Preserving the quality of stored diesel

Whether you use your diesel generator as a primary power source or rely on it for emergency back-up power it is essential that you have a supply of quality diesel ready to go. If stored well in optimum conditions, diesel can last between 6-12months.

Diesel fuel deteriorates for several reasons including oxidization, hydrolysis and through microbial growth. The hydrocarbons in diesel fuel react with oxygen inside your storage tank and the oxidized diesel can damage the engine of your generator as deposits are left throughout the fuel system, causing reduced atomization, power, and fuel starvation.

Ways to preserve the quality of stored diesel:

Antioxidants and stabilisers
To reduce oxidisation in stored diesel antioxidants and stabilizers can be added. The presence of free water in the tank can also accelerate the process of oxidisation.

Additives and separator filters
Diesel fuel additives are designed to remove water from the fuel, similarly a fuel/water filter can be used to separate the two.

Topping off the tank
Diesel attracts moisture so topping off a storage tank with enough space for fuel expansion can reduce condensation inside and lower the chance of water dripping back into the fuel.

Store in a cool, dry area
The higher the temperature in which diesel is stored, the faster the diesel will deteriorate, ideally it should be stored at less than 20°C.

Not too far below 20°C however
Between 0°C to -12°C the naturally occurring paraffin wax in the diesel fuel will start to solidify, at the colder end of the range the fuel will start gelling.

Biocides
Bacterial and fungal contamination of stored diesel is also known as ‘Diesel Bug’ and can be caused by the presence of water and oxygen in the tank. Biocides are designed to kill microbes present in the fuel.

Buy from a trusted supplier
Even fresh fuel can be affected so make sure you purchase from a reputable source and always look for fuel that is clear and free from particles.