Your backup equipment is only as reliable as the fuel that powers it. You can have the best generator on the market, but if the diesel in your tank has been idle for a year, collecting water and growing bacteria, it won’t help you when the power goes out.
Below, we explore whether you can restore old diesel fuel, what makes it degrade, how to spot the warning signs and what you can do to fix it.
Diesel fuel degrades over time, potentially compromising your emergency preparedness strategies. In facilities where uptime isn’t optional, a generator that fails to start can mean patient care interruptions, data loss or mission-critical operations grinding to a halt.
Taking fuel quality seriously is part of having a solid plan.
Diesel is a mix of hydrocarbons that naturally breaks down over time. It can begin to degrade in as little as 28 days, though it will last longer when stored under ideal conditions. However, temperature swings, humidity and how the supplier stored your fuel before delivering it to you can speed up degradation. If your fuel has sat unused in a tank for over a year, it’s likely not in great shape anymore.
Understanding why diesel breaks down helps you appreciate why your stored fuel needs attention.
Water can enter diesel tanks in several ways. For example, temperature changes may cause condensation inside the tank. Sometimes, water comes in during fuel delivery or through unsealed vents and fill caps.
Water intrusion into diesel fuel systems may seem minor, but it is the primary factor in microbial contamination.
Once water is in your tank, it creates a breeding ground for bacteria and fungi. These microbes live where the water and diesel meet, feeding on the fuel’s hydrocarbons and proliferating under ideal conditions.
As these microbes grow, they form sticky biofilms and create acidic byproducts along with a thick sludge. Acids corrode metal components, while sludge clogs your filters. When your generator tries to pull fuel through a filter packed with this biomass, it will struggle to keep up and might fail.
Diesel will degrade even without the presence of water or microbes due to oxygen exposure, which breaks down the fuel’s molecular structure over time.
Long-term storage reduces oxidation stability, allowing the fuel to form insoluble particles like sediment and gum. These particles can clog injectors and damage your fuel system.
Some red flags indicate whether your stored diesel has gone bad.
A visual check of your diesel fuel can reveal these warning signs of degradation.
Color changes: Fresh diesel is usually clear or slightly amber and looks clean. The color will darken noticeably as it degrades.
Cloudiness or haziness: If your fuel sample appears cloudy or hazy rather than clear, it may indicate water or microbial growth.
Sediment and particles: Sediment at the bottom of your tank or floating particles in a fuel sample may indicate the fuel has started breaking down or collecting contaminants.
Degraded fuel creates the following noticeable problems with your equipment.
Clogged fuel filters: Needing frequent filter changes may indicate a problem with the fuel.
Difficulty starting: Engines that are slow to start or won’t turn over at all often point to contaminated fuel.
Loss of power and rough idling: Degraded fuel can’t deliver the energy your engine needs. You’ll notice reduced performance, rough idling or engines that struggle under load.
Excessive smoke from exhaust: Contaminated or degraded fuel can produce more smoke than normal during combustion.
Visual checks and performance symptoms give you clues, but professional fuel testing is the only way to pinpoint the problem. Testing analyzes water presence, microbial contamination, sediment and chemical stability. It’s also a typical regulatory compliance requirement.
Luckily, a technique called fuel polishing makes it possible to restore old or contaminated diesel to usable condition. This filtration process removes water, sediment and other microbial contaminants. It’s a multistage system that circulates the fuel through specialized filters until it meets industry standards.
The goal in diesel fuel polishing is to restore the fuel to a clear, bright state. Polished fuel is ready to use and won’t clog your filters or damage your equipment.
The process starts with sampling. From there, professionals use equipment that circulates fuel from the tank through progressively finer filters and returns it to the tank. Water separators extract free water, and filters catch sediment and biomass.
The fuel keeps circulating until testing confirms it meets specifications. Depending on the extent of the contamination and the amount of fuel in the tank, this can take several hours or longer.
Polishing can fix the immediate problem, but keeping your fuel in good long-term shape requires a maintenance approach. Specialized fuel additives can stabilize diesel for extended storage and prevent recurring microbial growth.
Regular tank inspections, water removal and periodic testing can help you avoid diesel fuel degradation before it becomes a crisis. You can install tank monitors to remotely monitor fuel levels and proactively prevent unwanted outages instead of reacting to problems as they arise.
Diesel fuel degradation is a fixable challenge. Foster Fuels can transform stored fuel from a hidden liability into an asset you can count on in a time crunch.
Our fuel quality services include professional testing, diesel fuel polishing and maintenance programs. We work with businesses to ensure their stored fuel is ready when they need it. Working with us gives you the knowledge to identify fuel risks, the diagnostic tools to assess your current situation and a path to ensuring your stored diesel supports your business continuity plan instead of undermining it.
Contact us today to learn more about diesel fuel polishing.
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