Fuel Tank Maintenance


What You Need to Know

Diesel generators are critical when it comes to keeping mission-critical facilities such as hospitals, data centers, and grocery stores powered. However, maintenance is key to ensuring consistently good performance. This article aims to help you understand why tank maintenance is required, and how to create an effective maintenance strategy.

There are two main enemies of diesel fuel: water vapor, and bacteria. Water vapor condenses in fuel tanks, which creates conditions for microbial growth. This can result in severe microbial contaminations of the fuel system, leading to costly repairs and downtime. Changes in fuel color are good indicators that the fuel has been contaminated. Negative effects of microbial growth in fuel tanks can include:

  • Reduced combustion efficiency
  • Elevated pour point and cloud point
  • Poor detergency
  • Increased corrosion of fuel components
  • Plugged fuel filters

Microbial contamination of fuel is caused by both bacteria and fungi, which need food and water to survive. In the case of the fuel tank, diesel is their food. Given the fact that oil and water do not mix, the best place for microorganisms to congregate is the fuel-water interface, which is typically formed at the bottom of the fuel tank. This is the first key to keeping fuel clean and microbe-free: the less water available, the less opportunity for fuel bugs to thrive.

The best way to keep fuel tanks clean is to avoid contamination in the first place. This prevention requires evaluation and control of:

  • Fuel monitoring program for microorganisms
  • Fuel system maintenance
  • Fuel treatment

Fuel Monitoring

Periodic sampling and testing of your fuel is important, since problems can be minimized by early detection. Be sure that your test lab follows procedures outlined in ASTM D-4057-81 and D-4177-82. When Clean Fuels tests your fuel, we use an independent third-party lab to ensure unbiased results!

Fuel Storage Maintenance

The most effective maintenance practice in storing diesel fuel is to minimize exposure to water. Procedures designed to minimize water accumulation include:

  • Fuel tank insulation (to stabilize fuel temperature)
  • Recycling of fuel through water separators
  • Routine discharge of water bottoms

In addition, sludge should be removed from fuel tanks on a regular basis, and periodic tank inspections and cleanings should be scheduled. Regular treatments with preventative doses of EAP approved diesel fuel biocides will help prolong the time interval between tank cleanings.

Fuel Treatment

These proactive maintenance steps may be insufficient to stop stored fuel from becoming heavily contaminated with microbial growth. At this stage, the fuel and water bottoms need treatment to control the infection. Removal of biomass from the system is also required.

Heavy microbial growth must be treated using a diesel fuel biocide at a shock level after fuel clarification and mechanical processing of the fuel, water bottoms, and sludge. This is known as fuel scrubbing and polishing.

Contaminated diesel fuel will need to be removed from the tank and dewatered, then clarified using filtration methods, then polished using a mixed media filtration system (sand or diatomaceous earth) with a fiber filter. The shock level of the diesel fuel biocide is then injected into the clean stream of the mechanically processed fuel.

The contaminated storage tank must be cleaned and sterilized before re-use. Any residual material (slime, sludge, bottoms, etc) must be removed. A visual inspection of the tank interiors and internal pipe fittings should be done to inspect for corrosion, proper function, and clean lines.

Proper and thorough fuel tank maintenance is crucial for trouble-free operation of the diesel engines fueled by these tanks. Contact Clean Fuels today to schedule an inspection of your generators’ tanks!