Fuel quality is of utmost importance for the efficient performance and longevity of equipment. To address fuel contamination issues, biocides have been commonly used in fuel management.
However, it’s essential to understand the disadvantages and limitations associated with biocides. In this article, we will explore the drawbacks of using biocides and introduce a superior alternative known in the fuel management industry as fuel polishing.
Although biocides serve their purpose when used within the proper application, there are several reasons why biocides are not always the best option when it comes to proper fuel management.
Biocide Safety and Health Concerns
Biocides may pose risks to both human health and the environment. Exposure to biocides can result in severe skin irritation, burns, allergic reactions, liver damage, and serious eye irritation and damage.
For these reasons, it is crucial that biocides are handled and used by trained professionals who understand the associated risks.
Environmental Concerns with Biocides
Not only are biocides toxic to humans, they also pose an environmental risk.
Microbiocides, such as the ones used in many common fuel biocides, have been shown by the EPA to be toxic to aquatic life, including fish and ducks.
If a fuel tank leaks, it can cause harm to the surrounding environment. However, the negative effects would be further amplified if the fuel had been treated with biocides. The potential environmental impact calls for a more sustainable approach to fuel management.
The Limitations of Biocides in Fuel Contamination Removal
One significant drawback of biocides is their inability to remove contaminants and organic matter from the fuel itself. While biocides can effectively target microbial growth, they leave behind contaminants that can clog filters and impact fuel performance.
This frequent clogging leads to increased maintenance and operational costs, as well as potential equipment malfunctions.
The main issue with biocides is that they only temporarily treat a symptom of the overall problem.
Microbes live in water and feed off of fuel. This microbial growth creates its own layer of sludge (commonly thought of as algae) in your tank.
Unfortunately, it takes the presence of only one spore or microbe to cause a problem, as these microbes reproduce asexually at a rapid rate.
Not only does the presence of water in a tank create a breeding ground for contaminants, water contamination can also cause other problems such as tank and fuel system corrosion as well as injector damage.
Treating a tank with biocide may kill the microbial contamination and temporarily stop the proliferation of sludge. However, once it is treated, dead or alive, your fuel tank will still contain sludge.
Beyond this, using excessive biocides in fuel treatment dilutes the fuel with an increased amount of non-petroleum foreign contaminants.
Instead of solely treating a fuel tank with biocide, fuel site managers should consider actively filtering out the sludge and contamination to completely remove it from the storage tanks.
This occurrence happens within the fuel industry and many other industries that use biocides including food manufacturing, cosmetics, and other consumer products.
Just as some bacteria that infects humans and animals are developing a resistance to antibiotics, microbes found within the tank ecosystem are following suit. This means that repeated use of a biocide in a tank may eventually become ineffective.
Fuel Polishing: A Better Option for Fuel Management
Fuel polishing equipment offers a superior alternative to biocides, addressing their limitations and providing comprehensive contamination removal. By physically removing contaminants, water, and organic matters from fuel, fuel polishing ensures higher fuel quality.
Because of this, there are a few key factors why fuel polishing is the preferred option for effective fuel management today.
Fuel polishing tackles the root causes of fuel contamination, going beyond symptom treatment.
By eliminating contaminants, water, sediments, and organic matter that accumulate in storage tanks, fuel polishing prevents blockages, injector foiling, and fuel system corrosion. This approach enhances equipment performance and reduces maintenance costs.
Fuel polishing focuses on achieving and maintaining optimal fuel quality.
By removing impurities and organic matter, fuel polishing ensures cleaner and more stable fuel. This improves combustion efficiency, reduces emissions, and ensures reliable equipment operation. Higher fuel quality translates to smoother running engines, increased fuel efficiency, and extended equipment lifespan.
Unlike biocides that only target microbial growth, fuel polishing eliminates contaminants that heavily contribute to filter clogging.
By proactively removing impurities before they reach the filters, fuel polishing ensures uninterrupted flow. This saves time, money, and minimizes operational disruptions.
By incorporating fuel polishing into your fuel management strategy, you protect your equipment investment.
Fuel contamination can damage equipment and lead to premature failure. Continuous removal of harmful contaminants, water, and sediments reduces the risk of corrosion, component wear, and engine damage. This extends equipment lifespan, reduces repair costs, and enhances overall reliability.
Considering the points above, it is clear the advantages of fuel polishing far surpasses the limitations of biocides in fuel management. Fuel polishing offers comprehensive contamination removal, ensures optimal fuel quality, prevents filter clogging, and extends equipment lifespan.
Fuel stability is crucial, particularly for stored fuel. Over time, fuel can degrade due to oxidation and the presence of contaminants. This degradation can result in the formation of sludge, fuel stratification, and the growth of harmful microorganisms.
By preserving fuel quality through proper fuel management techniques such as fuel polishing, you can maintain fuel stability, preventing fuel degradation and associated problems.
Fuel quality directly impacts combustion efficiency and emissions. Contaminated fuel can lead to incomplete combustion, resulting in reduced power output, increased fuel consumption, and higher emissions of harmful pollutants.
Maintaining high quality fuel is paramount for equipment performance and reliability. While biocides have been commonly used in fuel management, they come with significant limitations.
Biocides cannot remove contaminants and organic matter from fuel, leading to frequent filter clogging and potential equipment issues.
Instead, adopting fuel polishing as an alternative provides a comprehensive solution for fuel contamination, ensuring optimal fuel quality and maximizing the performance of your equipment.
Prioritizing fuel quality is a smart investment that yields long-term benefits in terms of operational efficiency, cost savings, and environmental sustainability.
Fuel Polishing Explained
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 and marine vessels to military bases and hospitals.
The fuel stored on-site is a critical asset that must be managed and maintained appropriately. Failure to maintain fuel properly can lead to a number of issues and impacts can be severe.
In this article, we will go over everything you need to know about fuel polishing and the impact fuel quality has on bulk fuel sotrage applications.
Why Should Fuel Be Polished?
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.
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”.
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.
For marine applications, contaminated fuel can lead to constant headaches. As a vessel rocks through the waters, the fuel within a tank is sloshed around constantly.
This sloshing causes contaminants to be kicked up from the bottom of the tank, dramatically increasing the likelihood of engine filter clogging compared to fuel stored in more stationary applications.
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). In this case, our energy source is the fuel, and optimal quality is achieved through proper fuel management and fuel maintenance procedures.
Fuel polishing equipment effectively removes various contaminants from the fuel. These fuel polishing Fuel maintenance systems that offer polishing features effectively remove harmful contaminants from the fuel.
These fuel polishing systems typically operate automatically on a programmed schedule. These systems will feature multiple stages of filtration that the fuel will flow through, each with its own unique filtration purpose.
Filtration Stages and Fuel Polishing
Fuel polishing systems often feature multiple phases of filtration, where the fuel is decontaminated.
Recommended filtration systems and stages can vary depending on fuel volume and the users’ unique needs. The placement of these filtration stages between systems may differ depending on the engineering & design.
In AXI’s LX-F Fuel Maintenance System, for example, fuel will first flow through filtration Stage 1 which features a magnetic fuel conditioner. This in-line device will capture loose metals and aid in breaking up clusters of fuel before passing into Stage 2.
Stage 2 is the primary filter of the system, and multiple filter media types are available.
There are different micron filtration options available for the primary filters, with the best option depending on the users' unique needs.
The micron (µ) level tells us the smallest size particles the filter media can capture. A 50-micron filter (50µ) will capture particulates as small as 50µ but any particles smaller than that (1µ, 10µ, 30µ, etc.) will still be able to pass through the filter media. LX-F users can opt for either 10µ or 30µ particulate filters. Instead of particulate filters, users can also opt to use a 60µ stainless steel screen.
In instances where the fuel may be heavily contaminated, the 60µ filter will capture the largest particulates while the fuel is being conditioned. This is because in some situations low micron count fine filters may have to be continually changed as they clog due to the severity of the fuel contamination.
After passing through either the particulate filter or screen, the fuel will then flow into Stage 3. When the fuel enters the centrifugal water separator, water is “spun” out of the fuel using centrifugal force.
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.
Once the fuel leaves the fuel water separator, fuel will now enter the pump. It is important to note that the primary filtration happens before the pump, which helps to keep the pump from being damaged by heavy particulates.
After flowing through the pump, the fuel will then enter the 4th stage of filtration which features a highly-efficient filter element.
These spin-on elements can capture particulates as small as 3 microns (3µ) in size and can use either fine or water blocking filters. Water block filters actively absorb water from the fuel that passes through them.
What can be perceived as redundancies, the strategic use of multiple filter stages can extend filter life, increase filtration efficiency and system effectiveness, as well as prolong the lifetime of critical operating equipment within these polishing systems.
By continual removal of contaminants, fuel polishing systems consistently ensure your fuel is of optimal quality, therefore, protecting the demanding equipment from premature onboard filter clogging, damage, and unexpected downtime.
Fuel polishing systems may also be equipped with additional features that work to maintain fuel quality. Fuel heaters can be integrated into systems where cold temperatures have caused the diesel fuel to gel, therefore being too viscous to flow through the system. A fuel heater will warm up the fuel as it enters the system so that it can be polished effectively.
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 onboard 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.
Second, using biocides doesn’t do anything to solve the root cause of rampant 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 of 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 initial biocide treatment, this residual water source will allow new microbial growth, adding to the contamination problem that the biocides were originally intended to treat.
How Does Water Get Into Fuel?
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 the 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 the 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 quality of the fuel 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.
Bacon bombs are a popular choice for sampling, as they allow the user to dip the sampler into the bottom of the tank and pull fuel from areas that may be denser with 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.
When testing is not an immediate option to determine fuel quality, there are also ways to tell visually and circumstantially if the fuel quality likely isn’t where it needs to be.
Instances, where fuel polishing would be recommended, include:
If the fuel has been sitting for an extended period of time
If the fuel access port wasn’t sealed properly and water, dirt, or other contaminants have seeped into the fuel supply
If unusual amounts of water are being captured by onboard filters and water separators
If fuel was received through the supply chain and was not tested for contamination prior to loading
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 experience rough idle, operational inconsistencies, or smoke, contaminated fuel may also be the culprit of these issues.
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 the 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.
t is recommended to run an ASTM-approved fuel test annually, with some specialized facilities recommending more frequent testing.
Some recommend that a fuel quality test be conducted every 6 months, and in certain applications this 6-month periodic testing is required.
What Fuel Polishing Options Do I Have?
Facilities have a few different options available for fuel polishing solutions. Depending on the operational application, some solutions may better align with the user’s needs than others.
Mobile Fuel Polishing
Mobile fuel polishing is a popular solution, as it allows a single system to be transported between different fuel tanks that are in need of polishing.
This portability gives users the flexibility to reach fuel supplies that may not have the space needed for a permanently-installed system.
Mobile fuel polishing systems are typically mounted on a cart or trailer. These are brought on-site to the fuel storage tank(s) periodically to polish the fuel.
Most fuel polishing services bring mobile fuel polishing systems on-site to service the fuel. These systems are typically mounted on a cart that can be moved independently between tanks. However, depending on how much fuel needs to be serviced, heavy-duty mobile systems designed for bulk volumes of fuel may be needed.
These heavy-duty fuel polishing systems are transported in enclosed trailers and can be unloaded, or operators can use industrial hoses to reach and circulate the fuel supply without the equipment having to be removed from the trailer.
Depending on 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.
Also, one of the critical drawbacks of mobile polishing solutions, is that this process can not be automated for operational efficiency. Because these systems are not permanently affixed to the fuel supply, the fuel will not be kept in-spec at all times. The fuel quality will often fall out of the desired quality spec before the fuel is polished again.
Although not a practical option for larger volumes of fuel, there are handheld fuel polishing systems available like the TK-240 XT.
These systems are highly portable and compact, allowing for easy transportation between fuel tanks or into tight areas, such as vessel engine rooms, to access fuel ports.
These systems feature a flow rate of 240 gallons per hour with primary and secondary filtration designed to remove problematic fuel contaminants.
Automated Fuel Polishing
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 on 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. These timelines can be “tightened”, resulting in more frequent polishing cycles that keep the fuel from falling out of the desired quality spec.
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.
Because these systems are permanent installations, the polishers can turn over larger volumes of fuel without “having to keep an eye” as system alarms will alert the user of any fault that requires user intervention.
Bigger systems can also be engineered to maintain fuel across multiple tanks, with users having the ability to determine which fuel supply loop they want polished and when.
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 of 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.
Do I Need To Empty The Tank?
One major misconception about fuel polishing is the idea that the fuel needs to be completely removed from the tank for polishing.
This is false, as it would be not only a colossal task but also impossible to displace all of the fuel in many bulk storage applications. It is an impractical concept as there simply isn’t anywhere else to transfer tens of thousands of gallons of fuel for holding while the fuel is being polished.
Fuel polishing equipment cycles through the entire load of the fuel tank through intentionally-designed fuel pick up and return lines that are placed in a manner that allows the system to cycle through all of the fuel from the top of the tank to the messy bottom.
Fuel Replacement vs. Fuel Polishing
Fuel polishing is considered an alternative to expensive fuel replacement. With some bulk tanks storing tens of thousands of gallons of fuel, fuel replacement costs would be high.
With some storage tanks holding over $100,000 worth of fuel, this fuel is considered an asset that needs to be maintained. It wouldn’t make fiscal sense to simply replace that much fuel when specialized equipment can bring new life to the “old” fuel at a much lower cost.
This is why facilities with bulk fuel storage will implement serious fuel maintenance procedures. Facility managers see fuel as a critical asset that must be protected and maintained.
The Effects of Diesel Fuel Contamination
Fuel contamination can be felt in many ways, particularly in the mechanical operability of your engine or equipment. Some of these symptoms often go unnoticed, or ignored, while other symptoms can be severe and impossible to ignore.
Not only can these failures be extremely costly to repair, but these catastrophic failures can be dangerous, especially when they occur on the road or at high speeds.
Fortunately, many of these failures can be prevented through frequent fuel testing and the implementation of preventative solutions.
In this article, we will cover the symptoms, causes, testing, and solutions for all types of diesel fuel contamination.
Symptoms of Fuel Contamination
Don't Ignore Your Engine Check Light
Many people have been or have known someone that was in a situation where the “check engine” light comes on in their vehicle out of seemingly nowhere. Anxious at first, they tone down their driving to see if they can feel any difference in how the vehicle is running.
Strangely enough, it doesn’t feel any different than before- so they convince themselves it probably isn’t anything other than the car or truck being a bit “finicky”.
At first, a few days go by and then a few months. The light is still on and since the vehicle doesn’t feel to be running any different, it’s running just as often and hard as it normally would.
However, under the hood, components are not operating as designed and the continuous operation of worn parts is damaging the very systems that keep the vehicle running.
At this point, detrimental engine failure could be just a matter of time, turning a couple hundred dollar repair into one that could quickly cost thousands.
Clogged Fuel Filters
Frequently clogged fuel filters are oftentimes one of the first initial signs of possible diesel fuel contamination. The filter is designed to capture particles in your fuel before they pass into the engine and these pieces of matter can be made up of clumps of sludge, metallic particles, or other unwanted particulates.
If a fuel system is experiencing an atypical recurrence of fuel filter replacements, the problem’s root could lie in the quality of the fuel being supplied to the filter.
Heavily contaminated fuel would consistently provide particulates and other undesired materials that quickly clog filters, possibly leading to other issues in the fuel system.
This contamination could be stemming from either the fuel source itself or from the internal corrosion of the very fuel tank being used to fuel the engine.
Failing Fuel Pump
With frequent fuel filter clogging, fuel pump failure is often to follow. Because of the restriction caused by the clogged filters, the fuel pump could be working harder than designed to deliver fuel from the tank to the engine.
While a fuel pump is failing, the fuel pump will not be able to deliver a steady flow of fuel, interrupting the mechanical stroke and function of the engine. This can be especially noticeable under acceleration, where fuel demand is increased however the fuel pump is unable to deliver the fuel at the requested rate.
Symptoms of a failing fuel pump may include:
Jerks or sputters at high speeds
Power loss on acceleration
Power loss while driving up a slope
Power loss while towing
Engine surging while acceleration is not engaged
Engine will not fire
When a fuel pump is exerted to the point of failure, it is past the point of simple maintenance to get the engine running again. When a fuel pump fails, fuel line pressure is lost thus not being able to deliver any fuel for the engine to fire up. Downtime of equipment for major repair is expected at this point to get the fuel flowing properly again.
Partial Injector Failure
Unfortunately, partial functional failure of an engine will often go unnoticed until it is too late.
Engine inefficiencies are seldom felt by a user but can result in serious losses in operability and revenue.
A major reason for engine inefficiency stems from the partial failure of an engine’s fuel injection system, something not well understood by a majority of people.
Partial functional injector failure isn’t a failure point that is well-documented in many industries, leaving a lapse in the understanding of the symptoms that come with this kind of failure.
Although the equipment is still operable, partial functional failure of a fuel injection system is generally one that reduces engine efficiency or performance. The symptoms of such failures within an injection system may include the following:
Low power from the engine
Reduced engine RPM
Increased fuel consumption
Poor cycle times or low speed
Smoke
Lower gear selection
Noise
Poor starting
Poor idle
Many of the symptoms mentioned above are difficult to diagnose without the proper tools and equipment, which makes needed repairs something that often falls behind.
By continuous operation of the equipment, the user is at risk of experiencing events of a catastrophic engine or component failure.
To understand the role fuel injection plays in the engine mechanically, one must understand the stroke cycle as referenced below.
During the power stroke, fuel is injected into the cylinder and ignites, creating the energy needed to transfer to the mechanical output that drives the vehicle or equipment.
Prior to manufacturing, diesel fuel injectors are designed with specific functional tolerances. If these injectors begin to fail or veer from the designed tolerances in any way, then the fuel spray trajectory within the combustion chamber is drastically affected.
Injectors can deviate from their tolerances through the introduction of contaminated fuel. Contaminated fuel can deteriorate and corrode the metal surfaces in injectors, with a higher likelihood after prolonged use of contaminated fuel.
Any number of these factors can alter the engineered functionality of a fuel injector, leading to a snowball effect of internal engine damage that could eventually progress into full functional engine failure.
Catastrophic Engine Injector Failure
When catastrophic engine injector failures are experienced, the engine fails to continue operation due to these sudden occurrences. Typically, these experienced events can only be restored through costly repairs that often result in prolonged equipment downtime.
Operations and equipment managers rely on proper equipment functionality to maintain revenue margins and business profitability. It is for these reasons that attention should be directed at managing, predicting, and preventing these failures from occurring through proper equipment maintenance and operation.
Equipment specialists and OEMs typically operate their equipment around recommended maintenance procedures that are designed to limit component failure and prolong equipment life.
It is common for OEMs to recommend these maintenance procedures to uphold warranties. Fuel injector replacements are a critical component to these OEM warranties, with recommendations often being at the engine’s half-life.
This is recommended because OEMs are aware that engines are not commonly supplied with quality fuel and are instead typically supplied with contaminated fuel that can damage injectors over time and jeopardize reliability.
Although equipment maintenance personnel are responsible for managing engine equipment and remediating potential issues, not all can be predicted and/or prevented. This is often the case with contaminated fuel, as operations managers are often limited in the fuel they can procure.
With the use of contaminated fuel, erosion of the injector valve seat is likely, resulting in a partial functional failure that will eventually lead to a full functional failure of the fuel injector valve.
The Failure Chain Reaction
Contaminated fuel is sent through fuel injectors
Fuel injector valve deterioration begins
Fuel pressure through injector nozzle reduces
Fuel volume through the injection system reduces
Engine ECU increases fuel load to compensate
Reduced fuel atomization
Soot generation within the cylinder
Emissions increased
Experienced power loss
Partial injection failure point
Injector wear continues
Fuel consumption increases
Visible and audible signs of engine distress
Full injection failure
Within a high-pressure common rail fuel injector, there are three main components that are harmed the most by the effects of diesel fuel contamination. These are:
Fuel injector nozzle holes
Needle valve and seat
Electronic Piezo or solenoid-controlled valve
Fuel Injector Nozzle
Fuel injector nozzles are designed to spray a mist of fuel into the cylinder for piston compression and fuel combustion. These fuel nozzles primarily come in two designs: the SAC (area around pintel tip) nozzle and the VCO (valve-covered orifice) nozzle.
High-pressure common-rail (HPCR) injectors primarily use the VCO type. This design allows the injector to quickly and totally shut off the fuel as the injection completes. This allows for increased control of the fuel injection as it is critical in HPCR injectors.
This design enables the injector to abruptly and completely shut off the fuel at the end of an injection event, thus providing a more stringent control of the fuel injection event. The two designs can be seen below.
The VCO injection needle valves are known for having particularly fine tolerances and are extremely sensitive to partial failure during the rise and fall actions.
The rise and fall injection actions can occur dozens of times every second in a diesel engine. That is why injector tolerances are critically important in maintaining reliable operation and avoiding partial failures in the fuel injection function.
Typically, fuel injector nozzle holes are susceptible to two circumstances that can lead to injector failure. These two circumstances are blockages and erosions.
The precision involved in the operation of HPCR fuel injectors, although impressive, makes for sensitive components that require specific circumstances for combustion to take place as intended.
When achieved as designed, the fuel mist that is injected into the combustion chamber is burned out before the fuel droplets reach the lining of the engine cylinder. This ensures that the fuel combustion does not damage the cylinder, something that is especially critical for the fuel injection systems to function as intended.
When fuel is unable to complete combustion as it should, soot builds up within the engine and harmful exhaust emissions such as Nitrogen Oxide, Carbon Monoxide, and Particulate Matter are created.
HPCR fuel injectors ordinarily have 5-8 holes that are machined into the injector tip which allow for fuel to be injected into the combustion chamber and achieve atomization.
When the fuel injection action occurs, diesel fuel is sprayed into the combustion chamber. During the power stroke, the piston moves downward and pulls injector fuel spray deeper into the combustion chamber.
When injector tolerances have been compromised, fuel droplets from the injector nozzle may not be able to achieve complete combustion, often resulting in smoke and soot emissions. If the issue is not addressed, soot will build on the injector tips and eventually cause blockages. These blockages can also occur within the engine valves, cylinder walls, and exhaust system.
When injector nozzle holes are blocked due to this build-up, fuel velocity through the open nozzle holes increases due to more fuel being forced to exit the injector through the remaining unobstructed holes.
Blockages in the injector nozzle result in ineffective atomization which contributes to engine inefficiencies and harmful emissions.
When these partial functional failures within the injector occur, it is perceived as best practice to use diesel fuel additives that are chemically designed to clean soot build-up from the fuel injectors.
Although the use of these additives can help, these additives do not rectify the true underlying issues that contribute to injector blockages. Contaminated fuel will still wear down injectors and the fuel additive solution may only act as a bandage for a more serious issue.
Fuel Injector Needle & Control Valve
There are two commonly used fuel injectors in modern engines, electronically controlled unit injectors (EUI) and high-pressure common rail injectors (HPCR). The needle valve in both of these fuel injection types is engineered to stop the fuel from running through the injector tip after the fuel injection action.
When a needle valve fails to properly seal, fuel will drip down into the engine cylinder and onto the piston(s). This dripping fuel can be the catalyst for severe engine problems and catastrophic failures.
In HPCR injection systems, the fuel injectors are continuously under sustained pressure while the engine is running. This leads to a higher likelihood of harm if a fuel injector’s needle valve fails.
Both types of electronic fuel injectors have a control valve that functions to manage the timing of fuel injection sequences.
The control valves in EUI injectors are controlled by an electronic solenoid. HPCR injectors are controlled with a Piezoelectric actuated valve. These Piezoelectric valves are often seen as the most critical injector component because they enable the injection system to have more control of the distance of valve movement and valve speed.
The Piezoelectric valves are especially sensitive to fuel contamination because it wears and damages the components and compromises the designed injection tolerances.
With prolonged exposure to contaminated fuel, contaminants can build up within the injector and result in lethargic movement of the needle valve. This causes wear on the valve, and eventually leads to partial, if not full, functional failure of the needle component within the fuel injector.
Causes of Fuel Contamination
Particulates in the Fuel
Particulate within diesel fuel is the most common form of contaminants. From microscopic fragments of ferrous metals to dirt and grime that is introduced to the fuel, various contaminants can be to blame for a majority of fuel-related issues.
Following the refinement process, the fuel passes through numerous tankers, trucks, and vessels before it reaches you. Because of this, there are many potential sources of unwanted particulate contamination. Older fuel tanks, particularly those made of black iron, are highly susceptible to rust and corrosion.
Because of corrosion, fuel that was previously clean could be contaminated when introduced to a tank that has rust build-up within. If in a transport tanker or truck, constant vibrations and sloshing could mix the particulates with the fuel to a point where all of the fuel is contaminated.
This fuel can often find its way into other tanks for distribution and bulk storage, where it can then contaminate other tanks or equipment, as well as other fuel that will eventually find its way there.
This cycle evolves into a constant problem for equipment and engine operators, making it difficult to pinpoint the source or cause of contaminated diesel fuels.
Rarely is it known exactly where fuel has been passed through before making it to you, leaving the likelihood of receiving contaminated fuel to chance.
Water Contamination
Water in diesel fuel is one of the most troubling types of contaminants, and also one of the toughest to combat in large bulk fuel tanks.
Since fuel is often kept, transferred, and purchased out-of-sight, contamination and build-up of water in diesel fuel can be extremely difficult to spot, unless it is properly tested for.
Water can enter the fuel in a number of different ways.
Diesel fuel is a hygroscopic fluid, meaning that it is able to absorb moisture from the air around it. This can become a problem in fuel tanks where full capacity is not maintained for extended periods of time.
By allowing the fuel in a storage tank to have more air overhead to pull water from, emulsified water can develop and become mixed with the fuel in suspension.
Combined with water from condensation, this results in an unfavorable ratio of fuel to water, which can result in contaminated fuel being introduced into the engine or equipment it is being supplied to.
In some cases, water contamination can cause fuel injector tips to explode, should the water make it through the fuel filter and into the engine.
As a potentially catastrophic contaminant, excessive levels of water in fuel can reduce engine performance because of the reduction of energy available within the fuel.
Not only this, but water in fuel can increase the temperature the fuel will freeze at within engine components. This can be especially problematic in cold climates where fuel gelling is already a concern.
Another type of water contaminant is free water. Free water develops as a layer beneath stored fuel after phase separation occurs.
With the presence of free water in a fuel storage tank comes the possible proliferation of microbial growth within the fuel.
When the presence of free water is ignored, microbial proliferation will occur in the layer where the water meets the fuel. Hydrocarbons in fuel provide food and energy for the “diesel bug” (that is often referred to as “algae”) to rapidly spread.
Once microbial growth exists in a fuel tank, sludge develops as a waste byproduct of the hydrocarbons being consumed by the microbes.
Fuel indeed “goes bad” over extended periods of time in storage.
Many people aren’t aware that diesel fuel has a shelf life, however fuel stability is important to the mechanical operability of your engine.
Good fuel samples are typically bright in color and clear. Degrading fuel samples can often be determined visually, with fuel turning dark and murky because of the development of tar and asphaltenes within the fuel.
High sulfur diesel shelf life recommendations are less than a year, while ULSD and biodiesel blends have an even further reduced long-term stability.
When fuel loses stability during degradation, the gums and waxes that develop can contribute to corrosion and damaging deposits on engine components.
Many automotive mechanics will first flush fuel lines and replace the fuel if a troubled vehicle was known to be sitting for even a few months.
With most engines designed to be in frequent use, such as fleet vehicles, fuel stability isn’t something most consumers have at the top of mind.
If you have fuel that is going to be sitting for extended periods of time, such as bulk fuel storage for a fleet or on-site fuel storage for backup generators, equipment managers should be aware of fuel stability timelines.
Diesel fuel composition can begin to change within a month of sitting in storage, with recommended maximum storage timelines without significant degradation of six months to one year.
However, these recommendations are contingent on the fuel being purchased from suppliers and stored in tanks with the appropriate cleanliness and quality standards.
To properly store fuel (especially in large amounts) for extended periods of time, fuel should be polished to maintain optimum fuel quality that is ready for use at any moment.
How to Test for Fuel Contamination
Fuel Testing Tools
To be proactive and catch fuel contamination early, fuel should be sampled and tested from a bulk fuel storage tank at least once every six months. Testing for different contaminants can be achieved in a number of ways, here are the most common tools for fuel sampling and testing:
Fluid sampling pumps are often used to obtain fluid samples from hard-to-reach spots using flexible tubing. This allows for fluids to be drawn without the worry of cross-contamination, as the fluid never comes into contact with 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 admits a sample into the unit. To sample from any desired level in the tank, the plunger can be actuated by a pull-chain attached to the device.
Once fluid samples are obtained, they must be sent to a lab for testing. Getting results from the lab could take days, up to waiting periods of weeks.
For quicker results, Kolor Kut ® Water Finding Paste is a product used to instantly report if there is a presence of water in petroleum fluids such as gasoline, kerosene, diesel, and heavy fuel oil. The paste is applied to a rod and dipped into the tank, with the color of the paste changing instantly upon contact with water.
FUELSTAT ® PLUS is a simple fuel testing kit that provides results in less than 10 minutes. 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.
Liqui-Cult Microbial Test Kits accurately detects and quantifies bacterial and fungal growth in a variety of fluids. Liqui-Cult tests for microbial growth in fuel samples over a period of a few days.
Through frequent fuel testing, the presence of contamination can be determined and action plans can begin to be determined. Depending on the scope of contamination levels and volume of fuel contaminated, some solutions may be more practical to implement than others.
Solutions to Fuel Contamination
What is Fuel Polishing?
Fuel polishing is a fuel filtration technique used across many industries to increase and maintain fuel quality in stored fuel. Through these fuel filtration systems, various forms of contamination are removed and prevented.
Mobile Fuel Polishing
These polishing systems can be mobile units built onto carts or skids, or these systems can be mounted (sometimes in an enclosure) that is plumbed into the bulk fuel storage tank.
The mobile polishing systems are advantageous when having to maintain a number of different fuel tanks without having to incur the financial cost of installing multiple fixed systems. Mobile systems come in a number of different sizes and flow rates, and we recommend you visit our Mobile Fuel Polishing page to view the different systems that are available.
Mobile fuel polishing may seem like the perfect solution especially if you have multiple tanks, however that is not always the case.
As these units are not fixed onto the fuel storage tank, these systems must be hauled out on a scheduled basis to maintain fuel cleanliness. The problem arises not when fuel is cleaned to the desired fuel cleanliness standard, but rather when fuel is again left to sit untreated.
This causes the fuel to fall back out of the desired cleanliness specifications where it must be polished again. This creates a cycle, which is illustrated below, that gives chance that the fuel fails to maintain the quality requirements if stringent polishing cycles are not maintained.
Now, you can see where this fuel polishing cycle could turn into something that proves to be quite taxing, especially in situations where multiple fuel tanks on a specific site need to be treated on a regular basis.
Automated Fuel Polishing
Automated fuel polishing systems can be beneficial to fuel storage in facilities where frequent access for mobile polishing isn’t preferred or practical.
Our Automated Fuel Maintenance and Enclosed Fuel Maintenance systems are engineered to allow for the scheduling of periodic fuel polishing so that fuel is constantly being cycled and polished. This eliminates the concern for fuel to fall out of the desired fuel cleanliness and quality standard.
For facilities that are reliant on backup power systems, this is immensely important. Mission-critical facilities, such as hospitals and data centers, cannot risk electrical downtime in the event of a power outage.
With these facilities having large volumes of stored fuel to power the backup generators, it is important that fuel quality is maintained to ensure quality fuel is delivered to the backup power system at a moment’s notice. Any fuel quality issues could render the backup generator inoperable, putting critical systems at risk.
Levels of Fuel Filtration
Fuel polishing systems have a number of components necessary to ensure that fuel is being cleaned and contamination is removed in an appropriate manner.
Micron filtration removes clumps of fuel and other particulate that could harm equipment. By passing fuel through micron filters, contaminants such as dirt, grime, and sludge can be caught by the filter and removed from the fuel.
With water separation, free water is captured and removed from the fuel to prevent the proliferation of microbial growth. By capturing the water, fuel polishing systems effectively remove the conditions to which “the diesel bug” thrive.
Not only that, but by removing the water from the fuel it keeps the engine and fuel injection system from receiving water that could pose harm to the integrity of the equipment.
AXI International’s LG-X Inline Magnetic Fuel Conditioners are a proprietary part of our fuel polishing systems that use a magnetic field to achieve a number of things.
Through running fuel through the magnetic chamber, metallic particles and fragments are captured and thus prevented from making their way into critical engine components. These metals could be comprised of various ferrous metals or even rust.
Rust is typically a sign of the presence of water within a fuel tank. Rust can only develop where there is water, and if fuel was previously clean but rust was found during the polishing cycle of a fuel tank, chances are that there is water present as well.
The magnetic field is also responsible for breaking down clumps of diesel fuel known as agglomeration where the fuel molecules in diesel fuel, over time, naturally pull together creating thick clumps of fuel. By passing these clumps through a magnetic field, the intermolecular bonds are weakened, allowing clusters to fall apart and return to a more fluid-like state.
Fuel Additives
Fuel additives can also prove to be beneficial for those concerned with fuel contamination issues. However, with such a wide variety available on the market, it could be hard to decide which additive is best suited for your unique needs.
Fuel stabilizers as a fuel additive work in a manner that prolongs the stability of fuel in storage. These fuel stabilizers are often used in circumstances where fuel is expected to sit for an extended period of time without any fuel maintenance.
By dosing the fuel tank appropriately, this fuel additive prevents fuel from oxidizing and experiencing a chemical breakdown.
Combustion catalysts can be used to not only enhance engine performance, but also provide for a more complete burn of fuel being supplied to the combusting cylinder, which results in reduced carbon deposits. This, in turn, reduces engine emissions as less unburnt fuel is released from the exhaust system.
By increasing power output, combustion catalysts can often result in a healthier engine response.
Corrosion inhibitors in certain fuel additives prevent corrosion on metal surfaces, which prolong engine life and equipment operability. This reduces the amount of “surprise” equipment maintenance that is needed due to the failure of certain parts within an engine’s mechanical system.
The corrosion inhibitor is comprised of compounds that attach to component surfaces and form a film that acts as a lubricant which reduces engine wear and extends the lifetime of mechanical components.
We recommend AFC Fuel Additives as the go-to fuel additive to add to your fuel maintenance schedule. As the only fuel additive offering all of these features and benefits within a single formula, AFC Fuel Additive is the smart choice for your equipment. With a concentrated formula, just eight ounces of AFC Fuel Additive is able to treat 320 gallons of fuel. AFC is also available in 1 Gallon (treats 5,000 gallons), 5 Gallon (treats 25,000 gallons), and 55 Gallon (treats 275,000 gallons) quantities.
Summary
Through gaining an understanding of what diesel fuel contamination is, what causes it, how to test for it, and how to treat and prevent it, we hope to give you greater in-depth knowledge on just how critical your fuel quality is.
From lawnmowers to tractor trailers, fuel quality is something that affects everyone logistically- for it could be the reasons behind your car not running and your generator failing. Sometimes, the application is small, and fuel is simply replaced before damage is done and you are on your way again.
But, in many cases, this can be a costly solution especially when there are thousands of gallons of fuel at risk. And in the worst-case scenario, this fuel can not only be contaminated, but also further contaminate and cause detrimental mechanical issues within the equipment the fuel was being supplied to.
Engines and equipment rely on quality fuel to operate as designed, and when that standard of fuel isn’t being supplied (which is often the case), gradual wear and breakdown of components could lead to costly repairs, particularly in and around the fuel injection system.
To ensure fuel quality and mitigate the effects of contamination, it is recommended to instill fuel maintenance systems and procedures. At the general consumer level, this could mean using a fuel additive when you fuel up your vehicle. At the business operational level, this could mean installing automated fuel management systems to polish bulk fuel and prevent contamination from proliferating.
Addressing "Algae" in Diesel Fuel
There is nothing worse than opening your tank to discover your diesel fuel is contaminated with “algae“. If this fuel were ever to be used, it could wreak havoc on your fuel filters and consequentially your engine.
In acknowledging this, you may be asking yourself, "how do I get rid of this “algae” and prevent it for good?"
Luckily, we have some answers to those very questions. In this article, we’ll explain what the “algae” really is, where it comes from, common methods to combat it, and best practices to keep it at bay.
Understanding the "Algae" Problem
In order to properly address this fuel contamination issue, we must first understand what it is we are trying to combat and where it is that it comes from.
A Common Misnomer
For decades, it has been a common misconception that the dark sludge forming in your fuel tank is actually “algae”. As a result, many still refer to it as such today. In reality, what you are actually witnessing is an over-proliferation of microbes in the fuel.
How do we know this?
For starters, your fuel tank is far too dark to harbor any known species of algae. These plant organisms need sufficient sunlight to survive.
The problem of microbial contamination originates when water present in the diesel separates into a distinct layer below the fuel. This is commonly referred to as "phase separation". At this point in the process, you may begin to notice a dark layer forming in the fuel.
Another term often used to refer to this form of fuel contamination is the “diesel bug”.
The interface between the diesel fuel and the water creates the perfect breeding ground for various bacteria and fungi to thrive. The microbes will live and proliferate in the water while consuming the hydrocarbons from the diesel fuel above.
In time, the accumulation of microbes will form visible biomass (rag layer) between the water and diesel fuel. By-products and dead cells from the growing microbial communities also fall towards the bottom of the tank to create a viscous sludge.
The Effects of Microbial Growth
When churned up, the sludge by-product of microbial contamination can clog any engine filter with ease.
A clogged engine filter, especially one clogged at a time of importance, can cause serious problems.
For example, data centers relying on diesel generators for backup power may experience unexpected downtime due to clogged filters. This can result in costs of hundreds to tens of thousands of dollars a minute while unplanned maintenance is being carried out.
On a smaller scale, clogged filters on many marine vessels such as boats and yachts can often leave their operators stranded on the water.
“The diesel bug may start on a microscopic level, but it is clear it can lead to macroscopic consequences.”
Common Solutions for the "Diesel Bug"
There are a lot of opinions on how to best prevent “algae”/microbial proliferation in the fuel.
Some will push for the use of biocides which use hazardous chemicals to kill the microbes directly.
Others prefer fuel additives designed to prevent phase separation from happening.
At AXI International, we understand that neither of these solutions is perfect, but recognize they embody two valid methodologies for controlling microbial growth in diesel fuel.
You can either kill them directly or prevent the very conditions they need to thrive.
Biocides
Although initially effective, biocides are not the end-all solution to microbial growth and sludge formation.
Placing health, safety, and environmental concerns aside, frequent use of biocides can create resistant microbes that no longer die upon application.
This is due to the fact that it is nearly impossible to completely sterilize diesel fuel. As a result, the surviving microbes, through means of natural selection, will exhibit increasingly resistant traits that eventually render the biocides ineffective.
Best Practices for Microbial Contamination
If microbial growth has progressed to a point that it is noticeable, no treatment already mentioned will effectively remove or break up the sludge already formed in the tank.
Removing Microbial Sludge
In order to remove sludge from the fuel, you will have to employ the use of a mobile fuel polishing service or system.
These systems are designed to effectively remove both large and small contaminants like particulates and sludge while also helping to prevent future microbial contamination through the removal of water.
Unfortunately, a single fuel polishing serve will not prevent microbial growth indefinitely. Water will find its way back into the tank through means of refueling and condensation formation. If fuel polishing is your preferred method of prevention, prepare to schedule multiple servicings throughout the year.
Preventing Microbial Growth
In some cases, fuel additives that pull water up into the fuel by means of an emulsifier can be an appropriate response to stifle microbial growth.
The additives work by addressing the problem at its source. Without phase-separated water, microbes cannot over-proliferate in the fuel.
In time, the emulsified water can exit the fuel tank as it is fed into the engine alongside the fuel and vaporized out the exhaust.
Preventative Solutions for Tier-4 Engines
For applications involving Tier-4 compliant engines, water emulsifiers are not a recommended solution as they will only create additional problems. This is because Tier 4 engines have a High-Pressure Common Rail (HPCR) system that feeds the fuel into the combustion chamber at extremely high pressures with very little tolerance for anything other than the fuel itself.
Emulsified water, being much larger than the 2-4 micron injector openings, can cause abrasive wear and eventual failure of the injector tips. Due to this reality, Tier 4 engines require a much more technical solution.
For Tier-4 engines, automated fuel maintenance systems are the best approach to prevent “algae”/microbial growth in diesel fuel. Fuel maintenance systems are permanent installations that work on a programmed schedule to regularly pull fuel from the tank to filter out contaminants.
Unlike fuel polishing systems, fuel maintenance systems are better at maintaining the fuel as opposed to reactively restoring it from a highly contaminated state.
By the same effect of fuel polishing systems, fuel maintenance systems prevent “algae“/microbial growth through the removal of water.
Ultra Low Sulfur Diesel (ULSD): the Good, the Bad, and the Rusty
You have probably heard mixed reviews about Ultra Low Sulfur Diesel (ULSD). Some say it is great for the environment while others claim it causes more problems than it solves. If you are looking for an unbiased take on the ins and outs of ultra-low sulfur diesel, you are in the right place.
Below we cover why ultra-low sulfur diesel exists, its benefits and disadvantages vs. traditional diesel, and what you can do to protect your vehicle or equipment from any negative side-effects of ULSD.
Why Does Ultra Low Sulfur Diesel Exist?
In a nutshell, Ultra Low Sulfur Diesel (ULSD) was created in response to a number of regulatory actions aimed at reducing diesel fuel emissions.
Clean Air Act Amendment (1990):
In 1970, Congress passed the Clean Air Act as a means to reduce harmful emissions from automobiles. The Clean Air Act was later amended in 1990, requiring stricter emission reductions of hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter.
Concurrently, the EPA started imposing sulfur content limits on diesel fuel in an effort to help buses and trucks become compliant with other emission standards coming into effect that year.
In 2001, the EPA finalized a federally mandated program called the 2007 Heavy-Duty Highway Diesel Program. This program was established to further decrease emissions by enabling the use of advanced emission control technologies for new highway diesel engines. Although effective, these technologies were found to be easily damaged by sulfur, requiring serious sulfur reductions in diesel fuel in order for them to be used. Effective June 2006, the maximum sulfur limit in diesel was slashed from 500 to 15 parts per million (ppm).
This reduction officially marked the switch from low sulfur diesel (500 ppm) to ultra-low sulfur diesel (15 ppm).
Clean Air Off-Road Diesel Rule (2004):
Shortly after the highway diesel program’s inception, the EPA issued the Clean Air Non-Road Diesel – Tier 4 Final Rule. This rule mandated sulfur reductions for off-road diesel engines, effective 2007.
As a result, the maximum sulfur limit in off-road diesel fuel dropped from 3,000 to 500 ppm in 2007 and later 500 to 15 ppm in 2010.
The Pros & Cons of Ultra Low Sulfur Diesel
The intended effect of lowering sulfur content in diesel fuel has led to many positives that can be derived from the large reductions in harmful emissions. Unfortunately, to achieve reduced sulfur levels, the fuel must first be processed. This processing has led to some less than desirable side effects due to the changes it makes to the fuel’s chemistry. Whether the benefit of reducing emissions outweighs the negative side effects of ultra-low sulfur diesel is a judgment we will leave for you to make.
The Good: Emission Reductions
Since the 90s, EPA mandates have resulted in a 99.7% reduction of sulfur content in diesel fuel. This reduction is directly responsible for a decrease in sulfur dioxide (SO2) emissions which, alone, have been a major contributor to serious health and environmental issues.
Health concerns related to sulfur dioxide (SO2) exposure include respiratory problems and lung damage. Tree, plant, and stone damage, acid rain, and haze are some of the environmental effects of sulfur dioxide (SO2) emissions.
Sulfur reduction in diesel fuel has also enabled the use of advanced emission control devices in modern diesel engines. These devices have been able to reduce nitrogen oxide and particulate matter emissions by 90% and 95% respectively. Nitrogen oxide and particulate matter have both been found to contribute to serious health problems such as premature mortality, aggravation of respiratory and cardiovascular disease, aggravation of existing asthma, acute respiratory symptoms, chronic bronchitis, and decreased lung function. In addition to these issues, NOx and particulate matter emissions are suspected to be carcinogenic and contribute to the development of lung cancer.
In 2004, it was estimated that heavy-duty trucks and buses were responsible for about 1/3 of all nitrogen oxide and particulate matter emissions. By reducing emissions from these popular modes of transport, it can become apparently clear that the benefits of ultra-low sulfur diesel lie in the betterment of both public health and the surrounding environment.
The Bad: Changes in Fuel Chemistry
Removing sulfur contents from diesel fuel has been shown to greatly alter the lubricity and overall chemical composition of the fuel. Refineries use severe hydrotreating to remove sulfur. This is a process that also happens to decrease diesel’s natural lubricity, lower energy density (fuel economy), and increases overall production costs.
While hydrotreating does increase the fuel’s cetane level, most of the side effects of hydrotreating are less than desirable. The fuel economy of ultra-low sulfur diesel is estimated to decrease by 1% and, according to the EPA, severe hydrotreating also increases fuel production costs by 5 to 7 cents per gallon. However, these costs may be significantly higher depending on the market, distribution, and other production factors. Lower fuel lubricity is known to contribute to increased engine wear which can also increase maintenance and repair costs for equipment that consume ultra-low sulfur diesel.
The Rusty: Corrosive Effects of ULSD
In 2007, pollution awareness and prevention were on the rise as emission mandates came into full effect. Since then, tank corrosion has hit an all-time high for both gasoline and diesel storage. A recent study suggests this may be symptomatic of fuel tankers participating in switch loading where tanker trucks might transport ethanol-based gasoline one day only to haul ultra-low sulfur diesel the next.
Alone, ultra-low sulfur diesel has a higher affinity to water than traditional diesel. Water is known to be one of the main contributors to tank corrosion while also fostering rapid microbial growth in diesel. It has been shown that mixing ULSD with small amounts of biofuel, such as ethanol, may accelerate tank corrosion. This is due to the microbes in the diesel fuel digesting trace amounts of ethanol, creating high-enough levels of acetic acid to cause significant corrosion of the surrounding tank.
In conclusion, the benefits of ultra-low sulfur diesel are undeniably noble but, as with many significant changes, there will always be trade-offs to consider.
Fortunately, there are a number of products and technologies created to help mitigate the undesirable side effects of ULSD.
Preventing Problems Caused by ULSD
There may be several issues created from the processing of Ultra Low Sulfur Diesel (ULSD) but almost none of them are unable to be addressed through the adoption of new fuel technologies and products.
Addressing Reduced Lubricity & Fuel Economy
As previously mentioned, hydrotreating diesel fuel to remove sulfur does reduce overall lubricity and energy density (fuel economy). To effectively address these problems, one can adopt a fuel additive, possibly addressing both issues with a single bottle. Using a fuel additive does require the individual to regularly dose their fuel supply upon fill-up, but the benefit they receive from doing may exceed that of simply restoring what was lost during the hydrotreating process.
Much like the supplement industry, there is no shortage of fuel additive offerings on the market. Some of these options work quite effectively while others are simply well-marketed “snake oil”. When looking to adopt a fuel additive we strongly encourage you do your own research before putting your hard earn dollars to the test.
AXI International provides a line of broad-spectrum fuel additives, all of which feature a broad set of benefits in addition to increasing fuel lubricity and improving fuel economy. In many cases, it has been shown that our AFC fuel additives have more than paid for themselves with fuel efficiency gains alone. This is mainly achieved with a fuel catalyst which enables a more complete combustion of the fuel, burning more fuel for power in the engine and sending less unburnt fuel out the exhaust. To learn more about our fuel additives click here. If you would like to discuss our additive offerings with one of our experts, fill out the form here.
Preventing Corrosion & Unplanned Downtime
Accelerated tank corrosion is no doubt a serious issue, especially for companies storing large volumes of Ultra Low Sulfur Diesel (ULSD) for backup power applications. ULSD’s high affinity to water and the practice of fuel switching are two factors contributing to this alarming problem. Luckily, there is a solution to this in the form of regular fuel filtration.
Water in diesel fuel has long been an issue leading to tank corrosion and rampant microbial growth (“the diesel bug”).
When microbes proliferate in the fuel, they begin to produce a sludge byproduct that prematurely clogs onboard filters of connected equipment like backup power generators. The clogging of these filters can lead to unplanned maintenance and downtime, a serious issue for mission-critical facilities. In addition to producing sludge, these microbes will break down trace amounts of biofuels, producing acetic acid. This acid, alongside water, contributes to accelerated tank corrosion.
By regularly filtering water out of the fuel, one can prevent accelerated tank corrosion from occurring. Without water, microbial contamination cannot occur, and without microbial contamination, acetic acid cannot be produced from the trace amounts of biofuel often found in ultra-low sulfur diesel.
So one may ask, how is it that water continually finds its way into the fuel and how do I regularly filter water out of the fuel?
To answer the first question, water is always present in fuel to some degree. This presence is usually higher in ultra-low sulfur diesel and biofuels due to their chemistry. Through tank condensation, water is continually reintroduced into the fuel supply as warm days turn into cooler nights. To answer the second question, you generally have two options to filter contaminants, such as water, out of your fuel supply:
Option #1: Periodic Fuel Polishing
One can purchase a mobile fuel polishing cart or hire a service to bring specialized equipment to filter your fuel supply. This service is usually done in a reactive manner as regular fuel testing is carried out to detect if water or microbial contaminants have reached a certain level to justify the servicing.
Although effective, this option is not recommended for mission-critical and backup power applications due to its reactive nature. A lapse in fuel testing or filtration can easily lead to fuel contamination issues outside of tank corrosion such as sludge and particulate accumulation.
Option #2: Automated Fuel Filtration
One can also purchase and install a fuel maintenance system to automatically filter the attached fuel supply on a scheduled basis.
This option requires minimal involvement outside of periodic filter changes on the installed fuel filtration system. Regular fuel filtration is considered a best practice as it ensures the fuel remains free of water and other damaging contaminants, protecting your tank and the attached equipment from the shortcomings of ultra low sulfur diesel and newer biofuels.
EPA Tier 4 Engine Emissions Standards Explained
Engine emissions and the concerns around the potential harmful effects on people and the environment has been a growing conversation over the last few decades.
With a focus on these harmful emissions, the Environmental Protection Agency (EPA) has since implemented regulations to reduce various kinds of harmful exhaust emissions in both on-road and nonroad (or off-road) engines.
These regulations were aimed to improve the efficiency of a diverse range of equipment including generators and gensets, forklifts, tractors as well as other types of construction, agricultural, and industrial equipment.
By introducing these regulations through phases, the EPA was able to give engine manufacturers, engineers, and the market itself the time required to develop the necessary technologies to meet future compliance.
Air Quality & Public Concern
Before the EPA introduced the tiered emissions standards, the Clean Air Act set air quality standards in the United States. The EPA Tier standards simply expanded on these regulations with an aggressive focus on non-road diesel engines.
Through the 50s and 60s, the health impact of smog was of rapidly increasing interest to the general public as they gained publicity across the nation.
With a majority of urban-metropolitan areas (such as New York City and Los Angeles) across the United States being impacted by lingering smog from various mechanical & industrial emissions.
Enacted in 1963, the Clean Air Act is seen as one of the most stringent air quality regulations around the globe.
As science and public knowledge has grown through the following decades, the Clean Air Act has been amended accordingly, with the latest amendment being passed in 1990.
The Clean Air Act is divided into the following six titles: Title I: Programs and Actives, Title II: Emissions Standards for Moving Sources, Title III: General Provisions, Title IV: Noise Pollution and Acid Deposition Control, Title V: Permits, and Title VI: Stratospheric Ozone Protection.
An exemption was included in the Clean Air Act allowing California to set their own emissions limits. By establishing the California Air Resources Board, the State of California was able to make their restrictions even more strict than the federally recognized EPA standards.
The EPA may also approve other states to opt into the California Air Resources Board standards.
Tier 1 - Tier 3 Emissions Standards
Introduced in 1991, because of the growing public concerns for harmful exhaust pollution, the EPA published Tier 1 standards to reduce engine emissions and was then phased in through the late 1990’s.
These regulations increased federal authority and furthered the government’s responsibility by allowing them the power to issue and deny operating permits on regulated equipment.
Adopted in 1999, Tier 2 standards specifically addressed pollution, with a focus on nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), and non-methane hydrocarbons (NMHC). Tier 2 standards covered all engines under 37kW from 2001 to 2005.
Between 2006 and 2008, Tier 3 standards were implemented, restricting exhaust emissions for engines between 50 and 750 horsepower. Through 2010, highway engines would be required to have advanced exhaust treatment systems to reduce harmful emissions.
The EPA finalized a new emissions standard for automobiles and gasoline fuels in March of 2014 under Tier 3. These standards are currently being phased-in from 2017 and will be completely implemented in 2025.
Tier 4 Emissions Standards
Tier 4 is the most recent engine emissions standard implemented by the EPA. Signed in 2004, these emissions standards Tier 4 emissions standards were phased-in from 2008 to 2015.
The goal in Tier 4 was to significantly reduce NOx and PM emissions, while CO emissions limits remained the same from Tier 3.
Tier 4 also brought a new ultra-low sulfur diesel fuel to achieve emissions targets. As we’ve grown familiar with ULSD through its expanding use, we also now understand all the pros and cons of ULSD.
These recent tier 4 standards also brought forward heightened standards in advanced engine technologies and exhaust gas after-treatment systems.
The estimated costs of adding the emissions equipment ranged between 1-3% of the total equipment price. The EPA suggested that the efficiency savings alone would dwarf the additional costs of the equipment.
Engine & Exhaust Design Improvements
To achieve these various advancements in mechanical efficiency, various components within combustion engines themselves had to be redesigned and engineered to operate and function with federal standards in mind.
Engines at their core had to be redesigned to operate on finer tolerances than ever before. Engine design technologies were advanced, with fuel injection timing being improved to limit NOx and PM emissions.
Exhaust gas recirculation systems were also developed to reduce NOx emissions.
Engine manufacturers used intake manifold boosting to achieve PM reductions, as well as intake temperature management technologies to aid in limiting emissions.
To further control PM emissions, combustion chamber design was innovated upon. Beyond just engine design improvements, engine manufacturers also improved the fuel systems.
Lubricating oil was used to reduce overall fuel consumption and alternative fuels were introduced that engine manufacturers could adopt to reduce carbon dioxide emissions.
Exhaust systems were a priority target for these EPA emissions standards, and manufacturers had to introduce new technologies to help combat harmful emissions. Selective Catalytic Reduction (SCR) was introduced into the exhaust systems to reduce NOx levels.
Diesel Particulate Filters (DPF) were developed to capture PM and significantly reduce emissions. Although successful in reducing harmful emissions, with time the faults in DPF systems began gaining national attention.
Exhaust Gas Recirculation (EGR) systems were also developed, and Diesel Oxidation Catalysts (DOC) became a standard to enhance exhaust after-treatment system performance and reduce heightened levels of harmful emissions such as NMHC and CO.
These design improvements also included standards for smoke opacity, ammonia emissions, emergency operation, DEF refill intervals, and crankcase ventilation.
Because of the increased regulations and standards, engine manufacturers were able to design and develop technologies that reduce the negative impact of harmful emissions on people and the environment.
What's Next for the EPA? Tier 5?
As of the writing of this article, the EPA hasn’t put forth any future changes in emissions standards beyond what’s known as Tier 4 standards.
Hobbyists are doing this for performance improvements to either increase power or towing capacity through removing restrictive systems. Through various enforcement actions, the EPA has addressed violations by a number of diesel mechanic shops.
This work is often done under the understanding that it is for nonroad use only, which could be seen as a loophole by many.
However, the EPA has recently exercised efforts to enforce action against these companies as they believe it violates federal provisions that exist to protect the public health.
According to the EPA, “Illegally-modified vehicles and engines contribute substantial excess pollution that harms public health and impedes efforts the EPA, tribes, states, and local agencies to plan and attain air quality standards”.
Moving forward, we can only assume that the EPA will continue to strive for advancements in both engine efficiency and emissions. But, with alternative energy sources becoming more feasible, the EPA's next round of serious regulations may not be directed to exclusively internal-combustion engines.
