<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=1663564727022060&amp;ev=PageView&amp;noscript=1">

Stored Fuel Testing Part 2: The best tests to run

Posted by: Erik Bjornstad

As a service to our customers, dealers and friends, Bell Performance hosts quarterly webinars on fuel topics of interest to their friends and their customers. This is a transcript of one of these recent webinars held on The Fuel Tests You Need to Know About. We will be publishing it as a three-part series. If you would like to watch the archived presentation, please click here.

Click here to read part 1.

What are the best tests to run?

Well, in order to answer that question, you need to have a handle on what you're looking for and in order to, after you know what you're looking for, then you need to know what tests are going to tell you what you're looking for. Basically in a nutshell, if you're approaching this from a high level view, you need to know what current state your fuel is in. If it's good right now or if it's not. It would also be useful for you to know how long it's likely to stay that way or if there are any possible problems that may be possibly on the horizon for you and so the best fuel test for you are going to be the ones that give you that kind of information.

fuel-testing-and-compliance2.jpgBy and large, the best fuel test that we're talking about are the ASTM tests. ASTM tests kind of the gold standard test, if you will.

ASTM is the American section of the International Association for Testing Materials, and they have all of these test procedures for measuring certain kinds of things in fuel, among other things, and these procedures have been developed in conjunction with consultation with industry groups. The groups that actually know what's going on, on the field level. The advantage of ASTM fuel tests are multiple. First of all, they're reproducible. That means there's a defined test protocol that can be done a specific way by anybody and that means that the results that you get from those tests are comparable across the spectrum. That means that somebody in California who runs a test can take his results and compare it to the results on the same test done by somebody in Detroit and somebody in Miami and somebody in Romania and somebody in Nigeria. They're all comparable provided they followed the test protocols, and there's plenty of places for them to have these kind of tests run as well.

Let's dive into the tests themselves, okay. We've spent some time setting up the context here. Let's talk about the tests.

We need to know which test should matter most to those that rely on stored fuel, right. We want to have some context on how they're run so that we understand them a little bit better. We want to know what each test will tell us and if possible, what it doesn't tell us. Then we want to be able to apply it to the different kinds of stored fuel users and see what the value of each test might be for them.

All right, so first test, first recommended test that we're going to throw out there is the ASTM D2709, water and sediment content. Now this test is one of the ones that's specified in the D975 standard. That means in order to, for something to legally call itself diesel fuel, it has to pass this test. Now how do they run this test? Well, they take a fuel sample and they put it in a centrifuge and they centrifuge it so that all of the water and sediment that's actually in the fuel sample goes to the bottom. Then they can isolate it and they can measure it as a percentage of the volume of the fuel.

That's what the test is measuring. It's measuring the amount of water and the amount of sediment that's present in the test. Now what does this fuel tell us about possible problems that for somebody whose test doesn't, whose fuel comes back with a subpar results on this test. Well, first point is that if you have excess water in that fuel, that's a key supporter of microbial growth in the fuel and storage tanks and this would be, this is a universal problem, whether it's hospitals, backup generators, really anybody who relies on stored fuel, having too much water and having possible microbial growth is a serious, serious issue. Second thing is that if you have a failing reading on this water and sediment test, it's actually a strong indicator or a strong correlator to the presence of actual tank corrosion damage in that storage tank. That was one of the conclusions that the EPA found in their July 2016 fuel studied storage tanks.

There was the number one correlator, a failing test on water and sediment in a fuel sample, what's the strongest correlator they found to actual going into the tank that they pulled that fuel out of and looking at the inside of that tank and seeing moderate to severe corrosion damage. Water sediment content of course, also affects how the engines and the equipment run that use that fuel. For their service entities, fuel service providers and the generator service entities, this kind of test is useful, is one of the ones that's useful to document to their customers how they have improved the fuel's specifications from before to after so they can show the customer that before the service, the fuel failed this test. It had excess content and after they did their fuel servicing, the content, the fuel was back in the spec, they can show that to the customer and the customer has proof that they did something meaningful for their fuel. If you have a failing test on this, what does this imply that your plan of action should be?

Well, first thing to consider is the only way to correct a poor result on this test is to actually remove that water and sediment contents. I mean, make sense, right? This implies the need for some kind of tank cleaning and fuel filtration or fuel cleaning in order to do this so this is good news for the fuel servicing market. This kind of test, this kind of water and sediment test demonstrates the need for their services. Now a good fuel servicer or a good fuel cleaner so to speak, they're going to do a number of different things. They're going to use a combination of tank cleaning services. They're going to do actual filtration, mechanical fuel filtration of that fuel and they're going to add certain kinds of chemicals to the fuel.

They do all that together and they give the customer a complete solution, the filtration and the fuel, people call it fuel polishing, but the fuel filtration removes the water and sediment, which brings the fuel back into spec, but if they don't also add some kind of like stabilizers or water control elements to that fuel, they're not going to do, be able to do anything by keeping the problem from coming back, which is implicitly also what the customer expects, right. A good fuel service company will also incorporate quality chemical fuel treatments such fuel stabilizers and biocides as well so that fuel will stay in spec for as long as possible after they leaked. This water and sediment test, first essential fuel test that all the users of stored fuel really need to be aware of. Second recommended test is called the cetane index test. This is ASTM D4737 and it is able to estimate the cetane value in that fuel. Now there's another test called a cetane, well, a cetane number test, D617.

It's important to note that they're not exactly the same. They both tell you the same thing. The cetane number test measures the cetane value of that fuel. The cetane index test actually gives a very good estimation of that same value from a couple of other simpler tests that it uses. It uses measure of the density of the fuel and then they also run a distillation curve and there's a specific formula that the ASTM has come up that they plug those in and they're able to very accurately calculate what the cetane value of that fuel should be. Now what's the difference? Why do they have to do an estimation versus just measuring it? Well, it comes down to difficulty in cost. The cetane number test is actually run on a specific kind of engine that not very many people have so it's expensive and it's time consuming. It can cost you, I don't know, maybe like $1,000 to run that test and most people don't want to spend $1,000. The cetane index test if reliable enough that legally, you can use it as a substitution for the cetane number test.

Second caveat, I will touch on this again a little bit later in some other aspects, is that the cetane index test is good for telling you the starting cetane value, the base line of that fuel, but if you add cetane improvers to try and raise the cetane number or the cetane value of that fuel, the cetane index test can't actually detect that change because of the fact that it's using results from other tests in order to estimate that value. Now you might say, "Well, if it can't do that, then why do I need to consider it?" Well, because it's very valuable in telling you if you have a possible problem that you need to take corrective action on. What we're going to touch on here in a minute is that because you can't document if that action has actually worked, you're going to have to rely on other people to be able to tell you if that's happened or not.

Therefore, you need to have a partner that you can collaborate with, that you can actually trust that they know what they're talking about if they say, yes, your problem should be solved or no, you need to do a little bit more. All right, so given that cetane and cetane index are reflections of the combustion quality of the diesel fuel, what would the subpar test value tell you about possible problems that might result. Well, first thing, the problem with a subpar cetane rating in fuel is that the fuel is going to have a combustion deficiency. It's not going to burn as well as it should in that engine so you're going to have starting problems. You're going to have rough operation. You're going to have more black smoke production and if the cetane value has, let's say you've got some really, really old fuel that hasn't been checked for a long time and the cetane value is just really, really down in the dumps, it's possible that engine may not actually even start or it may not actually even maintain load if you try to use it on this bad fuel.

That is an important implication for people who have emergency backup generators, hospitals and healthcare groups. If the fuel isn't going to support the operation of their essential backup system, they have a real problem and it also has important implications for fuel polishers, for fuel service companies because again, if they're servicing their customer's fuel and one of the problems with their customer's fuel is poor cetane rating but they don't know about it, then when that customer goes to use that fuel and it doesn't do what they're supposed to, again, who's going to get blamed for it? The fuel service company because they were the last ones to have touched that fuel and they should have solved that problem. Whether that's fair or not is another issue, but they are the ones that are going to get blamed for it. Poor cetane value in the fuel, what should you do? What's the action step? Well, the action step is actually pretty easy here. A problem with low cetane value in the fuel is a little unique in that it can't be remedied by the removal of something.

It's not like the water and sediment test where you remove excess water and sediment, you solve the problem. The remedy is actually to add a chemical cetane improver, something that you can blend into the fuel that actually raises the overall cetane value. Now if you do this, then you're going to make the diesel engine or the piece of equipment easier to start. It's going to run more smoothly and it's going to have fewer, less black smoke emissions and so for somebody who's really relying on that, it's also going to give them better peace of mind. I mean how would you feel if you had an essential backup generator and your fuel service provider came to you and said, "This test shows that your cetane in that fuel is 36 and needs to be at least, 40, 45.", so you haven't solved the problem, how would that, what kind of peace of mind would that give you and what kind of value would that be? It'd be pretty substantial right. Cetane improver additives today, the dominant chemistry is what they call 2-EHN, 2-Ethyl-Hexyl Nitrate.

It's a pretty powerful chemical and depending on how much you add, you can very easily raise cetane rating of fuel by at least two to six points and typically more if you use more of it, just depends how much your fuel needs. Now exactly how much you would need to use, depends on where your fuel's starting from, and this is where we cycle back to that thing we were talking about earlier. Cetane index test won't tell you, after you've added cetane improver, how much that has increased. What you're going to have to do is you're going to have to rely on the entity that's adding or servicing the problem or adding this cetane improver to know the proper amount to add. Now it's not rocket science so to speak.

There are specific, well documented calculations that can very reasonably tell you how much you're likely to need to have, but the average group, the average you know telecom company or government entity, they don't know that, but fuel service providers should know that and that means whoever you partner with to service your fuel and take care of this problem, you need to be able, first of all, to know that they know what they're talking about if they recommend something and that you need to know that, you need to have confidence that their recommendation has your best interest in mind. If you have a fuel service provider or a service partner that you can have confidence that that's true, then you can have confidence that that problem has been solved and such, okay. That's water and sediment test, cetane index test. Third test, very important, microbial presence test. Okay, this is more important than ever. Microbial presence in stored fuel that serves any kind of critical function is not something that you want to mess around with, not at all.

It used to be that in order to check for microbial presence, you had to, the only options used to be that you take a fuel sample, you ship it off to a lab and you'd have to wait like 28 days for the culture results to come back. That's just not going to work. It's too long and luckily, those days are behind us. There are a number of different options available to people on the field level that allow for them to do actual in field, on the ground testing for microbial presence in their fuel. Let's talk about three main kinds here. The first one is what we would call a test culture strip. Some people might call them a dip slide and there should be a picture of that here at the bottom of the slide there. There's different kinds of them. They're really easy to use.

Basically, you have the fuel, you dip them in the fuel, you put them in a sealed container and you wait three to five days so it's not 28 days, it's maximum three to five days and they'll give you a rough indication, they're an indicator, yes, you have a microbe problem. No, you don't. There are some of them that will also distinguish between different kinds of microbes. Yes, you have a bacteria problem. You don't have a fungus problem, and that can be useful because certain kinds of microbes respond better to certain remediative actions and vice versa, so that can help you make a better decision there. Another good thing about test culture strips is that they're fairly inexpensive. Yeah, between $5, maybe $10 a test, so fairly inexpensive for the information that they give you.

Second one is what we would call indicator test. A biochemist would call it an immunoassay test, which basically means they are tests that detect and measure the presence of a certain kind of molecule in a given solution. In this case, molecules that are associated with microbes.

Their advantages, they’re relatively fast to administer. They're not three to five days fast. They're like 10 minutes, five to 10 minutes fast, which is a nice feature.

They have a couple of downsides. They're not deal killers, but they are a couple of downsides.

First of all, most of these indicator test are not quantitative. Basically, they say, yes, you have a microbe problem. Yes, you have a fungus problem or a bacteria problem, but they don't tell you how serious it is so to speak. The second thing is that they can be a little pricey. There are some out there that can cause upwards of $100 to $150 a test. For many people, that's a little bit of a sticker shock. Still, for other people, they can justify that expense because they may manage millions and millions of gallons of fuel and it may not be any problem for them to spend $150 on an immunoassay test, so just depends who you are, depends on your tolerance for that, okay.

Third one, ATP field test. It's still kind of newer technology and these detect the presence and they also measure the amount of microbial ATP that's in a sample. They're compliant with the ASTM 4012 test, so they have an ASTM protocol associated with them and they have some real major advantages here.

First of all, like the indicators, they give you test within a few minutes. Again, really, really valuable however, in contrast to typical indicator test, they actually give you a quantitative measurement of the amount of microbial presence so to speak in your fuel and that can be really valuable because what you can do is you can use ATP test and you can put them as part of a monitoring protocol and you can actually monitor the microbial levels in your storage tank over time. Why that matters is that when you suddenly notice it start to spike, you can then take action at that time and that's going to be before any of these really serious and expensive problems develop.

That is a huge, huge plus because it means that you can use them in the field and you can get almost an instant reading right there and then you can make decisions immediately on what you need to do before that problem really gets worse. This ability to have fast results is really important because if you look at the ASTM regulations that govern measuring microbial contamination in fuel, that specification is D6469. It's not up there on the slide. It's D6469 and it actually specifies that if you can't test the fuel for microbial presence on site, then you need to have the fuel tested between four and 24 hours after you draw the sample. Some people can't do that, so having an on site test like this that can give you very quick results, will help you overcome that problem. Those are the advantages.

Having a quantitative test that you can do in the field and get results in the field right there, is really valuable for being able to do that kind of thing and that's why as this kind of test gets more and more common in the industry, more and more companies and stored fuel users are going to be moving towards a model of not just preventive maintenance on their fuel, but predictive maintenance where they're monitoring microbial levels because they couldn't do that before. Now they can so they're monitoring microbial levels and they're able to solve problems before they start so that's a really neat thing that we can do now that we couldn't do before. Then lastly is they're fairly inexpensive. They're not as cheap as the first one, the culture strips, but they're a lot more valuable. Now typically with an ATP test, you'll have a piece of hardware like a luminometer that is an initial outline. Typically, it's maybe $3,000 or $4,000.

Some companies have those where you can rent them. You can do to a rent to own or they'll charge you like $400 a month and after, so you get to use it and for after a year, you own it. That helps take out the sticker shock. The actual consumables to run each test like $10, $15 test. That's huge compared to, when you compare that and weigh that next to the benefits and the information that you're going to be getting from it.

Okay, so those are three options for detecting microbial problems in the fuel. If you have, you get a positive test back, what kind of problems? Well, you're going to see these kind of problems referenced over and over because they're associated with a number of different test and a number of different factors here.

If you have excess microbial presence, you got to worry about stuff like storage tank corrosion because microbes produce acids that corrode tanks.

You got to worry about fuel degradation because the microbes consume elements of the fuel and basically destroy its stability.

You got to worry about biomass formation and filter plugging in the fuel, in the fuel source tank rather and all of those lead to you got to worry about whether your equipment's going to run or not, emergency equipment failure. If you think about it, that last one's really the big one. It's the one that many of these entities, certainly like hospitals and healthcare facilities, that's the one that they fear the most. They're okay if their storage tank has some corrosion damage, but they absolutely, positively cannot have that emergency equipment fail when they really need it. What's the action step? If you have a positive microbial presence test or an excess microbial presence test that's indicated, what are the implications of what you need to do? Well, in terms of the implications, government entities and hospitals worry about this a lot because they both really have to be able to provide services to their constituents no matter what and the microbial presence is a major hurdle to them doing that.

Same thing for generator users as well. They have the same concerns about reliabilities that these other people have because when you're talking about generator users, you're talking mainly about mission critical backup generators and they need those to run at all times. Fuel service companies and generator service companies, they're at risk for microbes causing them problems because the microbes are going to cause problems for their customers and their customers are going to blame them for those problems. How do you get rid of or solve a microbial presence problem in that storage tank if you do a testing that comes back positive?

Well, here's what you do. First, recommendation would be, you need to amend your PM practice to make sure that you can detect those, okay. That's really a kind of a before recommendation. You want to make sure that your regular monitoring of microbial levels in your storage tanks as a regular protocol that you do at regular intervals because you can use those results to predict when you're about to have that problem.

Once you detect that problem, the best practices would be as follows. First thing that you would want to do is you would need to drain the water bottoms out of that fuel and you'd need to apply biocide. Now this is important to pay attention to. Biocide application is the most important part of this process once you remove the free water.

Now you need to make sure that you use a biocide and not a biostat. There's a difference between the two. A biocide is the only thing that actually kills the living microbes. Again, it's the only thing that actually kills them.

Now a biostat is a broader category and a biostat is defined as something that makes it more difficult for microbes to grow, essentially, but if the microbes are already growing in that tank, it's not going to actually kill those. Now there are plenty of fuel additives out there that run around, talking about how they remove water from fuel so they kill microbes. That is absolutely, positively wrong. If they're not a biocide, if they've not been registered as a biocide, if you can't see EPA registration and fulfillment numbers on their label, they're not a biocide and they're not going to solve your microbe problems. That's number one, apply the biocide after you've removed the water, then you want to filter the fuel, process it to remove any existing contaminants plus remove the dead microbes because once you've killed the microbes, you still got the dead bodies in there. You do fuel processing, filtering that removes the microbes, removes any microbial biomass that's in the tank and gives you cleaner fuel. Third action step is you need to use a biomass dispersant and anti-corrosion treatment.

The biomass dispersant is something you'd actually add before you added the biocide because it will break up any biomass formations that are in that tank and actually make the biocide more effective because the microbes won't be able to be shielded from the biocide by hiding behind their biomass formations that are stuck to the sides of the tank, but the EPA also recommends specifically these anti-corrosion treatments. Anti-corrosion treatments will basically lay down a layer of protection on tank surfaces and will actually protect those from corrosion, from things like acids and things like that. Bottom line here is it's really important to stay on top of microbial issues especially if your top priority is making sure that that fuel is available for emergencies.

Fourth test, fuel pH level. This is pretty simple. If you remember from high school chemistry, pH is the measure of the acidity of a substance. You have a zero to 14 pH scale, seven being neutral. Diesel fuel typically will fall between five and a half and let's say eight, somewhere in there. You can measure fuel pH pretty easily.

Some people use chemical test strips like those strips that you use back in chemistry lab and those can give you a general reading, but we find that if you have lot riding on getting this kind of thing right, you want to be a little bit more rigorous or a little bit more specific in your pH and that means using a pH meter. You also want to make sure that you take pH readings of both the fuel and the water samples, especially the water samples. In fact if you have to choose between the two, you would choose to take the pH of the water because if you've got an acid problem in the fuel, it's also going to show up in the water bottoms, that's in there. You take the pH and it comes back abnormally, right. Something has to have caused that. The fuel just didn't decide to change pH on its own. Most likely cause of that is some kind of microbial activity in the fuel.

That's number one, possible microbial growth in the fuel and from that, you've got possible tank corrosion problems and degradation of the fuel quality. They're all tied together. In terms of how these problems would impact the different market verticals, well, we would just say the same thing that we just said before because the answers are still the same. A low pH reading in that fuel is an indicator that the fuel is either already degraded or that it may be on its way and that's a nuance of it to consider because if you're one of those people, you have stored fuel and you get fuel drops, your fuel's provided by somebody else and they bring the fuel to you.

Now you may be very very careful, very rigorous about how you take care of your storage tanks and how you take care of your fuel. You may do water monitoring every other week. You may do microbial testing on a weekly basis.

You may be the most careful fuel manager in the world, but not everybody is as careful as you and when you get fuel from somebody else, you are at the mercy of how careful they are and it's not beyond the realm of possibility that you can inherit a pH problem from somebody else who brings you their fuel and let's just say they weren't as careful as you are. That's why it's important to do pH testing on your own fuel as part of your regular preventive maintenance predictive maintenance protocol. Once you have a failing test or an abnormal test, what are your action steps? What are your possible protocols? First thing to consider is that since a low pH level is strongly indicative of microbial presence, what you first thing that you would do is you would do a microbial presence test to confirm that you had or did not have microbes in that tank.

Most of the time, you will have microbes in that tank and if you use a quantitative test method like let's say an ATP test, it will tell you how serious that problem is and so if you have established then through that secondary testing that you have microbes in that tank, well, now you become what we were just talking about before, the action items for solving a microbe problem. Now what if you don't have microbes in your tank? Well, if you don't have microbes in your tank, it's still useful to treat with biocides and to get rid of the water and to do some of these things in order to make sure that that fuel is as, say as in spec as possible in those other areas, but the bottom line is that once you've corrected the other contributing problems, once you've solved the microbe problem, once you've taken the water out, you're still going to have fuel that has an acidic pH and the question becomes, what do you do with that fuel?

First thing you have to consider is there's nothing that you can add to that fuel, to that stored fuel that is going to correct that fuel pH. I mean sure, you can add some kind of base, something to neutralize acid, but the problem is since you don't want to do that because that's not something that's approved to put in fuel. There's nothing approved that you can put in fuel that will correct a pH problem. However, the good news is that you can still use acidic fuel, it's still going to burn. The other thing to consider though is that if you have a seriously acidic pH problem, then that's probably not the only problem that that fuel is going to have and we're not talking about microbes here. It's probably going to already be stratified, it's probably already going to have excess water and sediment in it and you're going to have to need to clean those things up as well and if you can't or if the fuel is really really really acidic, then you're just going to have to call somebody to dispose of it.

All of this means is that you want to do everything that you can to stay on top and prevent this problem, but luckily, if you do simple things like monitoring your water, staying on top of your microbe counts, you really have a great chance of not having a fuel pH problem and that's really the bottom line takeaway here for that.

Okay, fifth test, water content test. Now first, when we talked about was water and sediment, so are they the same? Well, as you can probably guess, no, they are not the same. What's the difference? The water and sediment test, which is the first test that we talked about, it looks at the total free water content and sediment content in that fuel. The kind of water test and we're really going to be talking about two tests in this group here. The kind of water content test we're considering here, look at multiple kinds of water content whether it's free water, emulsified water and dissolved water, the three main kinds.

Now there's two recommendations that you should be doing if you manage fuel.

The first one is probably one if you manage any amount of fuel, you probably already been doing this for as long as you've been in the job and that is sticking the tanks with water finding paste. Simple, easy thing to do, almost anybody can do it. All you need is a tank stick and some water finding paste, again most of you probably already know how to do that. If you don't, talk to us afterwards, there probably a blog on the Bell blog that talks about how to do that, but it will tell you the amount of free water phase that's in that tank. Now just one thing to keep in mind about sticking tanks is you want to be consistent where you stick the tank because if you stick the tank in the same place and you do that, over time, multiple times, that gives you consistency in your readings and you can meaningfully compare them.

Another thing to consider is that storage tanks have the tendency, sometimes they can shift and they can settle after they're in the ground and many times, you're going to find a storage tank that's actually tilted, one end is a little bit higher than the other. That means if you were to stick the tank on one end, the water level that you detect may not be as high as if you were to stick it on the other end because the water has rolled downhill because the tank's not level. That's just something to keep in mind. The other main test is called Karl Fischer titration test. That's kind of the dominant test or the most widely used water detection test when you need to have a highly accurate, quantitative measurement of the percentage of all kinds of water in your fuel, not just free water, not just some of that emulsified water like you can see here, all of the water in there.

Karl Fischer tests are run by any number of labs. You just send a sample off to them. It costs like a couple hundred bucks, but if you're managing large amounts of fuel, couple hundred bucks may not be all that amount to pay. Bottom line here is that you need to monitor water content and make sure that it doesn't get out of hand because water content is a strong contributing factor to a bunch of different causes of fuel problems in that fuel. I'm talking about, obviously microbial growth. We've already established that microbes need water. If you have excess water content in there, then it's very likely that you're going to develop a serious microbial problem. Tank corrosion, contributes to that. It can contribute to equipment damage if you get some of that free water sucked up, it can damage fuel injectors, it can cause problems with common rail diesel engines.

It's really a problem for anyone that has stored fuel, so in view of all this, one thing that we can conclude is that monitoring your water content has a really high, should we say really high diagnostic value because of the number of serious problems that water content is associated with. Action steps, you have excess water content in there, what should you do about it? Well, once you detect water content, it's not that hard to remediate and you have several options to consider. If you have excessive free water like you stick the tank and you have more than let's say a quarter to a half inch of water phase, then you're going to want to mechanically remove as much of that free water as possible, whether pumping it out or draining it out depending on the design of your tank. Next thing that you would want to consider is using some kind of water scavenging fuel treatment or if you have emulsified water in there, you're going to need to add a demulsification fuel treatment.

Now a demulsification treatment, what that's going to do, you would actually add that first and it would actually break that emulsion and cause that emulsified water to separate from the fuel and drop down to the bottom of the tank where you can then mechanically remove it. Now third thing that you would want to consider is to have some kind of fuel processing, fuel servicing, some people would call it fuel polishing. We typically refer to it as mechanical fuel filtration, fuel servicing. That's one of the main things that they do is they remove, they filter out water so you want to get a good fuel service company to remove as much of that water as possible. The bottom line takeaway here with respect to test number five, water monitoring should be a regular part of fuel monitoring for anyone who has significant amount of stored fuel whether you're a hospital, whether you're a government entity, whether you're a non-retail fuel user or whether you're a backup generator. You really need to monitor your water content at regular intervals because of the possible problems that it can be associated with.

Okay, sixth and final test. This is an important one, fuel stability test. Now stability test categorically, they measure the ability of the fuel to resist changes to its composition over time. This is what people mean when they talk about a fuel's storage stability. When you leave fuel in a storage tank under regular ambient conditions, it's exposed over time to oxygen, to heat, maybe some water gets in there, how well or how long will the fuel stay in its original state or how quickly will it react and oxidize and stratify and form solids and gums and sludge and all that staff. That's the kind of thing that fuel stability testing gives you a window into so to speak. There are at least a couple of tests that measure stability. The two main kinds that people tend to hear of, first is called a thermal stability test or they might call it an accelerated thermal stability test. That is not the one that we're talking about here, but it is one that you will hear of if you nose around and do a little bit of research, you'll see this one referenced.

All that one basically tells you is how stable will the fuel be if it's kept at elevated temperatures for a long period of time, but the one that we're recommending here is, this ASTM D2274 test. It's known as an oxidative stability test or some people would call that accelerated stability or accelerated oxidative stability. Basically, what it focuses on is how stable is the fuel when it's exposed to oxygen? As we know, that's pretty much the, all fuel is exposed to oxygen as it's stored down the real world so to do this test, they take a fuel sample. They warm it up and they put it in a chamber where they expose it to a lot of oxygen over an accelerated period of time and then what that does is it causes the fuel to form sediments and form sludge and to form solids at a faster rate, but in the same way that it would do it if you just left it down the storage tank. They're just speeding up the process.

Then they isolate those and they measure how much solid content that fuel generated and so what this is able to tell them then is how likely or how quickly is that fuel going to go bad, form solids and stratify and all that stuff in the near future. Fuel stability testing is really important to monitor the condition of your stored fuel so that you can predict possible problems that may be coming. Now important thing to remember is that fuel stability testing is predictive. The results of the test predict the fuel's condition and predict its state of stability at some point in the future and that's a little bit different from something like a water and sediment test. The water and sediment test tells you the amount of sediment that's currently existing in the fuel right now, at the time that you test it. This test tells you how quickly can you expect this fuel to form solids and sediment and to go bad in the fuel and that can be really important for any keeper of stored fuel so to speak.

From this test, you get a predictive score that illustrates the state of the fuel in your tank and what it's likely to do in the future. If you have a subpar score on this test, what kind of problems could that infer that might be on the horizon for you? Well, again the answer is a lot of the same problems we've been talking about. We're talking about stuff like reduced combustion properties. Fuel that has a high amount of solid content, then it is not going to burn as completely as fresh healthy fuel will. Is it going to form injector and engine deposits, which will of course, would lead to performance issues and elevated black smoke stuff like that, and is it going to have, or you're going to have performance uncertainty for the critical equipment. If you have fuel that's severely unstable, it may not be able to sustain proper engine operation and that is a serious potential problem for places like, for government entities that serve constituents, backup generator owners, mission critical, hospitals and healthcare, all those people, that's a really serious problem for them.

Then lastly, it relates to polishing service efficacy or fuel filtration efficacy. We mentioned this early with the water and sediment test, but it's exactly the same thing. A fuel servicer can use an accelerated oxidative stability test to show the customer that your fuel was unstable before, we did the service now. It's back in spec, your fuel has changed for the better, here's the proof and the customer says, "Hey, that's awesome. Now I don't just have to assume that you did something good, I have the proof right here in my hand." That's a win-win situation for all those people. With respect to what to do about a failed stability test, because it's a predictive test, you actually have two kinds of remediative action to consider here. First thing that you need to do is you would need to do something to remove the existing molecular precursors that are already in the fuel.

Fuel that has these present, you can't always see molecular precursors in the fuel so fuel may look healthy, but it may actually have heavy molecules that have formed that are in that fuel, but they're not big enough to, for you to be able to see them with the naked eye, but when you put them in an accelerated environment like this test does, they form sludge and solids faster and the fuel does worse on the test. What you want to do first of all is you want to remove the solids and you want to remove the precursors by having a good mechanical cleaning, mechanical filtration service done on that test. That should be able to markedly improve the stability score of your fuel. Then the second thing that you would want to do is you would want to treat the fuel with a good chemical stabilizer in order to prevent the formation of insolubles in the future.

That's why we talk about a complete solution for fuel involves both things, involves mechanical filtration or some kind of mechanical servicing of the fuel and chemical treatment because mechanical, each one of those does covers an aspect of the situation better than the other one does so you need to use both of them together. Okay, so with that, we have covered the bulk of the information that we need to cover. Typically, what we do here now is we do a quick review just so, you know what they say, if you want to have the best learning experience, you say what you're going to say, you say it and then you talk about what you said. Last thing to throw in here as we start to wind this down as you know, we've had the six test, water and sediment, fuel pH, microbial presence and water presence, cetane index fuel stability, those are the six tests that we picked out as being the ones that we feel are the most important ones to concentrate on.

There are other tests you can do. You can have a sulfur content test or you can have a distillation test, you can measure any number of things, but these six tests, we feel are the best combination of being the most meaningful/most important and the easiest ones for the user to run or have run on their behalf, okay. Real fast, what are the six tests that we covered? 

Okay, water and sediment test gives you a picture of the viability of the fuel at a specific time because it documents the level of contaminants present in the fuel. 

The microbial presence test documents its, how much microbial presence you have, which makes it very important for being able to keep on top of what is pretty much the most problematic, most damaging element into the universe of fuel storage is microbes. Microbial presence test would be pretty essential to sound decision making on how and when to use, let's say biocide treatments. 

Cetane index test documents the combustion quality of the fuel at a given time and gives you a strong inference on whether the fuel can support full load usage by let's say emergency equipment.

Fourth one, fuel pH is easy to do and it can give you warning sign that damaging conditions are forming in that storage task especially with respect to inferring possible microbial activity along with it. 

Fifth one, water content test, essential element or proper fuel preventive maintenance. It gets linked to microbial presence. It's linked to possible fuel instability. It's linked to storage tank corrosion and it's not a hard set of test to do. 

Then the last one, fuel stability is the predictive test, but it's essential to have run because it really gives you a good picture of the fuel's ability to withstand changes to its condition in the near future. 

Click here for Part 3 of our Stored Fuel Testing Series: The Needs of your Business

The Essential Fuel Tests You Need to Know About

This post was published on August 24, 2017 and was updated on August 30, 2017.

Topics: Fuel Storage