AXI International Logo
AXI International Logo

Fuel Polishing: How It Really Works

Posted August 27, 2020 by Tyler Moore

Why Should Fuel Be Polished?

Globally, there are hundreds of millions of gallons of diesel fuel sitting in fuel storage tanks awaiting use. The demanding equipment can range from truck fleets to military bases and hospitals to hyper-scale data centers. The fuel being stored on-site is a critical asset that must be managed and maintained appropriately.

Through the logistical chain of fuel transportation and fuel storage, it is not uncommon for fuel to “pick up” contaminants along the way.

These fuel contaminants come in many forms including water, sludge, dirt, and other particulates that could jeopardize the integrity of the fuel or cause critical damage to the demanding engines that rely on the fuel as an energy source.

Upper Left: Solid contaminants visible in a fuel sample. Foreground: Fuel contamination scraped from the bottom of a fuel storage tank.

This could potentially cause downtime for mission critical facilities such as data centers and hospitals, or could leave fleet truckers stranded and ship captains “dead in the water”.

According to a study conducted by the Ponemon Institute, the average cost of a total data center outage was approximately $901,500.

The financial pitfalls of these potential vulnerabilities are a big reason why mission critical facilities are prioritizing fuel quality and maintenance, so that the backup power systems are reliable in the event of an unexpected power outage.

How Effective is Fuel Polishing?

Fuel polishing has become an important part of maintaining the operation of any facility or site that stores large quantities of fuel.

When power systems rely on an energy source, it is critical for that energy source to be of optimal quality for the demanding system(s). This is achieved through proper fuel management and fuel maintenance procedures.

Fuel polishing equipment effectively removes various contaminants from the fuel. These fuel polishing systems typically operate automatically on a programmed schedule and feature multiple phases of filtration within them, the first phase being a fuel water separator.

The fuel water separator typically features various stages of filtration where the water and large particulates are removed from the fuel with the use of centrifugal force and a filter element.

FPS FX Fuel Maintenance System marine installation on a Sabre Yacht.

With water being heavier than the fuel that it resides in, the fuel water separator can successfully remove the majority of the water present in the fuel by spinning the fuel and its contents at a high velocity.

As an extra layer of filtration, the fuel water separator typically features a filter element to capture larger particulate (usually 30 microns and larger).

Once the fuel leaves the fuel water separator, most fuel maintenance systems feature a final or secondary stage of filtration that features a highly-efficient fine filter element. These elements can capture particulate as small as 3 microns in size in addition to absorbing any remaining water.

Fine filter elements are available in a wide range of micron sizes, and can be designed to capture water in addition to particulates if it's deemed a water blocking element.

What can be perceived as redundancies, the strategic use of multiple filters can extend filter life, increase filtration efficiency and effectiveness, as well as prolong the lifetime of critical equipment within these polishing systems.

By continual removal of contaminants, fuel polishing systems can consistently ensure your fuel is of optimal quality therefore protecting the demanding equipment from premature onboard filter clogging, damage, and unexpected downtime.

Biocides Do Not Solve The Contamination

Biocides are often sold/bought with the idea that it will solve all contamination issues rooted in microbial growth. Unfortunately, it is impossible to perfectly sterilize your fuel, meaning there will always be microbes waiting to repropagate, especially with water still present within the tank.

Microbial growth, often mistaken as algae, is responsible for the development of a sludge-like byproduct that is usually responsible for the premature clogging of on-board engine filters.

The use of biocides to address microbial contamination presents a number of issues in its use.

First, through “killing” the microbes, you are left with the same levels of unwanted biomass within the fuel. Introducing biocides does nothing to remove the sludge or particulate present in the fuel.

Excess sludge and microbial growth captured in a fuel filter.

Second, using biocides doesn’t do anything to solve the root cause of rapant microbial growth, water.

These microbes thrive where the fuel and water layers meet, living in the water while consuming the hydrocarbons in the fuel. By removing water from the fuel, you are reducing the ability for the microbes to proliferate in the first place.

Biocides simply add more foreign non-petroleum contaminants to the tank, diluting your fuel further. This does nothing to remove the contaminants from your fuel.

The use of biocides may just cause you to clog filters more frequently, while not addressing the water that is in your fuel tank. After intital biocide treatment, this residual water source will allow new microbial growth, adding to the contamination problem that the biocides were originally intended to treat.

Where Does The Water In Fuel Come From?

Typically, condensation occurs within the fuel tank resulting in water droplets getting into the fuel. The more headspace (the space between the top of the fuel load and the top of the fuel tank) there is the more room for condensation to develop. In time, free water will accumulate as its own layer beneath the fuel.

Water can also be introduced into the fuel during transportation. After fuel is refined, it is often “passed through” multiple tanks and trailers before reaching its final destination. Many of these tanks hold potential to have accumulated condensation and water of their own.

This leaves multiple opportunities for the fuel load to be exposed to and contaminated with water that may have already been present in one of these tanks or trailers.

Logistically, it is tough for fuel providers to properly vet the fuel, creating a lapse in time between intended fuel quality and the actual fuel quality the consumers may receive.

This is why it is important for consumers to be vigilant regarding the fuel quality they receive.

How Do I Know I Need To Polish My Fuel?

There are a number of ways to determine if the fuel you have stored is in need of polishing. With fuel quality being so important to operational reliability, it should be a priority for maintaining the integrity of this critical energy source.

The most accurate way to know if your fuel is contaminated is to sample the fuel and get it tested for microbial growth and other forms of contamination.

Many testing labs can take more than a few days to receive, test, and report on the results of the tested fuel sample. There are alternatives to this method of testing, and FUELSTAT® instant fuel test kits are available to test fuel on-site and report results within fifteen minutes.

This testing method not only reports results quickly but eliminates the possibility of inaccurate results due to the time it may take for the samples to be tested.

When testing is not an immediate option to determine fuel quality, there are also ways to tell visually and operationally if the fuel quality isn’t where it needs to be.

If engine filter changes are becoming more frequent than usual, the buildup of fuel contamination can likely be the cause. If large amounts of thick sludge are found in your filters, it is likely that there is a much greater presence of sludge within the fuel tank.

When the equipment/engines that the fuel is supplying experiences rough idles, operational inconsistencies, or smoke, contaminated fuel may also be the culprit of these issues.

Side-by-side fuel samples taken before and after fuel polishing.

Visually, clean fuel will be yellow, orange, or red in hue (depending on fuel type and dye) and shouldn’t be extremely cloudy or difficult to see through. When fuel has been sitting for a prolonged period of time (6 months or longer), it is best practice to polish the fuel as stored fuel becomes more susceptible to degradation and contamination over long periods of time.

How Often Should I Polish My Fuel?

Fuel polishing cycles can vary between volume and conditions, but there are a few recommended best practices known to keep fuel within the desired fuel quality range.

There are two types of fuel polishing systems, mobile and automated.

Mobile fuel polishing systems are often mounted on a cart or trailer and are brought on-site to the fuel storage tank(s) periodically to polish the fuel. The portability of these systems allows one fuel polishing cart to service multiple tanks.

MTC Fuel Polishing Trailer being used to polish fuel within fuel storage tanks.

If mobile systems are not used often enough, this could cause the fuel in the storage tanks to fall out of the desired fuel quality specification.

Depending how many fuel tanks are in need of polishing, a single mobile system may not be practical enough to keep all of the fuel within the desired fuel quality specification.

Automated fuel polishing systems are typically mounted near the fuel storage tank and have programmable features that allow for fuel polishing schedules to be determined and executed without human intervention.

STS Enclosed Fuel Maintenance System installed on a outdoor fuel storage tank.

This outshines mobile systems in that the fuel is routinely being cycled through the polishing system. In doing so, the fuel does not sit for long periods of time, preventing degradation and contamination.

What To Remember About Fuel Polishing

Biocides are not an effective alternative to fuel polishing when combating fuel contamination. Fuel polishing is critical to maintaining the operational integrity of your energy source.

Contaminated fuel can spell disaster in many applications, and by prioritizing fuel cleanliness you are increasing the overall reliability of your engine, equipment, site, or facility.

By creating a fuel maintenance procedure that includes fuel polishing, the stored fuel can last much longer than if it wasn't being polished. Keeping the fuel free from harmful contaminants allows the fuel to be a long-term reliable energy source that is less likely to harm the equipment it is meant to supply.

List of organizations AXI International is associated or a part of. This include PEI, AFCOM, Better Business Bureau, 7x24 Exhange, NFPA, EGSA, Green Clean Certification
All company names, logos, and brands are property of their respective owners. Use of these names, logos, and brands does not imply endorsement.
Copyright © 2021 AXI International | All Rights Reserved.
AXI International linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram