What is FAME?
Biodiesel is a diesel replacement fuel, which in the UK is manufactured from mostly recycled cooking oils but may also be made of a variety of blends of renewable and recyclable material including
tallow (animal) fats and plant oils. The biodiesel manufacturing process converts these oils and fats into long chain molecules. These molecules are also referred to as Fatty Acid Methyl Esters
and are more commonly referred to as “FAME”. FAME has been blended into UK road fuel since 2004 in levels up to 7%.
FAME is a powerful solvent, with good detergency properties – it is effectively a paint stripper! Unlike diesel, FAME is “hydroscopic” which means it attracts and holds onto water.
There is considerable experience within the automotive sector and oil industry regarding the use of FAME in diesel and much of this will have some relevance to SFGO. The main issues to be aware of include: -
- Material incompatibility (many common rubbers, plastics and surface coatings will degrade from contact with fuels containing FAME)
- Residual deposits causing clogged filters
- Water uptake - with enhanced potential for mould, bacteria and algae growth
- Fuel stability (may degrade over time by oxidation and hydrolysis)
- Cold flow waxing and precipitation problems
Ideally, before taking a delivery of any bio fuel, the tank should be cleaned internally with water and solid deposits or mould growth removed as efficiently as possible. This may require specialist tank cleaning service.
If time is limited and you are unable to undertake a full clean before receipt of the first delivery, then distributors should at least initiate an immediate initial check on the tank - checking condition and suitability.
This should include the construction material(s), age, condition and appearance of the tank, any damaged areas and surface coating(s). Any obvious deficiencies should be remedied.
There is a risk of microbial growth for all distillate fuels, but the biodegradable nature of biofuel blends is thought to heighten this risk. Therefore, more regular tank checks will be required, (due to FAME’s strong detergency, solvent and hydroscopic properties) compared with those of purely hydrocarbon fuels.
Tanks should be examined for signs of degradation in structure, material or coating. Prompt and appropriate removal or remedial action must be taken for any water, dirt, mould or growth present in the tank.
Note: tanks that don't already have drain points for removing water are likely to need modification. Examine sight gauges on older fuel storage tanks for signs of leakage and replace any leaking seals.
Filters should be examined at frequent intervals and fuel filters replaced after two or three deliveries.
Pipework, seals, pumps and other components must be checked continually for signs of actual, or potential, oil leaks and, if found, remedial work and/or material replacement undertaken immediately.
If you are having tanks serviced before you receive the new fuel it would be advisable to replace fuel seals as a one-off, precautionary exercise.
Most NRMM engines, maintained in compliance with manufacturer’s service guidelines, are fully compatible with fuel containing FAME in the proportion found in fuel. However, some fuel system components on older engines, including seals and pipes, may not be compatible.
Water is possibly the biggest problem with regards to SFGO containing biodiesel. Therefore, all effort must be done to safeguard any tanks or containers from water ingress by rain or moisture in the air as
well as regularly draining any water off. Additionally, keeping a tank brim-full ensures that there is little air left in a tank to draw moisture out of. Once in a fuel, water brings about increased corrosion of equipment and worse, allows bacteria to breed.
To reduce these risks, many industry webpages suggest that biodiesel (and therefore bio SFGO) has a limited shelf life and some suggest it is best to avoid storing FAME blends for more than six months.