Vibration and Temperature Measurement Based Indicator of Journal Bearing Malfunction

This paper aims to present the development and implementation of the new malfunction indicator in journal bearings, based on vibrational and thermal records, called DFJB-Defect Factor Journal Bearing. Briefly, the indicator contains the specifically processed information about the bearing vibrations and temperature, on the basis of which the DFJB is calculated using fuzzy logic, and thus the state of the journal bearing may be determined. It should be pointed out that the DFJB is developed in a manner that besides the temperature and the total number of absolute vibrations, it may also integrate following parameters of monitoring: the parameters of rotating vibrations, vibrations spectrum, the thickness of oil film in the journal bearing, the intensity of the ultrasound emission of the bearing etc. These parameters may in certain cases offer more reliable malfunction identification. Experimental investigations conducted in this work, on real machine equipment and in real exploitation conditions, have shown this method to be reliable in the identification of malfunctions in journal bearings. As a result of implementation of DFJB, the time necessary to collect measuring data is significantly shortened, whereas the diagnosis procedure for journal bearings is highly simplified. This is particularly important in complex technical systems with a vast number of measuring points, which often result in the overload of the operator

Influence of the Cobb 500 hybrid parent age and egg storage period on incubation parameters

Main goal of this research was to determine the influence of Cobb 500 hybrid broiler parent age (BPA) and egg storage (ES) period, the impact of egg maturity on egg fertilization and chick hatching, as well as on embryonal mortality of chicks during incubation period. There were three phases of production cycle, three different ages of broiler parents 25, 41 and 58 weeks (BPA25, BPA41, BPA 58). The eggs there were differentiated according to storage time: eggs stored up to 7 days and eggs stored over 7 days (ES7). Using the random sample method, 1.050 eggs were chosen (total number of chosen eggs was 6.300), with the aim to determine above mentioned reproductive parameters, one day old chick weight and relative share of chick weight in total egg weight were determined. Age of broiler parents had the highest influence on egg fertility as the highest number of fertilized eggs was recorded during the middle of production cycle (BPA41 = 97.05%), then at the beginning of the cycle (BPA25 = 96.09%), and lowest number of fertilized eggs was during the last phase of the cycle (BPA58 = 93.00%). The storage period of the eggs did not have any influence on egg fertility. However, the age of broiler parents and storage period had significant influence on hatching, therefore it influenced embryonal mortality during incubation period. Without considering the storage period, the lowest embryo mortality was detected with eggs that originated from BPA41 - 13.05%, eggs that originated from BPA58 had significantly higher embryo mortality rate 15.87%, and the highest mortality rate was noted with eggs that originated from BPA25 16.93%. However, extended storage period for the eggs or egg maturity (ES7) had influence on total embryonal mortality rate in all three phases of the production cycle. Moreover, broiler parent age had statistically significant influence on increase of egg weight (P<0.001) and hatched chick weight (P<0.001), while the relative share of chick weight in total egg weight was decreased, therefore storage period in all three phases of production cycle had negative influence on chick percent, with increase of storage time of the egg, relative share of chick weight in total egg weight decreased, especially during start BPA25 and end BPA58 phase of the production cycle (P<0.001)

Modeling and simulation of hydraulic buffering valve for power-shift transmission

Introduction/purpose: The hydraulic buffering valve has the greatest influence on the dynamic characteristics of power-shift transmission. The hydraulic buffering valve is a transmission element that controls increase in pressure in friction assemblies during the gear shifting process. By choosing the optimal control of pressure increase during shifting, reduction of dynamic loads in gear transmissions and thermal loads in friction assemblies is achieved. Methods: The paper analyzes the principle of one of hydraulic buffering valve solutions as well as the influence of certain parameters on the control of pressure increase. After the analysis of the working principle of the hydraulic buffering valve, a simulation model was developed in the MATLAB/Simulink software package. Results: The results obtained using the simulation model were compared with the experimental results of the selected pressure modulator solution. The selected hydraulic buffering valve was developed as part of the development of a device for power-shift transmission. The simulation results showed a satisfactory match with the experimental results. Conclusion: The developed simulation model enables a relatively easy and quick change of the parameters of the hydraulic buffering valve as well as a possibility of a faster and better understanding of the influence of individual parameters on pressure increase during the gear shifting process

Some aspects of biodiversity, applied genetics and agronomy in hyacinth bean (Lablab purpureus) research

Our intention was to give a very rough draft of 1) our contemporary knowledge on various aspects of the hyacinth bean (Lablab purpureus (L.) Sweet) biodiversity, 2) most important aspects of breeding this crop for forage, grain and biomass yield and ornamental purposes and 3) innovative approaches in its agronomy, such as intercropping with other legumes

Savremene metode analize ulja u tehničkim sistemima / Modern methods of oil analysis in technical systems

Analiza ulja na osnovu pravilno definisanog programa predstavlja veoma efikasan metod monitoringa stanja tehničkih sistema koji obezbeđuje rane upozoravajuće znake potencijalnih problema, koji vode ka otkazu i zastoju tehničkih sistema. Ova analiza je veoma efikasan alat programa za monitoring stanja tehničkih sistema. Mnogobrojni uređaji i testovi za analizu ulja omogućavaju kvalitetan monitoring i dijagnosticiranje problema koji nastaju u procesu podmazivanja. Korišćenjem programa za analizu motornih ulja: skraćuje se neplanirano vreme otkaza vozila, poboljšava pouzdanost vozila, produžava radni vek motora, optimizira interval zamene ulja i smanjuju troškovi održavanja vozila. / Different technical systems require an appropriate lubricant to be used at an appropriate place, at appropriate time and in appropriate quantity. Determination of technical systems condition has a very important role in the development of theory and practice of friction, wear and lubrication. Lubricant is, as a contact element of tribomechanical systems, a carrier of information about the state of the whole system, from the aspect of tribological and other ageing processes. The analysis of oils, based on a properly defined program, thus represents a very effective method for monitoring the condition of technical systems, which ensures early warning signals of potential problems that could lead to failure and break down of technical systems. Introduction It is not always simple to determine a type of lubricant, frequency of lubrication and the quantity of lubricant to be used. The optimal recommendation would be to follow specifications of technical system manufacturers, experience, lab research or professional recommendation of lubricant suppliers. Rational lubricant consumption can be obtained by timely oil replacement, which then enables a maximum possible period of use as well as high-quality lubrication. Since the primary role of lubricants is to reduce negative effects of tribological processes related to friction, wear and temperature increase in tribomechanical systems, all types of maintenance include lubrication as a very important part of the whole procedure. On the other hand, lubricant is, as a contact element of the system, a carrier of information about the condition of the whole system, from the aspect of tribological and other ageing processes. Therefore, an analysis of oils, based on a properly defined program, represents a very effective method for monitoring the condition of technical systems, which ensures early warning signals of potential problems that could lead to failure and break down of technical systems. Besides mechanical components in a system structure, the condition of lubricant itself is also affected, which leads to a loss of lubricating properties. Contamination and degradation of lubricating oils There are numerous opportunities for contamination and degradation of lubricating oils. Contamination and degradation of oil exploitation cannot be completely prevented, but can be significantly reduced, which is very important both for oil and for a technical system itself. The rate and degree of degradation of oil are proportional to the rate and extent of contamination. It is therefore important to prevent rapid contamination of oil, before and during use. The spectrum of oil contaminants is considerably wide. Any contaminant destructive impact on oil, reducing its physical-chemical and working properties, results in shortening its service life as well as the service life of the technical system in question. During oil exploitation, changes occur in: chemical compositions and properties of base oils, chemical compositions and properties of additives, and consequently chemical compositions of oils in general, as a result of contamination and degradation. The most significant oil contaminants are base oils degradation products, additives degradation products, metal particles as a result of wear processes, solid particles from the environment, water and products of fuel combustion. During the operation the following changes occur: contamination of oil by the products of its own degradation, by products of incomplete combustion of fuel and by contaminants of various origin. The main objectives of the analysis and monitoring of oil exploitation in vehicles The main objectives of the analysis and monitoring of oil exploitation in vehicles are: - analysis of system element wear processes, - analysis of lubricant contamination processes, - monitoring changes in the properties of lubricants in order to optimize the life of system functionality control (penetration of contaminants, temperature and pressure, filter efficiency, etc.) and - determining the extent of damage and causes of failure. The analysis of the contents of different metals in lubricants is very important. Metal particles are abrasive, and act as catalysts in oil oxidation. In motor oils, they can originate from additives, wear processes, fuel, air and cooling liquid. Metals from additives may be Zn, Ca, Ba, or Mg and they indicate additive deterioration. Metals originating from wear are: Fe, Pb, Cu, Cr, Al, Mn, Ag, Sn, and they point to increased wear in these systems. The elements originating from cooling liquids are Na and B, and their increased content indicates the penetration of cooling liquid in the lubricant. The increased content of Si or Ca, which originate from the air, points to a malfunction of the air filter. Condition monitoring through oil analysis tests There are many different types of oil analysis tests that are used to evaluate lubricants. The tests must cover three areas: technical system condition, contamination condition, and lubricant condition. From the technical system condition aspect, attention should be paid to the presence of any metal particles in oil and the tendencies in their change. The second focus would be the lubricant condition, especially viscosity change, increase in oxidation, and signs of additive depletion. The third focus would be impurities, where the emphasis should be placed on particle number, water content and metal impurities. Theoretically, oil analyses are divided into three classes. In reality, all three condition-monitoring classes are interrelated and must be considered as a whole. For example, an increase in viscosity could be an indication that a lubricant is oxidizing. But oxidation could be an incorrect conclusion, if there is no indication of an increasing oxidation tendency obtained either by the acid number (AN) values analysis or the Fourier Transform-Infrared (FT-IR) analysis. Lubricant monitoring enables its refreshing or replacement before serious technical system damage occurs. If damage is noticed in the course of operation, and is caused by impurities or lubricant problems, the technical system condition can be monitored and the system may be shut down immediately to minimize damage. There are the two types of alarms, i.e. warning signs used in oil analysis: absolute and statistical alarms. An effective oil analysis relies on the combination of both types. The warning limit is the absolute alarm. The statistical tendency takes into account variability based on oil sampling and its contamination and represents the standard deviation. The deviation from the normal variability indicates serious problems, which is the first signal for taking action and dealing with the problem. As the deviation tendency approaches the warning limit, oil replacement, oil purification or a system inspection is required. Metal particles content and viscosity or some other parameters can be tested. The normal variability range takes into account minor variations caused by analytical accuracy, sample homogeneity, etc. Statistical alarms, which provide the earliest possible warning without false alarms, are difficult to achieve. The factors such as oil adding or changing, filter changes and a sampling technique can distort the results. The following tests are most frequently used in technical system condition monitoring: - Spectrometric Analysis, - Analytical Ferrography, - Rotrode Filter Spectroscopy (RFS), - Infrared Analysis (FT-IR), - Viscosity, - Total acid number (TAN), - Total Base Number (TBN) - Water and Particle Count

Monitoring lubricant performances in field application

The need for more effective maintenance and possibility of continuous exploitation of equipment has developed numerous strategies and methods for machinery maintenance. The maintenance strategy by condition, that requires continuous monitoring and equipment overlook, has initiated the development and use of lubricant analysis. Monitoring the performance of lubricants in practical application has multiple significance for both the consumer and the lubricant manufacturer. The primary significance for the consumer is extended life and timely change of lubricants, which keeps the costs of maintenance down. The lubricant manufacturer gains by creating a partner relationship with the consumer, as well as creating the possibility of gathering information about the performance of his product which will serve as a foundation for the further improvement and development of his product. If we wish to maintain technical systems so that they have as little halts and costs caused by halt removal or system failure as possible, we must monitor data indicating equipment condition throughout the system operation. It is especially difficult to obtain data on equipment condition for parts which cannot be observed due to their position. In such cases, oil analysis enables a continuous equipment condition monitoring and timely response in order to prevent undesirable prolonged halts

Analiza stepena kritičnosti tehničkih sistema / Analysis of the criticality level of technical systems

U radu je analizirana kritičnost nekog tehničkog sistema kroz neophodno sprovedene postupke analize kritičnosti delova sistema sa aspekta mogućnosti nastanka i posledica pojave otkaza. Analize otkaza, koje se sprovode tokom celog životnog veka nekog tehničkog sistema, najčešće se vrše radi utvrđivanja i izolovanja uzročnika otkaza, kao i za definisanje preventivnih i naknadnih intervencija. Pod pojmom analiza otkaza podrazumeva se postupak koji ima za cilj utvrđivanje nekih od navedenih karakteristika: 1) otkaza nastalih usled degradacije maziva; 2) otkaza usled nepravilnog podmazivanja; 3) otkaza zbog neodgovarajućeg kvaliteta maziva; 4) mehanizma nastajanja otkaza; 5) otkaza zbog greške u konstrukciji; 6) uzroka, oblika i posledice otkaza. Jedna od najpogodnijih metoda za analizu otkaza jeste analiza stabla otkaza (FTA-Fault Tree Analysis), koja je prikazana u ovom radu. / This paper analyses the criticality of a technical system using the criticality analysis of system parts from the point of view of possible failure effects. Failure analyses, performed throughout a technical system lifecycle, are generally conducted as to determine and isolate failure causes as well as to define prevention measures and subsequent interventions. The term failure analysis involves a procedure for determining some of the following: 1) failures due to degradation of lubricant; 2) failures due to incorrect lubrication; 3) failures due to poor quality of lubricant; 4) mechanism of failure development; 5) failures due to construction error; 6) causes, types and effects of failures. One of the optimal methods of failure analysis is the FTA-Fault Tree Analysis

Monitoring stanja kroz testove analize ulja / Condition monitoring through oil analysis tests

U radu su prikazani testovi analize ulja koji se koriste za procenu njegovog stanja. Predočeni su zahtevi koje testovi moraju da zadovolje, a odnose se na stanja tehničkih sredstava, stanja nečistoća i stanja maziva. Pokazano je da posebnu pažnju treba obratiti na pojavu i trend promene broja metalnih čestica u ulju. Takođe, razmatrani su znaci koji upućuju na promenu viskoznosti, povećanje oksidacije i trošenje aditiva. Razmatrano je stanje nečistoća u ulju, gde je posebna pažnja posvećena brojnosti čestica, sadržaju vode i metalnih nečistoća. Pokazano je da je neophodno koristiti program za analizu motornih ulja, koji osigurava nekoliko prednosti: smanjenje neplaniranog vremena otkaza vozila, poboljšanje pouzdanosti vozila, što je korisno pri organizovanju efikasnog plana održavanja, zatim produženje radnog veka motora, optimiziranje intervala zamene ulja i smanjenje troškova održavanja vozila. Prikazani su i rezultati eksperimentalnih istraživanja fizičko-hemijskih karakteristika uzorkovanih ulja iz motora vozila Mercedes OM 345 koja su bila u eksploataciji. Realizovanim ispitivanjima konstatovano je da dolazi do promena fizičko-hemijskih karakteristika ulja za podmazivanje u motoru vozila, koje su u direktnoj zavisnosti od stanja svih elemenata tribomehaničkog sistema motora, odnosno u zavisnosti od njihovih funkcionalnih karakteristika. / The paper presents the tests in the oil analysis, used for the assessment of oil condition, as well as the requirements to be fulfilled by the tests, regarding the state of technical equipment, impurities and lubricants. Special attention should be paid to the occurrence of metal particles in oil and the tendency in the change of their number. The signs that point to changes in viscosity, oxidation increase and additive wear are also considered. The state of impurities in oil was discussed, with a particular focus on the number of particles, water content and metal impurities. It is inevitable to use an oil analysis programme in the case of motor oils, which provides several advantages: reduction of unscheduled vehicle downtime, improvement of vehicle reliability, help in organizing effectiveness of maintenance schedules, extension of engine life, optimization of oil change intervals and reduction of cost of vehicle maintenance. The paper also gives the results of the experimental research of physical- chemical characteristics of the motor oils sampled from the engines of Mercedes OM 345 vehicles in operational use. It was shown that there is a change in physical-chemical properties of lubrication oils. These changes are in a direct correlation with the state of all the elements of the tribomechanical motor system, i.e. with their functional characteristics. The conclusion based on the realized testing comes at the end of the paper. Introduction As a contact element of the tribomechanical system, lubricant is a carrier of information about the state of the whole system, from the aspect of tribological as well as other ageing processes. Therefore, an analysis of oils, based on a properly defined program, represents a very effective method for monitoring the state of technical systems, which ensures early warning signals of potential problems that could lead to failure and break down of technical systems. Using Oil Analysis programs for engine oils has several benefits: reduction of unscheduled vehicle downtime, improvement of vehicle reliability, help in organizing effectiveness of maintenance schedules, extension of engine life, optimization of oil change intervals and reduction of vehicle maintenance costs. Physico-chemical characteristics of lubricating oils Basic physico-chemical characteristics which determine the quality of oil are: a) physical characteristics: viscosity, density, flash point, cloud Point, pour point, volatillity, emulsibillity, deemulsibillity, foaming, air release, viscosity index, etc. b) chemical characteristics: neutralization number (TAN-total acid number), total base number (TBN), oxidation stabillity, chemical and thermal stabillity, corrodibillity, ash content and carbon residue, water content, compatibility, toxicity, etc. Diagnostics of the tribomechanical system of an internal combustion engine The diagnostics is based on the prediction (recognition) of damage and/or failure through characteristic diagnostic parameters. This allows prevention of delays and increases reliability, cost-effectiveness, and usage life. The diagnostics of the tribomechanical system can provide verification of the system condition, working capacity and functionality, and can point out the place, form and cause of a failure. The diagnostics is carried out through the detection of symptoms, determining the value of the characteristic parameters and their comparison with the limit values. If the engine assemblies are considered from the aspect of tribomechanical systems (e. g. piston-piston ring-cylinder, cam-valve lifter, bearing journal bearing) defined by tribological processes, it can be shown that the determination of the content of wear products, content of contaminants, state of lubricants and lubrication conditions have a significant influence on the implementation of maintenance of these systems. We should emphasize the importance of monitoring oil for lubrication of tribomechanical engine assemblies, which provides identification of potential causes and phenomena leading to damage and failure in the early stages of the functioning of the system. Prediction, i.e. detection of potential and/or current damage and failures in the system, checking the functionality of oil and determination of usage life are the main factors of the implementation of oil monitoring. Since mobile components of tribomechanical system engines are necessarily exposed to wear and contaminants and wear products deposit in the lubrication oil, it is necessary to monitor changes in fluid properties during exploitation, because the monitoring of lubricants is the key monitoring technique for maintenance as well as for achieving certain techno-economic effects. The analysis of the contents of different metals in lubricants is very important. Metal particles are abrasive and act as catalysts in the oxidation of oils. In motor oils, the origin of the particles may be from additives, wear, fuel, air and cooling liquid. Metals from additives can be Zn, Ca, Ba, or Mg and that indicates the change in additives. Metals originating from wear are: Fe, Pb, Cu, Cr, Al, Mn, Ag, Sn, and they point to increased wear in these systems. Elements originating from cooling liquids are Na and B, and their increased content indicates the penetration of the cooling liquid into the lubricant. The increased content of Si or Ca, originating from the air, points to the air filter malfunctioning. Wear of the parts is the main cause of malfunctioning in the process of exploitation of mechanical components of vehicles. Wear is characterized by the change in shapes and dimensions of working parts. Friction leads to surface wear which causes the increase of clearance between moving joined parts and the change in their mutual relations, thus resulting further in deviations from required specifications of assemblies and vehicles in general. Diagnostic procedure for the condition of lubricants 1) Selection of a type of vehicles and vehicle parts from which oil samples will be taken. 2) Consideration of the mode of the system (vehicle assembly) operation, lubrication systems, exploitation conditions and its purpose, and an overview of the basic technical characteristics. 3) Analysis of the tribological processes in components of motor vehicles. 4) Analysis of the failure of functional components of vehicles (as tribomechanical systems) 5) Information about the condition of a vehicle assembly and oil during the analysis and monitoring Results of motor oil investigation during exploitation In this part of the paper, the results of the experimental testing of motor oils in the Laboratory for fuels and lubricants, VTI Belgrade, are presented. The physico-chemical characteristics of oils were examined in accordance with standard methods, shown in Table 3. The analysis was done on fresh (new) oils and oils used in vehicle engine assembles. Testing of used samples was carried out in accordance with common criteria defined by the quality of used oil. The values of allowable deviation limits of individual characteristics of oil depend on the type of oil, working conditions and internal recommendations of the manufacturer of lubricants and users. The limited values of oil characteristics which condition the change of the oil charge from the engine are given in Table 4. They represent the criteria for the oil charge change. Deviation of only one characteristic results in the change of the oil charge, regardless of the characteristic itself. The research was carried out on three vehicles (MERCEDES O 345 buses) with the Mercedes-Benz engine, OM 447HLA type. This is a four-stroke engine with six in-line cylinders, turbo Diesel, liquid cooled and with combined lubrication, which meets Euro 2 emission standards related to exhaust gases. The research was conducted through periodic sampling of oil from the engines of the vehicles listed above. Apart from fresh oil ('zero' sample), samples were taken after 10.000 km, 20.000 km and 30.000 km. After 30.000 km oil charges were replaced in all three engines. During the oil sampling, the sampling sites were carefully chosen, taking care of actual oil usage, which enabled each sample to be a representative one. Each sample was taken from the living zone, i.e. zone closer to the elements in contact. The sampling of oil from the bottom of the motor housing (discharge outlet) was thus avoided, as the highest concentration of contaminants occurs there. This is achieved by simply modifying the outlet for oil, by extending it towards the active zone of oil within the housing with a tube of appropriate length. Special attention was also paid to the preservation of samples from contamination, both in the phase of sample taking and in the phase of manipulation, which is fully met by applying the prescribed procedures. A very high level of purity of all elements in the chain of the sampling systems was thus provided as well as the separation of samples in a way that does not perturb the integrity of their data on the state of the vehicle components from which the sampling was done. Conclusion On the basis of all the mentioned above, the following conclusions can be drawn: - motor oil VALVOLINE, API CF and ACEA E4, of SAE 10W-40 gradation, analyzed during exploitation, achieves its primary function and meets the prescribed replacement interval of 30.000 km in the EURO 2 engine category, which was found by the analysis of characteristic physico-chemical properties of oil and wear products (Fe and Cu) during exploitation; - the fall of viscosity is evident during the first 10.000 km, and after this period, viscosity remains approximately constant until the end of the interval changes of the oil charge. Maximum viscosity fall during the exploitation of the oil from all three engines is significantly below the allowed limit of 20 %; - after 30.000 km the TBN value has not exceeded the allowable limit for oil samples from all three engines; - the content of insoluble substances in the oil is negligible in comparison with the limit value, because there is no significant presence of oxidation products and mechanical impurities or insoluble substances such as coke, scale, dust, soot, particles originated from wear contact area of the engine tribomechanical systems and other mechanical impurities; - small decrease of the flash point values shows that there was no significant penetration of fuel into the system for lubrication; - content of iron and copper is significantly below the allowable limits for all three vehicles; - the appearance of water in the samples is not found, - after 30.000 km, oil is replaced, following exactly the manufacturer's recommendation about the oil charge change

Results of experimental research of the tribological characteristics of oils from engines and power transmitters of vehicles

Nowadays, a special attention is focused on the development of modern devices and methods for monitoring condition changes of tribomehanical characteristics in systems. There are different physical and chemical methods and tribology methods for tribomehanical system diagnosis. Experience in technical systems exploitation showed that the most effective failure prognosis is based on particles created as a result of wear. The analysis of oil samples containing particles-products of wear, enables the evaluation of system tribology conditions in different phases of system exploitation. The paper presents the tribological tests in the analysis of oils used for the assessment of its condition. The paper also deals with the results of the experimental research of tribological characteristics of motor and power transmitter oils sampled from engines and power transmitters of the Mercedes O 345, PUCH 300GD and PINZGAUER 710M vehicles in exploitation. The investigations showed that there is a change of tribological characteristics of lubrication oils in the vehicle engine and power transmitters. These changes are in a direct dependence of the state of all elements of the tribomechanical engine and power transmitters system, and they depend on their functional characteristics. The conclusion is based on the realized testing

Promena fizičko-hemijskih karakteristika sredstava za hlađenje motora tokom eksploatacije vozila / Change in physic-chemical characteristics of engine coolants during vehicle exploitation

Identifikacija stanja sistema hlađenja bez narušavanja njegove funkcije, u uslovima kada do otkaza dolazi, pre svega, usled promene fizičko-hemijskih svojstava rashladnog sredstva motora, ima velike tehničke i ekonomske efekte. Kako se promena funkcionalnosti složenog sistema hlađenja najčešće ogleda u promenama karakteristika sredstva za hlađenje, promena fizičko-hemijskih karakteristika sredstva za hlađenje može se usvojiti kao parametar za ocenu stanja sistema hlađenja. Za ocenu i analizu fizičko-hemijskih karakteristika sredstva za hlađenje danas postoji veoma razvijena merna oprema. / Identification of the condition of a cooling system without disturbing its function, when failures primarily occur due to changes in physic- chemical characteristics of engine cooling agents, has considerable technical and economical effects. Since change in functionality of complex cooling systems is most often a consequence of changes in the characteristics of cooling agents, the change of physic-chemical characteristics of coolants can be accepted as a parameter for evaluating cooling system conditions. There is nowadays a wide range of sophisticated measuring equipment for evaluation and analysis of physic-chemical characteristics of coolants