With fuel costs skyrocketing, it is now more important than ever to vigilantly monitor the quality of your diesel fuel. There are several common diesel fuel issues that can significantly impact on the operation of your diesel engines if not caught early and remediated.
Diesel Fuel Quality Issues
The most common diesel fuel quality issues are water, wax deposits, particulates, and bacteria.
Water
Water in your diesel fuel can come from a variety of sources. Cold temperatures can play havoc with diesel fuel. During engine cooldown, dissolved water is released as droplets. This may or may not settle at the bottom of the fuel tank and requires monitoring and possibly daily draining to eliminate any negative effects. Warm or humid air encountering cold diesel fuel in storage will create condensation in a fuel storage tank. Flooding, while not an everyday occurrence, can significantly impact on equipment that have been trapped in flood waters.
Water in your diesel fuel can:
- Promote rust, corrosion, and sludge deposits in tanks.
- It can also accelerate bacteria and algae growth.
- Both issues can reduce fuel lubricity and fuel flow, clogging filters and fuel injectors.
Wax
Wax build up, or gelling, occurs when the paraffin wax in diesel fuel solidifies because of a drop in temperature. When cold soaked, the paraffin wax present in diesel solidifies, giving the fuel a cloudy appearance. The fuel can begin to cloud at temperatures as high as 32°F (O°C), but it will continue flowing. The fuel must stay very cold (below -10°F (-23°C)) for long periods (48-72 hours) before it will gel. The reason diesel fuel has a wax component is because it gives fuel a good cetane value for increased power and better engine responsiveness. Wax content is lower in winter fuels but is still present in diesel blends.
The effects of wax include:
- Disruption of fuel lubricity and flow
- Increased fuel filter consumption
- You can tighten fuel filter micron rating to extract gel from your fuel system. However, if the same filters from warm months are used during cold months, you may see an increase in filter consumption.
- Fuel injector damage
- Loosening the fuel filter micron rating will increase filter life but it can significantly increase the potential damage to injectors.
Particulates
Particulate contamination can enter your fuel system during delivery (when filling storage tanks) or when refiling your equipment. Fuel degradation due to oxidative breakdown can also cause particulate formation. This form of fuel degradation occurs when fuel is exposed to air and light (e.g., during tank ventilation or refueling). This results in the formation of particulates, water, and gum causing the fuel to become discolored.
The effects of particulate contamination include:
- Increased fuel filter consumption
- Increased levels of contamination will shorten the expected life of the fuel filter.
- Damage to injectors
- Suspended particles slowly abrade fuel injectors over time and alter spray patterns. Long time contamination can cause debris build up in injectors and reduce movement of the ball seat, nozzle, and electronic triggers.
- Promotes wear and bacteria growth
- Suspended particles promote internal wear of fuel system. Some contaminants will accelerate bacterial growth as well.
Bacteria
As noted above, the presence of water in your diesel fuel for extended periods of time results in bacteria and algae growth. Additionally, some contaminants and metals can act as a catalyst for bacterial growth in your fuel. Bacterial growth can also be impacted by climate – warmer and humid environments can accelerate bacterial growth.
The effects of bacteria contamination include:
- Fuel degradation
- As microbes attack fuel components, you can see changes in color, heat of combustion, pour point, cloud point, detergent, and anti-corrosive properties.
- Sludge formation
- The algae-like substance in which cells adhere to each other on the tank surface or at the fuel water interface. The sludge settles to the bottom of a fuel tank and can clog filters when the vehicle is fueled.
- Increased engine wear
- Flow restriction due to sludge can also affect piston and cylinder wear rates and even engine failure due to fuel starvation.
Monitoring Diesel Fuel
Diesel fuel should be regularly monitored for contamination and degradation. Routine testing can help to:
- Validate whether fuel is suitable for use prior to final use
- Optimize fuel economy by assuring consistent fuel quality
- Verify diesel fuel characteristics during delivery or storage
- Confirm that fuel meets cleanliness standards set by OEMs
- Validate whether fuel is suitable for use
- Ensure fuel is suitable for cold weather applications
- Troubleshoot fuel and performance issues
A variety of lab tests can be done to monitor diesel fuel quality such as:
- Water: Karl Fischer titration analysis
- Cleanliness: ISO Particle Count
- Gelling: Cloud Point
- Contaminants: Sulphur, Active Sulphur (copper corrosion)
- Grade: Cetane Index, Distillation, Density
- Other tests: Pour Point, Color/Appearance/Odor, etc.
Improving Quality
When looking to improve the quality of your diesel fuel management program, consider the following:
Current storage practices
- Are your storage tanks in a proper climate and environment?
- Do you have tools in place to prevent contamination (breathers, pre-filtration before dispensing, etc.)?
- Are your tanks in good condition (rust, paint, etc.)?
Fuel handling and dispensing process
- Does your fuel cart or mobile fuel unit have a filtration unit attached?
- Do you have a formal dispensing process in place to assure for contamination control?
- Do all of your technicians follow the same protocol?
Evaluating changes in fuel quality
- Send fuel samples off for analysis to verify quality of fuel at delivery and in storage.
- Analysis reports can also be used to measure success of newly implemented fuel quality processes.
With costs of fuel increasing due to multiple environmental, supply chain, and global issues, monitoring fuel quality across the entire fuel delivery chain is an important element of your maintenance program. Fluid Life offers a variety of diesel fuel test packages to suit a variety of needs. Talk to us about setting up a diesel fuel monitoring program that can help to mitigate potential issues and keep your costs down.