Blotter Spot Test Helps Improve Engine Reliability

8/10/2019 Blotter Spot Test Helps Improve Engine Reliability

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Blotter Spot Test Helps ImproveEngine ReliabilityThe blotter spot test dates back to the early 1950s. It is one of the oldest techniques used toidentify excessive engine soot, evaluate a lubricant s dispersancy and detect the presence ofglycol, diesel fuel and other conta!inants in diesel engine crankcase lubricants. "everaldifferent field !ethods and even sophisticated instru!ents are used to take advantage of thissi!ple technique. #or large fleet operators, this si!ple, yet po$erful technique can providevaluable infor!ation $hen used as a screening tool. In fact, this !ethod is so po$erful that%rupo #lecha &!arilla of 'eon, (exico, one of the largest transportation co!panies in(exico, found a significant reduction in catastrophic engine failures in its passenger bus fleetby integrating offsite laboratory)based oil analysis $ith onsite blotter spot testing.

#lecha &!arilla operates !ore than *,500 buses, each logging approxi!ately 500 !iles dailyunder stop)start conditions. "tandard operating procedure required changing the oil every*5,000 !iles, $hich led to about 1,500 oil changes per !onth.

The procedure also required an oil sa!ple to be taken at every oil change and sent to alaboratory for co!plete oil analysis.

+il analysis $as perfor!ed in an independent laboratory located in ouston and the results$ere delivered electronically to each service shop for trending and interpretation. Theturnaround ti!e fro! the ti!e the oil sa!ple $as collected to the ti!e analysis results $ere

received averaged 1- days. This $as !ainly due to the logistics associated $ith consolidatingthe oil sa!ples fro! different service shops and sending the! to the lab.

The oil analysis progra! delivered so!e benefits to the co!pany, alerting it to diesel fuelleaks and glycol conta!ination. It also helped the co!pany detect co!bustion proble!s andabnor!al $ear. o$ever, the !aintenance !anager $as not satisfied because he had to $aitup to *0 days to find out $hen an engine had a proble! ) all the ti!e $ith the engine inoperation. In so!e cases, the proble! !ight be present in an engine for !ore than 0,000!iles before oil analysis identified the proble!. This delay so!eti!es led to !a/or enginefailures, even though an oil analysis progra! $as in place.

To aid the !aintenance depart!ent in identifying proble!s before they caused !a/or enginefailure, a plan $as presented to refine the procedure and use the blotter spot test onsite as ascreening tool. The test $as seen as a $ay to quickly detect proble!s in the diesel enginesand as a decision tool for those engines requiring i!!ediate !aintenance inspections andcorrective action.

Dual Analysis and the Learning CurveThe strategy e!ployed by #lecha &!arilla $as si!ple. & sa!ple $as taken at each oilchange interval and $as initially pre)screened using the blotter spot !ethod see The lotter"pot (ethod, page *-2. &ny abnor!al result $as used to trigger either an exception field test

or inspection, or !ore in)depth analysis by the outside lab. "a!ples that sho$ed no initialproble! fro! the blotter spot test $ere sent to the outside lab for routine analysis #igure 12.


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Figure

&n i!portant part of i!ple!enting a successful progra! $as to co!pare the blotter spot testresults $ith data provided by the outside lab. 3henever an abnor!al oil analysis result $asflagged by the lab, !aintenance staff analy4ed the blotter spot results to try to correlate theappearance of the blotter $ith the lab data. y doing this over a period of !onths, their

!aintenance staff began to recogni4e ho$ different proble! conditions such as soot, glycoland fuel dilution identified by the lab appeared on the blotter. ventually, !aintenancepersonnel beca!e so co!fortable $ith analy4ing the test data that they could rely on theresults to !ake i!portant !aintenance decisions, $ell in advance of data being returned fro!the lab.

The Blotter Codes &bnor!al results $ere classified according to severity and a code $as created for eachcategory. This si!plified the interpretation and decision process. &lso, a reference standard$as created to help i!ple!ent the progra! in different service shops #igure *2.


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Figure !

& three)digit blotter code $as created to report results in a pseudo quantifiable fashion. Thefirst digit indicates soot load, the second fuel dilution and the third relates to glycol

conta!ination soot)fuel)glycol2. ach code has three possible categories, $hich are relatedto the observed conditions and correlated to laboratory data Table 12.

3hen results are reported, the position relates to the conta!inant or condition, $hile thenu!bers identify the proble! s severity. #or exa!ple, an oil sa!ple that indicates excessivesoot load, but is negative for fuel and glycol, $ill have a 6)1)1 result 6 soot, 1 fuel, 1 glycol2.

Cli"# Here to See Tables and !$

Chromatogram %atternsIn addition to the blotter codes, four different 4ones for each chro!atogra! $ere createdTable *27

8 ) 8enter one ) &rea $here the original oil drop $as initially deposited & ) &ureole one ) :ings for!ed outside of central 4one ; ) ;iffusion one ) &rea of diffusion of !ediu! to s!all si4e particles T ) Translucent one ) nd of the chro!atogra! base oil and diesel fuel2

The !ost frequently detected proble!s are diesel fuel dilution and excessive soot load.%lycol has been the !ost difficult to detect. o$ever, based on severe dispersancy failureand sa!ples that are thought to contain glycol, a filter inspection is ordered to confir! the

glycol leak. %lycol conta!ination is confir!ed if the filter paper is $avy and saturated $ith gel
http://media.noria.com/sites/archive_images/backup_200307_blotter-tab1-2.gifhttp://media.noria.com/sites/archive_images/backup_200307_blotter-tab1-2.gif


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or sticky !aterials, again allo$ing corrective action to be taken in advance of catastrophicfailure.

3hile the blotter spot test is not a substitute for quality, laboratory)based oil analysis, #lecha &!arilla has found that by integrating onsite blotter spot analysis $ith offsite oil analysis,i!portant insight can be gained into co!!on engine oil proble! conditions, such as excesssoot loading and dispersancy failure, fuel dilution and glycol leaks. "ince the routine blotterspot test progra! $as put into practice, no !a/or engine failures have occurred and proble!sare no$ controlled in the early stages, helping increase engine life.

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Blotter Spot Test Helps Improve Engine Reliability