 This lecture is an oil analysis. In fact, this is a continuation of the earlier class on contaminant analysis. As you know, wear and debris analysis almost constitute 20 percent of the CBMs or condition based maintenance techniques, which are adopted throughout the world. So, right now we will be talking about this oil analysis. So, as you know just to recap, you know tribology is the study of friction lubrication and wear and it is when two of these machine components, when they interact either they slide or rub and these surfaces are actually very rough. If you see the surface roughness, they are very rough and they have a central line average. So, what happens to reduce this kind of friction? We need to give a layer of lubricating oil. Now, because of forces which are responsible for the contact, these surfaces could rub against each other, they may slide, they may roll and this is how the two surfaces meet. So, to reduce friction, we need to give lubricating oil. Now, during the course of the time operation of the machine, what happens? These particles they will wear out, particles will wear out and in the last class, we had seen how these particles are contaminants, because they are going to contaminant the oil which is there. So, these particles will wear out and get deposited in the lubricating oil. Now, because of this contamination of the oil, this becomes an indicator of the machine's health, indicator of the machine's health condition. Now, you will see that in every machine be it an IC engine, be it a pump, blower etcetera, we need to have lubricating oil between the components particularly at the bearing locations, particularly at the wherever the surfaces are contacting each other, they are sliding over the one over the other, we need to give oil. Apart from it, there is another scenario, one is this lubricating oil, another component which becomes this hydraulic oil. There are many operations particularly the earth moving equipment, earth moving equipment, when you talk about big shovels, dumpers, excavators etcetera, they actually use lot of hydraulic oil for actuating the loading and loading mechanisms and so on. So, what happens to consider or to understand the health of this machine, we may periodically look into the condition of the hydraulic oil, condition of the lubricating oil. So, what happens initially, these oils have some properties be it the physical properties in terms of their density, viscosity, their temperature stability or the viscosity index, how the viscosity varies with temperature. These are some of the physical properties on top of it, their chemical properties in terms of their composition, in terms of their bonds which are there, we give some stabilizing elements to the oils to be stable, so that the bonds do not break up and then they lose their properties. But in due course of time because of the fact that because of the machines rubbing against each other where particles will bound to get deposited, they have no place to go but the lubricating oil or the hydraulic oil. So, in process what happens, the physical and chemical properties of this lubricating oil or hydraulic oil do change with time. So, if we have some mechanism as to we collect this oil, do a test in a laboratory wherein we measure their physical properties or chemical properties and see how much they have changed or gone for the worse from the initial conditions of the virgin oil or the new oil or the brand new oil. We will get a clue as to there is something perhaps wrong with this machine. So, this is what is the most important preamble and then why we do oil analysis in to find out the machine's condition. So, with time what happens the oil condition, the oil condition could be many like we have some physical properties and some chemical properties and we have may be they will change may be and or it could be either way also. So, between a tolerable band you know this is the tolerable band because these two are the tolerable bands. So, if the properties deviate beyond this tolerable bands upper limit and lower limit, we know time to change the oil time to change the oil to change. I will just give an example as to for example, when we have periodic maintenance, we actually in a regular interval change oil in the machine. Now, this is good for an individual for example, a very good example I always give is you know when you have an automobile be it a two wheeler or a four wheeler. You go as per the OEM manufacturer they say every 5000 kilometer you go for an oil and filter change or sometimes say or 3 months whichever is earlier. If you if you go see the car malar service manual or the two wheeler service malar this is what it normally says. Now, it may so happen that your oil condition was much within the tolerable bands I just talked about somewhere here and we are unnecessary changing the oil because you know your three months has come here in time or. So, you say you know it is time to change my oil, but you say the oil is still in a good condition there was no necessity to change the oil, but because we are following religiously the OEM manufacturer recommendations we are changing it. Now, imagine if in an plant where we have may be in a thousands of such locations where oil change is done and it so happened that the condition of the oil was within the tolerable bands, but then because we are changing the oil oil may be good we are wasting good oil. So, wasting good oil if I do what is the no no no this periodic maintenance and there have been reports and people have shown statistics were done surveys and found out that by not changing the oil periodically as has been mentioned by the OEM, but changing it only when it is required because the properties have gone beyond the bands you know somewhere we are here here etcetera then only we change the oil. So, oil change is to be done only when it is required oil change is to be done only when it is required. Now, who tells us that it is time for the oil to change and this is where our oil analysis comes to the help and going back to the earlier example there have been lot of cost savings when we do oil change as per the recommendation or as per the findings of the oil analysis. Otherwise we need not change the oil and there have been lot of considerable lot of saving in finance when you when you do an oil change only when it is required. Particularly in many plants you know many of these automation plants where we use lot of hydraulic oils you know if you if you talk about an automatic currency note printing shop you know we have currency note printing plant very close to Kharagpur and where they use lot of hydraulic oils for operating of the machines where in the currency sheets are printed you know the way they are measured counter then the way they are packed in bundles they are all hydraulic operations. So, we have done survey wherein we found out that it is cheaper and much economic if you change the oil only when it is required in this case being the hydraulic oil and not regularly religiously every 3 months or 4 months change the oil. So, in a plant in the long run actually oil analysis serves you two purpose you know one is it tells you that what is the present condition of the oil and next is you can know whether it is time for me to change the oil or not change the oil. So, just going back to the overall tribological analysis for condition machine condition monitoring we have what is known as the contaminant analysis and which we discussed yesterday that is a spectroscopy where the particle size are less than 2 microns then we have the wear debris analysis or ferrography wherein the particles go from. As I was telling this oil analysis is to be done only when oil change is to be done only when it is a required. Now, question is who decides what is required it actually when it is required this is actually done by oil analysis by oil analysis. Now, I will just give an example we have a currency note you know the rupee currency note which is printed we have a currency note printing plant very close to Kharagpur actually there in the after the printing press the sheets of paper because you know counting is very very important when you are doing currency note printing the counting and the process of packing and bundling etcetera are all done through hydraulic actuated actuators hydraulically activated actuators and there are lot of hydraulic oil flowing in the plant in the circuits different actuation mechanisms or the counting mechanisms and it was reported that earlier when very religiously they were doing this hydraulic oil change in a periodic manner they were incurring lot of cost rather when they did the hydraulic oil analysis and only change whenever the oil analysis recommended or indicated that the oil quality has deteriorated and now it is time to change the hydraulic oil they followed this practice and then there has been considerable savings in the plant because of implementing oil analysis in the in the hydraulic oil requirement and same of course you can do the engine lubricating oils particularly in the in in such a plant actually mostly it is hydraulic oil but the DG set the diesel generator sets which are required for backup power are actually the lubricating oil are actually analyzed. So, now next question is in this oil analysis let us see what are the tribological analysis for machine condition monitoring one is this contaminant analysis which I talked about in the last class and where the contaminants can actually be categorized into three categories the spectroscopy is the contaminant size are less than two microns wherein actually in spectroscopy just to recap actually in spectroscopy because the particles are of such a small size we cannot see them so unless we have very very high magnification like in a scanning electron microscope or otherwise in a spectroscopy is used actually to find out the chemical constituents of the where particles in terms of the chemical elements it could be how much percentage of iron is there how much percentage of aluminum is there how much of copper zinc etcetera is there next comes actually this wear debris analysis wherein the samples are of the size from may be ten microns to know as high as may be fifty microns and when the particle sizes become large actually the the contaminant particle count actually becomes a good indicator about the wearing a mechanism and this particle count is actually given in how many parts per million in a given milliliter of that oil but in this class we are focusing on oil analysis right in the beginning I told you because this oil has got contaminant and it is going and because it has been subjected to lot of temperatures you know temperature fluctuations could happen because of lot of oil because once when two members are mating against each other there will be lot of heat generation and you know if you shut off the machine shut down the machine there will be lot of temperature cycling so because of load temperature cycling etcetera the oil are going to lose its property all properties change change then of course of the contaminant themselves properties change okay so we need to do the oil analysis I will briefly recap regarding the contaminant analysis because this contaminant and oil analysis actually go together side by side and to begin with just to give an overview why this oil properties change you know in a typical oil other than the virgin oil we give lot of additive agents to the oil for example so in this table if you will see the first column is the oil additive then the second column is the purpose why this oil additive has been given to the oil and certain remarks so to have an anti oxidation to slow down the formation of oil oxidation which produces lacquers actually if the oils oxide they will become very gummy type of things okay and they could unnecessarily increase the friction etcetera certain anti wear additives are there so that the wear is reduced and actually a thin film is produced and obviously into some of the soils we need to give corrosion inhibitors which basically is an alkali which we mixed so that it counters the development of acids okay and thus high alkalinity is given to the oil demulsifier to separate the water from oil usually in the plants the lot of problem comes because these oils get ingested with water okay and this water forms a layer and sometimes you must have seen a well in in oil once this water is mixed a lot of problem okay and it will it has a lot of a detrimental effect on to the properties extreme pressure agent improve the surface of metal under pressure and chemical reaction is caused by this additive viscosity index improver reduce the change in viscosity with temperature and actually the long chain polymers which open up with temperature basically viscosity index as I was telling you the problem the oil are subjected to lot of temperature cycling and you know viscosity is a function of temperature okay but then this viscosity index improvers are given so viscosity index is actually the function of how the viscosity changes with temperature we would not like oil to drastically change the viscosity with temperature but you know you must have noticed in just as an example in engine oil particularly not in our countries but in the countries in the northern of the southern hemisphere close to the poles actually there is lot of temperature variations of viscosity changes with temperature so they have a summer time engine oil and a winter time engine oil okay because of course you know if you go to the SAE grades you know SAE grades for the engine oil you can see how the temperature variation of viscosity is given okay so just to recap you know when you do the spectroscopic methods and actually the when you do the spectroscopic methods actually how are these contaminants we cannot collect contaminants of 2 micron size just by picking them up so actually they are as an suspension in the oil and this is our container so the suspension are nothing but the contaminants or the debris but in this class we are focusing as I was telling you on this oil whose property has changed okay and so you can take this same container okay if you have this oil which has been collected from a machine actually they are actually closed the cap okay there is a reason why I have mentioned this closed cap because when I am talking about sizes of 2 micron or less even the dirt particles in air in the ambient air can contaminate the oil sample so it is not very easy that just you open the engine and you know get a depth stick and or get a container and full of oil no there is a procedure detailed procedure of how this oil has to be collected so that our ambient air does not contaminant does not contaminate the sample other than we will not know whether it this particles which are there in the oil is it because of the machine or because of the environment okay to avoid such false negative tests we have to do this okay because you know ferrography are in different of formats no direct reading or the analytical ferrography from the ferrogram etc and the ferrographic wire particles which are there in the oil they have different sizes for example the normal rubbing wear the debris will look like flat platelets of the size 5 to 10 microns in size cutting wears are actually thin to thick curl strips spherical particles of smaller ball sizes 15 to 20 microns in size if there is a severe sliding wear the particles will be long and flat and larger than 30 microns if there are bearing wear particles there will be laminar particles edge plates and holes in gear particle gear wear particles are easily rough and irregular surface just to give you a brief idea regarding how the particles look like but the wear debris composition helps us the quality and composition of wear metals allows us to set alarm levels now this may be comes from experience now you know your parent material has so much of iron and so much of copper so much of zinc etcetera you can set your standards usually these standards are given in the national standards about may be you know if you have may be usually it is you know if it is more than 15 ppm in a particular 10 ml or whatever parts per million are available of iron or silicon or sulphur etcetera you need to be these are the alarm levels of course this this is very relatively speaking this levels but then you can set up your standards for you know for all the blowers in your plant all the gear boxes in the plant all the pumps in the plant all the engines in the plant you can set up the standard for what is the level of level of tolerance of contaminants suspended in the oil okay you can this yourself you can set up okay and of course coming back to this wear debris compositions another very important aspect is this knowledge of metallurgical composition is helpful in localizing source of wear metal production because once I am getting this contaminants or wear metal in the suspended oil I need to be I need to know where from this material came so the parent metallurgical composition of these elements is very very important for us and this what are the some strategies which we follow for the wear contaminant analysis one is we have to catch the faults early okay because low cost and planned and manageable remedy okay they have to be planned and we need to know the solution because many a times what happens when you are I will just give an example oil you have collected oil okay which has a particular concentration okay and you are doing the trending of the part of the concentration with time you are doing this but suddenly what happens in the plant in the machine in the meantime you have added new good quality good oil or virgin oil so if I add this this concentration is going to go less so we have to be careful that during my trending plot this is when I collect the next sample after this time that if the oil machine has been upgraded because you know we we do not care regarding from an operational point of view if they say that the machine has to be filled with so much of oil level from an operations point of view we have to ensure that the oil is full in the tank okay but it has so happened that when you collected the oil the oil actually was at this level okay so you will get a richer concentration okay of the contaminants and then now if you next dilute it with good oil this concentration is going to reduce so we have to be careful about this kind of planning so we should know what is the procedure to catch this defects so called in the oil of course identify precise source of all this requires different technology and analytical method like I was telling you like the spectroscopy methods or the ferrograms etc they are very cost intensive operations so in situ oil or contaminant analysis is not possible because of many reasons they are bulky they require a very clean environment to do these operations they are very costly and so on so we in in fact as opposed to you know just if you compare as opposed to maybe vibration monitoring one of the reasons why vibration monitoring is very popular I would say is a couple of things one is in situ measurements are possible and they are very very cheap and because of the signal processing techniques right away by having a signal analyzer we can right away tell the cause can be cause can be immediately immediately known okay so and in fact that is the reason why with this vibration monitoring is popular but the oil analysis actually complements complements the other vibration monitoring because if you have got some clue or some cause known from vibration monitoring you can confirm confirmation can be done by an oil analysis or an wear debris analysis in fact in many plants when they do machinery troubleshooting machinery troubleshooting they adopt both the techniques okay they do an in situ vibration monitoring and analysis and then they collect the oil sample they send it to a lab do the analysis and the labs will also say suppose for example I will tell you that the vibration monitoring says that you are in a let me give you another example say for example I have a shaft which is supported on in one case the general bearings one case is an anti-friction bearing this is an anti-friction bearing and actually there is a casing and so on this is filled with some oil this could be carrying couple of disc rotor just as an example okay now it may so happen that by having vibration monitoring if I put a transducer here and it says that I am getting a 0.45x peak okay other than I am getting a predominant 0.45x peak in this spectrum okay and this corresponds to 0.45x frequency I am getting some amplitude okay this is the vibration signature looking at this knowing that there is a journal bearing we may think that this is an oil well which is occurring because of 0.45x usually it is 0.45 442 but then we are getting around 0.45x so it we may lead to a conclusion that there is a strong case of journal bearing defect okay and how this is this is complemented through oil analysis is now if you collect the oil from the same machine and and say that it has and then do a analysis of the contaminants collect oil collect oil and do the analysis of the contaminants you will see that there is a rick presence of of zinc this means that the journal bearing has zinc has worn out so oil analysis is also now confirming your earlier observation that there are the defect in the journal bearing because I have got a 0.545x peak and now because of this oil analysis I am seeing a rich amount of zinc and this means that there is a defect in the journal bearing and this is how it helps us okay so the wear particle analysis tactics is improving the quality, turnability and design of the density of the data particularly we have to very careful about the errors in the sampling process and analysis like the example I was telling you two examples one is you are collecting the samples in an environment where the environment itself has a lot of suspended dirt particles particularly the case of a coal mine where in the lot of coal dust so and this dirt could be of size of more than 5 microns we should not be collecting samples during environmental contaminants during sampling sampling from dead zones like dead zones where all the sediments come and get deposited normalization of data because dilution because of new oil addition reduced data noise poorly filtered oil so these are the techniques which we have to take care of and we know about the wear debris compositions I will be not dwelling much on this and rather I will go to the fluid analysis part so the forms of metal wear present metal only means mechanical wear metal oxides means oxidation corrosion dissolved or metallic components could be because of chemical corrosion so an effective oil analysis program needs to have these features in the mine we obviously cannot start an oil analysis schedule after the machine has gone bad so we have to establish the objectives on oil analysis schedule in a regular manner handle the oil sample correctly because these samples from say for example in a plant I have thousand different locations wherein I have to sample the oil samples so every collected point has to be named numbered date when it is collected this has to be done and then proper communication with the analysis lab because you are somewhere your plant is somewhere and your lab is may be you know thousands of kilometers away from your plant so we need to communicate with this analysis lab as to where from this oil have been collected how they have been collected what are the different analysis time analysis test which needs to be done and of course put the right oil in the right machine you know extend oil drain intervals when needed identify the quantity of contaminants identify the origin of contaminants provide feedback to the laboratory evaluate the cost effectiveness because the same oil is serves both the purpose both one purpose of doing the oil analysis the next purpose of doing also also the contaminant analysis now what are the lubricating oil analysis properties basically the lubricating oil is analyzed for these parameters one is the viscosity the contamination the fuel dilation solids contain the fuel soot oxidation nitrogen so there are actually many standards which are available so we need to specify either to the lab tell by telling them the standard numbers or tell them the procedure which they follow should be an international standard so in this few slides I am going to tell you about some of the standards which are internationally followed for doing such tests and when you in your plant give the oil sample to another test agency or an analysis laboratory we need to specify the standards for example if you need to do the atomic emission spectroscopy these are the NTSL01 NTSL02 FTIR spectroscopy you need to specify these standards so the purpose of giving these standards means that you need to be aware of the standards of course now these standards are available from the sources and then you can study them particularly when we do the physical property test the kinematic viscosity at 40 degree Celsius and 100 degree Celsius needs to be calculated or measured as for this ASTM standard viscosity index and the specific gravity the acid number base number oxidation stability so these numbers given here are actually the ASTM standards so the purpose of letting you know in this class is not to discuss about how the standard is or what the standard is just to make you aware that such standards do exist so all you have to do is collect the oil sample and send it to a particular lab and specify a standard by which they need to do these tests similarly very important is this contamination test in the oil the gross water content by crackle test crackle test is actually you know once you heat that oil sample you will hear a lot of crackling noise and that is why the name crackle test came and then we have moisture absorption by the Karl Fischer method chlorine content of lubricating oil and these are some of the tests you know which you may be aware of in your chemical chemistry lab or in your chemical analysis lab and then of course there are certain standards as to count as for the SAI standard or the NEPA standard basically basically through a laser light you will see a laser light being incident on this suspended oil particle and once this laser light gets reflected the intensity of reflection gives you a clue as to the measure of the amount of contaminant in that oil and that is how either you have a particle count or by having sieves or filters of different diameter you can also do the pore blockage particle counts and then and there are few more wear debris and contaminant analysis by direct read photography millipore patch test these are all NTSL standards which are available. Now a very important fact which we need to consider is how do I collect the oil it is just not that you know I open the drain plug and collect all the oil in fact let me tell you the drain plug in an engine is not the place to collect oil but for convenience many do that I know suppose this is something I am not going to discuss about the internals but and this is the drain plug and imagine if this machine was not operating and then the oil was not in motion what would happen all the heavy sediments would come to the bottom of the tank heavy sediments. Now if I collect the oil just by opening the drain plug and then I will get a very rich heavy sample of contaminants and that is not the right way to collect oil this is definitely not a method and obviously when the safety risk is very important if I if I tap a hole because the oil could be under high pressure and high temperature so they may just squid out and and create harm harmful to the operator of the technician. So, safety risk has to be considered because there will be hot fluid pressurized so this one has to be very careful that it is just not very simple that you know I just you should in fact never open a machine anything in a when because there are lot of dynamics occurring in shaft rotating at very high speeds lot of fluid under pressure they can damage and criticality of equipment or example like I said how frequently we need to consider this oil sample is it every now for example if you talk of an aircraft engine do you mean to say after you know every every you know two years you are going to just open the collect the oil samples no depending on the criticality of the equipment we need to increase the frequency of the oil sampling environmental conditions whether it is a very dirty environment whether it is a very clean environment these also factors going to the consideration of oil sampling. So, the sampling objective is that produce a sample that is representative of the material the system is producing and the contaminant that has entered the system ensure proper timing for sampling prevent contamination of the sample during sampling by now you get an idea like I told you about the coal mine where there are lot of hydraulic operating shovels drag lengths excavators you know such an environment you have to be very very careful as to how to collect this oil samples this is a figure from an caterpillar website some of this figures which are actually from the you can go to some of this website actually these figures are from that site. So, these are some of the if you have an engine there is a lube oil and these are the filters. So, some these are the good locations to collect the oil and these are definitely not the the cross ones are the bad points actually the sampling bottle some look something like this and the bottles themselves have to be a very clean and then their ISO standards for cleanliness of the sampling bottle because the bottles themselves if you are talking about a bottle the bottle itself should not have contaminants it should be no contaminants but no is difficult to define. So, there are ISO standards as to say what is what and and how you collect it actually through a vacuum pump or valve drain valve etcetera this is how they are collected. So, this ISO 3722 cleanliness of sampling method tells that it is clean when they are there are less than 100 particles greater than 10 microns per milliliter super clean less than 10 particles greater than 10 microns per milliliter ultra clean glass bottles washed and dried in clean environments of such cleanliness of sampling method is very very important because I cannot have an dirty bottle wherein there are contaminants. In fact, sometimes when this tubings are required in this vacuum pump this tubings once you have collected oil from one place like a machine your collected oil in the next when you go to next machine you should discard the tubing and you should put a fresh tubing. Otherwise the contaminants from the earlier machine are going to get get deposited in the walls of the tubing and it is going to contaminate the second reading. So, contamination has to be avoided at any cost and that is why this cleanliness is essential to be maintained through this ISO 3722 standards. Now, before I conclude this class I will I will be telling you some of the effects the contaminants or the oil do to damage bearings and these are available in the hand books particularly the tribology hand books. So, this is just a figure as to the general view of corrosion damage due to water contamination during storage particularly when you know when you when you go the ships the naval ships the propeller shafts are supported by padded journal bearings. And if you if you go to the hull of the ship wherein and this is the machine and actually they are when they go to the high seas they store this bearing pads you know on on on on this hull and whenever extra bearing pads are required they just to move and keep it. And during storage for a long time you know because of the moist environment there is a lot of water contamination during storage and you can see if it goes neglected there will be this corrosion marks which are there on the bearing. Severe cavitation damage of an alternative bearing attributed to chronic water contamination you see the cavitation damage in an alternative bearing. Scoring an impact damage from severe debris entrained in the oil because if there was an wear particle it was there in the oil it would score and then damage it is just like this you know bad patches on the road and if this goes undetected and uncared for these are going to become bigger and bigger and eventually there will be a huge failure of the bearing. Next is you know there is a lot of acid phase of a copper bearing lead bearing. Lead is very susceptible to acid attack you know as talking about this acids which are there and they lead to corrosion and that is why we need to give in the soil a lot of anti-corrosion additives basically an alkali treatment. Acid attack of bearing material the bearing material has been completely dissolved showing the overlay of the nickel interlayer underlay and steel backing. Acid attack is very very dangerous of course this is because of a fatigue loading, actual fatigue damage the small end bush and of course this you can see the overload balls showing plastic deformation fatigue and scoring. Fatigue damage due to a roller pin, severe axial shaft is misalignment overloading one edge of the bearing and see a overloading at one edge of the bearing. Electrical discharge damage to an alternator bearing estimated at about 50 millivolt per level lot of discharge occurs in which I was describing in the last class particularly when this sparks occur. So, in conclusion and of course again a scoring and pitting from electrical discharge and an operating high speed alternator generalize bearing wear due to insufficient oil film thickness probably the result of oil dilution with a distillate fuel. So, in conclusion in this class we discussed about how oil analysis is important and how oil analysis or contaminant analysis can complement whatever we have done through vibration monitoring. And in particular what are the techniques of oil sampling or what are the precautions we need to take regarding oil sampling and how important the cleanliness of the sampling bottle is what is the importance of the cleanliness of the sampling bottle and what happens if to the bearings if this oil have contaminants and how they can damage the bearings. So, in a nutshell this oil and contaminant analysis actually form 20 percent of the cases of CBM throughout the world and they actually help complement the vibration monitoring techniques. Thank you.