Onsite power systems need to fire up on demand every time they are called. To ensure readiness, every component of the system must properly maintained, and that includes the diesel fuel in the tank.

It is easy to take the fuel for granted, but as a longtime fuel quality specialist who has encountered more than a few fuel suppliers cutting corners in pursuit of larger margins, I am here to tell you that you’re best off taking preventive measures at every stage.

In this article – a follow-up to Reliable Backup Needs Reliable Fuel in the March/April issue of Powerline – I’ll highlight diesel fuel analysis and why testing is imperative. Diesel fuel reliability is the heart of our work at Fuel Management Services, and routine fuel analysis may very well be the most important step an operator can perform to ensure fuel reliability. Through fuel testing a generator operator or service department can keep an eye on the mission-critical fuel storage system. Learning the condition of fuel and monitoring for fuel tank contamination are essential steps to head off problems that could knock a generator offline. 

Based on testing results, operators and service teams may take corrective action to improve fuel quality, eliminate contamination, and ensure trouble-free fuel. If no corrective action is necessary, that’s great. The main point here is that without periodic fuel analysis there is no way of knowing what is happening inside the fuel tank. And as I pointed out in my last article, a lot can be happening in your fuel and your tank, and what you don’t know can be a real problem.

The best first step for preventing problems with your fuel, tank and components is to ensure that you are buying only high-quality fuel. Take nothing for granted. The vast majority of fuel suppliers will deliver high-quality diesel every time, but as a buyer, you want to put your supplier on alert that you are paying attention. Here are some simple, common sense procedures that every fuel buyer should follow when receiving delivery to their generators. 

First, find a reputable fuel dealer. 

Second, inform your fuel dealer how critical it is to have top quality fuel delivered to your generator. Diesel engines are far less finicky than gasoline engines, which means that fuel suppliers may take advantage of the wiggle room when it comes to fuel quality. Take the simple step of informing your supplier that you require on-specification Ultra Low Sulfur Diesel (ULSD) fuel. Communicate the seriousness of your business: If you are a hospital, for example, fuel quality could be a matter of life and death. Also, communicate to the fuel dealer that you are instituting a fuel quality assurance/quality control (QA/QC) program to ensure fuel integrity. 

These two simple steps cost nothing and show your supplier that you are serious about the quality of fuel being delivered. You are putting some responsibility on the supplier not to cut corners by selling inferior diesel or biodiesel. 

The third basic measure to enact is to obtain a fuel sample from the delivery truck. Put the sample fuel into a clear glass jar and do a simple visual inspection. This is a no-cost action that puts your supplier on alert. When the delivery driver goes back to his supervisor and tells him how particular you are, it shows a level of oversight that gets their attention and positions you as an informed buyer. 

Once you have enacted these procedures, you’ll most likely have made your fuel supplier a bit nervous – and that’s not a bad thing. Believe me, if you saw “price is king” dealing that some fuel suppliers do to add one 10th of a cent to their margin, you would be surprised. Again, these are simple, no-cost steps you can take to help shore up the front end of fuel delivery.

Once you have your diesel fuel in the tank, you cannot afford just to forget about it for months or years on end. There is too much at stake in terms of both generator readiness and the integrity of storage tanks and fuel-system components.

The days of ignoring stored diesel fuel went away when refineries revised their practices, first to derive more usable products from every barrel of oil and then to meet new specifications on sulfur content. As I explained in the last article, ULSD and biofuels are significantly different in terms of chemical composition from the higher sulfur fuels we used to use. These modern, mandated fuels have different properties and characteristics that, if not routinely monitored, can be very troublesome. These are dynamic liquids that have shown strong propensities to corrode tank walls and fuel system components and to cause fouling problems throughout fuel storage and fuel metering systems. You can imagine what corrosion and component fouling can do to negatively affect reliable generator operation.

To protect your equipment and ensure reliability, you need a fuel condition monitoring program as part of your regular operations or your service contract. With a program of periodic, routine fuel laboratory analysis to identify the conditions of the fuel and the storage tank environment, you can cost-effectively prevent and mitigate any problems that might be lurking. 

What we are recommending is a practice of  “condition monitoring” for diesel fuel. Wikipedia defines condition monitoring as “the process of monitoring a parameter of condition in machinery in order to identify a significant change which is indicative of a developing fault. It is a major component of predictive maintenance.” A generator can run reliably without every nice bell and whistle available, but it cannot run without fuel. Fuel that has quality or contamination issues is a serious barrier to reliable performance. 

A perfect analogy is the practice of monitoring the conditions of your health through periodic routine exams that normally include laboratory blood testing. The purpose of this practice is to detect any deficiencies or problems that may need attention. Subsequent diagnosis – if any – then leads to recommended corrective action of some sort before a condition worsens. Diesel fuel can be considered the lifeblood of a generator engine, and it is only logical to have that vital fluid checked regularly. The same purpose and reasons for human blood testing can be transferred to diesel fuel testing. Just as a human ages and body chemistry changes, so goes it with today’s fuels. With proper diagnosis, any fuel deficiencies or problems can be identified, and recommended corrective action taken. Tests might also confirm that the fuel and systems are in good shape, and there is no cause for concern. 

Let’s conclude this examination with a brief introduction to fuel testing parameters – a topic I will explore in greater detail in a subsequent article. There are many different parameters that a reputable fuel laboratory can perform. The most common approach is to use ASTM testing procedures, which are widely accepted and respected for their rigor and comprehensiveness. 

ULSD and biodiesel that are sold by reputable refiners and blenders meet clearly defined ASTM specification requirements when they leave the refinery. Oversight at the refinery level ensures that any fuel distributed and sold as ULSD meets minimum ASTM specifications. 

Biodiesel undergoes similar oversight, but there is some variability. Not all biodiesel is created equal, even if it meets specification. The different available feed stocks (soybean oil, animal fat, etc.) and blending methods can create challenges to fuel quality and necessitate different storage and handling standards. The biodiesel industry operates the BQ-9000® program, which enables refiners and marketers to achieve quality assurance certification by maintaining high standards for adherence to specifications. By choosing only BQ-9000-certified marketers, buyers give themselves extra protection on fuel quality. Non-BQ-9000 marketers generally produce fuel that meets the ASTM biodiesel specification (D6751), but there are exceptions. Determine whether you are buying diesel-biodiesel blends, and ask your supplier what they do to ensure the quality of their fuel blends. ASTM specification testing in a lab simply results in a determination that fuel is in fact diesel or biodiesel fuel. Testing parameters are important to prove the fuel is fit to move out of the refinery, but in short order most of those ASTM specifications become irrelevant. The takeaway here is that just because a diesel fuel meets ASTM D975 specification at the refinery, there is no assurance as to the reliability of that fuel once it moves through the complex distribution chain and is eventually placed in a generator storage tank. There are many points of potential contamination along that chain, and liquid fuel is dynamic and can change state quickly. 

Herein lies the challenge, because most ASTM D975 specification tests are not applicable to the fuel once it moves out of the refinery and is placed in your storage. Fuel testing done post-refinery should be applicable to potential contamination types and relevant to the changes that fuel undergoes. Please watch for future Powerline articles that will provide more details on fuel testing parameters and their relevance to our generator market.