STP 1491

Engine Coolant Technologies: 5thVolume

William N. Matulewicz, editor

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least one editor. The authors addressed all of the reviewers' comments to the satisfaction of both the technical editor(s) and the ASTM International Committee on Publications.

The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of the peer reviewers. In keeping with long-standing publication practices, ASTM International maintains the anonymity of the peer reviewers. The ASTM International Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM International.

Printed in Columbus, OH April,2008

ForewordThis ASTM international publication contains manuscripts from The Fifth International

Symposium on Engine Coolant Technology sponsored by ASTM Committee D15 onEngine Coolants. Held in Toronto, Canada, May 2006, this symposium provided a forumfor the presentation and exchange of information on advances in engine coolant systemcomponents, experimental testing, uses and users experience of both automotive andheavy-duty applications. These papers presented and contained in this publication,focused on areas of 1 international coolant development 2 field testing of coolantadditives 3 engine coolant recycling 4 engine component and coolant additive com-patibility 5 alternate coolant base technology 6 extended life oxidation and thermalstability 7 new testing methods of cavitation, erosion and localized corrosion. Thesepresentations offered a view of the unique and ongoing research current in engine cool-ant technology. Much of the work presented is part of continued support offered to ASTMD15 to modify existing and to establish new standards for engine coolants.

Fifth International Symposium on Engine CoolantTechnologyOpening Comments by William Matulewicz

This meeting marks my 20th anniversary in the ASTM D15 Engine Coolant Committee.I now qualify as one of the Old Guards at D15. Certainly not as high a level of Old Guard as JessStarke and Frank Duffy, who are both at the Master Old Guard level, but certainly I have beenin D15 long enough to be at the entry level of Old Guard.

When I attended my first D15 meeting I considered myself an expert in engine coolanttechnology. I was well versed in all of the ASTM D15 standards, which were all of those used inD3306, plus one or two additional standards. I knew how to formulate a high performance enginecoolant. Basically, mix ethylene glycol together with phosphate/borate, silicone/silicate, nitrate/nitrite, tolyltriazole, a little dye preferably uranine and a little antifoam. Make sure to addenough caustic to yield the proper pH and RA, balance the DEG and water content and you hada very good engine coolant.

Dont forget the 12 months/12,000 mile rule. I still love the sound of that phrase, 12months, 12,000 miles. If you turned the TV on and heard that phrase, you knew the air wasgetting crisp, the leaves were changing color and most importantly, it was time for football. Oh,and change your coolant. Thats right, back then you actually changed your own coolant.

Those were good times, all you needed to know was phosphate/borate, silicone/silicate,nitrate/nitrite, tolyltriazole, dye yellow and antifoam. Sure, I had heard that there were someexotic formulas in Europe and a TEA/borate fluid in Asia, but we didnt pay much attention.

I walked into my first meeting and soon began my education in engine coolants.Apparently there were two sides to this engine coolant coin, coolants used in trucks and coolantsused in cars. I also learned a new acronym, SCA. The truck guys actually added inhibitors toextend the service life of coolants, they did not honor the 12/12 rule.

The D15 committee was clearly divided with truck coolant on one side and car coolanton the other. The truck coolant side claimed that there was a problem with phosphate and silicate,something about inhibitor fallout, overheating, pump failures and green goo. What would youexpect from a group that does not follow the 12/12 rule? D15 eventually constructed standards forthese truck folk and established new definitions, such as, Heavy Duty and Light Duty. Both sideslearned to reach across the line, embrace each other and work together to establish D15 standards.Thank goodness for recyclers!

OK, I could live with Heavy Duty standards, but I did not see the tempest of newstandards to come in the following years. Little did D15 know that events in CT and TX weregoing to result in numerous new standards, definitions and debates.

The Lime, CT area was host to 2 historical events. The first was the disease traced backto a tick bite, hence the name Lymes disease. The second occurred at the same race track wherePaul Neuman was known to race. A race team in Lime Rock was experimenting with reversingthe coolant flow in an engine and using concentrated propylene glycol. Claims of better heattransfer, better gas mileage, better corrosion control and lower toxicity soon surfaced.

Over a number of years and much debate, D15 established standards and definitions forpropylene glycol based coolants.

At about the same time down in TX, a man with a star was promoting engine coolantsbased on an additive that is used to make monofilament fishing line. It was claimed that this newlonger, life fluid could last 30, 50 maybe even 100,000 miles. They wanted to totally trash the12/12 rule!

This sebacic acid additive, long life concept grew in popularity, caught root, and landedin D15. Long Life standards and definitions were established and continue to be established todayand include the Organic Acid Technology or OAT fluids.

By the mid-90s recycling engine coolants became a major issue in D15. Both OEM andthe States were demanding performance and chemical standards for recycled coolants. Recyclingtechnology at that time ran the gamut from passing used coolant through a machine with gaugesand blinking lights coming out the other end virtually unchanged, to add packs that raised the pH,to reverse osmosis, to distilling and then adding inhibitors and buffers.

This recycle technology led to D15 standards for recycled coolants plus a host of newdefinitions such as; Recycled Coolant, Prediluted Coolant, Recycled Ethylene Glycol and VirginEthylene Glycol.

Along the development of OAT and long life fluids, not to be confused with extendedservice fluids, it was found that blending traditional coolant technology with OAT fluids couldimprove performance. This was the start of Hybrid fluids. I have heard the term HOAT todescribe these hybrid organic acid technology fluids. I have heard the term NOAT to describenitrite containing OAT fluids and MOAT to describe mixed OAT fluids. New research is nowinvestigating developmental organic acid nitate technology, or DONT.

More standards, more research, more definitions, more challenges. Compatibility issues,oxidation stability issues, new technology issues. Being an expert in engine coolant technologyin 2006 is a little more demanding than the 1986 expertise of phosphate/borate, silicone/silicate,nitrate/nitrite, tolyltriazole, a little dye preferably uranine and a little antifoam.

But being a new member of the Old Guard at D15 I am entitled to long for days past,meetings with no cell phones or lap tops and breaks with long lines at the pay phone. Days whenblackberry was a fruit, blue tooth meant a trip to the dentist and yahoo meant you were reallyexcited.

20 years ago was a simpler time when 12 months and 12,000 miles ruled.

ContentsOverview ix

Coolant Development in AsiaH. EGAWA, Y. MORI, AND M. L. ABEL 1

Heavy Duty Diesel Engine Coolant Technology: Past, Present, and FutureH. J. DEBAUN AND F. C. ALVERSON 8

Field Test for Carboxylate Inhibitor Levels in OAT CoolantsR. J. PELLET,L. S. BARTLEY, JR. AND P. O. FRITZ 17

A Comparison of Membrane Technologies for Engine Coolant RecyclingR. HUDGENS,E. SCHMIDT, AND M. WILLIAMS 26

New Electrochemical Methods for the Evaluation of Localized Corrosion in EngineCoolantsB. YANG, F. J. MARINHO, AND A. V. GERSHUN 45

Compatibility Testing of Multi-Vehicle Coolant ChemistriesA. P. SKROBUL,S. L. BALFE, AND F. C. ALVERSON 59

Investigation of Interaction Between Coolant Formulations and Flux Loading/Compositions in Controlled Atmosphere Brazed (CAB) Aluminum Surfaces in HeatExchanger ApplicationsC. JEFFCOATE, M. RANGER, J. GRAJZL, B. YANG, P. WOYCIESJES, AND A. GERSHUN 69

Effect of Fluoride on Corrosion of Cooling System Metals in Ethylene Glycol-BasedAntifreeze/CoolantsB. YANG, A. V. GERSHUN, F. J. MARINHO, AND P. M.WOYCIESJES 77

Heavy-Duty Diesel Engine Cavitation TestG. DAVIS AND M. SARLO 87

Component Durability and High Mileage Performance of a Full Carboxylate Coolantin Heavy Duty Diesel (HDD) EnginesP. O. FRITZ, L. S. BARTLEY, JR.,R. PELLET, V. MOSER, AND C. ULABARRO 96

Cavitation Protection Performance of Nitrite-Free Organic Acid Based Coolantfor Heavy-Duty EnginesY. MORI, M. L. ABEL, AND Y. MIYAKE 109

Accelerated Oxidation and Corrosion Testing of Engine Coolants Using a RotaryPressure Vessel Oxidation TestF. C. ALVERSON, S. L. BALFE, AND A. P. SKROBUL 119

Coolants at Elevated TemperaturesS. CLAEYS AND S. LIEVENS 129

Comparison of Bench Test Methods to Elevate Heavy Duty Coolant ThermalStabilityY. CHEN, R. D. HUDGENS, AND E. R. EATON 139

vii

OverviewIn May of 2006, the ASTM D15 Committee on Engine Coolants sponsored the Fifth Interna-tional Symposium on Engine Coolant Technology in Toronto, Canada. The advances in coolantsystem components and construction continue to impact the modern automotive, heavy-duty,locomotive and free standing engine design and performance. The expanding use of lightermetals, advances in non-metallics, changes in fluid control technologies and coolant filtration intodays engines, plus advancing discoveries in EGR and fuel cell technologies in engines of thefuture are a few of the challenges facing the experts in engine coolant formulating. Challenges oftoday include extended service life, liner pitting, the impact of EGR, advances in turbo chargingand component compatibility. Research areas must consider state and local regulatory require-ments for increasing the use of recycled fluids and efforts for global standardization of testmethods.The symposium presented an open forum for the presentation of new research in modern enginecoolant formulating addressing the complex issues mentioned above. The symposium was wellattended by international technical representatives from OEM and engine coolant producers. Thepresentations were followed by open comments and questions from the attendees resulting in arobust, professional exchange of ideas.The contents of this STP are the fourteen papers presented at the Fifth International Symposiumon Engine Coolant Technology after the completion of a thorough peer review, which includedauthors/editors exchange of comments and suggested revisions, according to the guidelines ofthe ASTM Editorial Staff. These papers include current overviews of heavy duty coolant tech-nology and coolant development in Asia, new testing methods, both in field and at the bench,designed to help determine localized corrosion by electrochemistry, erosion corrosion, degrada-tion of coolant components at elevated temperatures and under accelerated oxidation, and deple-tion of corrosion inhibitor additives. Compatibility issues are also presented addressing bothmulti-fluids mixing and affects of fluid composition on engine components.I want to thank the reviewers that volunteered their valuable time to complete the critique of thepapers presented. I also wish to thank the ASTM Editorial staff for providing the guidance andexpertise that enabled the successful completion of the Fifth International Symposium on EngineCoolant Technology and the construction of this STP.

William N. MatulewiczWincom, Inc.

Blue Ash, OhioSymposium co-chairman and STP editor

ix

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SilicatEuropean/negative emance relphosphateences in ththe Asian/Jcoolants dnonamineorganic acantifreeze/coolants resulted in increased durability and a five year change interval for antifreeze/coolantsby certain car manufacturers and heavy duty truck company recommendations converting from a semian-nual antifr

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ManuscriptASTM SymW. Matulew1 CCI Corpo2 CCI Manuf

Journal of ASTM International, Vol. 4, No. 6Paper ID JAI100368

Available online at www.astm.org

Copyright 2eeze/antirust change interval to long life coolant being used 710.rganic acid technology OAT movement began in European/North American regions in theke advantage of the increased durability of the antifreeze/coolant. Development of organic acid

received January 27, 2006; accepted for publication November 7, 2006; published online July 2007. Presented atposium on Engine Coolant Technologies: 5th Volume on 17 May 2006 in Toronto, Canada;

icz, Guest Editor.ration, 12 Shin-hazama, Seki City, Gifu, Japan.acturing IL Corporation, P.O. Box 339, Lemont, IL60439.

007 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

1gawa, Yasuaki Mori, and Michael L. Abel

t Development in Asia

RACT: Historically speaking, there have always been three major regions, North America, Europe,sia, where antifreeze/coolant developments take place independently. These developments wereon the perceived needs of the engine manufacturers, influenced by governmental/regulatory authori-nd heavily influenced by the requirements geography placed upon automobile manufacturers 13.early days of ethylene glycol based engine coolants, simple inhibitor systems based on borates,

hates, etc., and utilizing a soft metal inhibitor were sufficient to satisfy the needs of a cast iron engineopper brass radiator. With the advent of aluminum engines and their rapid usage growth throughout80s and 1990s, engine manufacturers of the regions began to place more stringent requirements onticorrosion performance of the OEM coolants. Based on the specific strategies utilized by the cooling

m component manufacturers, divergent requirements began to be placed upon the coolant makeup.aper will speak generally to the regional history of coolant trends and specifically on the activity for

nt development in Asia.ORDS: coolant, automobile, engine, Asia, Japan, anticorrosion, inhibitor, technology,

num

Direction of Engine Coolant in Asia

0s European/North American regions used ethylene glycol based coolants and borate was theorrosion inhibitor for the antifreeze/coolant as cast iron engines and iron-containing components. On the other hand, in Japan, representing the Asian region, usage of borate inhibited coolanted; however, the main antifreeze/coolant became ethylene glycol based with ethanolamine, andinhibitor system coolant was adopted due to the BS3150 standard existence and the believedof aluminum metals corrosion protection by amine and phosphate versus borate as a main

. The engine antifreeze/coolant chart for each region since the 1970s is shown in Fig. 1.es were being increasingly used as an inhibitor in the 1970s to protect aluminum metals inNorth American regions. The usage of silicates was avoided in Japan due to silicates having affect on the mechanical seal material of the water pump at that time and the stability perfor-ated to gelling was an issue 5,6. Then the engine antifreeze/coolant trend became aminebased to protect aluminum, and borate usage was discontinued. This is the point when differ-e direction of inhibitor technology developed between European/North American regions andapanese region. In the late 1970s, Japanese automotive manufacturers avoided nitrite antifreeze/ue to Northern Europes Sweden countermeasure towards nitrosamine. The movement toantifreeze/coolant was due to Norways 1987 regulations on triethanolamine, thus phosphate andid salt antifreeze/coolant P-OAT were developed. The phosphate and organic acid salt

technologyprotection

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SoutheastThroughouwarm climcorrosion pof anticorr

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apparent.

ChinaThe Chinesame situacompaniescomparedindustry glogical gro

2 ENGINE COOLANT TECHNOLOGYantifreeze/coolant occurred in Japan as well; however, due to insufficient aluminum corrosionunder severe operating conditions, the OAT technology was not widely applied.2000 in Japan, the main-stream antifreeze/coolant developed and utilized is organic acid salt,hate, long-life coolant LP-OAT 11,12.

t is composed of Japanese type phosphate and organic acid salt antifreeze/coolant and European/erican type silicate/borate type coolants due to the Korean automotive industry receiving tech-assistance from auto manufacturers in all of the European/American/Japanese regions.

Asia Countriest the 1980s and into the early 1990s, water-based antirusts were mainly used due to the regionsate as the antifreeze function was not necessary. Then came the issue of cooling systemroblems apparent in the marketplace because antirust is inferior to antifreeze/coolant in the area

osion performance.late 1990s, the number of aluminum radiators increased and antirust usage was converted tocoolant which was determined to be important to maintain aluminum anticorrosion perfor-for antifreeze/coolant types, European/American/Japanese formulas are mixed in this region.

der to maintain proper dilution ratio instructed by automotive manufacturers, as well as qualityof dilution water, an increased usage of prediluted antifreeze/coolant in the marketplace is

se antifreeze/coolant market is a mixture of European/American/Japanese formulations, thetion as in Korea and Southeast Asian, due to technical assistance from parent and cooperativefrom the various worldwide regions and the historically newness of the industry in China

to European/North American/Japanese regional companies. However, the recent automotiverowth in China is rapid and well documented and it will be interesting to see what the techno-wth pattern will eventually be.

FIG. 1Current status of engine coolant.

DirectionThe Japancation JISASTM D 3testing, an

SeveraD 3306 fothe test spnarrow. Hononmetalli

Current JAntifreezemanufactubeen imprin vehicletion, and a

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The senology hasthe predomtechnology

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EGAWA ET AL. ON COOLANT DEVELOPMENT IN ASIA 3of Japanese Coolant Specificationsese antifreeze/coolant specification was established in 1965, as the Japanese Industrial Specifi- JIS K2234 13 Engine Antifreeze Coolant. The current specification is a modified version of306 14, and has typical performance as well as the glassware corrosion test, simulated service

d cast aluminum heat exchange corrosion testing.l characteristics of the specification, per Table 1, are more strict when compared to ASTMr glassware corrosion test and simulated service test, as the test solution is at 30 % volume andecimen appearance no corrosion is added and the weight change of the test specimens is morewever, it does not contain sections on cavitation durability performance and compatibility withc parts, thus these issues will be future topics.

apanese Coolant Technology/coolant development in Japan is derived from the close relationship between the automotiverer, parts supplier, and the antifreeze/coolant supplier. The antifreeze/coolant performance hasoved consistent with the objectives of the automobile company vehicle advancement, resultingweight reduction, faster warm-up to optimum engine operating temperature, less fuel consump-contribution to lower emissions.

rst major change was the nonamine antifreeze/coolant P-OAT movement of the 1990s and,important, the movement of the heavy duty truck manufacturer to the usage of long-life

coolant technology 810. The addition of phosphate and organic acid salt inhibitors as maints allowed for the increased durability of nonamine coolants. Since then, modified phosphatecoolant for the protection towards aluminum corrosion under very high temperature operatinghave improved due to new anticorrosion inhibitor formulation selections and have been neces-the engine components and heat exchanger becoming more aluminum alloy intensive.cond major recent change was that since about the year 2000 the new antifreeze/coolant tech-changed from phosphates being the dominant inhibitor component to organic acid salts beinginant component with phosphate acting as one of the supporting components resulting in thisincreasing the durability of antifreeze/coolant LP-OAT.

ong-life engine coolants LP-OAT are being used worldwide, Japan, Europe and the Americas,ver five years of actual usage in the marketplace. Not only meeting the general specifications of3306, per Tables 24, it has yielded good results in the European FVV testing method test as

TABLE 1Corrosion test in glassware.

Item JIS K2234 LLC ASTM D 3306Test Solution Concentration 30 vol % 33 vol %Specific ValueAppearance of After Test Specimen No Corrosion Weight Change, mg /cm2Copper 0.15 0.37Solder 0.30 1.12Brass 0.15 0.37Steel 0.15 0.37Cast iron 0.15 0.34Cast aluminum 0.30 1.04Weight Loss, mg/specimenCopper 4 10Solder 9 30Brass 4 10Steel 4 10Cast iron 4 10Cast aluminum 9 30Note: data have been converted.

CharacterMain comLLC whic

4 ENGINE COOLANT TECHNOLOGYistics of Coolant Technology in Japanponents of coolant in each area are shown in Table 5. In European/North American regions, OATh contains organic acids as the main inhibitor but does not contain borate, silicate, or phosphate,

TABLE 3Heat test results.

PropertyFVV R476

Specific Values LP-OAT A OAT LLCWeight loss mgG-AlSi10MgNew State/Deionized Water40 v /v % 50 max 3.3 19.9New State/10dGH20 v /v % 50 max 1.4 28.340 v /v % 50 max 2.1 36.3Aged for 120 h 100 max 5.8 70.940 v /v %GG 25New State/Deionized Water40 v /v % 20 max 9.1 6.0New State/10dGH20 v /v % 20 max 7.8 6.240 v /v % 20 max 9.1 6.8Aged for 120 h40 v /v % 40 max 13.0 9.4

TABLE 2Vibration test results.

PropertyFVV R476

Specific Values LP-OAT A OAT LLCWeight loss mg/hAlCuMg2New state20 v /v % 10.08 max 8.3 7.340 v /v % 10.08 max 7.2 8.0Aged for 120 h40 v /v % 12.60 max 10.2 8.5GG 25New state20 v /v % 5.30 max 4.1 3.240 v /v % 5.30 max 4.9 3.6Aged for 120 h40 v /v % 7.95 max 4.0 4.0

TABLE 4Corrosion test results.

PropertyFVV R476

Specific Values LP-OAT A OAT LLCWeight loss g /m2G-AlSi10Mg 10 max 1.17/1.27 2.28/2.48AlMn 8 max 1.03/0.77 3.18/3.52AlCuMg2 8 max 1.59/1.62 2.95/2.91GG 25 2 max +1.07 / +0.17 0.71/1.22Steel RRSt 14.05 2 max 0.55/0.28 0.47/0.39E-Cu 3 max 0.24/0.20 0.67/0.67CuZn 3 max 0.87/0.83 0.79/0.83Solder L-PbSn 40 Sb 6 max 1.50/1.77 2.00/2.00Note: After final cleaning Pack 1/Pack 2.

and B,Si-OOn the othcontain bophosphate

LP-OAaluminumEuropeanexcellent a

Also,level stabisee Fig. 5global coo

Technical

The worlddevelopedantifreeze/turer can utive manu

Last bSustainabias concern

technology

ComponentOrganic acidPhosphateBorateSilicateTriazoleNitrateNitrite

Note: OOCo

EGAWA ET AL. ON COOLANT DEVELOPMENT IN ASIA 5AT which contains organic acids, borate, and silicate are used most prevalently by the OEM.er hand, in Japan, P-OAT and LP-OAT which contain organic acids and phosphate but do notrate and silicate are typically used, as it is a characteristic for coolants in Japan to contain

.T have not only superior durability see Fig. 2 but also excellent anticorrosive property againstdue to suitable selection and quantity of organic acids and phosphate. Test results of the

evaluation method CEC C-23 Dynamic Corrosion Test are shown in Figs. 3 and 4. LP-OAT hasnticorrosive property against aluminum when compared to P-OAT and OAT LLC.the latest generation of Japanese antifreeze/coolant technology, even while containing a lowlized phosphate inhibitor, gives excellent results in the GFC L-106-A-90 hard water stability test. Therefore, LP-OAT that was developed utilizing the latest Japanese coolant technology is alant that is being used, without reservation, all over the world.

Direction of Next Generation Coolant

automotive manufacturers are consolidating engines and platforms and utilizing architecturein one region throughout their globalized distribution system and the next generation of

coolant will be an antifreeze/coolant that possesses performance that any automotive manufac-se. Such antifreeze/coolant will be influenced by local/regional regulations as well as automo-

facturers specification.ut not least, automotive manufacturers will be influenced by LOHAS Lifestyles of Health andlity consumers; such consumers will be more demanding and not settle for current technology,

for the environment has increased. As a result, automotive manufacturers will bring newvehicles for the new world and new long-life coolant must be developed with new technology.

TABLE 5Main components of currently used coolants.Japan USA Europe

LP-OAT P-OAT OATB,Si-OAT B,Si-AF OAT

B,Si-OAT

OO O OO O OO OO OO O O O O O O OO O O O O O O

O O O O O O O O O O

ntained as a Main Component; OContained;; Not Used.

FIG. 2Aging tendency of LLCs.

Reference

1 LieSAE

2 Duf3 Shi

corr

4 KawEng

5 KirCooEng

6 HerPap

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8 HarTru

6 ENGINE COOLANT TECHNOLOGYs

bold, G. A., Meszaros, L. L., and Schmidt, H. H., European Automotive Coolant Technology,Tech. Pap. Ser., No. 900430, 1990.

fey, F. R., The Status of U.S. Coolant Standards, SAE Tech. Pap. Ser., No. 900431, 1990.otani, E., Overseas present conditions of coolants and brake fluids and the trend of metalosion tests. Bosei Kanri, Vol. 35, No. 10, 1991, pp. 357366.amoto, S., and Suzuki, H., The Problems of Using Anti-Freeze and Anti-Rust in Aluminum

ines, Bosei Kanri, No. 3, 1974, pp. 2127.yu, K., Tsuchiya, K., Shimomura, T., Yanai, T., Okada, K., and Hirabayashi, H., The Effect oflant Additives and Seal Composition on Performance of Water Pump Seals of Automotiveines, SAE Tech. Pap. Ser., No. 890609, 1989.camp, R. D., Silicate Galation in Heavy-Duty Diesel Engine Cooling Systems, SAE Tech.. Ser., No. 852327, 1985.uchi, M., and Tajima, H., Development of Coolant for Heavy Duty Vehicle, Jidosha Gijutsu,. 42, No. 4, 1988, pp. 471477.a, H., Kishi, Y., and Miyamoto, T., Development of Non-Amine-Type Long Life Coolant forck and Bus, Mitsubishi Motors Corporation Technical Review, Vol. 1, 1988, pp. 110119.

FIG. 3Dynamic corrosion test results.

FIG. 4Appearance of test specimen (cast aluminum) after chemical treatment.

FIG. 5Appearance of after hard water compatibility test.

9 HasCooSyu

10 TanJido

11 OsaLow

12 NisLon

13 JIS14 AST

Lig

EGAWA ET AL. ON COOLANT DEVELOPMENT IN ASIA 7himoto, T., Nishizawa, Y., Kuwamura, I., Taniai, M., and Koide, H., Development of Long Lifelant for Heavy-Duty Commercial Vehicles, Jidosha Gijutsu Kai Gakujutsu Kouen Kai Maezuri, Vol. 10, No. 902136, 1990, pp. 11491152.ge, K., Ishiura, T., and Ashikawa, R., Durability Evaluation of Coolant for Automobile,sha Gijutsu, Vol. 45, No. 6, 1991, pp. 8691.wa, M., Morita, Y., and Nagashima, T., A Study of Extension of Engine Coolant Life Using

Phosphate Organic Acid Inhibitors, SAE Tech. Pap. Ser., No. 2003-01-2023, 2003.hii, M., Arai, H., Nakada, T., and Tami, H., A Study of Anticorrosive Technology in Superg Life Coolant, SAE Tech. Pap. Ser., No. 2004-01-0055, 2004.K2234-1994, LLC.M, D 3306, Standard Specification for Glycol Base Engine Coolant for Automobile and

ht-Duty Service, Vol. 15.05, ASTM International, West Conshohocken, PA.

Heather J 1 2

HeavyPresen

ABSTcreasdesigemisspactemetaltempeity, ancoolaimpropaperperforand nKEYWcorroscoola

Introduct

Diesel engbeing drivreliability.injection,greater thebeen as siengine spepaper willcooling sy

Modern D

Emission Compliant EquipmentIn 2002, hoxides NOmeet theselation EGthe turboc

In mecoolers are

Manuscript rASTM SymEditor.1 Senior Proj2 Coolant Ad

Journal of ASTM International, Vol. 4, No. 1Paper ID JAI100336

Available online at www.astm.org

Copyright 2eavy duty diesel engine manufacturers were faced to meet lower emissions standards for nitrousx and hydrocarbons. The NOx regulation lowered from 4 to 2 g /bhp-h Fig. 1. In order toregulations, most engine manufacturers have employed the use of cooled exhaust gas recircu-

R because it offers better fuel economy than retarded timing 1. The exhaust gas is cooled andharger boost pressures must increase to increase the air into the cylinder.eting the lower NOx requirements, the recirculated exhaust gas is cooled. Stainless steel EGR

used to cool the exhaust gas with engine coolant. The use of EGR involves diluting the air/fuel

eceived June 8, 2006; accepted for publication October 19, 2006; published online November 2006. Presented atposium on Engine Coolant Technologies: 5th Volume on 17 May 2006 in Toronto, Canada; W. Matulewicz, Guest

ect Engineer, International Truck and Engine Corporation, 10400 West North Avenue, Melrose Park, IL 60160.visor, Shell Global Solutions, 3333 Highway 6 South, Houston, TX 77082.

007 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

8. DeBaun and Fred C. Alverson

Duty Diesel Engine Coolant Technology: Past,t, and Future

RACT: Significant advances have been made in heavy duty diesel engine technology to meet in-ingly stringent environmental regulations for emissions. Todays heavy duty diesel engines are beingned with lighter and softer metals, greater turbocharging, increased combustion controls, and newion reduction equipment. The cooling systems contained in these vehicles are similarly being im-d by smaller designs, new cooling system configurations, and increased usage of lighter, softers. Vehicle thermal loads have significantly increased due to increased power densities, higher engineratures, and greater metal-coolant fluxes which places greater emphasis on oxidation/thermal stabil-d high temperature corrosion protection performance of the coolant. Other operating conditionsnt flow rates, turbulence, pressure drops, deaeration are also becoming more severe calling forved erosion-corrosion protection, cavitation protection, and elastomer, seal, hose compatibility. Thisreviews the changes in heavy duty diesel engine technology and provides information on coolant

mance in 2002-4 emission compliant engines. Predictions are also made on future engine technologyext generation engine coolants.ORDS: heavy duty engine coolants, cooling system trends, oxidation stability, erosionion, cavitation, elastomer compatibility, traditional fully-formulated coolants, extended service

nts, extended life coolants, supplemental coolant additives

ion

ines continue to be the work horse engines of industry. Advances in diesel engine technology areen by needs for increased power, emission reductions, improved fuel economy, and longerTodays modern diesel engines include turbochargers with intercoolers, electronic timed fuelcomputerized combustion controls, and emission reduction equipment which are all placingrmal loads on the coolant. Recent advances in engine cooling and the cooling system have notgnificant. The cooling system still utilizes an engine-driven water pump and fan controlled byed r/min and a mechanical thermostat controlled by radiator bulk coolant temperature. Thisreview some of the changes in heavy duty diesel engine technology and the impacts on the

stem and coolant along with future trends in the cooling system and coolant technology.

iesel Engines

mixture engas lowersformation325F wh2535 %radiator sitemperaturcoolant lif

Cooling SThe OEMsheat loadson the radclutches, iefficient hmetals witsofter met

Overato furthertemperaturthe cylindtransfer is

In addconfiguratit more di

DEBAUN AND ALVERSON ON HEAVY DUTY DIESEL TECHNOLOGY 9tering the engine with a small amount of exhaust gas 515 % . The addition of the exhaustthe oxygen content and lowers the combustion temperature which reduces the high temperature

of NOx. The EGR cooler uses the engine coolant to cool the exhaust gas down from 1300 toich results in significant heat rejection to the coolant. Heat rejection of the coolant increases by2 due to the cooling of exhaust gas. In some cases, bulk coolant temperatures increase ifze cannot be increased in order to make up for increased coolant heat rejection. The highes in the EGR cooler led to localized boiling, increased degradation of the coolant, and reducede.

ystem Changesand cooling system component suppliers are using multiple approaches to handle the increased

on the coolant including increasing the boiling point of the coolant by raising the pressure limitiator cap 7 to 10 psi and higher in some applications, using higher performance fans and fanncreasing water pump size or speeds, or both i.e., coolant flow rates, and using larger and moreeat exchangers. With regard to heat exchangers, the trend is toward the use of lighter, softerh narrower clearances/tolerances that improve heat transfer efficiency. The use of the lighter,als often have maximum flow rate limitations which must be considered during system design.ll bulk coolant temperatures have risen to meet the 2004 emission requirements and are expectedincrease to meet 20072010 emission regulations Fig. 2. Along with the overall bulk coolante rise, the coolant is exposed to significantly high metal-coolant heat fluxes in regions around

er heads and liners, and exhaust gas recirculation if equipped. In some of these regions, heataccomplished by nucleate boiling which places additional stress and demands on the coolant.ition to the increased thermal loads on the coolant, the newer engine designs, under the hoodions, and severe operating conditions of higher water pump speeds/coolant flow rates are makingfficult to achieve satisfactory deaeration of the coolant. Residual air bubbles in the cooling

FIG. 1U.S. emissions regulations.

FIG. 2Heat rejection history [3].

system cosystems an

Charge Ai

Diesel enguse of a turesulting iair-to-liquicombustiocoolant. Funder the

Direct Fue

Todays dideliver preof sensorselectronicand fewervolume du

Auxiliary

The additiheat loadsengine cootemperaturAutomaticadditionaloperation.soaking ofcoolant selowered to

Elastomer

Elastomercooling syNBR, hypropyleneperformanpropylenemay formcoolant innitrite, nitcoolant co

The mtures, greacoolant lifcooler or wcan plug tfailure, or

Theretemperaturfield probl

10 ENGINE COOLANT TECHNOLOGYntribute to oxidation and thermal degradation of the coolant. Vehicle and engine deaerationd characteristics must also be taken into consideration during cooling system design.

r Coolers

ine OEMs are achieving higher power through the use of turbochargers or superchargers. Therbocharger allows more air to be forced into the engine which allows more fuel to be burned

n increased power. To achieve even more power, the air may be cooled through an air-to-air ord charge air intercooler which increases the density and makes more oxygen available forn. For air-to-liquid charge air intercoolers, the intercooler adds an additional thermal load on theor air-to-air charge air intercoolers, the challenge is locating and achieving sufficient air flowhood without adversely affecting air flow for the radiator 4.

l Injection and Combustion Controlesel engines inject the fuel directly into the cylinders using engine control modules ECMs thatcisely the right amount of fuel when needed. The ECM communicates with an elaborate arrayplaced at strategic locations to monitor engine speed to coolant and oil temperatures. The

controls mean that the fuel burns more thoroughly, delivers more power, greater fuel economy,emissions 5. With regards to engine cooling, the increase in power output for given cylinderring combustion results in increased heat rejection to the coolant.

Equipment

on of auxiliary equipment air conditioning, transmissions, oil coolers, etc. is also increasingon the engine coolant. The air conditioning compressor adds an additional thermal load onling, particularly under heavy load and idle conditions. Transmissions are operating at higheres resulting in additional heat rejection to the coolant through the transmission fluid cooler.transmissions with torque converters used in bus applications and package van service place

heat rejection requirements on the coolant due to significant energy loss heat generation duringIn addition, these vehicles may operate with numerous starts and stops, often resulting in hotthe coolant which raises the coolant temperature and can cause boiling. In some cases, engine

rvice intervals for extended life and extended service coolants used in these vehicles are beingautomotive service intervals.

s, Seals, and Hoses

s, seals, and hoses are extremely important since they are widely used throughout the engine andstem. Common elastomer materials used in the engine and cooling system include nitrile rubberdrogenated nitrile rubber HNBR, ethylene propylene terpolymer EPDM, tetrafluoroethylene-copolymer FEPM, and silicone. Previous studies have been conducted on comparing the

ce of these materials in laboratory aging studies 6. In one study on ethylene glycol andglycol-based coolants containing silicates, it was shown that significant amounts of precipitatewhich may represent leached hose components or destabilization of the silicate from hose andteractions, or both 7. A recent study conducted on a hybrid OAT coolant containing borate,rate, and silicate with three different EPDM sulfur-cured hose materials in a plugged hose-mpatibility test at 168 h at 104C 220F showed similar test results Table 1.ore severe operating conditions higher coolant temperatures, higher under the hood tempera-ter amount of hot regions in the engine may be having effects on both elastomer/hose ande. In some cases where coolant passages are extremely narrow almost filter size such as oilater pump seal faces, or both, hose-coolant interaction products or other contaminants, or both,

he passages resulting in reduced heat transfer, severe oxidation of the coolant, or equipmenta combination thereof.also have been some problems in the field with certain engines containing silicone seals in highe regions using OAT-based coolants which resulted in loss of compression set and leakage. Theems were corrected by the addition of a silicate field fix or change in elastomer seal material, or

both. Addito extend

Impacts o

The morean impactpredominacoolants acontainedcoolant adextended lthe world,there is leUnited Sta

Engineoxidation-

DEBAUN AND ALVERSON ON HEAVY DUTY DIESEL TECHNOLOGY 11tional cooperative work is required between the OEM, elastomer supplier, and coolant supplierthe temperature limitations of elastomers and to improve coolant and elastomer compatibility.

n the Engine Coolantsevere operating conditions and environments in which heavy duty diesel engines operate haveon coolant formulations and performance. Ethylene glycol-based engine coolants are still thently used heat transfer fluid for heavy duty applications. Several different types of enginere used in heavy duty applications, which may be classified by the type of corrosion inhibitorsin the formulation. In the United States, conventional coolants with the addition of supplementalditives SCAs, traditional fully formulated coolants, extended service interval coolants, andife coolants are all used in heavy duty applications. In Europe, Asia Pacific, and other parts ofconventional, hybrid, and extended life coolants are used in heavy duty applications. However,

ss distinction between light duty and heavy duty coolants and less usage of SCAs outside thetes. A description of the various types of heavy duty HD coolants is provided in Table 2.coolants used in heavy duty applications must provide satisfactory performance in the areas of

thermal stability, high temperature corrosion protection, cavitation corrosion protection, erosion-

TABLE 1Plugged hose-coolant compatibility results.

Coolant Result New Hose 1 Hose 2 Hose 3Sediment, vol % Nil 1.6 1.6 2.0pH 8.1 7.8 7.8 8.0Silicon, ppm 130 51 48 51Sulfate, ppm Nil 325 335 370Oxidation, ppm Nil 170 120 130Zinc, ppm Nil 15 55 13

TABLE 2Type of HD engine coolants.Conventional coolant Contains inorganic corrosion inhibitors such as

borate, molybdate, nitrate, nitrite, phosphate, silicate.In Europe, phosphate is generally not used due topotential hard water compatibility problems. In Asia,silicates are generally not used due to gel and waterpump seal abrasion concerns.

HD Extended lifecoolant

An engine coolant containing OAT providing longservice life. These products may contain nitrites ormolybdate, or both, and may be refortifiedwith an extender at typical service intervals of300 000 miles or longer.

HD Extended serviceinterval coolant

An engine coolant also providing extended servicelife. SCAs are typically added at 100 000150 000mile intervals.

Hybrid coolant An engine coolant containing a combination ofinorganic and organic corrosion inhibitors. Europehybrids are phosphate free. Asia hybrids are silicatefree.

Organic AdditiveTechnology OAT

Any group of carboxylic acids including aliphaticmono and diacids and aromatic acids applicable ascorrosion inhibitors in coolants.

Supplemental CoolantAdditive SCA

A chemical additive that is periodically added to thecoolant to maintain protection against generalcorrosion, cylinder liner pitting, and scaling in heavyduty engines.

Traditional fullyformulated coolant

A conventional coolant containing an initial dosageof SCA. These coolants require periodic addition ofSCAs typically at 20 000 mile 32 000 kmintervals.

corrosionnondepletiengine tec

OxidationSince engiwhich invHO-CH2-Csuch as noxidationtemperaturtodays en

A signemission cmore rapidused coolathat traditiing satisfaengines w

With rblack coolnewer vehUsed coolstressing apotentialcorrosionhigh temp

12 ENGINE COOLANT TECHNOLOGYprotection, elastomer compatibility, hard water stability, anti-scaling properties, and preferablyng coolant chemistry. As discussed in the preceding paragraphs, the advances in heavy dutyhnology are placing greater demands on the coolant in all of these performance areas.

-thermal Stabilityne coolants are hydrocarbon based, the ethylene glycol-based fluid is susceptible to oxidationolves reaction of ethylene glycol with oxygen to form glycol degradation acids glycolic acid:OOH, formic acid: HCOOH, oxalic acid: HOOCCOOH, etc.. Certain additives in coolants

itrites, which are used to protect cast iron/cylinder liners from corrosion, may also undergoto form nitrates. The increased thermal loading and more severe operating conditions higheres, aeration, pressure, and any cooling system contaminants/corrosion metals occurring ingines are factors that can accelerate oxidation and shorten coolant life.ificant amount of test data has been generated on engine coolant performance in 20022004ompliant engines. In the case of EGR equipped engines, the used coolant data show slightlypH decline, more rapid nitrite reduction, and increased glycolate formation rates compared to

nt data obtained from similar non-EGR engines Figs. 3 and 4. The overall test results indicateonal fully formulated, extended service interval and extended life coolants overall are perform-ctorily with only minimal impacts on oxidation and coolant life. It is anticipated that 20072010ill require increased oxidation and thermal stability.egards to oxidation stability, there also have been some sporadic incidents in the field involvingant and engine failures. Reports indicate that the incidents have occurred in both older andicles/engines with and without emission compliant technologies using a variety of coolants.

ant and failure analyses have often indicated that the failure mechanism includes severe thermalnd oxidation of the coolant. Additional investigation into root causes has indicated a variety ofcontributing factors may be involved including poor maintenance coolant concentrations/inhibitor levels/SCA dosages, mechanical problems, or abnormal operating conditions, or botheratures, hot spots, aeration, etc..

FIG. 3Engine coolant nitrite results.

FIG. 4Engine coolant pH results.

CavitationProtectionimportancthe coolancylinder wthe surfaceanti-thrusteroding thcylinder lidesign mabased upoengine coofactory co

Enginelife coolancorrosionconditionsextended slife OATcavitationengine app

Anti-scalinScale resuagents canstudies repcan signifiaround the9. Scalealso acceleconsideredand prope

Erosion-CErosion-coaluminumoperatingexcessivenaturally pcritical orvelocity, cvanic effeattack. Eroalloy oil cbeen resola combina

DEBAUN AND ALVERSON ON HEAVY DUTY DIESEL TECHNOLOGY 13of wet cylinder liners against cavitation corrosion liner pitting continues to be of paramounte with diesel engines. Liner pitting is the result of cavitation and erosion processes that occur ont side of the cylinder liner. Cylinder liners vibrate from the motion of the piston within thehich can cause low pressure regions of the fluid causing vapor bubbles to form and collapse onof the liner. The repetitive formation and collapsing of the bubbles generally on the thrust orside, or both, of the cylinder impinge on the metal surface, removing protective films and

e metal. Previously published work provides an extensive overview of cavitation corrosion ofners and its prevention which can be reduced by good coolant maintenance practices, engine andterials to minimize vibration, and cooling system design 8. A heavy duty engine cavitation testn an internal John Deere cavitation test is being considered for adoption as a standard ASTMlant cavitation test. The test has been shown to discriminate between satisfactory and unsatis-

olants with regard to cavitation erosion-corrosion protection.coolants conventional, traditional fully-formulated, extended service interval, and extended

ts along with SCAs have commonly used nitrites or a combination of nitrites and molybdateinhibitors, or both, for cylinder liner corrosion protection. In view of the more severe operating

which can contribute to more rapid nitrite depletion, it is anticipated that extended life orervice nitrite free coolants, or both, will be used to a greater extent in diesel engines. Extendedcoolants that are nitrite free have shown satisfactory performance in the heavy duty enginetest formerly the John Deere cavitation test and have been used satisfactorily in almost alllications in the field.

g Performancelting from the use of hard water, cooling system contaminants, and corrosion inhibiting filmblock the ability to transfer heat resulting in overheating and metal fatigue failures. Previous

orted that scale layers in the range of 0.01 to 0.05 in. 0.254 to 0.127 cm on the metal surfacecantly retard heat transfer and increase metal surface temperatures 100200F /3893Chead or upper part of the cylinder liner depending on conditions of heat flux and coolant flow

tends to form in specific areas of the hot side of the engine resulting in localized hot spots, whichrate oxidation degradation of the coolant. The hot scale and deposits 9 test is currently beingfor establishment as a formal ASTM method for engine coolants. The use of good quality water

rly inhibited coolants minimizes these deposits.

orrosionrrosion protection is becoming more important in view of the increased use of soft metals, copper, and lead in various engine and cooling system components and the more severe

conditions of higher coolant flow rates. Erosion-corrosion is typically caused or accelerated byflow conditions which generate shear forces sufficient to remove corrosion passivating films orrotective oxides, or both. Erosion-corrosion is most prevalent with soft metals which havelimiting flow velocities Table 3 provides several examples which above the critical flow

orrosion rapidly accelerates. Other factors including turbulence, cavitation, impingement, gal-cts, and abrasive contaminants casting sand, machining debris can add to the severity of thesion-corrosion problems have been observed in the field with brass fuel injector cups, aluminumoolers, and aluminum heater cores with several different types of coolants. The problems haveved by changes in metallurgy, addition of flow restrictors, or cooling system design changes, ortion thereof.

TABLE 3Metal flow rate limits [10].Metal Flow Rate LimitIron component 33 ft /sGeneral soft metal alloy 15 ft /sAluminum heat exchange tube 79 ft /s

Enginestudy wasan aluminthat at thesion of nitnum to fo

Future Tr

Diesel engmeet moreengine maogy and aparticulate

The 20utilize moefficiencieto achieve2002 emis

14 ENGINE COOLANT TECHNOLOGYcoolant chemistry can also influence erosion-corrosion protection. A recent erosion-corrosionconducted on two different commercially available coolants containing nitrite and molybdate inum alloy oil cooler module at elevated flow conditions 30 gpm. The results Figs. 57 showelevated flow conditions, the aluminum surface may become unpassivated resulting in conver-rite to ammonia which increases the coolant pH and further accelerates the corrosion of alumi-rm aluminate corrosion metals which are soluble in the coolant.

ends

ine OEMs are conducting extensive research on various technologies to reduce emissions tostringent 2007 and 2010 environmental regulations for NOx and particulate matter PM. The

nufacturers anticipate meeting these limits through a combination of changes in engine technol-dditional emission reduction equipment, particularly heavy EGR to reduce NOx and dieselfilters to reduce PM.07 emissions regulations will require the use of lower sulfur fuels which may require OEMs tore sophisticated fuel systems. Some engines will be utilizing dual turbochargers for betters. Larger EGR coolers or dual EGR coolers will be required to lower combustion temperatureslower NOx. EGR levels are expected to significantly increase from the levels used to meet thesions, possibly increasing heat rejection by an additional 25 %. The higher levels of EGR may

FIG. 5Erosion-corrosion studypH effects.

FIG. 6Erosion-corrosion studynitrite conversion.

cause an iincrease thto requireistries.

Dieselcoolant, bufrom the dincrease aNOx emis

The emwill be useto reject hdouble EGcooling sy

It is albe incorpobenefits inelectric puElectric vatures thanto the higadded to tsystem wicooling, em

Laboraboth, provcoolant aninterval cosuppliers wcapabilitietomers. Rebiodegradafor its imp

EngineCurrent ennanotechn

DEBAUN AND ALVERSON ON HEAVY DUTY DIESEL TECHNOLOGY 15ncrease in coolant temperatures, localized boiling, and high skin temperatures. All of these wille stress on the coolant and decrease the life of the coolant. The use of higher EGR is expectedimprovements in coolant oxidation/thermal stability and nondepleting corrosion inhibitor chem-

particulate filters will be used to lower the PM emissions. The filter itself will not impact thet may cause additional stress by modifying the way the engine runs. If the burning of the sootiesel particulate filter is through the cylinder post injection of fuel, cylinder temperatures will

nd coolant stresses will increase. The use of selective catalytic reduction technology to reducesions may reduce the load on EGR which will lessen the thermal load to the coolant.

ission reduction technologies will impact coolants and cooling systems. Larger water pumpsd to supply higher coolant flow due to higher power requirements. Larger radiators will be used

igher heat loads. Crankcase water jackets may be changed to handle higher pressures. Larger orR coolers will be needed due to higher EGR rates. Lighter, softer metals are being used instems, and specifically, aluminum is being used more widely for cooling systems.so anticipated that advanced modular thermal systems electric water pumps, valves, fans willrated into vehicles. The use of electric water pumps in place of conventional pumps will providedelivering the correct amount of coolant from cold start-up to high operating temperatures. Themp will also eliminate hot soak after shutdown by circulating coolant through the engine.lves may be used to provide more precise temperature control of coolant and engine tempera-conventional thermostats. The use of a single electrical fan may not currently be practical dueh power consumption required for operation. However, small auxiliary electric fans may behe cooling system to achieve more efficient cooling over a single mechanical fan. The coolingll also include computer controls to accurately control the temperatures for the primary engine

ission equipment, transmission, engine oil, and charge air cooler.tory and field data indicate that extended life coolants or extended service interval coolants, oride performance benefits in terms of oxidation-thermal stability which translates to longerd reduced usage of SCAs. It is anticipated that the usage of extended life and extended serviceolants will displace conventional and traditional fully-formulated coolants. In addition, coolantill develop truly next generation coolant technology that provides greater high temperature

s, is effective under high flow conditions, and possesses improved compatibility with elas-garding base fluids, propylene glycol 1,2-Propanediol may be used to a greater extent for thebility and toxicogical benefits. 1,3-Propanediol PDO is currently receiving significant interestroved oxidation and thermal stability.coolants in the far future are expected to provide significantly greater heat transfer properties.

gine coolants rely primarily on the water concentration/dilution for heat transfer. The use ofology particles of 5 nm size dispersed in aqueous medium exhibits significantly greater

FIG. 7Erosion-corrosion studyaluminum corrosion metals.

thermal coemergingheat transffluids mayThe use osystem de

Acknowled

The authoMr. Josepassistance

Reference

1 Nee199

2 McRec

3 Olslatio

4 Chailiar

5 JuRen

6 BusMoEd.

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8 HerTestPA,

9 Chein HBea

10 Tec0-6

16 ENGINE COOLANT TECHNOLOGYnductivities allowing more rapid heat transfer. Ionic fluids are a new class of fluids that areto replace organic solvents commonly used in chemical processing, cleaning, electrolyte, ander fluid applications. Ionic fluids are organic salts with melting points of less than 100C. Ionicbe used to reduce or replace glycol, or both, which would also improve heat transfer properties.

f nanotechnology or ionic fluids, or both, may require or allow significant changes in coolingsign, components, and materials.

gments

rs wish to thank Mr. Stede Granger and Mr. James Roberts, with Shell Oil Products U.S., andh Hill and Ms. Andrea McCoy, with International Truck and Engine Corporation, for theirand insight on coolant performance in todays heavy duty diesel engines.

s

dham, J. R., Doyle, D. M., and Nicol, A. J., The Low NOx Truck Engine, SAE paper 910731,1.Geehan, J. A., API: CI-4: The First Oil Category for Diesel Engines Using Cooled Exhaust Gasirculation, SAE paper 2002-01-1673.on, G. D., Vehicle Integration/Thermal Management as Result of 2007 Diesel Emissions Regu-ns, Society of Automotive Engineers Panel.llen, B. and Baranescu, R., Diesel Engine Reference BookSecond Edition; Chapter 15 Aux-ies, Thermal Loading, Society of Automotive Engineers, Warrendale, PA, 1999, 408pp.

st the Basics: Diesel Engine, U.S. Department of Energy, Office of Energy Efficiency andewable Energy.sem, H., Farinella, A. C., and Hertz, D. L., Jr., Long-Term Serviceability of Elastomers indern Engine Coolants, Engine Coolant Testing: Fourth Volume, ASTM STP 1335, R. E. Beal,, ASTM International, West Conshohocken, PA, 1999, pp. 142180.aney, J. P. and Smith, R. A., Engine Coolant Compatibility with the Nonmetals Found inomotive Cooling Systems Engine Coolant Testing: Fourth Volume, ASTM STP 1335, R. E.l, Ed., ASTM International, West Conshohocken, PA, 1999, pp. 168181.camp, R. D., An Overview of Cavitation Corrosion of Diesel Cylinder Liners, Engine Coolanting: Third Volume, ASTM STP 1192, R. E. Beal, Ed., ASTM International, West Conshohocken,1993, pp. 107127.n, Y. S., Kershisnik, E. I., Hudgens, R. D., Corbeels, C. L., and Zehr, R. L., Scale and Depositsigh-Heat Rejection Engines, Engine Coolant Testing: Fourth Volume, ASTM STP 1335, R. E.

l, Ed., ASTM International, West Conshohocken, PA, 1999, pp. 210228.hnology Transfer Systems, Inc., Impingement Corrosion, Engine Coolants, ISBN 0-9720927-, Technology Transfer Systems, Inc., Livonia, MI, 2002, 55 pp.

Regis J. P 1 2 2

Field T

ABSTinhibicarboVarioufield.test fdiscuKEYW

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Manuscript rat ASTM Symposium on Engine Coolant Technologies: 5th Volume on 17 May 2006 in Toronto, Canada; W. Matulewicz, GuestEditor.1 Senior Staf2 Chevron C

Journal of ASTM International, Vol. 4, No. 2Paper ID JAI100510

Available online at www.astm.org

Copyright 2f Chemist, Chevron Corporation, New Windsor, NY 12553.orporation, New Windsor, NY 12553.

007 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

17ellet, Leonard S. Bartley, Jr., and Paul O. Fritz

est for Carboxylate Inhibitor Levels in OAT Coolants

RACT: Wet chemistry test methods have been developed to determine the level of alkyl carboxylatetion remaining in used OAT coolants. The test strategy of these methods depends on the known alkylxylate ability to protect cooling system metals such as aluminum by forming insoluble metal soaps.s test configurations make this test strategy suitable for the rapid analysis of used coolants in the

This paper will document the initial test strategies and the development efforts that led to the first fieldor alkyl carboxylate-based coolants. Test kit performance with laboratory and field samples is alsossed.

ORDS: coolant, field test, organic additive technology, carboxylate, inhibitor

ionoperation, a heavy duty diesel engine can generate sufficient heat to warm five single familyinter. Only about 33 % of this heat is converted into crankshaft horsepower. In the past, it was

that 30 % of the heat generated was expelled through exhaust and 7 % was radiated directly intohere. This left about 30 % to be carried away by the cooling system. The amount of heatby the coolant has risen significantly since exhaust gas recirculation EGR was introduced byine manufacturers in 2002 in order to control emissions. In addition to removing heat generated

mbustion, the cooling system must also remove heat generated by other components such as theon and turbo charger.se of the severity of diesel engine operation and the stress that it places on the cooling system,ially important that coolant properties are routinely monitored to assure proper protection ofstem components and the engine itself. Moreover, rapid testing in the field is essential if neededs are to be made before damage occurs. At present there is an array of tests available toif coolant freeze and boil protection are adequate and if the coolants corrosion inhibition isto protect the engine components from damage. In addition there are tests to detect thermaln and contamination with aggressive agents.point is easily measured using a refractometer. Freeze point test strips are also available but can

hat less reliable than the refractometer due to interferences caused by the coolants color.ss reliable method for freeze point determination is the hydrometer which is significantlyby coolant temperature and by the possible mixing of ethylene glycol and propylene glycol

lants 1.t degradation can be followed to some extent by monitoring the coolant pH. pH test strips areovering the pH range from 612. These strips use multiple acid-base indicators to cover thise of interest 2,3. Coolant degradation and specifically glycol breakdown create acid decom-

roducts such as formic, glycolic, and oxalic acids which cause the coolants pH to drop. If theallowed to become acidic, inhibition becomes ineffective and corrosion damage will occur.

g coolant pH is a quick way to detect the possibility of thermal degradation in the field.d pH drop may also be caused by exhaust gas entry into the cooling system. Exhaust gas cancooling system through leaking head gaskets, for example. In addition to a rapid pH drop,s in the coolant may also be indicated by the presence of elevated levels of sulfate. There are test

eceived February 24, 2006; accepted for publication December 13, 2006; published online February 2007. Presented

strips avaisoluble bairreversiblby compar

Tests finhibitorscaused bytection; suliner proteInitially, nwise to aproduce thwas foundquently innitrite withamine also

With tcooling sycarboxylattion but th

OAT crequire frecoolant tecance with

Nonetresult in dover-diluticonditiontional cooladequate cwere limit

Shortlmine the lesamples, irapid analhas subseqsimplifiedfor the ear

ExperimeThe organon the alkin a nitritversion co

Metal Ion/Solubilityaluminumin 50/50 wwere preseAfter mixithen cooleplasma IC

18 ENGINE COOLANT TECHNOLOGYlable to rapidly determine sulfate levels. The test method uses a test pad, impregnated with arium salt and colored chelating agent. Sulfates in the coolant solutions will react with bariumy, removing it from the chelating agent and changing the pad color. Sulfate level is determineding pad color to a standard set of colors provided for that purpose 3.or corrosion inhibition focus on coolant nitrite or molybdate levels, or both. These two corrosionare present in most heavy duty coolants to protect the engines cylinder liners against damageliner cavitation. Nitrite, and to a lesser extent molybdate, are consumed as they provide pro-pplemental coolant additives SCAs are routinely added to the coolant to maintain adequatection. Routine testing is necessary to assure that effective refortification SCAs is occurring.itrite levels were determined using a wet-chemistry test, where cerous sulfate was added drop-test coolant until a color change from red to blue occurred; the number of drops needed toe color change was related to the coolants nitrite level 4. The presence of organic componentsto interfere with this test and a test strip method for both nitrite and molybdate was subse-

troduced in 1988 5. With the strip, nitrite levels were estimated colorimetrically by reactingsulfonamide in the test pad to produce a diazo compound which was reacted with an aromaticpresent in the pad to produce an azo dye 5. Pad color is related to nitrite level.

he advent of organic additive technology OAT in the U.S. in 1994, an alternate way to protectstem components, including cylinder liners became available. Organic additive coolants rely one corrosion inhibitors to provide protection; nitrites may also be present for added liner protec-e primary line of defense is provided by carboxylic salts 6.orrosion inhibition, provided by alkyl carboxylate salts, depletes quite slowly and so does notquent refortification by SCAs to assure on-going corrosion protection. Unlike conventionalhnology, frequent testing, performed in the field is not necessary in order to determine compli-an SCA refortification regimen.heless, inadvertent top-off with water or with conventional, silicated coolants will ultimatelyilution of the OAT inhibition and reduce the OAT coolants extended life properties. Whenon is suspected, a quick test suitable for use in the field would help the end-user determine theof his engines coolant and take appropriate action if warranted. As discussed above, conven-ant technologies rely on nitrite and molybdate test strips to determine if the coolant is providingylinder liner protection. Nitrite test strips can also be used with OAT coolants. However, optionsed if rapid field testing for carboxylates were required.y after the introduction of OAT coolants, a wet chemistry test method was developed to deter-vel of carboxylate inhibition remaining in used coolants. The test was highly accurate with field

ndicating a pass or fail condition based on carboxylate level. While the test was intended forysis in the field, the initial configuration did involve several steps and coolant manipulation. Ituently been replaced with a test strip method that employed the same test strategy but greatlyanalysis. The following sections document the initial test strategies and the development effortly field test. Test kit performance with laboratory and field samples is also discussed.

ntal Detailsic additive coolants used in this study for the development of a carboxylate field test were basedyl carboxylate, ethylhexanoate. These coolants were available commercially from Texaco, Inc.,e free version, as Havoline Extended Life Anti-Freeze/Coolant as well as in a heavy dutyntaining nitrite, as Texaco Extended Life Coolant/Antifreeze.

Carboxylate Ion Solubility Studiesdata were generated by adding 2.0 milli normal mN stock solutions of soluble metal salts of, iron, and copper to 2.0 mN stock solutions of carboxylic acids. All components were dissolvedater-glycol; the carboxylate solutions pH values were adjusted to 10 to assure that all acidsnt in the conjugate base form. Also, many commercial coolants have pH values in this region.ng, all solutions were heated in closed containers to 80C and then held at 80C overnight andd, filtered to remove insoluble matter and analyzed for metal ion content by induction coupledP.

AluminumThe followethylhexanFreeze/Costock soluing ethylha constantin all miethylhexanremaining

ColorimetThe followreactions wmixing 20Anti-Freez3.0. Totalreaction vomixtures whematoxyl1.0 g of sdeionizedof 30 % a

Field CooPrototypefleet. Thecontaininginvolved dvehicles hconcentratvehicle towithout reconcentratthose founand testedversions o

CarboxylaTexaco Exlate, ethylhion concenrevealed eevidence cvealed alualuminumaluminum

Metaltion mechametal ionFig. 1. Theanions. Da

PELLET ET AL. ON CARBOXYLATE LEVELS IN OAT COOLANTS 19/Ethylhexanoate Titrationing experiments were conducted to demonstrate the stoichiometric reaction of aluminum withoate corrosion inhibitor. Six solutions were prepared by adding Havoline Extended Life Anti-

olant in amounts varying from 0 to 10 to 20 mL aliquots of a 0.021 molar aqueous aluminumtion. Havoline Extended Life Anti-Freeze/Coolant is a nitrite free, automotive coolant contain-exanoate anion, EHA, as a key corrosion inhibitor. The mixtures were further diluted to obtainvolume of 50 mL for each resulting solution using deionized water. A precipitate was observedxtures to which coolant was added. Solutions were filtered to remove the aluminum-oate reaction product and then analyzed by ICP to determine the amount of aluminum cationand by ion chromatography to determine the amount of ethylhexanoate remaining after reaction.

ric EHA Test Developmenting experiments were conducted to demonstrate the feasibility of an EHA test method based onith aluminum cation and aluminum detection using hematoxylin. Five solutions were preparedg of aqueous aluminum stock solution 0.021 N with 0 to 24 g Havoline Extended Life

e/Coolant. The solutions were prepared to yield EHA to Al molar ratios of 0, 1.0, 1.6, 2.0 andmixture weight was brought to 50 g by adding additional deionized water to keep the totallume constant. In all but the 0 ratio mixture, an aluminum-EHA soap was formed. The resultantere filtered to remove this precipitate and then tested for the presence of aluminum using the

in test method 7. Specifically, the pH of each solution was raised to 8 by the addition ofaturated ammonium carbonate buffer; next 1.0 g of hematoxylin indicator 0.1 g in 100 g ofwater were added to each mixture; finally each solution was acidified by the addition of 1.0 gcetic acid.

lant Evaluationkit performance was evaluated using coolant samples from an over-the-road, heavy duty dieselfleet employed Texaco Extended Life Coolant/AnitFreeze TELC, an EHA based coolantnitrite. Vehicles in this fleet had been converted to TELC by flush-and-fill procedures, whichraining of conventional coolant, flushing with water and then filling with TELC. Additionalad been converted using Texaco Extended Life Corrosion Inhibitor Concentrate, a super-ed inhibitor package based on EHA. The super-concentrate was, on occasion, used to convert aextended life technology by addition to the conventional coolant already in place in the enginecourse to the drain, flush, and fill procedure. Because of the high EHA content of the super-e as well as variability of diesel engine cooling system volumes, EHA levels significantly aboved in fresh TELC were possible. For the purposes of test kit evaluation, 39 samples were obtainedby laboratory methods. Coolant samples were also evaluated using two different prototype

f the field test.

te Field Test Developmenttended Life Coolant was the first OAT marketed in the U.S.; it was based on the alkyl carboxy-exanoate. At the time of its introduction, there were no rapid and accurate tests for carboxylatetration in coolants. A clue to potential test methodology came from early field experience thatxcellent corrosion protection for cooling system metals, especially for aluminum 8. Primaryame from engine disassembly following extended field testing 300 000 miles which re-

minum components in like-new condition. Consistent with these observations was the fact thation was almost never detected in used coolant samples, even applications where significantcomponentry was present throughout the cooling system.ion/carboxylate ion solubility studies provide insight to help understand the carboxylate protec-nism. As one might expect, solubility of the metal carboxylate soap depends not only on the

but also on the chain length of the carboxylate. This can be seen in solubility data presented infigure presents the amount of soluble metal cation in the presence of various alkyl carboxylate

ta are presented for aluminum, copper, and iron ions. The graph shows that as the molecular

weight orgreatest focarbons. Tof carboxytest develo

It is inprovidedterminate

For thalkyl carbstarting soafter reactanoate ionbetween thmixture.

Fromadded toethylhexanthat the grstoichiome

This manoate ionfiltration. Ttrations stu

20 ENGINE COOLANT TECHNOLOGYchain length of the carboxylate increases, the amount of soluble metal decreases; the effect isr aluminum cation which is insoluble in the presence of carboxylates with more than twohe effect is least pronounced for copper cation which remains partially soluble in the presencelates up to ten carbons in length. Thus with Texaco Extended Life Coolant, used in the initialpment based on C8 and C10 carboxylates, aluminum cation is virtually insoluble.teresting to speculate that the effective corrosion protection, observed with this coolant, may beby this insoluble soap formation at the sight of incipient corrosion; soap formation wouldthe corrosion process before damage was done while consuming a minimal amount of inhibitor.e purpose of field test development, the quantitative reaction of aluminum with C8 and C10oxylates to form an insoluble soap can be related to the amount of carboxylate present in thelution coolant. This is demonstrated in Fig. 2, where the amount of aluminum cation remainingion with added ethylhexanoate anion EHA is plotted as a function of the amount of ethylhex-

added to the solution. From the graph, it can be seen that there is a linear, inverse relatione amount of aluminum remaining in solution and the amount of ethylhexanoate added to the

the graph, all aluminum is removed from the stock solution when sufficient ethylhexanoate isachieve a ratio of EHA to Al of approximately 1.75 to 1. This suggests that the aluminumoate precipitate formed has an empirical formula approaching Al EHA2. Importantly, the factaph of aluminum remaining versus ethylhexanoate added is a straight line suggests that thistry remains constant over the range of aluminum and EHA concentrations examined.ay be more apparent from the data in Table 1. Here, the amounts of aluminum and ethylhex-present in the initial solutions are compared with the amount of ions present after reaction andhe ratio of EHA and aluminum disappearing from solution remains constant over the concen-died.

FIG. 1Metal carboxylate solubility.

FIG. 2Al3 titration with ethylhexanoate anion.

This ocoolants. Trequired. C

In thisadded to aamount ofminimumsimply byaluminummixture inEHA inhibrefortified

Theretechniques

All ofcomplexesthe fact thheavy dutywere purpproposed bcolor, alum2, it can bviolet coloof hemato

Accorwithin a paluminum8.5 the cohematoxylate, uncomcomplex. Hchanges toafter form

T

InitialAl0.02130.02130.02130.02130.0213

PELLET ET AL. ON CARBOXYLATE LEVELS IN OAT COOLANTS 21bservation suggests that aluminum can be used to titrate or determine EHA levels in usedo render this method useful for rapid field analysis, a method of soluble aluminum detection inonceptually, a field test might be as simple as:

Al+3 + Ethylhexanoate AlEHA2 + excess Al+3

Excess Al+3 + Indicator AlIndicator colored complexconceptual test, a premeasured solution containing a predetermined amount of aluminum ismeasured aliquot of coolant sample from the field. The coolant sample contains an unknown

EHA inhibitor. The amount of aluminum in the aliquot can be preselected to be equivalent to theamount of EHA needed for good corrosion protection this EHA target value can be variedvarying the amount of aluminum cation in the test. The two solutions are mixed; a colorimetricindicator is added to the solution portion of the mixture. The presence of aluminum in thedicates there is insufficient EHA to precipitate all the aluminum and thus there is insufficientition. The colorimetric detection of aluminum indicates a failing coolant that would need to beto provide adequate corrosion protection.are several colorimetric tests for aluminum reported in the literature; a sampling of possibleis provided in Table 2.these tests permit the visual detection of aluminum at ppm levels by the formation of colored. Conceptually all could be used in the test described above. However, testing is complicated byat all heavy duty coolants are dyed to help to distinguish them from other engine fluids. Initially

extended life coolants were dyed red to distinguish them from conventional coolants whichle or blue. The red color of extended life coolant has since become an industry standard asy the Technology and Maintenance Councils Recommended Practice 351. Because of coolantinum indicators that turn red in the presence of aluminum may be of limited use. From Table

e seen that tests based on hematoxylin should not suffer from this limitation as it develops ar in the presence of aluminum. Initial efforts to develop a field test for EHA focused on the usexylin test which was first reported in 1924.ding to the hematoxylin procedure, a test solution containing aluminum must be buffered toH range of 6.5 to 8.5 using a saturated solution of ammonium carbonate in order to form theindicator complex. The purple colored complex will not form at pH values below 6.5. Abovemplex forms but decomposes fades rapidly. In addition to being an aluminum indicator,ins color is also sensitive to pH. At the pH of solutions made alkaline with ammonium carbon-plexed hematoxylin is red or purple, masking the violet color produced by the aluminumowever, when pH is lowered by the addition of acetic acid, uncomplexed hematoxylins coloryellow while the aluminum hematoxylin color is unaffected. Thus, lowering the mixture pH

ing the aluminum complex removes the interference and allows aluminum detection if present.

ABLE 1Aluminum and ethylhexanoate concentrations (moles/litre) before and after reaction and filtration.Initial

EHFinal

AlFinalEH

Changein Al

Changein EH

Change RatioEH /Al

0.0428 0 0.007 0.0213 0.0358 1.670.0341 0.00204 0 0.01926 0.0341 1.7710.0298 0.00407 0 0.01723 0.0298 1.730.0256 0.00641 0 0.01489 0.0256 1.720.0213 0.00930 0 0.012 0.0213 1.775

TABLE 2Colorimetric aluminum indicators.

Aluminum IndicatorAluminum complex

Color ReferenceHematoxylin violet 78-Hydroxyquinoline Oxine red 9Quinizarin red 10Aluminon red 11

To demonsolution wmixtures wammoniumsolution. TEHA /Al rcolor chan

Note tlaboratoryexcellentAgain, byadequate cnum. It isphotograp

Obviounless cartion as a gcontents o

The insured amoaluminumand the filtube contaampoule w

22 ENGINE COOLANT TECHNOLOGYstrate feasibility of this test method, solutions were prepared mixing aqueous aluminum stockith an EHA containing coolant to yield EHA to Al ratios ranging from 0 to 3. The resultantere filtered and then tested for the presence of aluminum by raising the pH with saturatedcarbonate buffer, adding hematoxylin indicator and then lowering the pH with acetic acid

he resulting solutions ranged in color from yellow to deep purple or violet; all solutions atatios above 2.0 were yellow; solutions with EHA /Al ratios below 2.0 were violet. The dramaticge can be seen in Fig. 3.hat the color change occurs precisely and sharply at the end-point previously determined usingmethods of ion chromatography and ion-coupled plasma. Thus a potential field test should be in

agreement with the more time consuming laboratory analysis requiring ion chromatography.selecting the amount of aluminum added to the field coolant, it is possible to determine if

orrosion inhibition is present as indicated by the coolants ability to precipitate all added alumi-also important to note that the dramatic color change is obvious even in black and white

hy and so utility of this colorimetric test would not be limited for a color blind observer.usly, despite its potential accuracy, this multistep test would be too cumbersome for field useefully designed to minimize coolant and solutions handling and manipulation. With simplifica-oal, a commercial field test kit was designed and ultimately made commercially available. Thef the commercial kit are shown in Fig. 4.itial commercial kit consisted of three components: a white-capped test tube contains a premea-unt of aluminum stock solution. A measured amount of coolant was added to this tube and anEHA precipitate was formed. The resulting mixture was filtered using the filter syringe providedtered solution was added to the red-capped plastic test tube. There were three ampoules in thisining ammonium carbonate, hematoxylin indicator, and acetic acid. The ammonium carbonateas broken first releasing the buffer and raising the mixture pH to 8; the second ampoule was

FIG. 3Al3 titration with ethylhexanoate using hematoxylin indicator.

FIG. 4Test kit for alkyl carboxylates.

then brokeampoule wcolor wouwhite-capppletely remindicated a

As iniwith laborcoolant safrom the fiall samplebased heavhad varyin

%Carboxylatea

01215193032343738434548495252535456646969999999101101101102106113119120122125127154160185262aPercentage of

PELLET ET AL. ON CARBOXYLATE LEVELS IN OAT COOLANTS 23n releasing the indicator and forming the purple aluminum-hematoxylin complex. The thirdas broken lowering the pH, removing uncomplexed hematoxylin interference. The resulting

ld be yellow if all aluminum had been precipitated by reaction with the coolants EHA in theed vial. The resultant color would be purple or violet if there was insufficient EHA to com-ove the soluble aluminum that was initially present. Thus, a final yellow or red/orange colorpass; conversely, a final violet color indicates insufficient carboxylate inhibition, a fail.

tially configured, the test took less than five minutes to complete and exhibited high accuracyatory samples. However, a more important indicator was performance with real world, usedmples from the field. To this end, prototype test kits were used to evaluate 39 coolants obtainedeld. The results of laboratory analysis of these field samples are provided in Table 3. Nominally,s were obtained from a fleet that was using Texaco Extended Life Coolant TELC, an EHAy duty coolant containing nitrite. However, from the table it can be seen that all coolant samplesg degrees of contamination with competitive coolant products indicated by the presence of

TABLE 3Laboratory analysis of used coolant samples.

pH%

WaterB

ppmSi

ppmMoppm

NO2ppm

NO3ppm

PO4ppm

TTZppm

8.3 52.2 212 79 276 1160 307 4680 3807.06 39.8 246 81 37 11.6 2020 12.2 1107.87 54.7 122 80 116 660 955 2600 2808 47.4 256 82 130 1140 1500 2580 1008.37 49.5 527 86 154 2300 1800 2300 4708.75 45.1 206 79 176 866 520 4280 10608.18 51.5 586 129 270 2610 2230 3080 3008.5 55.0 140 72 2.7 362 599 1520 4107.83 50.6 123 53 222 761 538 2800 3008.22 42.4 314 57 156 695 996 2970 7407.6 44.0 460 87 46 1330 2020 562 2007.66 54.3 199 39 110 273 486 1650 4008.31 54.7 389 201 151 1870 1680 2250 6008.7 49.2 542 55 23 250 875 1120 8008.3 41.5 118 62 127 47.7 1160 2800 6007.83 49.4 109 80 22 490 458 79.7 4608.13 50.7 71 52 131 582 660 1410 5508.1 51.7 431 40 53 624 1770 1930 5007.85 43.5 1117 108 66 1250 2730 532 2108.73 59.2 155 21 1 242 305 664 7708.76 55.0 514 57 5.6 533 830 1270 5208.48 46.5 58 43 28 108 275 677 10708.73 54.8 320 33 2.1 580 680 1250 7708.11 52.4 7.2 40 1 2110 55.7 8 8008.13 53.0 454 88 48 564 1580 261 24508.54 48.4 10 4.9 12 2370 70 118 11008.51 47.7 7.6 4.7 9.2 2460 61 84 11008.65 37.5 349 75 140 301 940 2270 12008.31 51.7 203 66 79 71 620 1290 12008.78 58.1 17 56 6.2 20.5 251 1080 11208.49 36.9 291 83 159 381 1560 1860 7008.05 31.2 29 52 2.8 7 139 220 10008.12 58.7 189 56 1 18.9 243 205 11008.02 43.8 427 89 81 559 2450 1500 7208.54 45.5 276 62 38 611 548 569 10009.03 47.9 384 29 2.3 995 1200 2300 13808.97 48.6 200 47 18 422 381 249 14608.49 43.9 637 94 64 990 1540 2020 17008.8 33.8 206 60 78 276 515 772 2300

ethylhexanoate, relative to fresh TELC.

phosphatefresh TELarranged inThus a frewith convcantly.

All copresented

In thisresulted frEHA. A nfresh 100EHA levelare severa

would appconfiguredresults andmolybdatemany of thultimatelyfailing resampoule wallowing i

The mResults ofalmost elim

24 ENGINE COOLANT TECHNOLOGY, borate, silicate, molybdate, and nitrate. These conventional corrosion inhibitors were absent inC. Analysis also revealed varying degrees of dilution with water. In the table, coolants are

order of increasing EHA content which is expressed as a percent EHA relative to fresh coolant.sh coolant would have 100 % EHA. It can be seen that in real world use, coolant contaminationentional inhibitors is quite common. Water contents and coolant pH values also vary signifi-

olants were tested using the prototype test kit described above. The results of this evaluation aregraphically in Fig. 5.figure, results are tabulated as pass or fail depending on whether a yellow or purple color

om the prototype test kit. Results are presented in order of increasing carboxylate content %umber of observations can be made. First, in the initial configuration, coolants with less than% EHA routinely failed the test; there is only one false pass among the 22 coolant samples withs less than 100 %. Secondly, for coolants with greater than 100 % EHA, it can be seen that therel false fails; specifically of the 17 samples evaluated, seven yield a failing indication. Finally, itear that any coolant with less than 100 % EHA would fail the test as it had been initially. This high end-point and the several false fails observed needed to be corrected. Based on these

a close examination of the chemical analysis of the coolant samples, it was discovered thatinterfered with the test by yielding a near black complex with hematoxylin. Its presence ine samples with high EHA, resulted in the false fails observed. In a second test kit which wascommercially released, the amount of aluminum present in the white tube was lowered so thatults would only be obtained when EHA levels fell to below 75 % of fresh. In addition, anas added to the white tube containing a lead acetate; lead acetate will precipitate molybdate,

t to be removed upon filtration and prior to hematoxylin addition in the red tube.odified prototype was used to evaluate the same 39 coolant samples from the original test.that evaluation are presented in Fig. 6. Use of the lead acetate ampoule in the white vial hasinated the occurrence of false fail results and accuracy has risen to nearly 90 %. Furthermore,

FIG. 5Field performance with initial test kit.

FIG. 6Field performance with improved test kit.

by reducinto about 7indicator.

Conclusio

The first kmance in etest strategever, alumthis strategpresentedmolybdate

Ultimakits. The nsolution bstrip methprocedure

Reference

1 HudPap

2 KreOn-199

3 KreTesPap

4 Kolpp.

5 HemAnaAST

6 PellIron

7 HatChe

8 MoAci

9 LiaChr8-H

10 KdrDetAgg

11 Bermin

PELLET ET AL. ON CARBOXYLATE LEVELS IN OAT COOLANTS 25g the amount of aluminum cation present in the white vial it was possible to lower the fail point0 %, i.e., coolants with EHA levels less than 70 % of fresh would now yield the violet fail

ns

it for EHA field analysis was commercially introduced in 1998 and exhibited excellent perfor-valuating extended life, alkyl carboxylate coolants even with highly contaminated samples. Thisy, relying on aluminum solubility should work with any alkyl-based carboxylate coolant. How-inum cation is significantly more soluble in the presence of some aromatic carboxylates and soy may not be effective for coolants based on these inhibitors. While most of the field data,in this study, were obtained with heavy duty extended life coolant containing nitrite and, the strategy is also effective for automotive coolants containing alkyl carboxylates.tely, the hematoxylin method for detecting soluble aluminum was replaced with a tw