Fuel Polishing Services

Fuel Polishing Services

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Fuel Oil Polishing and Filtering Services Overview

Fuel oil polishing is a fuel cleaning process that filters diesel fuel in storage tanks to remove contaminants. Also known as diesel fuel tank cleaning services or diesel fuel polishing services, fuel filtering effectively removes water, microbial particles, and sludge from on-road and off-road diesel.

CommTank offers fuel polishing services to customers as an alternative in cases when it makes more sense than our tank cleaning service. Mission-critical facilities prefer fuel polishing because it requires no downtime. The fuel system remains online during filtration. The result is a clean oil tank with fuel that performs like new.

In the experience of our company, the high cost of diesel fuel is small when compared to repair costs for problems that develop without the proper maintenance of fuel tanks. A range of Information in this article details how diesel fuel polishing can restore fuel quality to meet the ASTM D975-10 specification.

Advantages and Benefits of Fuel Polishing

  • Polishing costs less than outright fuel replacement
  • Polishing increases fuel oil tank longevity by preserving the interior and removing sludge buildup
  • Polishing removes contaminants and restores diesel fuel to within acceptable limits of regulations such as the ASTM D975-10 standard specification for on-road and off-road diesel
  • Polishing requires no tank downtime, and allows the fuel system to remain online during the service
Diesel Fuel Polishing

Fuel polishing team cleaning diesel fuel in aboveground tanks.

CommTank’s Fuel Filtration Process for Above Ground and Underground Fuel Tanks

Our approach to successful fuel filtration typically follows this proven process:

  • Mobilize CommTank’s own in-house filtration equipment, to process fuel through multiple filters
  • Draw a pre-filtration composite fuel sample for baseline comparison to the post-filtration sample
  • Pump any settled water out from the bottom of the tank prior to filtering
  • Begin with a high-level filter (typically 100 or 50 microns) to remove the largest/heaviest particulate
  • Progressively cycle fuel product back into the tank, through progressively smaller filter mesh sizes (50 to 25 to 5 microns), depending on the amount and size of particulate contamination.
  • This process of cycling fuel through filters also separates out any water in the bottom of the tank
  • Pump out emulsified water using a low-micron filtration water separator, called a coalescing filter, to pull the water particles (suspended water emulsion) out of the fuel
  • Insert and circulate an antimicrobial additive product to suppress growth of harmful microbes and algae

The result of our company completing this fuel cleaning process is fully polished, on-spec, usable fuel that meets ASTM specifications.


Fuel Polishing Service Trailer

CommTank's fuel polishing service trailer.

CommTank is Your Resource for Fuel Polishing Experience, Expertise & Equipment

CommTank has all the resources people trust when they need cost-effective full-service fuel polishing.

Other fuel filtration companies typically use single filter carts. CommTank specialists use our own in-house developed multi-filter filtration trailer for reliable fuel polishing.

This specialized equipment has supply and return hose reels that push the fuel through a series of filters. Each filter is made of mesh with progressively smaller holes. The size range of the holes in the filter mesh is measured in microns. The smallest-size hole is 1 micron, and a 100-micron hole is 100 times larger.

Manufacturers do not recommend filtering particles smaller than 5 microns, as it can affect fuel’s Cetane value.

During the fuel polishing process, our technicians can identify any suspended water or very light particulate matter that cannot be filtered using various size mesh filters. They can then direct the fuel through a coalescing filter to effectively remove the suspended water and light particulate matter.

Stages of Fuel Filtering

These components of our standard fuel filtering process ensure effective fuel cleaning:

  1. Remove Large Particulate
  2. Perform Fuel Filtering with 25-Micron Filter
  3. Perform Fuel Filtering with 5-Micron Filter and Water Separation
  4. Insert Antimicrobial Additive
  5. Perform Testing of Polished Fuel
Clogged Diesel Fuel Filter

Clogged Diesel Fuel Filter

Why Diesel Sludge Removal is Important

Diesel sludge removal is important for maintaining the integrity of a storage tank and the fuel it contains.

Sludge consists of impurities and debris in fuel that settle out over time. Settled-out debris coupled with fuel contaminants lead to sludge buildup. Sludge essentially falls out of the fuel and typically collects at the bottom of tanks.

CommTank’s fuel filtering service typically circulates the fuel between 40-60 gallons per minute. This dredges up sludge sediment so it can be filtered.

Problems Caused by Fuel Contamination

Fuel tank contamination can cause many problems. The internal tank environment can deteriorate with any form of contamination. It can also damage the diesel engines of generators designed to provide automatic power. In the most serious cases, fuel contaminants can cause outright failure of the systems they power.

Contamination sources can occur throughout the diesel fuel supply chain, as well as inside a storage tank.

Mobile Fuel Polishing

Testing fuel sample with CommTank's mobile fuel polishing system.

Types of Fuel Contamination

Water Contamination in Fuel

  • Water in fuel can include emulsified, dissolved, or freestanding water
  • Corrosion and pitting of the interior can be caused by all forms of water contamination

Microbial Contaminants in Fuel

  • Microbial contaminants can include mold, yeast, bacteria, organic matter
  • Contaminant buildup can clog filters in the fueling system, and also lead to corrosion

Particulate Contamination in Fuel

  • Particulates can include dirt, soot, rust, and other solid particles
  • Buildup of particles can clog and damage engines

Top Reasons to Polish Diesel Fuel

If your fuel quality is compromised by contaminants such as mold particles, microbes, or chemicals:

  • It will not burn as efficiently in vehicles or equipment with diesel engines
  • It can clog fuel lines in diesel engines and affect performance
  • It can impede fuel systems by clogging fuel injectors so fuel doesn’t flow well in cold weather

CommTank offers fuel polishing as an alternative aboveground storage tank cleaning or underground tank cleaning services because it effectively removes sludge and suspended particulates.

Aviation Fuel Polishing

Fuel polishing team polishing aviation fuel at Worcester, MA airport.

Markets We Serve with Fuel Polishing Services

Fuel polishing is an ideal solution for maintaining backup power systems in any commercial industry.

Mission-critical facilities prefer this service because it requires no downtime. Their fuel system remains online during filtration, and their fuel is polished to meet the ASTM D975-10 specification.

Essential industries such as healthcare, data storage, research, transportation and more rely on CommTank’s comprehensive suite of commercial services. We install, inspect, test, maintain, and clean their fuel storage tanks and the diesel fuel that powers their generator systems.

Data Centers
CommTank’s generator fuel polishing service for data centers ensures safe, compliant performance of emergency and standby power systems, backup systems, and tank systems.

Research Laboratories, Bioscience and Pharmaceutical
Research labs, bioscience firms, and the pharmaceutical industry all depend on consistent power to maintain critical lab and production functions. For example, CommTank fuel polishing ensures that generators can power commercial equipment at constant temperatures for the COVID-19 vaccine and other vital laboratory samples and products.

Generator Fuel Polishing

Generator fuel polishing team filtering emergency generator fuel.

Hospitals, Healthcare Facilities and Nursing Homes
Hospitals accredited by the Joint Commission are typically required to have their fuel tested annually.

Testing requirement NFPA 110 governs emergency and standby power systems. It requires performance of an annual fuel quality test to ASTM standards for any fuel supply of an emergency power system.

When someone has doubt or concern that something about their fuel integrity could result in a problem with passing any element of an ASTM test, fuel polishing is one way to bring it back into specification.

CommTank provides pre-filtration and post-filtration samples, which allow for testing to ensure that the polished fuel meets ASTM standards per Joint Commission requirements.

Healthcare facilities can also request pre-audit fuel testing. CommTank offers our own Fuel Testing and Analysis services. We also partner with other labs to offer clients a variety of ASTM testing of diesel fuel.

Aviation Fuel Polishing Services for Life Flight

Aviation fuel polishing services for Life Flight.

Airports and Aviation Facilities
CommTank supports the aviation industry by ensuring the safety and compliance of tanks and fuel that powers commercial vehicles, generators and other equipment at airports and aviation facilities.

Vehicle Fleets and Equipment Maintenance Facilities
CommTank fuel polishing services are ideal for commercial vehicle and equipment maintenance facilities with fuel tanks and backup generators that power their fleets. Optimal fuel quality saves money by decreasing the amount of fuel used. It also saves time and money by supporting engine performance and decreasing the need for costly repair.

Marinas: Marine Fuel Tank Cleaning & Fuel Polishing
CommTank supports marinas by maintaining their diesel fuel and storage tanks that supply generators that fuel boat engines and other marina equipment. Marine fuel polishing ensures quality fuel that improves and extends the performance of boat engines and backup generators at marinas.

Marine Fuel Polishing Service

Marine fuel polishing services for the Nantucket Lightship.

Other Fuel Services

Fuel Testing for Mission-Critical Backup Power

Fuel filtering and polishing is one example of solutions we offer. More resources and solutions are detailed on our CommTank Fuel Testing and Analysis page.

Fuel Flush Treatment

CommTank’s fuel flush treatment is a type of filtration service we offer for commercial clients with smaller tanks. It is recommended when a CommTank specialist determines the fuel quality in a small tank cannot be brought to within the ASTM standard specification via a typical fuel filtering and fuel polishing service.

Our fuel flush treatment includes a full pump out of the tank followed by flushing, which involves introducing a small amount of clean diesel fuel to the tank, and flushing out as much particulate and sludge as possible using a similar circulation process as a typical filtration. The tank is left completely empty and ready for clean diesel to be added by the client’s own reputable fuel supplier.

Diesel Fuel Maintenance

Diesel fuel maintenance on pipes and filters.

Diesel Fuel Maintenance

Clients often request we perform diesel cleaning services regardless of the amount of contaminate buildup.

This preventive maintenance is offered as part of a greater testing and inspection plan, and incorporated into an annual maintenance program.

Most CommTank clients take advantage of setting up an annual fuel storage tank testing and inspection plan that can include fuel filtration and polishing. In most cases, tanks can remain in service during filtration.

Diesel Generator Fuel Polishing

Diesel generator fuel polishing for NorthEastern University.

Fuel Polishing: An Alternative to AST and UST Tank Cleaning

Advantages of Fuel Polishing versus Tank Cleaning

Fuel Polishing is a cost-effective alternative to:

  • Replacing all the fuel in an aboveground or underground storage tank
  • Cleaning a tank, if it is too small to enter and perform our traditional tank cleaning service
  • Taking a tank out of service to remove contamination, sludge or any type of particulate
Fuel Tank Polishing

Tank after fuel tank polishing.

When Fuel Tank Polishing is Recommended Instead of Fuel Polishing:

Cases when fuel tank polishing is typically recommended over fuel polishing include:

  • When fuel in the tank has such a high level of particulate contamination that it would not be feasible to complete the filtration process in a timely manner. That is, if it would take longer to filter the fuel in a tank than it would to simply enter and clean the tank.
  • When a tank has an internal configuration that’s not conducive to a filtration service, such as internal baffolds that would block the flow of fuel, impeding the circulation of fuel
  • When a CommTank specialist advises that a tank may not respond optimally to fuel filtration. Filtration can typically remove tank sludge and particulates and restore fuel quality to within the specifications of the ASTM standard. However, in some cases, our filtration service may not be the optimal solution.

Fuel Polishing Frequently Asked Questions

Fuel Polishing FAQs

Our antimicrobial fuel additive treatment, which is included in CommTank’s fuel filtering and polishing service, kills and suppresses new bacteria growth in diesel.

Two types of analysis can determine if your fuel is contaminated:

Qualitative testing involves taking a sample and performing a standard visual screening of the fuel, according to ASTM screening standards to quickly determine if the fuel is contaminated and off-spec. 

Quantitative testing involves in-lab, ASTM-standard testing.  A variety of test methods are used to obtain definitive results for qualities such as flash point, PPM count of particulate contamination, percent of water contamination, cloud point and pour point. 

Diesel fuel contains paraffin wax so at low temperatures it clouds up, gels up and does not flow or pour well.  Contaminated diesel can cloud up in higher heat and disrupt engine performance.

Depending on the age and contamination level of old diesel fuel, CommTank’s fuel polishing service can typically rejuvenate and bring it back to ASTM standard specifications, so it will work like new.

Proper tank maintenance is the most important thing you can do to store diesel fuel properly.

Diesel fuel stored in a well-maintained tank is less susceptible to contamination such as metal flaking into the fuel or leaky fittings introducing water into the fuel.

Many fuel suppliers recommend that diesel fuel stored for emergency use be replaced with new fuel if not used within a year. The cost of disposing of old fuel, cleaning the tank, and purchasing new fuel is expensive, especially for large aboveground and underground storage tanks. 

As an alternative, CommTank recommends testing fuel to measure it against ASTM standards as specified by the original supplier. If testing reveals contamination, our fuel polishing service can remove microbial growth and the water that supports it.  We re-test the fuel after filtering and polishing, to verify that it meets ASTM specifications.

Under typical operating conditions, CommTank recommends annual fuel polishing.

Yes. Any type of tank, whether gas or diesel, should be kept as full as possible.  This is one way to reduce water level on the tank’s interior, by providing less surface area for water condensation.

Contaminated diesel fuel can cause two major problems. First, it threatens storage tank integrity by accelerating the need for replacement due to deterioration.  Second, it increases the need to repair or replace diesel engines due to poor fuel quality that causes fuel systems to malfunction or seize.