isrotating.Pipework Layout Of The QMI Multiplex Monitoring Systemas shown in Figure 9.Figure 7: The DetectorsThese are mounted at each crank compartment, gearor chain-case housing and thrust bearing, housing ifthis has its own space. The detector incorporatesLED optos and a PCB. A microprocessor, that isbuilt into the unit, sends five sets of information tothe monitor each 0.5 seconds via a cable connectionMist is continuously being extracted by means of afan attached to the end of a manifold, to pull oil mistinto the detector where it is measured. From the fan,the oil mist is generally ducted to the enginebreather or returned to the crankcase.To get the best overall advantage of the system it isnecessary to either manually or electronically logsthe detector readings. These readings will thenindicate at a very early stage when a bearing orpiston failure starts.

Figure 9: Pipework Layout of QMI MultiplexTMRemedial work can then be carried out long beforea major incident occurs. QMI have overcome mostfalse alarm problems and have a system thatresponds very quickly to oil mist level changes.The Advantages Of The QMI Multiplex System:I.II.III.IV.True measurement of concentration of oilmist is achieved.Oil mist drop-out is minimisedDirect measurement at the crankcase bymultiple measuring cells gives high redundancy to the systemFaster response (0.5 seconds) means savingthe engine from damage caused by bearingfailures.V.Continuous parallel sampling directly eliminates the use of valves, which are highmaintenanceV1.Continuous true readings give trends foranalysis and accurate fault prediction.The following are figures giving an indication of thetype of results that are achieved by manual loggingor data-logging oil mist readings.Figure 10 shows how, on a B&W S 80MC Engineon the M/V "BRITISH PIONEER". Moving the oilmist detector to a higher location made it possible toobtain a clear and consistent picture of what istaking place in the crank compartment. The firstthree sets of readings were taken in the originalposition as indicated by B&W. Later, the detectorswere placed higher in the crank compartment. (Seeaccompanying notes to be read in conjunction withthe graph.)Figure 10: Oil Mist DetectorM/V British Poineer

Explanatory Notes - Tables 1 and 2Oil mist levels found in crank spaces of B&WEngines - Type S80MC1.The level of alarm was originally set at0.49mg/l until the 20th May '00, when itwas increased to 0.69mg/l. to ensure themonitor did not operate in the 50% andabove range, bearing in mind the LEL isapprox. 50mg/l.2.The readings of the monitor go up in 1%divisions to 30% of the alarm setting.Above this they go up in 5% divisions. Thismeans a 35% reading could be between 3139%, depending upon if the oil mist level isrising or falling. You will appreciate this isa very small amount of oil mist in terms ofmg/l.3.Note, the lower the RPM the higher the oilmist reading. This is as a result of the washQMI Advertout effect of the oil spray not being so greatand there being less turbulence whichallows the oil mist to increase.4.Detector readings 1 to 3 were taken whenthe detectors were installed, as per B&Wpositioning instructions. Readings 4 and 7 weretaken when the detectors were repositioned at thetop of the crank compartment, as specified by QMI.Readings then became higher and more stable.5.Detector No. 8 was mounted to monitor thechain-case and was set at 0.29mg/lReadings were low due to the oil mist beingwashed out as a result of very large amountsof oil splash. By setting the alarm lowerthan the detectors 1-7, should any problemoccur it would immediately slow or shut theengine down.To show the different type of figures that variousengines produce, the readings of a Caterpillar 3616on the M/V "STENA SEA LYNX II" are shown inTable 3.

B&W S80 MC ENGINENo Date Ship16/4 27686RPMSettingmg/lSetting0.29mg/lM/V British Pioneer% of Alarm Setting of Detectors1234567876.499610105948REMARKSNo. 8 Chain CaseBefore relocating 2/5?66"4035353524302075"?""404040403540302060 min63.7"00454040402914Baffles on No. 1 block head63/5 1795010 min after start-up of retrofit"""7""""030454545402917Baffles on No. 1 block head8""""035454545402910Baffles on No. 1 block head67.8"029454545453514Baffles on No. 1 block head94/5 1870410""""00/3045404540276BaffleNo 2 becoming blocked11""""00/3040354545248BaffleNo.2 becoming blocked12 20/5 2550073.69304035353528296Baffles unblocked No. 1&213 21/5"""28353535352929914 22/5"""304035403528352015 23/5 2730074"293535353529351816 24/5""253035353528261266"172530252622226"17 30/5 19000Table 1:The second set of figures were taken on the same type of engine on board the M/V "BRITISH PROGRESS".This shows the consistency that occurs. In other words, each engine type and make has its own characteristics.You will also note that the actual oil mist in a crosshead engine is normally very low, bearing in mind theseare percentage figures of the mg/l setting and the readings vary depending upon speed and load. The reasonfor low oil mist in this type of engine is because there is a large area of metal on which the oil mist condenses.If the detectors are mounted too low in the crank compartment there will be a washout of oil mist by the oildroplets.

No Date Ship RPM8 24/10 --Settingmg/l.49Setting0.29mg/lM/V British Progress% of Alarm Setting of Detectors123456784524305550293540REMARKSNo. 8 Chain CaseTable 2:M.V. STENA SEA LYNX II% READINGS OF 08080807575Table 3:

The last set of figures were taken from Paxman Valenta engines, type 12PR200L, which were on the test bedsat the Railway Works at Crewe. Every engine, irrespective of type and make, sent out by Crewe has a set ofthese figures that have been logged to prove the engine is in a perfect state before leaving the an Valenta 12 WKWKW12555550455045506060505045454550556060Serial No. S340Number of Cylinders34606050555555556055Paxman Valenta 12 35403545555550Serial No. P308Number of Cylinders34556045404045405045Paxman Valenta 12 PR200L1182822213029303535535405014171281414Serial No. S438Number of Cylinders346065454545504560655550504550The above readings show a good example of engines operating with no problems. The oil mist level willonly rise as a condition change takes place due to wear.

Tug BAUS. EngineTug BAUS. Engine M.e 8M551AK, 2360 kW, built 1970Information from BAUS' Chief Engineer.Normal readings on Multiplex; 12% of 1,99 mg/lWhen towing in ice; readings 30% of 1,99 mg/lA SELECTION OF LAND-BASED INSTALLATIONSSHOWING THEIR DIVERSITYLAND FILL SITES & MINES: CUSTOMER LOCATIONSITEShanks & McEwanDalesMagharaBrogboroughRixton HallEgyptNUMBER OF ENGINES214UNDERGROUND GAS STORAGE:CUSTOMER LOCATIONSITEDirect GasBelgiumNUMBER OF ENGINES5POWER STATIONS:CUSTOMER LOCATIONSITENUMBER OF ENGINESMetaldomManx ElectricityScottish & Southern PowerSolomon Isle PowerClub Med.Thames WaterSociete Des Ciments LibanaisDominicaPulroseLerwickSolomon IslandsDjiboutiCrossnessLebanon1561217TEST HOUSES: Engine BuilderResearch HousesRailwaysNavy

ConclusionThere are many advantages to be gained fromapplying modern Oil Mist Detection Systems to apower plant. Essential information is transferred toremote control stations away from the potentialdanger zone thereby enhancing safe workingconditions for engine room staff. New detectiontechniques, including those that have adopted lightscatter principles, have advanced this importantsegment of engine protection technology to not onlyprovide greater speed of response to any increase inoil mist but also to virtually eliminate spuriousalarms.Improvements in the accuracy andconsistency of detection components hasadditionally provided a facility whereby smallchanges can be more readily detected, opening upthe possibility that such systems could be used fordirection condition monitoring of the plant.The AuthorBrian Smith started his own company in 1961 toprovide a range of Swiss thermometers for sale tovarious industries including diesel enginemanufacturers. In 1965 he added to this bymanufacturing electrical thermometers andpollution control instruments. At the beginning ofthe eighties he formed a company called QualityMonitoring Instruments Limited to develop aunique method of detecting oil mist The result is asystem now recognised world-wide as being theleader in that field. The current developmentprogramme includes a number of new models,with a special emphasis on detecting oil mist in theatmosphere, which can be use in intrinsically safeareas .Questions AND ANSWERSBernard A. CookT.S.E. Rollo UK Ltd.QuestionCan this device be fitted to a negative pressurecrankcase engine, e.g. the E.M.D. Detroit enginesthat operate with negative crankcase pressure andsensitive crankcase pressure sensors that can shutdown the engine?AnswerWith our system it makes no difference as the oilmist sample is taken and returned to the enginewhich keeps the negative or positive pressure inbalance. With regard to pressure sensors, there is nointeraction between the two systems.Andrew StroudWärtsilä UK LimitedQuestionCan you please confirm there is no need to carry outmaintenance other than when the monitor indicatesthis is required. From your experience, are theship's personnel able to carry out the requiredmaintenance without affecting the performance orintegrity of the device?AcknowledgmentsAnswerI would like to give my very special thanks to DavidGillespie and Andrew Stroud for all their guidanceand encouragement during the writing of the paper.My thanks are due to Rodney Smith of TestbankShip Repair & Boiler Co. Ltd., for the practicalsuggestions he made. Thanks are also due othermembers of the Institution for all their support andh

An oil mist detection system can stop damage to the engine and, most importantly injury to engine room personnel by allowing early detection of engine wear and bearing damage which could lead to an explosive environment within the engine. Oil mist detection equipment, when u