Poor diesel fuel quality contributes to many generator failures with microbial growth being one of the most common causes. It only takes the slightest amount of water for microorganisms to survive and eventually thrive within diesel fuel. Even well-maintained fuel tanks are susceptible to condensation, so testing and management programs are necessary to ensure that Emergency Power Systems (EPS) are not threatened by microbial contamination and are available 24/7.

NFPA 110 (2022 Edition), 8.3.7* A fuel quality test shall be performed at least annually using appropriate ASTM standards.

Fuel Contamination vs. Degradation

Creating a proactive fuel maintenance program requires an understanding of the processes that occur within the tank. To properly react to the changes in your fuel supply, it is important to distinguish the differences between fuel contamination and fuel degradation.

Fuel contamination is often the result of some type of impurity, such as water or particulate, that enters the fuel supply. All forms of contamination can be removed through remediation or prevented with proper routine maintenance. If left within the fuel, some contaminants, such as water, can lead to fuel degradation resulting in the formation of other contaminants such as sludge.

Fuel degradation is classified as the molecular breakdown or changing of the fuel’s chemical characteristics over time. Contaminants aside, fuel can interact with its environment and change molecular form through processes like oxidation. If unaddressed with a proper fuel maintenance program, these processes, along with contamination, can eventually render your fuel supply incompatible with the demanding equipment.

The Fuel Maintenance Cycle

When managing bulk storage fuel, it is important to ensure that the fuel is of optimal quality should a demanding system require it. To make this process easier to manage, the fuel sampling and the testing cycle can be broken into four revolving steps:

Step 1: Sampling the Fuel

To collect a sample that accurately represents the current condition of your fuel, it is important to sample directly from the storage tank. Be sure to pull samples from problematic areas that are often hard-to-reach and/or are toward the bottom of the tank. It is in these areas fuel will often degrade due to stagnation and contaminants will collect after falling out of suspension. If your fuel system has multiple sources, be sure to test all locations to ensure the fuel quality is consistent and contamination has not spread beyond the original point of testing.

There are several devices one could use to collect fuel samples from the tank:

  • Fluid sampling pumps are often used to obtain fuel samples from hard-to-reach spots using flexible tubing. This allows for fluids to be drawn without the worry of cross-contamination, as the fuel never encounters the pump.
  • Fuel tank samplers, also known as “bacon bombs”, are industrial-strength stainless steel devices used to remove liquid samples from a bulk fuel storage tank. The device is lowered into a fuel tank until the sampler’s plunger makes contact with the bottom of the tank. The plunger then opens, which allows a sample to be drawn into the unit. To sample from a specific level in the tank, the plunger can also be actuated by a pull-chain attached to the device.

Step 2: Analyzing the Fuel

When it comes to analyzing your fuel sample(s), there are many acceptable testing methods to gain insight into the current condition of your fuel. For an in-depth analysis, you can send your fuel samples to a lab that specialize in fuel testing. It is here they will give you a breakdown of the different contaminates and contamination levels that were found in your fuel. This method is thorough; however, it can take up to a couple of weeks to receive the results thus hindering the accuracy of the test and response-times to potentially problematic results.

There are other testing methods that can be carried out on-site and can give fuel managers the insight needed to make critical decisions in 15 minutes or less. The following is an on-site test for microbiological contamination in fuels. This solution vastly outperforms all other testing methods and includes a free app to verify the results on your phone. Moreover, this testing method will ensure that your testing process meets best practices guidelines provided by ASTM D6469 – Standard Guide for Microbial Contamination in Fuels and Fuel Systems. ASTM D6469 states “Ideally, all testing should be accomplished at the sampling site, within a few minutes after a sample is drawn.”

FUELSTAT® Plus is a simple fuel testing kit that provides results in 10-15 minutes (video above). The objective of the test is to provide rapid screening of fuel samples to give a quick and accurate assessment of H. res., bacteria & other fungi within the fuel.

Step 3: Reacting to Test Results

Once fuel testing results are received, it is time to take the necessary actions to improve or maintain the quality of the stored fuel you are managing. It is especially important to act quickly when receiving less-than-desirable test results. Prolonged contamination issues can quickly elevate into bigger problems, resulting in complete equipment failure should that fuel make it to critical engine components.

Step 4: Repeating & Prevention

Regular fuel testing is critical in being able to manage an energy source. If unnoticed, contamination in a fuel tank can compromise an entire fuel system. This can leave room for vulnerabilities and unnecessary lapses in system integrity. Fuel can fall out of the desired spec in a matter of months or even weeks, requiring frequent testing to ensure your fuel remains optimal for use.

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